LIFE SCIENCE

Match the part of the cell with its description:

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Answer the following question using a Punnett square.

Angelfish exist in a number of different colorations. Black angelfish have the genotype (DD), indicating that the black gene is dominant. If you breed a black angelfish (DD) with an angelfish with a recessive gold (gg) genotype, what will result?

Note: A Dg genotype will result in a hybrid genotype and produce a hybrid black angelfish that has a milky black coloration.

Black: ___%

Hybrid black: ___%

Gold: ___%

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A puppy has its mother’s brown eyes. The puppy’s eye color is an example of ____________.

1.—C. The nucleus is where the DNA of a cell is found.

2.—E. The mitochondria is the site of the cell where substances break down to obtain energy.

3.—F. Ribosomes are the part of the cell where the synthesis of protein takes place.

4.—B. The plasma membrane is the element that controls the transfer of material into and out of the cell.

5.—D. Centrioles are cell parts found only in animal cells.

6.—A. Vacuoles are cell parts found only in plant cells.

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Black: 0%

Hybrid black: 100%

Gold: 0%

The Punnett square shows that when crossing a black angelfish that has dominant black genes (DD) with an angelfish that has recessive gold genes (gg), all the offspring (100%) will be hybrid (Dg).

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The puppy’s eye color is an example of phenotype. Phenotype is the physical or behavioral expression of a gene (for example, eye color, hair color, and so on).

Yellow (r) is a recessive allele in plants. Red is dominant (R). Complete this Punnett square for a homozygous yellow plant crossed with a heterozygous red plant.

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With yellow (r) as a recessive allele in plants and red as a dominant (R), what would the percentage of each type be if a homozygous yellow plant is crossed with a heterozygous red plant?

____% of the offspring would be homozygous yellow (rr)

____% of the offspring would be heterozygous red (Rr)

____% of the offspring would be homozygous red (RR)

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Yellow (r) is a recessive allele in plants. Red is dominant (R). Complete this Punnett square to show what would result if two heterozygous red plants were bred.

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50% of the offspring would be homozygous yellow (rr)

50% of the offspring would be heterozygous red (Rr)

0% of the offspring would be homozygous red (RR)

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With yellow (r) as a recessive allele in plants and red as a dominant (R), what would the percentage of each of the following types be based on the crossing of two heterozygous plants?

____% of the offspring would be homozygous yellow (rr)

____% of the offspring would be heterozygous red (Rr)

____% of the offspring would be homozygous red (RR)

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After 10,000 years ___% of the C14 sample remains.

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25% of the offspring would be homozygous yellow (rr)

50% of the offspring would be heterozygous red (Rr)

25% of the offspring would be homozygous red (RR)

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After 10,000 years 30% of the sample remains.

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After 20,000 years ___% of the sample remains.

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After 25,000 years ___% of the sample remains.

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After 20,000 years 10% of the sample remains.

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After 25,000 years 5% of the sample remains.

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A scientist finds a fossilized bone that has about 25% of the natural amount of the C14 remaining. Using the chart, what is the approximate age of the bone?

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Which of the following statements explains how biogeography is evidence for evolution?

A. Offspring carry the traits of both parents.

B. Different species are not likely to interbreed.

C. The fossil record shows the sequence of evolution in layers of sediment.

D. Neighboring species in different habitats often can share a common ancestor.

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The bone is roughly 12,500 years old.

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Choice D explains how one species can diverge into two species over time when divided into two separate habitats. A classic example of this is the case of finches on the Galapagos Islands, where finch species diverged from a common ancestor to adapt to the unique habitats of each island.

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The peppered moth lives in the in the United Kingdom and has both light and dark variations. During the Industrial Revolution (1760–1840), many of the trees on which the moths lived became covered with dark soot. Over a period of just 50 years, the population of peppered moths in Manchester, England, changed so that dark moths made up almost the entire population. After the Clean Air Act of 1956, the air quality changed and dark moths became rare. This is an example of ____________.

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Speciation provides evidence for the theory of _________.

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The body systems work together to stay in equilibrium or homeostasis. Which of the following is an example of the body trying to maintain homeostasis?

A. weight gain

B. bruising

C. digestion

D. shivering

This is an example of natural selection.

According to natural selection, whether a given trait is advantageous depends on the environment of the organism. In this case, the moths that were better camouflaged (those that were the color of the soot-covered trees) survived and reproduced.

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Speciation provides evidence for the theory of evolution. Evolution is the gradual change of inherited characteristics in a population over time.

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Choice D, shivering, is an example of the body trying to maintain homeostasis. The body systems work with one another to maintain a state of balance or homeostasis (functioning within a normal range). For example, shivering (“goose bumps”) and sweating are your body’s response to being too cold or too hot. Your skin and spinal cord sense cold and send signals to the muscles to contract and shiver. In contrast, as your temperature rises the blood vessels in your skin get larger, called vasodilation, which allows for cooling of the blood. Sweat glands are activated when you are hot in an attempt to cool the body and return to homeostasis.

From a nutritional perspective, list four problem areas with this burger.

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Answers will vary.

This burger is high in calories, high in total fat, high in saturated fat, high in cholesterol, and high in sodium, and more than 50% of its calories are from fat.

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Consider that the recommended daily intake for a 30-year-old woman is about 1,800 calories. From a nutritional perspective, list at least two health complications that could result from regularly eating food with nutritional content like this burger.

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Answers will vary.

The problems that can result from a diet that contains many similar items are weight gain, heart disease, obesity, high blood pressure, and diabetes.

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Match each of the functions with its correct system.

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List the following parts from simple units to complex:

• organ

• tissue

• cell

• body system

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Which of the following is an example of the body trying to maintain homeostasis?

• bleeding

• thinking

• sweating

• digestion

• crying

• dreaming

1.— D. Movement is a function of the musculoskeletal system.

2.— F. Breathing is a function of the respiratory system.

3.— E. Metabolism is a function of the digestive system.

4.— A. Homeostasis is a function of the nervous system.

5.— C. Blood flow is a function of the circulatory system.

6.— B. Hormone regulation is a function of the endocrine system.

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1. cell

2. tissue

3. organ

4. body system

Cells are the smallest and simplest unit in an organism. Tissues are made up of cells (for example, muscle tissue is made of muscle cells). Organs are made of tissues (a heart is made of heart tissue), and finally, organs are organized into body systems (for example, the nervous system, the digestive system, and so on).

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Sweating is an example of the body trying to maintain homeostasis through evaporative cooling.

African oxpeckers feed on the insects that are on the backs of zebras and other large African animals. This is an example of which of the following symbiotic relationships?

• parasitism

• mutualism

• commensalism

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Lice feed on the skin and blood of the host. This is an example of which of the following symbiotic relationships?

• parasitism

• mutualism

• commensalism

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Some spiders build their webs on blades of grass. This is an example of which of the following symbiotic relationships?

• parasitism

• mutualism

• commensalism

This is an example of mutualism. Both oxpeckers and the zebras are benefiting, which describes a mutualistic relationship. Parasitism describes a relationship between two organisms where one benefits at the expense of the other. Commensalism describes a benefit for one organism and no harm or benefit to the other.

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This is an example of parasitism. Lice are benefiting, and the hosts are being deprived of blood and skin, clearly a parasitic relationship. Parasitism describes a relationship between two organisms where one benefits at the expense of the other. Commensalism describes a benefit for one organism and no harm or benefit to the other. Mutualism describes a relationship between two organisms where both organisms benefit.

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This is an example of commensalism. The spiders are using the grass as a place to build their webs, but there is no impact on the grass, positive or negative. Commensalism describes a benefit for one organism and no harm or benefit to the other. Parasitism describes a relationship between two organisms where one benefits at the expense of the other. Mutualism describes a relationship between two organisms where both organisms benefit.

The pea crab lives in the mantle cavity of mollusks, oysters, sea urchins, or sand dollars, using the host for oxygen, protection, and a source of food. These tiny crabs ingest food that is part of the host’s diet and often may feed on the mucous strings that help carry the food to the host’s mouth, damaging them. This is an example of ___________.

• parasitism

• commensalism

• mutualism

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Gymnosporangium is a genus of fungus that first grows on juniper trees and has its spores grow on fruit trees. As those spores grow on the fruit trees, they cause a loss in fruit production, damaging the reproduction of the trees. This is an example of ___________.

• parasitism

• commensalism

• mutualism

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Schistosoma is a genus of fluke or flatworm commonly known as a blood fluke. This flatworm lives within the blood vessels of humans and is the major cause of a group of infections known as schistosomiasis, which can lead to internal organ damage and infertility. This is an example of ___________.

• parasitism

• commensalism

• mutualism

This is an example of parasitism.

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This is an example of parasitism.

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This is an example of parasitism.

The Mountain Alcon Blue butterfly larvae release chemicals that confuse Myrmica schencki ants into believing that those larvae are queen ant larvae. The ants then bring the butterfly larvae into the ant brood and feed the butterflies preferentially over their own larvae as they think they will turn out to be queen ants. This is an example of ___________.

• parasitism

• commensalism

• mutualism

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The energy available in an ecosystem is greatest at which level?

A. producer

B. primary consumer

C. secondary consumer

D. tertiary consumer

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Of the following options, in what way do humans contribute to desertification most?

A. drought

B. overgrazing

C. acid rain

D. overhunting

This is an example of parasitism.

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The energy available in an ecosystem is greatest at choice A, the producer level. The energy available is greatest at the bottom of the energy pyramid (producer) and decreases as you move up the pyramid and the population numbers decrease. Plants are producers. Secondary consumers feed on primary consumers and are carnivores or omnivores. Humans are tertiary consumers because we consume primary and secondary consumers.

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Humans contribute to desertification most by choice B, overgrazing. Desertification occurs when an already dry land area becomes increasingly arid and dry. It is less able to support plants and animals. Humans contribute to desertification of ecosystems through deforestation (often using trees and other plant material for fuel or for construction materials), overgrazing, and poor farming practices; therefore this choice is the correct answer. Drought is a natural occurrence and does not (in and of itself) cause desertification unless it occurs in the extreme. Acid rain does not contribute to drought. Overhunting can result in damage to the ecosystem, but is not the best answer.

Harmful algal blooms are naturally occurring events, but they appear to be increasing in intensity and frequency. Blooms occur when environmental conditions change to be more favorable to increased algae growth. Nutrients such as phosphates (phosphorus) and nitrogen (found in fertilizer and animal waste products) encourage the growth of algae.

What are some human practices that could be contributing to the increase in harmful algal blooms?

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Which of the following conclusions can be supported by the graph?

A. Parasitic mites caused the decline in bee populations.

B. Bee populations will become extinct because of parasitic mites.

C. Parasitic mites may have contributed to a decline in bee populations.

D. Bee populations increased until the introduction of parasitic mites.

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Answer will vary. Here is an example.

Since algae like nitrates and phosphates, which are found in fertilizer and animal waste products, farming practices and fertilizer use can be contributing to increases in algae blooms. Runoff from farms (especially animal farms) near waterways or watersheds can result in wastes and fertilizers flowing into the ocean and other bodies of water during storms. Similar results can occur with fertilizer use.

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The correct answer is choice C. The introduction of parasitic mites is not the only cause; however, it may have contributed to the decline in bee populations. Bee populations were in decline prior to the introduction of mites in 1983. Although there is a downward trend in bee populations, there is no way to conclude that bees will become extinct. Bee populations were decreasing before mites were introduced.

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Tapeworms are segmented flatworms that attach themselves to the insides of the intestines of host animals such as cows, pigs, and humans. They survive by eating the host’s partly digested food, depriving the host of nutrients.

This is an example of which kind of relationship?

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The plasma membrane of a cell regulates transport of materials. Osmosis occurs when molecules inside a cell are highly concentrated and are forced to move through the membrane to an area of lower concentration. What is the word for this pressure that pushes these molecules?

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When osmosis occurs in a cell, where molecules move from where they are highly concentrated through the cell membrane to where they are less concentrated, what is the word for these concentration levels being the same?

This is an example of parasitism. A parasite species benefits at the expense of another species.

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This is called osmotic pressure. If the word osmosis is in the description, it is possible to see the relationship with the word osmotic. This type of pressure forces osmosis to happen.

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The word for the same concentration of molecules on both sides of a cell membrane is equilibrium.

In the diagram, in what direction would the sugar molecules move in this container through osmosis?

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Of the items listed here, which are specific to a plant cell?

• nucleus

• chloroplast

• cytoplasm

• cell wall

• mitochondria

• ribosomes

• vacuoles

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Cells in a multicellular organism have specific purposes. Blood is composed of plasma as well as red and white blood cells. One of these cells carries oxygen throughout the body, and the other fights pathogens as a part of the body’s immune system. Which does which?

The sugar molecules would move to the right in order to achieve equilibrium, as can be seen in the following illustration.

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Chloroplast, cell wall, and vacuoles are all specific to plant cells. The rest are all common to both animal and plant cells.

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Red blood cells carry oxygen and white blood cells fight pathogens.

What is the Golgi complex?

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Which of the following parts of a cell contains enzymes that help with intracellular digestion?

• Golgi complex

• endoplasmic reticulum

• lysosomes

• cytoplasm

• mitochondria

• nucleolus

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The genotype of an organism affects the phenotype of that same organism. Is each item in the list a genotype or a phenotype?

• recessive eye color genes

• blue eyes

• sex determination

• female

• curling tongue

• dominant hair color genes

The Golgi complex is a series of small sacs that synthesizes, packages, and secretes cellular products to the plasma membrane. Its function is directing the transport of material within the cell and exporting material out of the cell.

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Lysosomes contain enzymes that help with intracellular digestion. Lysosomes have a large presence in cells that actively engage in phagocytosis—the process by which cells consume large particles of food. White blood cells that often engulf and digest bacteria and cellular debris are abundant in lysosomes.

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recessive eye color genes—genotype

blue eyes—phenotype

sex determination—genotype

female—phenotype

curling tongue—phenotype

dominant hair color genes—genotype

Mitosis and meiosis are both forms of cellular reproduction. Mitosis is the splitting of a cell into two with all the same genetic information being reproduced in both new cells. Meiosis involves splitting of a cell and combining with another cell, with the genetic information being split in half and combined with the other cell.

Is each process in this list an example of mitosis or meiosis?

• skin regeneration

• blood production

• pollen production

• growth of a multicellular organism

• egg cell production

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The genotype of an organism affects the phenotype of that same organism. A Punnett square can be used to represent the possible ________ that offspring of parents with known ___________ could have.

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Human males have an X and a Y chromosome while human females have two X chromosomes. Since meiosis involves splitting up the genetic information in the sex cells, do the male’s or the female’s chromosomes determine the sex of a human offspring?

skin regeneration—mitosis

blood production—mitosis

pollen production—meiosis

growth of a multicellular organism—mitosis

egg cell production—meiosis

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A Punnett square can be used to represent the possible phenotypes that offspring of parents with known genotypes could have.

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The sex chromosome supplied by the male determines the sex of the human offspring.

In birds, males have a matched pair of sex chromosomes (WW), while females have an unmatched pair (WZ). In this case, do the male’s or the female’s chromosomes determine the sex of the bird offspring?

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Twins occur when either a fertilized cell splits or when two different egg cells are fertilized by two different sperm cells. If the twins are a boy and a girl, which of these happened?

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Genetic mutations are usually harmful or do not directly affect the organism, but there are sometimes beneficial mutations. Here are some mutations. Is each of the following harmful or beneficial?

• white fur on polar bears

• cystic fibrosis

• lactose tolerance in humans

• antibiotic resistance in bacteria

• sickle cell anemia

• cancer

In birds, the sex chromosome supplied by the female determines the sex of offspring.

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These are fraternal twins, so two different egg cells were fertilized by two different sperm cells.

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white fur on polar bears—beneficial

cystic fibrosis—harmful

lactose tolerance in humans—beneficial

antibiotic resistance in bacteria—beneficial for the bacteria

sickle cell anemia—harmful

cancer—harmful

What is the term for how life developed on Earth?

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Fossils are often located in sedimentary rocks, which form during compression of settling mud, debris, and sand. The order of layers of sedimentary rock shows the sequence in which life on Earth evolved. In what sequence would the fossils listed here appear?

• fish

• mammals

• single-celled organisms

• multicellular organisms

• amphibians

• reptiles

• birds

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Fill in the blank with the correct term.

An _____ is an organism that requires an oxygen source for survival and growth.

Evolution is the term for how life developed on Earth.

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single-celled organisms → multicellular organisms → fish → amphibians → reptiles → birds → mammals

The simplest organisms are in the bottom layer, while top layers contain increasingly complex and modern organisms in a pattern that suggests evolution.

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Answer: An aerobe is an organism that requires an oxygen source for survival and growth.

Which of the following is artificial selection and which is natural selection?

• Wild mustard becoming broccoli, cauliflower, kale, and cabbage

• A polyphemus moth with eye-shaped spots on its wings

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Match each of the body parts with its correct system.

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Messages are sent from parts of the body to other parts through the nervous system. What is an example of such a message?

Wild mustard becoming broccoli, cauliflower, kale, and cabbage is artificial selection, as farmers bred and manipulated the wild mustard plant into becoming these various other common vegetables.

A polyphemus moth with eye-shaped spots on its wings is natural selection, as this was a mutation that led to the survival of the moths with those spots, as they kept predators from eating the moths.

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1.—D. The tendon is a part of the musculoskeletal system.

2.—A. The spinal cord is a part of the nervous system.

3.—B. The lymph nodes are a part of the circulatory system.

4.—E. The larynx is a part of the respiratory system.

5.—C. The gallbladder is a part of the digestive system.

6.—F. The thymus is a part of the endocrine system.

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Your answer may vary.

Any input from a sensory organ like the nose, eyes, skin, ears, and tongue is transmitted through the nervous system. For example, if eyes see an apple, that message goes through the nervous system to the brain, which then sends information to other parts of your body, such as to the digestive system to prepare to digest the apple.

As your temperature rises, the blood vessels in your skin get larger. This process, called vasodilation, allows for cooling of the blood. What is the purpose of this cooling of the blood?

• circulation

• digestion

• homeostasis

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List at least three general parts of the body that are included in the musculoskeletal system.

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Which of the following is true about osmosis?

A. Water will move across a semi-permeable membrane from an area of high solute concentration to an area of low concentration.

B. Water does not move across semi-permeable membranes.

C. Water moves across a semi-permeable membrane driven by a difference in the amounts of solute on the two sides of the membrane until equilibrium is reached.

D. A semi-permeable membrane allows large particles to move across with the help of water molecules.

The correct answer is homeostasis, which is how the body systems work with one another to maintain a state of balance.

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Answers will vary.

Muscles, ligaments, tendons, bones, and cartilage are all part of the musculoskeletal system.

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The correct answer is choice C. Osmotic pressure forces highly concentrated molecules to move across a membrane into areas of lower concentration until a balance in reached. This balance is called equilibrium. The other choices are incorrect because the first option is the opposite of what actually occurs, water does move across semi-permeable membranes, and a semi-permeable membrane allows only small particles to move across.

Cells are the building blocks of life. Which of the following is NOT true about cells?

A. Only some cells contain genetic material.

B. Given the right conditions, cells will remain alive outside of the body.

C. Cells respond to their environments.

D. All cells contain a membrane that controls which molecules enter the cell.

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The graph shows the population of rabbits in one particular area. What is the carrying capacity of the rabbit population?

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Some plants have fungus colonies that live on their roots. The plants provide carbohydrates to the fungus in return primarily for phosphate and nitrogenous compounds. This is an example of:

A. mutualism

B. predation

C. commensalism

D. parasitism

All cells contain genetic material, so choice A is NOT true.

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The carrying capacity is 65, because this is where the population levels out after increasing steadily. The reproductive ability of the population is limited by the available resources. Under ideal conditions, with ample food and space and no predators, all living organisms have the capacity to reproduce infinitely. However, resources are limited, limiting the population of a species. This is called carrying capacity of the population. The carrying capacity of a population is the maximum population size that the environment can sustain given the necessary resources (food, habitat, water) available in the environment.

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The correct answer is choice A, mutualism, which is the type of symbiotic relationship in which both organisms benefit. This is not a predatory relationship in which one organism captures and feeds on another. Commensalism is symbiosis in which one organism benefits and the other is neither harmed nor rewarded, but here the fungus as well as the plants are benefiting from this relationship. In a parasitic relationship, one organism benefits at the expense of the other.

Tay-Sachs disease is a rare genetic disorder that impacts muscle coordination and cognition starting at 6 months of age and typically results in death at an early age. The allele for Tay-Sachs disease is recessive.

Complete the Punnett square for two parents who are carriers of the gene (Tt).

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Based on a Punnett square for carriers of a Tay-Sachs disease gene (Tt), what is the likelihood that the children of two heterozygous parents will carry the gene for
Tay-Sachs disease (homozygous or heterozygous)?

TT: ________%

Tt: ________%

tt: ________%

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Which of the following statements is NOT true about the endocrine system?

A. Diabetes is a disease that affects the production of glucose-regulating insulin in the endocrine system.

B. It works toward homeostasis in the body.

C. It includes the pituitary, thyroid, thymus, and pancreas.

D. Glands in the endocrine system send out chemical messages via hormones.

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TT: 25%

Tt: 50%

tt: 25%

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Choice B is the only false statement. The endocrine system does not have anything to do with maintaining homeostasis in the body.

What common terms are used for pathogens?

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What are some of the ways that disease can spread? List three.

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What statement is NOT true about noninfectious diseases?

A. They are often hereditary and pass as genetic disorders from generation to generation.

B. They are sometimes related to aging.

C. They are often passed on through fungi or bacteria.

D. Environmental factors can cause them.

bacteria, fungi, viruses

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Answers will vary.

Direct body contact, body fluids, contact with an object that an infected person has touched; through air via coughing, sneezing, dust, spraying of liquid; and via blood are a few of the many ways that disease can be transmitted.

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Choice C is not true. Noninfectious diseases are NOT caused by fungi or bacteria.

What statements are true about the conditions that can cause an epidemic?

• There is plenty of medicine for the disease.

• Diseases develop a resistance to medicine and drugs.

• Environmental conditions are favorable for a specific type of disease.

• Fungi and bacteria are prolific in the area.

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Place each of the listed items in the appropriate box of the table.

• smoking             • regular sleep

• regular alcohol use             • lack of exercise

• regular meals of green vegetables             • insomnia

• good portions of protein             • walking

             • potato chips for dinner

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What is the difference between vaccines and antibiotics?

• Diseases develop a resistance to medicine and drugs.

• Environmental conditions are favorable for a specific type of disease.

These two statements are both true about conditions that can cause an epidemic. The first statement is untrue as plenty of medicine would be more likely to prevent an epidemic. The last statement is untrue simply because it is too specific and would only be an environmental condition for a specific type of disease.

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Answers may vary.

Vaccines are made from a dead organism known to cause an immune response (such as a virus) or from a weakened or inactive form of the organism. Antibiotics are chemical compounds designed to kill bacteria without harming cells.

When presented with a weaker or deactivated form of an organism that would normally make a person very ill, the body produces an immune response without causing any illness. Then, if the body ever comes in contact with the strong form of a virus, the _______ that were formed during the immune response to the weaker version are able to fight off disease.

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What is one of the current dangers of using antibiotics for problems like acne?

A. The acne is not cured.

B. Antibiotics are being used for something inappropriate.

C. Bacteria become resistant to that antibiotic.

D. Bacteria end up on the person’s face.

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What is the best way to describe an ecological network?

A. the physical environment of interacting organisms

B. networking events directed toward exotic, natural environments to support conservation

C. the condition of a region as regards material prosperity

D. the interaction of various species within an ecosystem

When presented with a weaker or deactivated form of an organism that would normally make a person very ill, the body produces an immune response without causing any illness. Then, if the body ever comes in contact with the strong form of a virus, the antibodies that were formed during the immune response to the weaker version are able to fight off disease.

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The correct answer is choice C, bacteria become resistant to that antibiotic. Someone who took antibiotics for treating acne could accumulate bacteria that are capable of destroying the antibiotic. If that same person became infected with a serious disease that is treated with the same antibiotic, the resistant bacteria could destroy the antibiotic before it was able to act on the disease.

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The correct answer is choice D, the interaction of various species within an ecosystem. The other descriptions are for ecosystems, ecotourism, and economics.

Energy flows in an ecosystem through a chain of events called the food chain. Place the following members of the food chain in order of most energy to least energy.

• decomposers

• producers

• secondary consumers

• omnivores

• primary consumers

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Place the listed organisms into the correct category of the food chain.

• mouse

• cow

• snake

• ant

• grasshopper

• hawk

• mushroom

• fern

• human

• bacteria

• grass

• cougar

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1. producers

2. primary consumers

3. secondary consumers

4. omnivores

5. decomposers

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A cattle egret forages in a field among a herd of cattle. As the cattle graze and move around the field, insects are disturbed and fly up that are then caught and eaten by the cattle egret. This is an example of ___________.

• parasitism

• commensalism

• mutualism

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Orchids are found in dense tropical forests, where sunlight does not easily reach the floor of the forest. Orchids solve this issue by growing with their base attached to the branches of trees, thus raising themselves up to access adequate sunlight and gather any nutrition that flows down the branches of the tree. As orchids do not grow very large, the tree is not harmed by this attachment. This is an example of ___________.

• parasitism

• commensalism

• mutualism

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Remora fish are small fish that have suckers on their fins allowing them to attach to sharks, whales, and sea turtles. They use the larger sea organism as transportation and protection from other predators. The remora fish also eat any scraps of food that remain when the larger organism eats its prey. This is an example of ___________.

• parasitism

• commensalism

• mutualism

This is an example of commensalism.

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This is an example of commensalism.

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This is an example of commensalism.

The monarch butterfly at the larval stage eats milkweed that is full of a poisonous chemical known as cardiac glycoside that is harmful to most vertebrates. Once the butterfly has reached its mature butterfly form, if a bird or other vertebrate eats the butterfly, it finds the butterfly distasteful and will become sick. Because of this, birds and other predators avoid eating monarch butterflies. The relationship between the monarch butterfly and milkweed is an example of _______.

• parasitism

• commensalism

• mutualism

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Burdocks are weeds that have seeds with long, curved spines attached to them. They are most often found along roadsides, on barren land, and in fields. The spines of the seeds easily catch onto fur and clothing of passing animals and humans, which then carry them and drop them off in other areas. This allows the seeds to disperse while the carriers remain unharmed. This is an example of _________.

• parasitism

• commensalism

• mutualism

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A certain kind of bacteria lives within the intestine of humans and other animals. Humans cannot always digest all the foods that they eat. The bacteria eat that food and partially digest it, allowing the human to finish the job. The bacteria get food and the humans benefit by being able to digest the food as well. This an example of ________.

• parasitism

• commensalism

• mutualism

This is an example of commensalism.

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This is an example of commensalism.

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This is an example of mutualism.

Protozoa within the abdomen of a termite help with the digestion of wood. This is an example of _______.

• parasitism

• commensalism

• mutualism

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A bee lands inside a flower to gather nectar, which is made into food for the hive. The flower happens to have pollen inside of it as well, which ends up covering the hairy body and legs of the bee. When the bee lands on the next flower, some of the pollen that was on its body rubs of into the new flower. This is an example of ________.

• parasitism

• commensalism

• mutualism

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Spider crabs live in the shallows of the ocean floor and have greenish-brown algae living on their backs. This allows the crabs to blend into their environment, avoiding notice by predators, while the algae have a solid place to live. This an example of _________.

• parasitism

• commensalism

• mutualism

This is an example of mutualism.

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This is an example of mutualism.

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This is an example of mutualism.

What is the term for the maximum population size that an environment can sustain?

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Read the description of a symbiotic relationship and select the correct term for the relationship from the following list.

Mistletoe attaches to spruce trees. Using specialized structures, mistletoe penetrates into and extracts water and nutrients from the tree’s branches.

• commensalism

• mutualism

• parasitism

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Read the description of a symbiotic relationship and select the correct term for the relationship from the following list.

E. coli bacteria live within the intestinal tract of humans, obtaining nutrients from the food particles that pass through the intestines. Vitamin K produced by the E. coli is absorbed through the intestinal walls for use in the human body.

• commensalism

• mutualism

• parasitism

This is called carrying capacity.

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The symbiotic relationship exhibited by mistletoe and spruce trees is parasitism. The mistletoe receives a benefit in the form of a source of nutrients and water. The spruce tree is harmed because it loses nutrients and water, which can eventually lead to the death of the tree. Parasitism is occurring when one organism benefits (mistletoe) and the other organism is harmed (spruce tree).

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The symbiotic relationship exhibited by E. coli and humans is mutualism. The E. coli receive a benefit in the form of nutrients and a habitat in which to live. The human also receives a benefit because the E. coli produce vitamin K, which is then used within the human body. Mutualism is occurring when both organisms benefit.

Refer to the following passage to answer the next two questions.

Veterinary clinics often treat pets with illnesses resulting from parasitism. Three common parasites diagnosed in dogs are the dog flea, deer tick, and Cheyletiella mites.

Dog fleas and deer ticks both feed on the host animal’s (dog’s) blood, and can transmit diseases to the host animal through their bites. Dog fleas lay their eggs on the host animal’s body, and can survive on the host animal or on surfaces the animal comes in contact with, such as bedding. Deer ticks lay their eggs on the ground and attach to the host animal only while feeding.

Cheyletiella mites live within and feed on the keratin layer of the host animal’s skin. Cheyletiella mites reproduce on the host animal, and can survive away from the host animal for only short periods of time.

According to the passage, all the dog parasites gain which benefit from their symbiotic relationships with the host dogs?

A. a habitat for living

B. a vector for disease

C. a source of nutrients

D. a site for reproduction

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A veterinary technician is preparing to examine a dog suspected of having Cheyletiella mites. Which precaution would most effectively prevent the transmission of mites to other animals in the clinic?

A. administering a vaccine to the infected dog

B. wearing disposable gloves while examining the dog

C. avoiding contact with open wounds on the dog

D. sterilizing the exam room prior to examining the dog

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The correct answer is C, a source of nutrients. The fleas and ticks obtain nutrients from the host animal’s blood, and the mites obtain nutrients from the host animal’s skin. Although the fleas and mites may live and reproduce on the host animal’s body, the ticks do not. And while parasites can transmit diseases to the host animal, this does not provide a benefit to the parasite.

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The correct answer is choice B. The passage states that Cheyletiella mites live within the outermost layer of the dog’s skin, and have difficulty surviving away from the host animal’s body. Wearing gloves that are disposed of after examining the dog helps prevent mites transferred to the technician’s hands from being transmitted to other animals in the clinic.

Vaccines can be administered to non-infected individuals to prevent the transmission of diseases caused by viruses, but mites are arthropods that live on the host animal’s body, and cannot be eliminated with a vaccine. Avoiding contact with open wounds would help prevent the transmission of bloodborne pathogens, such as those transmitted by fleas and ticks, but would not help with the transmission of mites. Also, sterilizing the exam room after, not before, examining the infected dog could help prevent the transmission of mites to other animals in the clinic.

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The table compares characteristics for four different groups of plants. A “1” indicates the characteristic is present and a “0” indicates the characteristic is absent.

A cladogram illustrates the relatedness of organisms based on shared characteristics. Branches below a given characteristic represent organisms that do not exhibit that characteristic. Branches above a given characteristic represent organisms that do exhibit that characteristic. Each branch represents one plant type.

Use the information in the table to organize the plant types onto the appropriate branches in the cladogram.

• conifers

• ferns

• flowering plants

• mosses

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In a cladogram, the group that exhibits the fewest characteristics is listed on the bottom left branch, and the group exhibiting the most characteristics is listed on the top right branch.

Mosses are placed on the first (lowest) branch because they exhibit none of the characteristics listed in the table. Ferns contain vascular tissue, so are listed on the second branch. Confers are on the third branch because they contain vascular tissue and produce seeds. Flowering plants exhibit all three characteristics listed in the table, so are on the fourth (highest) branch.

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The food web for a woodland ecosystem bordering an area of farmland is shown here.

According to the concept of consumers and producers, rabbits are considered primary consumers because they

A. feed on grasses and carrots

B. are consumed by foxes only

C. compete with grasshoppers only

D. are the only consumer of carrots

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The correct answer is choice A. A primary level consumer feeds on producers. Producers, such as plants, make their own food using energy from sunlight. Rabbits feed on two producers, carrots and grasses, making rabbits a primary level consumer.

An organism’s feeding level is determined by how it obtains its food, not by the organisms that it provides food for. Although the rabbits in the food web are consumed by foxes, this does not determine the rabbits’ feeding level. Competition with other organisms does not affect how an organism’s feeding level is classified. Also, the presence of other organisms that consume the same food source does not affect how an organism’s feeding level is classified.

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The food web for a woodland ecosystem bordering an area of farmland is shown here.

Which three organisms in the food web obtain energy directly or indirectly from grasshoppers?

A. owls, birds, and mice

B. owls, birds, and grains

C. foxes, rabbits, and mice

D. foxes, owls, and birds

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A bacterial disease has destroyed most of the farm’s carrot crop for the past two seasons. As a result, the rabbit population has been forced to rely more heavily on grasses for a food source.

Explain how this disruption is likely to affect the rest of the ecosystem’s food web. Include multiple pieces of evidence and discuss specific populations (other than carrots and rabbits) as examples to support your answer.

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The correct answer is choice D. An organism provides energy to all organisms above it in the food web. In this food web, the grasshoppers provide energy to the birds, owls, and foxes. The birds and owls obtain energy directly when they consume the grasshoppers. The foxes obtain energy indirectly when they consume birds that previously consumed grasshoppers.

Although owls and birds obtain energy from grasshoppers, mice do not obtain energy from grasshoppers. Grains provide energy to grasshoppers; they do not obtain energy from grasshoppers. Rabbits and mice do not obtain energy from grasshoppers either directly or indirectly.

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Answers may vary.

The interrelatedness of populations in the food web makes it likely that all populations will be affected in some way by the shift in the rabbits’ feeding habits. The rabbits’ increased reliance on grasses will cause a domino effect on the availability of food for all primary consumers. Since grasshoppers directly compete with rabbits for grasses, the availability of grasses for grasshoppers may be limited. As a result, grasshoppers would likely increase their dependence on grains, decreasing the availability of this food source for birds and mice. The overall increase in competition among primary consumers may cause some decreases in population sizes, which would also limit the population sizes of higher-level consumers.

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The table illustrates the range of normal body temperatures in Fahrenheit for different age groups.

The formula for converting Fahrenheit to Celsius is shown here.

(°F – 32) × ⁵/₉ = °C

The normal body temperature range of a newborn baby is _____°C to _____°C. (You may use a calculator to complete this question.)

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The normal body temperature range of a newborn baby is 36.5°C to 37.5°C.

Blank 1: The formula for converting temperature from Fahrenheit to Celsius is given as (°F – 32)× ⁵/₉ = °C. Replacing the lower variable °F with 97.7 and solving gives (97.7 – 32)× ⁵/₉ = 36.5.

Blank 2: The formula for converting temperature from Fahrenheit to Celsius is given as (°F – 32)× ⁵/₉ = °C. Replacing the lower variable °F with 99.5 and solving gives (99.5 – 32)× ⁵/₉ = 37.5.

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The process of meiosis is depicted in the following diagram.

The daughter cells produced during meiosis are used for what purpose?

A. growth

B. tissue repair

C. differentiation

D. reproduction

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As indicated in the diagram, the daughter cells produced during meiosis each have half the total number of chromosomes as the parent cell has. These daughter cells, called gametes, are used for choice D, reproduction. When reproduction occurs, two gametes (egg and sperm) unite to create a cell with a full set of chromosomes.

To allow an organism to grow larger and repair tissues, the daughter cells produced must be identical to the parent cell. Cells used for growth and tissue repair are produced by the process of mitosis. Cell differentiation occurs when a single, non-specialized cell is converted to a specialized cell type, like a blood cell or skin cell. No daughter cells are produced during the differentiation process.

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Meiosis produces cells containing one chromosome from each chromosome pair. This diagram shows the chromosome combinations that can be produced from a cell containing two pairs of chromosomes.

A barley plant has seven pairs of chromosomes. How many unique combinations of chromosomes can result from meiosis in barley?

A. 7

B. 14

C. 49

D. 128

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The correct answer is choice D, 128. Each new cell created by meiosis must contain one chromosome from each of the seven chromosome pairs. As illustrated in the diagram, these single chromosomes can be combined in multiple ways. To determine the total number of unique chromosome combinations, the number of chromosomes in each set (pair) must be multiplied. Seven sets of two chromosomes each means that 7 twos must be multiplied (2 × 2 × 2 × 2 ×2 × 2 × 2 = 128) to determine the total number of unique chromosome combinations possible.

There are seven total chromosomes in a cell produced by meiosis, but the specific chromosome present from each chromosome pair can vary. Two chromosomes in each of seven pairs provides a total of 14 chromosomes, but since the specific chromosome present from each pair can vary, multiplying 7 × 7 does not provide the total number of chromosome combinations possible. To determine this, the number of chromosomes in each pair must be multiplied by the number of chromosomes in each other pair.

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A student draws the model shown here to represent the process of aerobic respiration.

Which change would improve the accuracy of the student’s model?

A. connecting all the circles to each other to show bonds

B. moving the energy symbol to the left side of the equation

C. adding five triangles to balance the right side of the equation

D. making the rectangles smaller to show relative molecular sizes

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The energy produced by respiration is in what form?

A. ATP

B. oxygen

C. glucose

D. carbon dioxide

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The correct answer is choice C. The products of respiration are six molecules of carbon dioxide, six molecules of water, and energy. On the right side of the model, six rectangles are present, but only one triangle. To accurately represent a balanced equation, all molecules must be represented in the model.

The circles represent the six molecules of the reactant oxygen. Connecting the circles would not improve the model’s accuracy because separate molecules are not bound to each other. Energy is a product of the respiration reaction, and is therefore appropriately placed on the right side of the equation. Moving the energy symbol to the left side of the equation would indicate that energy is a reactant. Reducing the size of the rectangles is not the most needed change, since the other molecules are not represented to scale.

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The correct answer is choice A. The purpose of respiration is to convert energy into a form that is usable by cells. Respiration produces ATP, a high-energy molecule, which the cell can use to carry out cellular functions.

Oxygen is a reactant, not a product, of aerobic respiration, and does not provide energy for the cell. Respiration uses the glucose in food to produce ATP. Respiration does not produce glucose. And, though respiration does produce carbon dioxide, this molecule does not provide energy for the cell.

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Explain the benefit of having two pathways for respiration in the human body.

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Answers may vary.

The human body may utilize two different pathways to carry out respiration. The presence of two different pathways is valuable because it allows a cell to choose the pathway that best meets its current energy needs. Aerobic respiration produces the greatest amount of ATP per glucose molecule. Under normal conditions with adequate oxygen, this pathway provides the greatest possible amount of energy to the cell. Anaerobic respiration produces much less ATP per glucose molecule, but does not require oxygen. Under strenuous conditions when the cell demands energy faster than the oxygen supply can be replenished, this pathway provides enough energy to maintain cell functions. The ability to switch between aerobic and anaerobic pathways allows the human body to function properly under varying conditions.

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Artificial selection is the process of breeding plants or animals to increase the occurrence of desired traits. Farmers use artificial selection to produce new crop species from existing plant species. The diagram illustrates six crop species that have been derived from the common wild mustard plant.

Based on the information in the passage, how did farmers produce kale?

A. Farmers removed the stems and flowers from mustard plants as they grew.

B. Farmers allowed only wild mustard plants with large leaves to reproduce.

C. Farmers bred small-leafed plants with large-leafed plants to increase leaf size.

D. Farmers prevented wild mustard plants with large leaves from reproducing.

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The correct answer is choice B. Kale is a leafy crop species. According to the diagram, wild mustard plants were selected for leaves to produce kale. This means that wild mustard plants that had large leaves were specifically bred together to increase leaf size. This selective breeding over multiple generations led to a new species (kale) characterized by large leaves.

Plants with desired characteristics (large leaves for kale) must be bred together to produce offspring plants with those characteristics. Removing stems and flowers from existing mustard plants will not increase leaf size in subsequent generations. Breeding small-leafed plants and large-leafed plants allows the possibility that offspring will have either small or large leaves. To ensure offspring have the best chances of large leaves, large-leafed plants should be bred together. Preventing plants with large leaves from growing works to remove the large-leaf trait from subsequent generations rather than increase its appearance.

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Every person has two copies, or alleles, of the ABO blood type gene. A person’s ABO blood type is determined by their specific combination of alleles. The table shows the allele combinations that cause the four different ABO blood types.

A mother’s allele combination is I^Ai and a father’s allele combination is I^AI^B. Which of the following statements is true about the blood type of their first child?

A. The child will have the same blood type as the mother.

B. The child cannot have the father’s blood type.

C. The child will have a blood type different from both parents.

D. The child cannot have blood type O.

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Choice D is the only true statement. The blood type O can only be produced by the allele combination ii. A child receives one allele from each parent. Since the mother has an i but the father does not, the allele combination ii is not possible for their children.

Based on the table, the mother’s blood type is A. The child can receive I^A or i from the mother and I^A from the father, resulting in type A blood caused by the possible allele combinations I^AI^A or I^Ai. However, the child could receive I^B from the father, which would result in a blood type different from the mother. Based on the table, the father has blood type AB. The child can receive I^A from the mother and I^B from the father, resulting in the possible allele combination I^AI^B. This allele combination will produce the same blood type as the father’s. Also, based on the table, the mother’s blood type is A and the father’s is AB. The child can receive I^A or i from the mother and I^A from the father, resulting in type A blood caused by the possible allele combinations I^AI^A or I^Ai. The child can receive I^A from the mother and I^B from the father, resulting in the blood type AB caused by the possible allele combination I^AI^B. This means it is possible for the child to have the same blood type as either one of the parents.

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Blood glucose levels are tightly regulated in the human body by the hormones insulin and glucagon. When glucose levels become too high or low, the pancreas produces the appropriate hormone to return the body to homeostasis. The diagram shows the feedback mechanism for regulating blood glucose levels.

Diabetes mellitus is a disease in which the pancreas is unable to produce the insulin needed to regulate blood glucose levels. What result would occur from providing an insulin injection to a diabetic person with high blood sugar?

A. The insulin travels to the liver where it binds to and destroys excess glucose in the bloodstream.

B. The insulin signals the pancreas to produce glucagon, which increases the level of glucose in the bloodstream.

C. The insulin causes the liver to convert glucose to glycogen, removing excess glucose from the bloodstream.

D. The insulin breaks down glycogen into glucose, releasing stored glucose into the bloodstream.

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The correct answer is choice C. According to the diagram, when a person’s blood glucose level rises, the pancreas secretes insulin. The insulin signals body cells to absorb glucose from the blood, and signals the liver to convert excess glucose into the storage molecule glycogen. These processes remove excess glucose from the blood, returning the blood glucose level to homeostasis. Insulin injected into a diabetic person initiates the same pathway as insulin produced in the pancreas of a healthy person.

Insulin signals the liver to convert and store excess glucose as glycogen, not to destroy the glucose. Insulin and glucagon do not signal each other, but perform opposite functions. Insulin functions to decrease blood glucose levels, while glucagon functions to increase levels. Glucagon signals the breakdown of glycogen into glucose when blood glucose levels are low. Insulin signals the conversion of glucose to glycogen when blood glucose levels are high.

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How would you describe ATP?

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What are capillaries?

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What is a cytoskeleton?

Adenosine triphosphate (ATP) is a chemical that is considered to be the “fuel” or energy source for an organism.

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Vascular tissues that receive blood from the arterioles and release the blood to the venuoles.

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Organelles that are the internal “bones” of the cell. Cytoskeletons exist in thick and thin tubules.

What does DNA stand for?

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What is gel electrophoresis?

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DNA is the abbreviation for deoxyribonucleic acid. It contains all genetic material for an organism. The smallest units of DNA are called nucleotides.

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A process used in laboratories to determine the genetic makeup of DNA strands. This process involves the movement of chromosomes through a gel from one pole to the other. Magnetism is used to pull the chromosomes through the gel.

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Refer to the following passage to answer the next nine questions.

Anatomy of Muscles

Muscles are made of bundles of cells wrapped in connective tissue called fascicles. Each bundle contains many cylindrical muscle cells or muscle fibers. Like other cells, muscle fibers have mitochondria that provide energy, a plasma membrane that separates the inside and outside of the cell, and endoplasmic reticulum, where proteins are made. However, muscle cells are different from other cells in several ways. First, muscle cells have more than one nucleus. Second, the muscle cell’s plasma membrane surrounds bundles of cylindrical myofibrils that contain protein filaments and regularly folds into the deep parts of the fiber to form a transverse tubule or T-tubule. Third, the muscle cell’s endoplasmic reticulum is called sarcoplasmic reticulum; it is regularly structured, envelops the myofibrils, and ends near the T-tubule in sacs called terminal cisternae.

Look at the title of the passage. The title often previews what the reading will be about. What does this title reveal about the passage?

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Look at each sentence in the passage. Look at the subject of each sentence (we are showing the parts of each one, not the whole):

1. Muscles are made of bundles of cells. . . .

2. Each bundle contains many cylindrical muscle cells. . . .

3. Muscle fibers have mitochondria . . . , plasma membrane . . . , and endoplasmic reticulum. . . .

4. Muscle cells are different from other cells in several ways.

5. Muscle cells have more than one nucleus.

6. The muscle cell’s plasma membrane surrounds bundles of. . . .

7. The muscle cell’s endoplasmic reticulum is called sarcoplasmic reticulum. . . .

What do the subjects of the sentences have in common?

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The title tells us that the passage is going to be about the structure or anatomy of muscles.

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They all have muscle in common.

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The pattern of muscle as the subject of each sentence also provides a clue as to the subject of the entire passage. What do you think is the main purpose of this passage?

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What is the shape of a muscle cell?

A. sphere

B. cylinder

C. disc

D. cube

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Which is a difference between a muscle cell and another type of cell?

A. Only muscle cells have mitochondria.

B. The plasma membrane separates the inside from the outside of the muscle cell.

C. Muscle cells have more than one nucleus.

D. Muscle cells do not have endoplasmic reticulum.

The main purpose of this passage is to describe the structure of muscles. Both the title and the subjects of each sentence indicate this information.

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The correct answer is choice B, cylinder. The second sentence mentions that bundles contain many cylindrical muscle cells.

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The correct answer is choice C. The fifth sentence of the passage states that “First, muscle cells have more than one nucleus.”

“Muscles are made of bundles of cells wrapped in connective tissue called fascicles.” What word helps you with context for the word fascicles?

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“Each bundle contains many cylindrical muscle cells or muscle fibers.” What word helps you with context for the phrase muscle fibers?

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“Like other cells, muscle fibers have mitochondria that provide energy, a plasma membrane that separates the inside and outside of the cell, and endoplasmic reticulum, where proteins are made.” What helps you with context for the phrase endoplasmic reticulum?

The word called connects the term with its definition.

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The word or connects the term fiber with another more familiar term, cell.

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The comma connects the term endoplasmic reticulum with an explanation of its purpose, where proteins are made.

“Like other cells, muscle fibers have mitochondria that provide energy, a plasma membrane that separates the inside and outside of the cell, and endoplasmic reticulum, where proteins are made.” How do you get context for the phrase plasma membrane?

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The word that separates a clause that can convey important information. For example, “a plasma membrane that separates the inside and outside of the cell” reveals that the function of the plasma membrane is to separate the inside from the outside of the cell.

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Refer to the following passage to answer the next three questions.

In sexual reproduction, DNA is contributed by two parents with the goal of producing genetically distinct offspring. In most organisms, sexual reproduction includes a special form of cell division called meiosis, which results in the reduction of the number of chromosomes. Cells with only one complete set, or pair, of chromosomes are called haploid. Haploid cells are the reproductive cells, called either gametes or sex cells. Cells that contain two complete sets of chromosomes are called diploid. Almost all the cells in your body are diploid. Humans have 46 chromosomes or 23 pairs in each body cell. In sexual reproduction, two haploid cells, sperm and egg, combine to form a diploid cell, a zygote, which then develops into the offspring organism.

Haploid and diploid are designated by the algebraic notations n and 2n. Either number can be calculated when the other number is known. The table shows some of the haploid or diploid numbers for various organisms.

How many chromosomes are in the gametes of an onion?

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What is the difference between the number of chromosomes in non-sex cells of a human and a chimpanzee?

A. 1

B. 2

C. 22

D. 80

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There are 8 chromosomes in the gametes of an onion. A gamete is a haploid cell and has half the number of chromosomes as the diploid cell. A diploid cell of an onion has 16 chromosomes, so an onion’s gamete must have ¹⁶/₂ or 8 chromosomes.

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The correct answer is choice B, 2. A non-sex cell is a diploid cell. The diploid cell of a chimpanzee has 48 chromosomes (24 × 2 = 48). The diploid cell of a human has 46 chromosomes (the number is in the table). So, the difference in chromosomes between a human and a chimpanzee is 2 chromosomes (48 – 46 = 2).

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Which process produces a sperm or an egg?

A. trichinosis

B. meiosis

C. mitosis

D. metamorphosis

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Jim has two overweight dachshunds. He sees an advertisement for a new reduced-calorie dog food that claims to allow the dogs to eat normally, but still lose weight.

Propose a hypothesis to test the claim in the advertisement. What is the hypothesis?

Hypothesis: If _________________, then ______________.

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Jim has two overweight dachshunds. He sees an advertisement for a new reduced-calorie dog food that claims to allow the dogs to eat normally, but still lose weight.

Propose an experiment to test the claim in the advertisement. What is the suggested experiment?

The correct answer is choice B, meiosis. Sperm and egg cells are gametes, which are haploid cells that have half the number of chromosomes. The second sentence of the passage states that “In most organisms, sexual reproduction includes a special form of cell division called meiosis, which results in the reduction of the number of chromosomes.”

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The wording of your hypothesis may vary.

If Jim feeds one dog the new dog food, then that dog should lose weight compared to the other.

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The wording of your experiment may vary.

Feed both dogs at the same time with the same amount of dog food. Substitute the new reduced-calorie dog food for the normal dog food for one of the dogs. Separate the dogs when they are eating so that one dog does not eat the other’s food. Measure the weight of both dogs weekly over the course of six weeks.

Jim has two overweight dachshunds. He sees an advertisement for a new reduced-calorie dog food that claims to allow the dogs to eat normally, but still lose weight.

Propose a predicted result of an experiment to test the claim in the advertisement. What is the predicted result?

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The wording of your predicted result may vary.

The dog eating reduced-calorie dog food should lose weight compared to the dog eating normal dog food.

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A coffee retailer wants to know whether customers prefer brand A or brand B coffee. So, he sets up a blind taste test. He prepares pots of coffee with equal volumes using the same amount of coffee, either brand A or brand B. The coffees are brewed at the same temperature and the same time. The retailer knows which pot contains brand A and which contains brand B. He gives the pots to a clerk. A clerk pours two sample cups of equal volume for each customer, one from each pot. The pots of coffee are not labeled and the clerk does not know which coffee she is serving. For 100 customers, she has each customer taste each sample cup of coffee and write which choice he or she preferred. The clerk tallies the choices and gives the tally to the coffee retailer.

Identify the controlled and uncontrolled factors in the experiment.

Assign the correct variables into each box:

• amount of coffee in each pot

• coffee brand served

• coffee temperature

• coffee brewing time

• volume of coffee pots

• customer’s preferred coffee brand

• amount of coffee served

• The clerk does not know what brand she is serving.

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Experiment: Does fertilizer A help plants grow faster than fertilizer B?

Process: First, identify what variables will be tested and what variables should be controlled. Fertilizers A and B should be applied to the same type of plant. This makes the type of plant one of your controls.

Should all the plants be fertilized?

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Experiment: Does fertilizer A help plants grow faster than fertilizer B?

Process: First, identify what variables will be tested and what variables should be controlled. Fertilizers A and B should be applied to the same type of plant. This makes the type of plant one of your controls.

Should one plant get more sunlight or water or be exposed to different temperatures for different times than the other experimental plant?

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Experiment: Does fertilizer A help plants grow faster than fertilizer B?

Process: First, identify what variables will be tested and what variables should be controlled. Fertilizers A and B should be applied to the same type of plant. This makes the type of plant one of your controls.

The amount of fertilizer being applied ___________.

• should be the same

• can be different

No. There should be a control that has no fertilizer for comparison to make sure that both types of fertilizer are working.

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No. Water, temperature, and amount of light should also be controls, as well as the length of the experiment (time).

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The amount of fertilizer being applied should be the same. It should also be controlled in the experiment.

Experiment: Does fertilizer A help plants grow faster than fertilizer B?

Process: First, identify what variables will be tested and what variables should be controlled. Fertilizers A and B should be applied to the same type of plant. This makes the type of plant one of your controls.

The independent variable will be ___________.

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Experiment: Does fertilizer A help plants grow faster than fertilizer B?

Process: First, identify what variables will be tested and what variables should be controlled. Fertilizers A and B should be applied to the same type of plant. This makes the type of plant one of your controls.

The dependent variable will be __________.

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Experiment: Does fertilizer A help plants grow faster than fertilizer B?

Process: First, identify what variables will be tested and what variables should be controlled. Fertilizers A and B should be applied to the same type of plant. This makes the type of plant one of your controls.

How will you measure the plant growth (height, mass, etc.)? What instrument will you use?

The independent variable will be the type of fertilizer. The type of fertilizer will act as the independent variable because you want to know what effect it has on the plant.

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The dependent variable will be the plant growth. The plant growth will act as the dependent variable, the factor observed and measured to see if it is affected by the fertilizer.

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Responses may vary.

Measuring the plant height is the easiest way to measure growth. You can measure the height with a metric ruler.

Experiment: Does fertilizer A help plants grow faster than fertilizer B?

Process: First, identify what variables will be tested and what variables should be controlled. Fertilizers A and B should be applied to the same type of plant. This makes the type of plant one of your controls.

How many plants would make the best representative population sample for this experiment?

A. 2

B. 10

C. 100

D. 1,000

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The correct answer is choice B, 10. Of the choices, this makes the most sense; there are a significant number of plants in each group to be able to observe shared differences.

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Refer to the following passage to answer the next 12 questions.

Today, about 30% of the children in the United States are overweight or obese. This puts them at increased risk for diseases such as diabetes (measured by fasting glucose levels) and heart disease (due to high cholesterol levels). The local county health department wants to improve the health of the young children in the community. Most research indicates that changing diet and exercise is the best way to reduce obesity in children, but they suspect that children may not be willing to change both diet and exercise.

First, identify what variables will be tested and what variables should be controlled. Should all the children be placed in a program of diet and exercise?

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First, identify what variables will be tested and what variables should be controlled. Should both diet and exercise be only tested together?

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The county health department undertakes a new program to encourage children to eat better and exercise. They enroll 200 children in a six-month program and plan to set up three groups:

• Group 1: Diet and exercise

• Group 2: Diet only

• Group 3: Exercise only

The county health department hypothesizes that the children in the diet and exercise group will have the best outcomes.

Should one child participate in dieting and exercising longer than the other experimental children?

No. There should be a control that has no diet or exercise for comparison to make sure that both diet and exercise are working.

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No. Each variable of diet and exercise must also be tested separately.

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No. The length of the experiment (time) should be a control in the experiment.

The county health department undertakes a new program to encourage children to eat better and exercise. They enroll 200 children in a six-month program and plan to set up three groups:

• Group 1: Diet and exercise

• Group 2: Diet only

• Group 3: Exercise only

The county health department hypothesizes that the children in the diet and exercise group will have the best outcomes.

The amount of diet and exercise being applied _________.

• should be the same

• can be different

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The county health department undertakes a new program to encourage children to eat better and exercise. They enroll 200 children in a six-month program and plan to set up three groups:

• Group 1: Diet and exercise

• Group 2: Diet only

• Group 3: Exercise only

The county health department hypothesizes that the children in the diet and exercise group will have the best outcomes.

The independent variables will be ___________.

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The amount of diet and exercise being applied should be the same. It should also be controlled in the experiment.

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The independent variables will be application of diet and exercise, just diet, or just exercise.

The application of diet and exercise, just diet, or just exercise will act as the independent variables because you want to know what effect each has on the children.

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The county health department undertakes a new program to encourage children to eat better and exercise. They enroll 200 children in a six-month program and plan to set up three groups:

• Group 1: Diet and exercise

• Group 2: Diet only

• Group 3: Exercise only

The county health department hypothesizes that the children in the diet and exercise group will have the best outcomes.

The dependent variables will be __________.

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The county health department undertakes a new program to encourage children to eat better and exercise. They enroll 200 children in a six-month program and plan to set up three groups:

• Group 1: Diet and exercise

• Group 2: Diet only

• Group 3: Exercise only

The county health department hypothesizes that the children in the diet and exercise group will have the best outcomes.

How would the 200 children enrolled in the six-month program be best divided up?

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The dependent variables will be weight, cholesterol levels, and fasting blood glucose levels of each group. The weight, cholesterol levels, and fasting blood glucose levels of each group will act as the dependent variables, the factors observed and measured to see whether they are affected by the application of diet and exercise.

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The county health department should randomly assign the 200 children to one of three experimental groups, as well as a control group, as follows:

• Group 1: Diet and exercise (50 children)

• Group 2: Diet only (50 children)

• Group 3: Exercise only (50 children)

• Control group: No change in daily routine (50 children)

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The county health department undertakes a new program to encourage children to eat better and exercise. They enroll 200 children in a six-month program and plan to set up three groups:

• Group 1: Diet and exercise

• Group 2: Diet only

• Group 3: Exercise only

The county health department hypothesizes that the children in the diet and exercise group will have the best outcomes.

What measurements would need to be taken before the experiment begins?

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The county health department undertakes a new program to encourage children to eat better and exercise. They enroll 200 children in a six-month program and plan to set up three groups:

• Group 1: Diet and exercise

• Group 2: Diet only

• Group 3: Exercise only

The county health department hypothesizes that the children in the diet and exercise group will have the best outcomes.

What would be a reasonable description of the experiment and checks for Group 1?

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The health department would have to take measurements of all the children before the intervention begins, at two months, and at six months to measure the change over time. They would take height, weight, cholesterol levels, and fasting blood glucose levels. They would also need to ask questions about the diet of the children and the amount of exercise they do on a daily basis.

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The children in Group 1 (diet and exercise) would be on a diet lower in fat and sugar (weekly menus provided by the health department) and would be asked to double the amount of exercise they do in a week (e.g., if they normally exercise 20 minutes per week they would be asked to exercise 40 minutes per week). Parents would be asked to keep a food log and record the exercise on a daily basis.

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The county health department undertakes a new program to encourage children to eat better and exercise. They enroll 200 children in a six-month program and plan to set up three groups:

• Group 1: Diet and exercise

• Group 2: Diet only

• Group 3: Exercise only

The county health department hypothesizes that the children in the diet and exercise group will have the best outcomes.

What would be a reasonable description of the experiment and checks for Group 2?

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The county health department undertakes a new program to encourage children to eat better and exercise. They enroll 200 children in a six-month program and plan to set up three groups:

• Group 1: Diet and exercise

• Group 2: Diet only

• Group 3: Exercise only

The county health department hypothesizes that the children in the diet and exercise group will have the best outcomes.

What would be a reasonable description of the experiment and checks for Group 3?

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The children in Group 2 (diet change only) would be on the same reduced fat and lower sugar diet as the children in group 1, but would not change their exercise routine. Parents would be asked to keep a food log and record the exercise on a daily basis.

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The children in Group 3 (exercise change only) would not be asked to change their diets, but would be asked to double the amount of exercise they do on a weekly basis, as in Group 1. Parents would be asked to keep a food log and record the exercise on a daily basis.

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The county health department undertakes a new program to encourage children to eat better and exercise. They enroll 200 children in a six-month program and plan to set up three groups:

• Group 1: Diet and exercise

• Group 2: Diet only

• Group 3: Exercise only

The county health department hypothesizes that the children in the diet and exercise group will have the best outcomes.

What would be a reasonable description of the experiment and checks for the control group?

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The children in the control group would not be asked to change anything, but parents would be asked to keep a food log and record the exercise on a daily basis.

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Wolves crossed an ice bridge from Canada to the Isle Royale, Michigan, and established a population. Moose were native to the island. Since the 1950s, ecologists have studied the moose and wolf populations on the island. The population data are shown in the graph.

Ecologists noted several events, which are summarized in the table.

Based on the information, what can you conclude about the relationship between moose (prey) and wolves (predator) between 1959 and 1995?

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Your wording may vary.

The increase in the moose population (1964–1972) induced increased predation by wolves and a subsequent increase in the wolf population. Once the wolf population crashed from disease (1981–1984), the moose population recovered and increased through 1995.

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Wolves crossed an ice bridge from Canada to the Isle Royale, Michigan, and established a population. Moose were native to the island. Since the 1950s, ecologists have studied the moose and wolf populations on the island. The population data are shown in the graph.

Ecologists noted several events, which are summarized in the table.

Does this relationship hold after 1995?

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Your wording may vary.

No. After 1995, the moose population crashed and remained low due to the severe winter and disease, but the wolf population increased.

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A flu vaccine company wants to know which locations are most utilized by adults and children who receive influenza vaccines. Evaluate the graph and use the data to make a prediction as to where the vaccine company should target future sales.

Based on the information in the graph, what are the top three locations where the majority of children get flu vaccinations? Select your answers from the list that follows.

• Doctor’s office

• Clinic or health center

• Hospital

• Pharmacy or store

• Workplace

• Health department

• School

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The majority of children get flu vaccinations in doctor’s offices, health clinics, and schools.

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A flu vaccine company wants to know which locations are most utilized by adults and children who receive influenza vaccines. Evaluate the graph and use the data to make a prediction as to where the vaccine company should target future sales.

Based on the information in the graph, where do the majority of adults get flu vaccinations? Select your answers from the list that follows.

• Doctor’s office

• Clinic or health center

• Hospital

• Pharmacy or store

• Workplace

• Health department

• School

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A flu vaccine company wants to know which locations are most utilized by adults and children who receive influenza vaccines. Evaluate the graph and use the data to make a prediction as to where the vaccine company should target future sales.

If the flu vaccine company wishes to increase sales to both adults and children, then it should target future sales activities to _____________.

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If the flu vaccine company wishes to increase sales to both adults and children, then it should target future sales activities to doctor’s offices.

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In an experiment, Jan records the heights in centimeters of five plants:

10.1, 9.8, 10.0, 10.1, 9.9

The mean height of the plants is ____ cm.

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In an experiment, Jan records the heights in centimeters of five plants:

10.1, 9.8, 10.0, 10.1, 9.9

The median height of the plants is ____ cm.

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In an experiment, Jan records the heights in centimeters of five plants:

10.1, 9.8, 10.0, 10.1, 9.9

The mode height of the plants is ____ cm.

The mean height of the plants is 9.98 cm.

The mean is calculated like this:

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The median height of the plants is 10.0 cm.

First arrange the heights in ascending order:

9.8, 9.9, 10.0, 10.1, 10.1

The median is the middle value, which is 10.0 cm.

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The mode height of the plants is 10.1 cm.

First arrange the heights in ascending order:

9.8, 9.9, 10.0, 10.1, 10.1

The mode is the most frequent value, which is 10.1 cm.

In an experiment, Jan records the heights in centimeters of five plants:

10.1, 9.8, 10.0, 10.1, 9.9

Next, find the variance and standard deviation of the plant heights. The height values and mean have already been plugged into the table. Fill in the remaining cells in the table with the appropriate values. You may use a calculator.

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In an experiment, Jan records the heights in centimeters of five plants:

10.1, 9.8, 10.0, 10.1, 9.9

Now, complete the equation to find the variance using the sum you arrived at in the table in the previous flash card. Remember, n is the number of items in the sample.

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The variance is 0.017 cm.

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In an experiment, Jan records the heights in centimeters of five plants:

10.1, 9.8, 10.0, 10.1, 9.9

Get the standard deviation by finding the square root of the variance from the previous flash card:

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Remember, the standard deviation can be thought of as measuring how far the data values lie from the mean, so take the mean and move one standard deviation in either direction.

The mean of the values was 9.98 cm and the standard deviation is 0.13.

• 9.98 cm – 0.13 cm = 9.85 cm

• 9.98 cm + 0.13 cm = 10.11 cm

Therefore, the height of the population falls within one standard deviation from the mean (i.e., between 9.85 cm and 10.11 cm), except for the plant that is 9.8 cm tall.

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Refer to the following passage to answer the next five questions.

Hemophilia is a rare bleeding disorder in which the blood does not clot normally. People born with hemophilia have little or no clotting factor, the protein needed for normal blood clotting. It is usually inherited, meaning that the disorder is passed from parents to their offspring through genes. Hemophilia in humans is due to a mutation in a gene found on the X chromosome. Mothers always contribute an X chromosome to their offspring while fathers contribute either an X or a Y chromosome. If hemophilia is found on any of these X chromosomes, it can be passed on to the offspring. A carrier of hemophilia is a female with one normal X chromosome and one X chromosome carrying the mutation. A male cannot be a carrier because his genetic makeup is XY; thus, the presence of the mutation would result in the disease. The chart shown here is a Punnett square that shows the probability of a normal male and a carrier female producing an offspring with hemophilia.

Which piece of evidence from the passage best supports the statement that an affected male will never transmit the hemophilia gene to his sons?

A. Hemophilia in humans is due to mutation in a gene found on the X chromosome.

B. Mothers always contribute an X chromosome to their offspring while fathers contribute either an X or a Y chromosome.

C. A carrier of hemophilia is a female with one normal X chromosome and an X chromosome carrying the
mutation.

D. A male cannot be a carrier because his genetic makeup is XY; thus, the presence of the mutation would result in the disease.

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The correct answer is choice B. The statement “Mothers always contribute an X chromosome to their offspring while fathers contribute either an X or a Y chromosome” best supports the notion that an affected male will never transmit the hemophilia gene to his sons because the male does not donate an X chromosome to a son. While the other statements are true, they do not provide the best support.

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Which conclusion is best supported by the information in the passage and chart?

A. All the sons of female carriers will have a mutation on the X chromosome.

B. Half of the daughters of males with hemophilia and normal females will be carriers.

C. Female carriers and male hemophiliacs have the greatest risk of having hemophiliac offspring.

D. A female hemophiliac and a male hemophiliac have the highest chance of producing an offspring with hemophilia.

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The probability of a carrier female and a hemophiliac male producing a non-carrier, non-hemophiliac female offspring is ____%.

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The correct answer is choice D. This conclusion is best supported by evidence in the article because hemophilia is due to a mutation in a gene found on the X chromosome. Additionally, the Punnett square illustrates that females pass an X to sons and daughters and males pass an X to daughters. Therefore, if every X chromosome carried the mutation, every son or daughter would have hemophilia.

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The probability of a carrier female and a hemophiliac male producing a normal female offspring is 0%.

The Punnett square illustrates that all the possible female outcomes result in the gene showing up, either as a carrier or as a hemophiliac. 

The daughter will be either a carrier or a hemophiliac.

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Which hypothesis can be supported with evidence from the passage and chart?

A. If a female is a carrier, then she can pass the hemophilia gene to a son.

B. If two carriers have children, then they are likely to have children who are carriers.

C. If a male with hemophilia has a son, then the gene cannot be inherited from the mother.

D. If both parents do not carry the hemophilia gene, then potential daughters can only be carriers.

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The probability of a normal female and a hemophiliac male producing a normal male offspring is ____%.

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The correct answer is choice A. This hypothesis is supported with evidence in the Punnett square and the following excerpt from the passage: “If hemophilia is found on any of these X chromosomes, it can be passed on to the offspring.”

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The probability of a normal female and a hemophiliac male producing a normal male offspring is 100%. With this scenario, any daughters will have a 100% chance of being a carrier of the gene while sons have a 100% chance of not having hemophilia.

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Refer to the following passage to answer the next three questions.

A company claims that its new fertilizer, brand X, will make plants, such as tomato plants, grow faster and produce more fruit than a leading brand by another company, brand Y. The directions for each fertilizer indicate that they are used at the same concentration (50 g/kg soil). A scientist uses 150 tomato plant seedlings. He divides the seedlings into three groups of 50 plants. Each seedling is 10–12 cm high at the start of the study and is planted in a pot containing 1 kg of potting soil; the soil is identical for all groups. To one group (control), nothing is added to the soil. To a second group, 50 g of brand Y is added to the soil of each plant. To a third group, 50 g of brand X is added to the soil. All the plants are grouped together in the same greenhouse at a constant temperature of 25°C. The light in the greenhouse is uniformly illuminated and all plants are exposed to a 12-hour on/off cycle. The plants are carefully watered each day with 200 mL of water each. The height of each plant is measured and recorded weekly for 20 weeks. In addition, the amount of tomato fruit produced by each plant is noted at the end of the experiment (week 20).

Did treating the plants with fertilizers increase the fruit production?

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Consider the hypothesis. Did the plants treated with brand X produce more fruit than those treated with brand Y?

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Yes. The fertilizer-treated plants produced about twice as many tomatoes as the control plants.

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No. The plants treated with brand X produced slightly less fruit than those treated with brand Y.

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What would you conclude about the company’s claims regarding brand X? Remember that the company claimed brand X causes plants to grow faster and produce more fruit than brand Y.

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Your wording may vary.

The results of this study showed that while the company’s claim that plants treated with brand X grow faster may be true, its claim that the plants will produce more fruit than brand Y is not true.

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A student tests the hypothesis that lack of vitamin C will reduce growth in mammals. He takes two mice and puts them in separate cages. One mouse has normal food and the other mouse has food that has no vitamin C. Both mice have the same amounts of water available, the same room temperature, and the same day/night cycles. The student weighs each mouse weekly for two months. The data are shown in the table.

In a lab report, the student concludes that the hypothesis was incorrect. Which statement regarding the student’s experiment is true?

A. Measuring the weight of mice was not appropriate to test the hypothesis.

B. The weight of the mouse on the normal diet was not significantly different from that of the mouse on the vitamin C-deficient diet.

C. The experiment had no control.

D. The sample size was insufficient to test the hypothesis.

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The correct answer is choice D. A single mouse in each group was not sufficient to make a generalization that the hypothesis was true or false.

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A survey asks 100 respondents to rate how well they like a particular brand of cereal on a scale of 1 to 4. One (1) represented “Did not like at all,” 2 represented “Did not like or dislike,” 3 represented “Liked,” and 4 represented “Liked very much.” The responses were 10, 25, 35, and 30 for responses 1, 2, 3, and 4 respectively. You see that the responses are grouped into distinct categories (1, 2, 3, or 4). So, this is categorical data. One way to visually express this data is to organize it into a table. The first column contains the category of response. This column is usually the independent variable. In contrast, the second column contains the total number of respondents in that category, which is the dependent variable. The table would look like this:

The table allows you to see the data easily. What would you conclude from the data?

The majority of consumers surveyed

A. did not like the cereal at all.

B. did not like or dislike the cereal.

C. liked the cereal.

D. liked the cereal very much.

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The correct answer is choice C. Thirty-five of the 100 consumers surveyed (or 35%) liked the cereal, which was more than any other response.

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Inside each cell of your body, ribonucleic acid (RNA) contains information to build proteins. A molecule of ribonucleic acid has four nitrogen bases: adenine (A), guanine (G), cytosine (C), and uracil (U). A sequence of three nitrogen bases makes up a codon, which is a unit that codes for one amino acid.

How many distinct codons can be made from the nitrogen bases of RNA?

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Suppose a scientist wanted to make an artificial peptide containing five amino acids (there are 20 possible naturally occurring amino acids that she could use). Without repeating any amino acids, how any permutations are there?

• • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • •

The molecular biologist wants to make an artificial RNA codon of three nitrogen bases without repeating any single base and the order does not matter. How many possible combinations are there?

The answer is 64. There are three nitrogen bases in each codon. Each position can be filled with 1 of 4 nitrogen bases. So, using the fundamental rule of counting, we get:

k₁ · k₂ · k₃ = 4 · 4 · 4 = 64

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There are 1,860,480. For this example, n = 20 and r = 5. So, here’s the calculation:

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The correct answer is 4 combinations. Here’s the solution:

An agricultural scientist conducts 800 trials in crossing pea plants that produce seeds with round seed coats. In these trials, 20 produce seeds with wrinkled seed coats. What is the probability of producing a plant that will yield wrinkled seeds?

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The probability of having a male offspring is 50%, while the probability of having type O positive blood is 37.4%. The two outcomes are independent of each other. What is the probability of having a baby boy with type O positive blood?

A. 18.7%

B. 12.6%

C. 87.4%

D. 50%

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The answer is ¹/₄₀, or 0.025, or 2.5%. Here’s the solution:

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The correct answer is choice A, 18.7%.

Here’s the solution. Let A represent the outcome of having a male child and B represent the outcome of type O+ blood:

P(A and B) = P(A) · P(B)

P(A and B) = 0.5 · 0.374

P(A and B) = 0.1870 = 18.7%

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A biologist measures the size of a population over time. The data are shown in the graph.

Which statement best describes the data?

A. The population is increasing linearly without limits.

B. The population is decreasing exponentially to zero.

C. The population is increasing exponentially without limits.

D. The population is decreasing linearly to zero.

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The correct answer is choice C. The population is increasing nonlinearly, perhaps exponentially, without limits.

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A student reads a lab report on a population growth study. The report contains this graph.

Which best describes the model shown in the graph?

A. sigmoidal function

B. linear function

C. exponential function

D. parabolic function

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In a biology experiment, a student measures the mass of several mice in a control group. The masses (in g) are shown:

19.5, 18.2, 20.1, 20.1, 22.3, 17.9

Which is the median of the data set?

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The correct answer is choice A, sigmoidal function. This graph shows a sigmoidal curve, which is characteristic of population growth with limits from the environment.

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19.8

Here’s the solution. First put the data in order:

17.9, 18.2, 19.5, 20.1, 20.1, 22.3

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The probability of having a female offspring is 50%, while the probability of having type B negative blood is 1.5%. The two outcomes are independent of each other. What is the probability of having a baby girl with type B negative blood?

A. 0.75%

B. 48.5%

C. 50%

D. 51.5%

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The diagram shows the difference between an eye with normal vision and one with nearsighted vision.

Which part of the eye is best described as a layer at the back of the eye containing light-sensitive cells that trigger nerve impulses to the brain?

A. lens

B. pupil

C. retina

D. focus point

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The correct answer is choice A, 0.75%. Here’s the solution. Let A represent the outcome of having a female child and B represent the outcome of type B negative blood:

P(A and B) = P(A) · P(B)

P(A and B) = 0.5 · 0.015

P(A and B) = 0.0075 = 0.75%

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The correct answer is choice C, retina. The retina is defined as a layer of light-sensitive tissue lining the inner surface of the eye at the back of the eyeball. The cells that are sensitive to light trigger nerve impulses that travel along the optic nerve to the brain, where a visual image is formed.

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Water moves easily across cell membranes through special protein-lined channels. If the total concentration of all dissolved solutes is not equal on both sides, there will be a net movement of water molecules into or out of the cell. The diagram shows red blood cells in solutions with three different salt concentrations.

According to this diagram, when will homeostasis occur in red blood cells?

A. when the osmotic pressure of water is equal

B. when the concentration of salt is higher outside the cell

C. when the amount of water inside the cell is higher than outside the cell

D. when the osmotic flow of water out of the cell is greater than salt solution inside the cell

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The correct answer is choice A, when the osmotic pressure of water is equal. When the osmotic pressure outside the red blood cells is the same as the pressure inside the cells, the solution is isotonic with respect to the cytoplasm. This is the usual condition of red blood cells in plasma in a state of homeostasis.

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Refer to the following passage to answer the next three questions.

Tetanus is a non-contagious infection caused by rod-shaped, anaerobic bacteria, Clostridium tetani, or C. tetani, which affects skeletal muscles by releasing an endotoxin manufactured in the outer portion of the cell wall. The toxin infects the central nervous system and causes prolonged muscle spasms. Infection occurs through contamination of wounds and can be prevented by proper immunization. Most developed countries provide tetanus vaccinations as a standard of health care.

Often, tetanus is associated with rust. Rusting occurs when oxygen, water, and iron interact in a process called oxidation. Over time, the iron mass will convert to iron oxide, or rust. A rusted surface provides a thriving environment for organisms with low-oxygen needs.

Tetanus occurs worldwide, but is most common in hot, damp climates with manure-treated soils. C. tetani endospores are widely distributed in the intestines of many animals such as cattle, chickens, and sheep.

Explain how a non-contagious disease, such as tetanus, comes to be so widespread in certain parts of the world. Include multiple pieces of evidence from the text to support your answer.

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Answers may vary.

It is probable that the countries with the highest incidence of tetanus infection are those least likely to vaccinate while also harboring the most favorable soil and climate conditions for C. tetani endospores. Although C. tetani thrives on the low-oxygen surfaces of rusted metals, it is most common in the hot, damp climates of equatorial countries. Developed, vaccinating nations, such as the United States, Canada, and Australia, have low or no reported cases of tetanus. However, tetanus is strongly prevalent in third world countries such as India and those found in Africa. Less developed, third world nations are less likely to immunize people; thus, the rates of tetanus infections are strongly prevalent, even though it is not contagious. Toxins from C. tetani enter unvaccinated bodies through open wounds, attack the central nervous system, and cause prolonged muscle spasms.

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Anaerobic bacteria such as Clostridium tetani use the process of fermentation to obtain nutrition. The bacteria use organic compounds, typically found in the intestinal tracts of animals, to ferment sugars for energy, and produce various acids and alcohol by-products.

Identify the correct products in the fermentation equation that follows the list. Fill in each line with the correct term from the list.

• oxygen

• water

• ethanol

• energy

glucose → ________ + carbon dioxide (+ _______ released)

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The diagram shows some basic components of bacterial cells.

Based on the information in the passage and in the diagram, which cellular component is responsible for both the shape of Clostridium tetani and endotoxin production?

A. DNA

B. cell wall

C. cytoplasm

D. cell membrane

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glucose → ethanol + carbon dioxide (+ energy released)

The first product is ethanol. The phrase “alcohol by-products” clues the choice for the first product. Oxygen is clearly incorrect, as both the preceding paragraph and the passage indicate that the bacteria are anaerobic, and thus cannot use oxygen to respire. Water is a factor in the anaerobic fermentation process in that anaerobes are commonly found and used in waste water treatments, but it is not a component in the simplified fermentation equation.

The second product is energy. The statement “the bacteria use organic compounds, typically found in the intestinal tracts of animals, to ferment sugars for energy” indicates that the purpose of fermentation is to create energy to be released.

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The correct answer is B, cell wall. The cell wall provides rigidity to maintain cell shape. Additionally, endotoxins are produced in the outer portion of the cell wall.

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Refer to the following passage to answer the next three questions.

Bufo marinus, commonly referred to as the cane toad, can measure six to nine inches long and weigh up to four pounds. The cane toad is nocturnal, breeds year-round, and releases a toxin from the shoulders that is fatal to vertebrates. It eats crawling insects, small birds, mammals, and other amphibians, including smaller cane toads. It is native to tropical America, but is permanently established in Australia. In the 1930s, sugarcane farmers imported the toads to Australia in attempts to control cane beetles.

Adult cane beetles measure about 13 millimeters long and are black, hard-shelled, dome-shaped flying insects with strong legs. They eat the leaves of sugarcane while their larvae hatch underground and destroy the plant’s roots. The flying beetles and burrowing larvae are difficult to eradicate. There is no evidence that the introduced cane toads have had any impact on cane beetle populations. Cane toads have, however, had a significant impact on Australian ecology, including the depletion of native species that die when eating cane toads, the poisoning of humans and their pets, and the decline of native animals preyed upon by the toads. While many populations of native species declined in the decades following the introduction of cane toads, some are now beginning to recover. One species of crow has even learned how to eat cane toads from the underbelly in order to avoid the venom.

Which of the following pieces of evidence supports the theory that the behaviors of other organisms are limiting resources for young cane toads?

A. Adult cane toads often prey on juvenile cane toads.

B. Cane beetle larvae are buried underground and are inaccessible to cane toads.

C. Adult cane beetles have heavy exoskeletons and the ability to fly.

D. Cane toad tadpoles can exist only in aquatic environments.

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The correct answer is choice A. Adult cane toads often prey on juvenile cane toads. Adult cane toads could be a limiting factor for the juvenile cane toad population because large cane toads prey on other amphibians, even smaller cane toads.

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Based on the information in the passage, which of these terms best describes the effect seen in crows that eat cane toads?

A. speciation

B. adaptation

C. development

D. homeostasis

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Discuss the impact cane toads have had on the Australian ecosystem. Include multiple pieces of evidence from the text to support your answer.

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The correct answer is choice B, adaptation. Adaptation is the evolutionary process whereby an organism becomes better able to live in its habitat or habitats. Over time, the crows learned a way to prey on cane toads without exposing themselves to the toxins released from the cane toad’s shoulders.

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Answers may vary.

Cane toads are not native to Australia. They were imported about 80 years ago in an attempt to control the cane beetle, a pest that destroys sugarcane. Cane toads had no significant impact on the flying and burrowing beetle. However, they had a devastating impact on Australian ecology that includes the depletion of certain native species. Many species have been in decline for decades and are only recently beginning to recover.

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Refer to the following passage to answer the next three questions.

In a marine ecosystem, there is a unique relationship between corals and the photosynthetic protists that live on the coral reefs. The single-celled protists, called zooxanthellae, live in the tissue of corals and transform large amounts of carbon dioxide into usable energy. The photosynthetic products are used by the corals for metabolic functions or as building blocks in the making of proteins, fats, and carbohydrates.

Although many of a coral’s energy needs are supplied by these zooxanthellae, most corals also capture food particles with their stinging tentacles. Prey ranges in size from small fish to microscopic zooplankton. These food sources supply corals and zooxanthellae with nitrogen.

Based on the passage, corals and zooxanthellae demonstrate which type of symbiotic relationship?

A. mutualism

B. parasitism

C. amensalism

D. commensalism

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The correct answer is choice A, mutualism. The unique mutualism between corals and their photosynthetic zooxanthellae is the driving force behind the settlement, growth, and productivity of coral reefs. This mutualistic relationship is beneficial to the zooxanthellae by providing a host and expelled carbon dioxide for photosynthesis. The corals benefit when they use the products of the zooxanthellae’s photosynthesis for metabolic functions or as building blocks in the making of proteins, fats, and carbohydrates.

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Examine the trophic levels of a marine food web in the diagram. The trophic pyramid groups organisms by the role the organisms play in the food web.

Write the appropriate answers on the lines.

Zooxanthellae are described in the passage as __________.

Based on the trophic levels identified in this pyramid, zooxanthellae would be classified as ___________.

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Zooxanthellae are described in the passage as mutualistic photosynthesizers. Producers are described as autotrophic, which means they are able to make their own food. Just like producers on land, producers in the marine environment convert energy from the sun into food energy through photosynthesis. Phytoplankton are the most abundant and widespread producers in the marine environment.

Based on the trophic levels identified in this pyramid, zooxanthellae would be classified as primary producers. Organisms in food webs are commonly divided into trophic levels. These levels can be illustrated in a trophic pyramid, where organisms are grouped by the roles they play in the food web. For example, the first level forms the base of the pyramid and is made up of producers. The second level is made up of herbivorous consumers, and so on. On average, only 10% of the energy from an organism is transferred to its consumer. The rest is lost as waste, movement energy, heat energy, and so on. As a result, each trophic level supports a smaller number of organisms—in other words, it has less biomass. This means that a top-level consumer, such as a shark, is supported by millions of primary producers from the base of the food web or trophic pyramid.

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The diagram shows a marine food web.

Using the information provided within the passage, identify the organism in the marine food web that supplies coral with energy by circling it.

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The correct answer is zooplankton. The passage states, “Although many of a coral’s energy needs are supplied by these zooxanthellae, most corals also capture food particles with their stinging tentacles. Prey ranges in size from small fish to microscopic zooplankton.” The marine food web clearly depicts an arrow originating with zooplankton that points toward corals. This indicates that the flow of energy moves from zooplankton into corals.

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As seen in the following diagram, living things are highly organized, with specialized structures performing specific functions at every level of organization.

Select the correct sequence of cellular organization. Begin with the most specialized component.

A. red blood cell → blood → heart → cardiovascular system

B. cardiovascular system → heart → blood → red blood cell

C. red blood cell → blood → cardiovascular system → heart

D. heart → cardiovascular system → blood → red blood cell

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The correct answer is choice A: red blood cell → blood → heart → cardiovascular system. The correct sequence moves from most specialized to higher levels of organization.

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The letters shown here show the genotypes of two parents.

Yy × Yy

The Punnett square shows the possible combinations of parent alleles. Write the remaining correct combination of the parent alleles in the empty box.

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Probability is an important skill for figuring out answers to GED Science questions. This is an example of a probability question. Five parts of the human body and two diseases are written on scraps of paper and placed into a hat. What is the probability of picking a disease out of the hat?

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Judy measured the heights of several seedlings that she used in a control group of an experiment. The heights in cm were: 9.9, 10.2, 10.6, 9.3, 10.2, 10.2, 10.0.

What is the mean?

The correct answer is yy. In a Punnett square, the alleles combine, one from the side and one from the top, in each box. The two lowercase “y” alleles combine in the bottom right box of the Punnett square, indicating that a recessive phenotype is possible when two heterozygous genotypes combine.

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The event is choosing one of the two diseases rather than one of the five parts of the human body. This is what you want to answer:

1. The number of outcomes is the total number of scraps of paper, 7.

2. There are 2 diseases.

3. 2 ÷ 7 = 0.2857

The probability of picking a disease is 29% of the time.

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The mean is 10.1.

Let’s arrange the values in ascending order: 9.3, 9.9, 10.0, 10.2, 10.2, 10.2, 10.6.

The first descriptor is the mean (X) or average. It is calculated by adding up all the values and dividing the sum (Σx) by the number of values (n):

Judy measured the heights of several seedlings that she used in a control group of an experiment. The heights in cm were: 9.9, 10.2, 10.6, 9.3, 10.2, 10.2, 10.0.

What is the median?

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Judy measured the heights of several seedlings that she used in a control group of an experiment. The heights in cm were: 9.9, 10.2, 10.6, 9.3, 10.2, 10.2, 10.0.

What is the mode?

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What is the endoplasmic reticulum?

The second descriptor is the median or middle value. If n is an odd number, then the median value is easy to spot. If n is an even number, then the median is the average of the center two values. In this example, n is odd so the median is easy to spot. The median is 10.2.

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The third descriptor is the mode, which is the most frequent value. In this example, there are three values of 10.2 and one each of all the others. Therefore, the mode is 10.2.

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An organelle that is used to transport proteins throughout the cell.

What does inorganic mean?

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What is mitosis?

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What is meiosis?

A material that is neither plant nor animal in origin.

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A process of cellular reproduction in which cells produce genetically identical offspring.

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A process of cellular reproduction where the daughter cells have half the amount of chromosomes. This is used for purposes of sexual reproduction to produce sex cells that will be able to form an offspring with a complete set of chromosomes with different DNA than the parents.

What is a nucleotide?

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What is phloem?

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What is protein synthesis?

The smallest unit of DNA. There are five different types of nucleotides: adenine, guanine, thymine, cytosine, and uracil. The arrangement of genes is based directly on the specific arrangement of nucleotides.

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Vascular tissue found in plants that transports mostly sugar and water; can travel either “shoot to root” or “root to shoot.”

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A process by which DNA will transport its information by way of RNA to the ribosomes where proteins will be assembled.

What are veins?

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In plants, veins are found in the leaves. They are sometimes called the vascular bundle, which contains the xylem and phloem. In animals, veins are tubelike tissue that usually transports blood.

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Refer to the following passage to answer the next six questions.

A student is creating a science experiment for the science fair to research whether temperature affects the growth of tadpoles. He collects nine newly born tadpoles and separates them into three groups. He measures the size of each tadpole in each group, places them in equal amounts of water that is changed at the same time for each container, and feeds them equal quantities and types of food. In the first container, he maintains the temperature at 80 degrees. In the second container, he maintains the temperature at 68 degrees. The final container is left at room temperature, which varies around 75 degrees. Just as the tadpoles get to the twelfth week of their life cycle, the student measures the sizes of the tadpoles to determine whether the temperatures affected their overall growth.

What is the hypothesis?

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What is the independent variable?

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What is the dependent variable?

That the tadpoles’ size will be affected in some form by the temperature of the water.

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The temperature of the water in each container.

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The final measured sizes of the tadpoles.

What were the other variables and were they controlled?

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Was the number of samples adequate?

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Overall, was the experimental design appropriate to test the hypothesis?

The food and water quantities were also possible variables but were equal for each container.

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Nine tadpoles was probably not an adequate number for this experiment and the student would have been better able to confirm his hypothesis with more tadpoles.

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The design was appropriate, but the number of samples needed to be increased to confirm the hypothesis.