5 Steps to a 5: AP Biology 2017 (2016)
Review the Knowledge You Need to Score High
Taxonomy and Classification
IN THIS CHAPTER
Summary: This chapter discusses Linnaeus’s binomial system of classification and taxonomy in general. It gives information about each of the kingdoms (Monera, Protista, Plantae, Fungi, and Animalia).
Do not spend countless hours memorizing every detail about these various kingdoms. If you have time to burn and really want to learn all the details—go for it. If you are pressed for time, focus in on the basic and important information about each kingdom.
The seven categories of classification listed from broadest to most specific: kingdom–phylum–class–order–family–genus–species.
Autotrophs are the producers of the world; heterotrophs are the consumers.
The endosymbiotic theory states that eukaryotic cells originated from a symbiotic partnership of prokaryotic cells.
Be sure to learn the evolutionary relationships within each kingdom—this is fair game for a free-response question.
Taxonomy is the brainchild of Linnaeus, who came up with a binomial system of classification in which each species was given a two-word name. The first word describes the genus —the group to which the species belongs. The second word is the name of the particular species . For example, Homo sapiens is the binomial system name for humans.
Taxonomy is the field of biology that classifies organisms according to the presence or absence of shared characteristics in an effort to discover evolutionary relationships among species. A taxon is a category that organisms are placed into and can be any of the levels of the hierarchy. There are seven common categories of classification; listed from broadest to most specific, they are kingdom, phylum, class, order, family, genus, species. A way to remember this sequence is through the use of a silly sentence such as this:
“K araoke p layers c an o rder f ree g rape s oda” or
“K ing P hillip c ame o ver f or g ood s paghetti.”
A kingdom consists of organisms that share characteristics such as cell structure, level of cell specialization, and mechanisms to obtain nutrients. Kingdoms are split into phyla, which are split into classes, which are further divided into orders . Orders are split into families, which are made up of the different genera . The final and most specific division is the species . This is the only naturally occurring taxon. These seven categories apply to many but not all organisms. The plant kingdom has divisions instead of phyla. Bacterial species tend to be placed into groups called strains.
BIG IDEA 1.B.2
Phylogenetic trees are visual representations of ancestry .
Five or Six Kingdoms?
The current system of classification is a five-kingdom system that divides all the organisms of the planet into one of five kingdoms: Monera, Protista, Plantae, Fungi, and Animalia. Do not be confused or alarmed if you hear mention of a six-kingdom system. The difference in the six-kingdom system is that the kingdom Monera is split into Eubacteria and Archaebacteria. Other than that, the kingdom delineations are similar. Let’s begin the tour of the various kingdoms with the kingdom Monera.
The members of this kingdom are prokaryotes: single-celled organisms that have no nucleus or membrane-bound organelles. Since this chapter is an exercise in painful amounts of classification, subclassification, and further classification based on the previous classification of classifications, and so on, we thought we would point out a few of the many different ways that the kingdom Monera can be subdivided. The Monera kingdom can be further classified by nutritional class, reactivity with oxygen, and whether they are eubacteria or archaebacteria.
Moneran organisms can be classified as either autotrophs or heterotrophs. Autotrophs are the producers of the world:
1. Photoautotrophs: photosynthetic autotrophs (used to be called blue-green algae) that produce energy from light.
2. Chemoautotrophs: produce energy from inorganic substances (e.g., S bacteria).
Heterotrophs are the consumers of the world. Examples of prokaryotic heterotrophs, including parasitic bacteria that feed off hosts, and saprobes, such as bacteria of decay, which feed off dead organisms.
Reactivity with Oxygen
A second way to classify moneran organisms is by their ability to react with oxygen: whether they must react with oxygen to survive, whether they must be without oxygen to survive, or if they can survive with or without oxygen. There are three classes of oxygen reactivity: obligate aerobes and obligate anaerobes at the two extremes of the spectrum, and facultative anaerobes somewhere in between. Obligate aerobes require oxygen for respiration—they must have oxygen to grow; obligate anaerobes must avoid oxygen like the plague—oxygen is a poison to them; facultative anaerobes are happy to use O2 when available, but can survive without it.
Archaebacteria Versus Eubacteria
There are two major branches of prokaryotic evolution: Eubacteria and Archaebacteria. Archaebacteria tend to live in extreme environments and are thought to resemble the first cells of the earth. The major examples you should be familiar with include (1) extreme halophiles —these are the “salt lovers” and live in environments with high salt concentrations, (2) methanogens —bacteria that produce methane as a by-product, and (3) thermoacidophiles —bacteria that love hot, acidic environments.
Eubacteria are categorized according to their mode of acquiring nutrients, their mechanism of movement, and their shape, among other things. The following is a list of the names of a few groups of bacteria that you should be familiar with for the AP exam:
2. Gram-positive bacteria
6. Chemosynthetic bacteria
7. Nitrogen-fixing bacteria
The three basic shapes of bacteria you might want to be familiar with include:
1. Rod-shaped bacteria: also known as bacilli (e.g., Bacillus anthracis, the bug that causes anthrax).
2. Spiral-shaped bacteria: also known as spirilla (e.g., Treponema pallidum, the bug that causes syphilis).
3. Sphere-shaped bacteria: also known as cocci (e.g., Streptococcus, the fine bug that gives us strep throat).
To summarize, the kingdom Monera can be subdivided according to the following characteristics:
Bill (11th grade): “Important concept to know.”
The endosymbiotic theory states that eukaryotic cells originated from a symbiotic partnership of prokaryotic cells. This theory focuses on the origin of mitochondria and chloroplasts from aerobic heterotrophic and photosynthetic prokaryotes, respectively.
We can see why scientists examining these two organelles would think that they may have originated from prokaryotes. They share many characteristics: (1) they are the same size as eubacteria, (2) they also reproduce in the same way as prokaryotes (binary fission), and (3), if their ribosomes are sliced open and studied, they are found to more closely resemble those of a prokaryote than those of a eukaryote. They are prokaryotic groupies living in a eukaryotic world.
The eukaryotic organism that scientists believe most closely resembles prokaryotes is the archezoa, which does not have mitochondria. One phylum grouped with the archezoa is the diplomonads. A good example of a diplomonad you should remember is Giardia —an infectious agent you would do well to avoid. Giardia is a parasitic organism that takes hold in your intestines and essentially denies your body the ability to absorb any fat. This infection makes for very uncomfortable and unpleasant GI (gastrointestinal) issues and usually results from the ingestion of contaminated water.
The evolution of protists from prokaryotes gave rise to the characteristics that make eukaryotes different from their prokaryotic predecessors. Protists were around a long time before fungi, plants, or animals graced our planet with their presence. Most protists use aerobic metabolism. Since this is a chapter on classification, it would be silly, if not too kind of us, to not mention how these different protists are organized. They are usually grouped into three major categories:
1. Animal-like protists: heterotrophic protists, also called protozoa
2. Funguslike protists: protists that resemble fungi; also called absorptive protists
3. Plantlike protists: photosynthetic protists, also called algae
Protists are usually unicellular or colonial. This is why they are not considered plants, animals, or fungi. All protists are capable of asexual reproduction. Some reproduce only asexually, and others can reproduce sexually as well. This variability in the life cycles found among various members of the protist kingdom is just one reason why they are considered to be one of the most diverse kingdoms in existence.
Animal-Like Protists (Protozoa)
This division includes protists that ingest foods—as do animals. As with the rest of this chapter, you do not need to become an expert on protozoans and know everything about every member. But the following is a list that contains basic information about some names that may help you on the multiple-choice section of the test. We will italicize the most important things to remember about each of them.
1. Rhizopoda . These unicellular and asexual organisms are also known as amoebas . They get from place to place through the use of pseudopods, which are extensions from their cells. Every living creature has to eat, and they do so through phagocytosis .
2. Foraminifera . These marine protists live attached to structures such as rocks and algae. Their name is derived from the word foramen because of the presence of calcium carbonate (CaCO3 ) shells full of holes. Some of these protists obtain nutrients through photosynthesis performed by symbiotic algae living in their shells.
3. Actinopoda . These organisms move by pseudopodia and make up part of plankton, the organisms that drift near the surface of bodies of water. The two divisions of actinopoda include heliozoans and radiozoans. Just recognize the names; do not worry about anything more than that.
4. Apicomplexa . These parasites are the protists formerly known as sporozoans. They spread from place to place in a small infectious form known as a sporozoite. They have both sexual and asexual stages, and their life cycle requires two different host species for completion. An example of an apicomplexa is plasmodium, the causative agent of malaria (two hosts—mosquitoes, then humans).
5. Zooflagellates . These heterotrophic protists are known for their flagella, which they use to move around. Like rhizopoda, they eat by phagocytosis and can range from being parasitic to their hosts to living mutualistically with them. A member of this group is trypanosoma , which is known to cause African sleeping sickness.
6. Ciliophora . Their name is fitting because these protists use cilia to travel from place to place. They live in water and contain two types of nuclei: a macronucleus (which controls everyday activities) and many micronuclei (a function in conjugation ). A ciliaphora you may recognize is paramecium.
Fungus-Like Protists (Slime Molds and Water Molds)
This division includes protists that resemble fungi. Once again, we are going to provide a list that contains basic information about some names that may help you on multiple-choice questions. The most important things to remember are boldfaced or italicized .
1. Myxogastria . These heterotrophic , brightly colored protists include the plasmodial slime molds and are not photosynthetic. Unlike the acrasidae, they do not like to eat alone—they eat and grow as a single clumped unicellularmass known as a plasmodium (same name as the causative agent of malaria, but this entity does not cause malaria). This mass ingests food by phagocytosis . When Mother Hubbard’s cupboard is bare and there is no more food, the plasmodium stops growing and instead produces spores that allow the protist to reproduce.
2. Acrasidae . Known to their closer friends as cellular slime molds, these protists have a bit of a strange eating strategy. When there is plenty of food around, these organisms eat alone as solitary beings, but when food becomes scarce, they clump together in a manner similar to slime molds and work together as a unit.
3. Oomycota . These water-mold protists can be parasites or saprobes . They are able to munch on their surrounding environment owing to the presence of filaments known as hyphae , which release digestive enzymes. They are often multicellular, or coenocytic . One difference between these organisms and actual fungi is that their cell wall is made of cellulose, and not chitin as seen in fungi.
This division includes protists that are mostly photosynthetic. All of these organisms contain chlorophyll a . Focus your attention on the italicized points.
1. Dinoflagellata . Protists known for having two flagella that rest perpendicular to each other, and which allow them to swim with a funky spinning motion that makes them the envy of all other protist observers (or at least makes them really dizzy). Most dinoflagellates are unicellular . These protists are very important producers in many aquatic food chains.
2. Golden algae . Known as the chrysophyta, these protists move through the use of flagella and can also be found swimming among plankton.
3. Diatoms . These yellow and brown protists are also known as bacillariophyta and are a major component of plankton. They mostly reproduce in an asexual fashion, although they do rarely enter a sexual life cycle. They have ornate walls made of silica to protect them.
4. Green algae . Known as chlorophyta, they have chlorophyll a and b . Most of these protists live in freshwater and can be found among the algae that are part of the mutualistic lichen conglomerate. Most have both asexual and sexual reproductive stages. These organisms are considered to be the ancestors of plants.
5. Brown algae . Known as phaeophyta, most of these protists are multicellular and live in marine environments. Two members to know are kelp and seaweed .
6. Red algae . Known as rhodophyta, they get their color from a pigment called phycobilin . Most of these multicellular protists live in the ocean and produce gametes that do not have flagella. Many live in deep waters and absorb nonvisible light via accessory pigments.
Classification of plants is very similar to classification of the animal kingdom, except that plants are divided into divisions instead of phyla. So, instead of “Karaoke players can order free grape soda,” remember “Karaoke dancerscan order free grape soda.”
Reality again, folks . . . you do not need to become experts in the evolutionary history of plants, but you should be able to understand a phylogenetic representation of how the various plant types evolved.
Chlorophytes→bryophytes→seedless vascular plants→gymnosperms→angiosperms
Chlorophytes are green algae. Scientists have found enough evidence to conclude that they are the common ancestors of land plants. Plants are said to have experienced four major evolutionary periods since the dawn of time, described in the following sections.
CT teacher: “Know plant evolution very well. There are a lot of potential questions here. Including essays.”
Bryophytes were the first land plants to evolve from the chlorophytes. They include mosses, liverworts, and hornworts. Prior to bryophytes, there was no reason for these organisms to worry about water loss because they lived in water and had unlimited access to the treasured resource. But in order to survive on land, where water was no longer unlimited, two evolutionary adaptations in particular helped them survive:
1. A waxy cuticle cover to protect against water loss.
2. The packaging of gametes in structures known as gametangia.
Bryophyte sperm is produced by the male gametangia, the antheridia. Bryophyte eggs are produced by the female gametangia, the archegonium. The gametangia provide a safe haven because the fertilization and development of the zygote occur within the protected structure.
Because they lack xylem and phloem, bryophytes are also known as nonvascular plants . This lack of vascular tissue combined with the existence of flagellated sperm results in a dependence on water. For this reason, bryophytes must live in damp areas so they do not dry out. There are three nonvascular plants you should know about: mosses, liverworts, and hornworts. Mosses are special in that, unlike all other plants, the dominant generation in their life cycle is the haploid gametophyte. The moss sporophyte is tiny, short lived, and reliant on the gametophyte for nutritional support. One interesting fact about liverworts is that in addition to the alternation of generations life cycle, they are able to reproduce asexually.
Seedless Vascular Plants
The transition for plants from water to land was a tricky one. They needed to find a way to use the nutritional resources of the minerals and water found in soil, while not denying themselves access to the light needed for photosynthesis. Another problem facing these early land plants was the need to find a way to distribute water and nutrients throughout the plant—not as much of an issue when the plant was submerged in water. The solution to this issue was the development of the xylem and phloem, which you will read about in Chapter 14 , Plants. The xylem is the water superhighway for the plant, transporting water throughout the plant. The phloem is the sugar food highway for the plant, transporting sugar and nutrients to the various plant structures.
The first vascular plants (also referred to as tracheophytes ) to evolve did not have seeds. Two major evolutionary changes occurred that allowed the transition from bryophytes to seedless vascular plants:
1. The switch from the gametophyte to the sporophyte as the dominant generation of the life cycle.
2. The development of branched sporophytes, increasing the number of spores produced.
The major seedless vascular plants you should know are ferns, which are homosporous plants that produce a single spore type that gives rise to bisexual gametophytes. The spores tend to exist on the underside of the fern leaves. A heterosporous plant produces two types of spores, some of which yield male gametophytes (microspores ), and others produce female gametophytes (megaspores ). The dominant generation for ferns is the sporophyte.
The third major plant category to branch off the phylogenetic tree is the seed plant. Three major evolutionary changes occurred between the seedless vascular plants and the birth of seed plants:
1. Further decline in the prominence of the gametophyte generation of the life cycle.
2. The birth of pollination.
3. The evolution of the seed.
A seed is a package containing an embryo and the food to feed the developing embryo that is surrounded by a nice protective shell. The first major seed plants to surface were the gymnosperms. These plants are heterosporous and usually transport their sperm through the use of pollen —the sperm-bearing male gametophyte. Not all gymnosperms have pollen; some have motile sperm. The major gymnosperms you should remember are the conifers, plants whose reproductive structure is a cone. Members of this division include pine trees, firs, cedars, and redwoods. These plants survive well in dry conditions and keep their leaves year-round. They are evergreens and usually have needles for leaves.
The final major plant evolutionary category to branch off the phylogenetic tree is the flowering plant. Today there are more angiosperms around than any other kind of plant. There are two major classes of angiosperms to know: monocots (monocotyledons ) and dicots (dicotyledons ). A cotyledon is a structure that provides nourishment for a developing plant. One distinction between monocots and dicots is that monocots have a single cotyledon, while dicots have two.
One interesting evolutionary change from the gymnosperm to the angiosperm is the adaptation of the xylem. In gymnosperms, the xylem cells in charge of water transport are the tracheid cells, whereas in angiosperms, the xylem cells are the more efficient vessel elements. Don’t worry too much about this distinction, but store away in the back of your mind that vessel elements are seen in angiosperms, while tracheid cells are seen in gymnosperms.
What are flowers, really? Are they just another visually pleasing structure? No . . . they are so much more. Flowers are the main tools for angiosperm reproduction. Do not waste too much time learning every little part of a flower. Here are the most important parts to remember:
Stamen: male structure composed of an anther, which produces pollen.
Carpel: female structure that consists of an ovary, a style, and a stigma. The stigma functions as the receiver of the pollen, and the style is the pathway leading to the ovary.
Petals: structures that serve to attract pollinators to help increase the plant’s reproductive success.
Below is a quick display that lists many of the major evolutionary trends observed during the phylogenetic development of plants.
Remember these evolutionary trends seen in plants!
• Dominant gametophyte generation → dominant sporophyte generation
• Nonvascular → vascular
• Seedless → seeds
• Motile sperm → pollen
• Naked seeds → seeds in flowers
Nearly all fungi are multicellular and are built from filamentous structures called hyphae. These hyphae form meshes of branching filaments known as a mycelium, which function as mouthlike structures for the fungus, absorbing food. Many fungi contain septae, which divide the hyphae filaments into different compartments. The septa have pores, which allow organelles and other structures to flow from compartment to compartment. Fungi that do not contain septae are called coenocytic fungi. Fungus walls are built using the polysaccharide chitin. As was discussed in Chapter 9 , Cell Division, the fungus life cycle is predominately haploid. The only time they are diploid is as the 2n zygote.
The following is a list of fungus-related organisms that you should know:
1. Zygomycota . These coenocytic and land-dwelling fungi have very few septa and reproduce sexually. A classic example of a zygomycete is bread mold.
2. Basidiomycota . These club-shaped fungi are known for their haploid basidiospores and love of decomposing wood. Famous members include mushrooms and rusts.
3. Ascomycota . Many members of this group of saprobic fungi live as part of the symbiotic relationship called lichen. These fungi produce sexual ascospores, which are contained in sacs. Famous ascomycetes you may have heard of are yeasts and mildews. These are discussed again in Chapter 19 , Laboratory Review.
4. Lichens . These are formed by a symbiotic association of photosynthetic organisms grouped together with fungal hyphae (usually an ascomycete ). The algae member of this group tends to be cyanobacteria or chlorophyta and provides the food (sugar from photosynthesis). The fungus provides protection and drink (water).
5. Molds . These are asexual, quick-growing fungi known as deuteromycota or the “imperfect fungi.” If you check any college refrigerator, you can find many fine samples of this organism.
6. Yeasts . These are unicellular fungi that can be asexual or sexual. One member of this group, Candida, is known to cause yeast infections in humans.
Animals are the final kingdom to be discussed in this chapter. There are some characteristics that separate animals from other organisms:
As is the case with all of the other kingdoms in this chapter, you do not need to become the master of animal phylogeny and taxonomy. But it is definitely useful to know the general evolutionary history of the animal kingdom and how it diversified so quickly over time (Figure 13.1 ).
Figure 13.1 The animal phylogenetic tree.
Many people believe that the original common ancestor that started the whole process of animal evolution was most likely the choanoflagellate. During the evolutionary progression from choanoflagellate to the present, there have been four major branchpoints on which you should focus. Let’s take a look at all the important changes that have allowed such diversity of life.
The first major branchpoint occurred after the development of multicellularity from choanoflagellates. Off this branch of the tree emerged two divisions:
1. Parazoa: sponges; these organisms have no true tissues.
2. Eumetazoa: all the other animals with true tissue.
After this split into parazoa and eumetazoa, the second major branchpoint in animal evolutionary history occurred: the subdivision of eumetazoa into two further branches on the basis of body symmetry. The eumetezoans were subdivided into
1. Radiata: those that have radial symmetry, which means that they have a single orientation. This can be a top, a bottom, or a front and back. This branch includes jellyfish, corals, and hydras.
2. Bilateria: those that have bilateral symmetry, which means that they have a top and a bottom (dorsal/ventral) as well as a head and a tail (anterior/posterior).
The next major split in the phylogenetic tree for animal development involved the split of bilateral organisms into two further branches—one of which subdivides into two smaller branches:
1. Acoelomates: animals with no blood vascular system and lacking a cavity between the gut and outer body wall. An example of a member of this group is the flatworm.
2. Animals with a vascular system and a body cavity.
• Pseudocoelomates: animals that have a fluid-filled body cavity that is not enclosed by mesoderm. Roundworms are a member of this branch.
• Coelomates: a coelom is a fluid-filled body cavity found between the body wall and gut that has a lining. It comes from the mesoderm.
The final major branchpoint comes off from the coelomates. It branches into two more divisions:
1. Protostomes: a bilateral animal whose first embryonic indentation eventually develops into a mouth . Prominent members of this society include annelids, arthropods, and mullusks .
2. Deuterostomes: a branch that includes chordates and echinoderms . The first indentation for their embryos eventually develops into the anus .
These two divisions differ in their embryonic developmental stages. As already mentioned, the protostomes’ first embryonic indent develops into the mouth, whereas for the dueterostome, it becomes the anus. Another difference is the angle of the cleavages that occur during the early cleavage division of the embryo. A third difference is the tissue from which the coelom divides.
That concludes the evolutionary development portion of this chapter. Now let’s take a quick look at a few members of the various branches we mentioned above.
1. Porifera (sponges ). These are simple creatures, which, for the most part, are able to perform both male and female sexual functions. They have no “true tissue,” which means that they do not have organs, and their cells do not seem to be specialized in function.
2. Cnidaria . These organisms are of radial symmetry and include jellyfish and coral animals, and they lack a mesoderm . A cnidarian’s body is a digestive sac that can be one of two types: a polyp or a medusa. A polyp (asexual) is cylinder shaped and lives attached to some surface (sea anemones). A medusa (sexual) is flat and roams the waters looking for food (jellyfish). Cnidarians use tentacles to capture and eat prey.
3. Platyhelminthes . These are flatworms, members of the acoelomate club. They have bilateral symmetry and a touch of cephalization . There are three main types of flatworms you should be familiar with:
• Flukes: parasitic flatworms that alternate between sexual and asexual reproduction life cycles.
• Planarians: free-living carnivores that live in water.
• Tapeworms: parasitic flatworms whose adult form lives in vertebrates, including us (humans).
4. Rotifera . These are also members of the pseudocoelomate club; they have specialized organs, a full digestive tract, and are very tiny.
5. Nematoda . These are roundworms, found in moist environments. They have a psuedocoelomate body plan. Trichinosis, a disease found in humans, is caused by a roundworm that infects meat products, usually pork. Humans ingesting infected meat can become affected with this disease.
6. Mollusca . These creatures are members of the protostome division and include such species as snails, slugs, octopuses, and squids. They are coelomates with a full digestive system. Bivalves, such as clams and oysters, are mollusks that have hinged shells that are divided into two parts.
7. Annelida . These are segmented worms such as earthworms and leeches.
8. Arthropoda . This is the most heavily represented group on the planet. These creatures are segmented, contain a hard exoskeleton constructed out of chitin, and have specialized appendages . Some well-known members include spiders, crustaceans, and insects. One interesting tidbit about arthropods is that, like humans, some members of this group, when born, are miniature versions of their adult selves that grow in size to resemble adults. Others look completely different from adults and exist in a larva form in their youth. At some point, the larvae undergo a metamorphosis and change to the expected adult form.
9. Echinodermata . These are sea stars . These coelomates are of the dueterostome body plan. One neat characteristic of echinoderms is the presence of a water vascular system, which is a series of tubes and canals within the organism, that plays a role in ingestion of food, movement of the organism, and gas exchange.
10. Chordata . This group includes invertebrates (animals lacking backbones), and vertebrates (animals with backbones). Just in case you are asked to identify some vertebrates on a multiple-choice question, here are some members—fish, amphibians, reptiles, birds, and mammals. There are four features common to chordates you should know:
• Dorsal hollow nerve cord: forms the nervous system and becomes the brain and spinal cord in some.
• Notochord: long support rod that is replaced by bone in most (mesodermal in origin).
• Pharyngeal gill slits: slit-containing structure, which functions in respiration and feeding, present only in the embryonic stage of most chordates.
• Tail: extension past the anus that is lost by birth in many species.
1 . Which of the following is thought to be the common ancestor to plants?
2 . Which of the following pairs of organisms is most closely interrelated?
A. Sponge and halophile
B. Jellyfish and coral
C. Oyster and conifer
D. Lichen and roundworm
E. Bryophyte and mold
3 . Which of the following was an evolutionary adaptation vital to the survival of the bryophytes?
A. The switch from the gametophyte to the sporophyte as the dominant generation of the life cycle
B. The development of branched sporophytes
C. The birth of pollination
D. The packaging of gametes into gametangia
E. Evolution of the seed
4 . Which of the following is the most specific category of classification?
5 . Which of the following is not associated with flowers?
6 . Which of the following was the latest to branch off the animal phylogenetic tree?
For questions 7–10, please use the following answer choices:
A. Kingdom Animalia
B. Kingdom Fungi
C. Kingdom Plantae
D. Kingdom Protista
E. Kingdom Monera
7 . Thermoacidophiles are grouped into this kingdom that consists of single-celled organisms lacking nuclei and membrane-bound organelles.
8 . Arthropods are grouped into this kingdom whose members are multicellular heterotrophs that have the diploid stage as their dominant generation in the life cycle.
9 . This kingdom is divided into plant-like, animal-like, and fungus-like divisions.
10 . Molds, or deuteromycota, are grouped into this kingdom that consists of mostly multicellular organisms that are constructed out of hypha.
Answers and Explanations
1 . D —Chlorophytes are green algae that are the common ancestors of land plants. Chemoautotrophs are monerans that produce energy from inorganic substances. Choanoflagellates are the organisms thought to be the starting point for the animal kingdom’s phylogenetic tree. Chordata includes the invertebrates and vertebrates, and cnidarians are radially symmetric organisms such as jellyfish.
2 . B —Jellyfish and coral are both cnidarians of the animal kingdom.
3 . D —Since the bryophytes were the first plants to brave the land, they were still somewhat dependent on water and also needed protection for their gametes. The gametangia provided a safe haven for the gametes where fertilization and zygote development could occur. Answer choices A and B were adaptations made by seedless vascular plants. Answer choices C and E were adaptations made by the gymnosperms.
4 . B —K araoke p layers c an o rder f ree g rape s oda or K ing P hillip c ame o ver f or g ood s paghetti (enough said).
5 . D —Hyphae are associated with fungi. The other parts are all associated with flowers.
6 . E —Take a look at Figure 13.1 for this one; the deuterostomes were indeed the last to branch off.
7 . E
8 . A
9 . D
10 . B
Quickly review the following terms:
Taxonomy: Classification of organisms based upon the presence or absence of shared characteristics: kingdom → phylum (division) → class → order → family → genus → species.
Five-kingdom system: Monera → Protista → Plantae → Fungi → Animalia.
Six-kingdom system: Archaebacteria → Eubacteria → Protista → Plantae → Fungi → Animalia.
Autotrophs (producers) versus heterotrophs (consumers).
Obligate aerobes (require O2 ) versus obligate anaerobes (no O2 ) versus facultative anaerobes (either or).
Archaebacteria: halophiles (salt), methanogens (methane-producers), thermoacidophiles (hot and acidic).
Eubacteria: bacteria classified according to movement, shape, nutritional methods.
Endosymbiotic theory: eukaryotes originated from a symbiotic partnership of prokaryotic cells.
Plant-like protists: photosynthetic algae; all contain chlorophyll a .
Animal-like protists: heterotrophic protists (protozoa).
Fungus-like protists: absorptive protists that resemble fungi.
Chlorophytes: green algae that are the common ancestor of land plants.
Bryophytes: first land plants; two important adaptations—waxy cuticle (stop water loss), gametangia:
• Gametangia: protective structures to aid survival of gametes on land.
• Mosses: important bryophyte, dominant life cycle generation is a haploid gametophyte.
Seedless vascular plants: came after bryophytes and had two further changes:
• Switch from haploid gametophyte to diploid sporophyte as dominant generation.
• Development of branched sporophytes.
• Ferns: important member, homosporous (bisexual gametophytes).
Gymnosperm: came after seedless vascular plants and had three evolutionary adaptations:
• Further increase in dominance of sporophyte generation.
• Birth of pollination.
• Evolution of the seed.
Conifers: plants whose reproductive structure is a cone.
Angiosperm: flowering plants that came after gymnosperms divided into monocots and dicots.
Multicellular, built from hyphae, which can be separated by septae. Fungus walls are constructed from chitin.
Life cycle is predominately haploid.
Important characteristics: no cell walls, 2n is dominant, mobile, multicellular, heterotrophic, gastrulation.
Four major branchpoints (Figure 13.1 ).
Common ancestor: choanoflagellate.
Important members (in order of split from phylogenetic tree): sponges (parazoa), jellyfish (Radiata), flatworms (Acoelomates), roundworms (Pseudocoelomate nematodes), arthropods (protostomes), humans (Chordates).
Skim the information by each subdivision of this kingdom earlier in this chapter for more information.
Taxonomy and Classification
1 . Which of the following organisms are able to use oxygen available in the environment but are also able to survive in the absence of oxygen?
(A) Obligate aerobes
(B) Facultative anaerobes
(C) Obligate anaerobes
2 . Which of the following are unicellular and asexual organisms that get from place to place through the use of pseudopods and eat via phagocytosis?
3 . Which of the following represents the correct phylogenetic order of how the various plant types evolved?
(A) Bryophytes → chlorophytes → gymnosperms → angiosperms → seedless vascular plants
(B) Chlorophytes → bryophytes → seedless vascular plants → gymnosperms → angiosperms
(C) Chlorophytes → bryophytes → gymnosperms → seedless vascular plants → angiosperms
(D) Bryophytes → chlorophytes → seedless vascular plants → gymnosperms → angiosperms
4 . Platyhelminthes, which are acoelomates that have bilateral symmetry, are grouped into which kingdom?
Answers and Explanations
1 . B —Obligate aerobes require oxygen for respiration. Obligate anaerobes must avoid oxygen like the plague. Thermoacidophiles are bacteria that love hot, acidic environments.
2 . A —Foraminifera are marine protists that live attached to structures such as rocks and algae. Some obtain their nutrition via photosynthesis performed by symbiotic algae living in their shells. Zooflagellates are heterotophic protists known for their flagella, which they use to move around. Ciliophora use cilia to travel from place to place.
3 . B —Scientists have found enough evidence to conclude that chlorophytes are the common ancestor of land plants.