Cracking the AP Biology Exam




Directions: Each of the questions or incomplete statements below is followed by five suggested answers or completions. Select the one that is best in each case. Answers can be found on this page.

1. In pea plants, the allele for smooth seeds (S) is dominant over the allele for wrinkled seeds (s). In an experiment, when two hybrids are crossed, what percent of the offspring share the same genotype as the parents?

(A) 0%

(B) 25%

(C) 50%

(D) 75%

(E) 100%

2. An organism has three independently assorting traits AaBbCc. What fraction of its gametes will contain the recessive genes abc?

(A) 0





3. Which of the following findings provides the best evidence that an abnormal trait is sex-linked?

(A) The trait always skips a generation.

(B) Some members of a family are carriers of the disease.

(C) The trait appears in all of the offspring.

(D) The trait is passed from mother to daughters.

(E) The trait is passed from mother to sons.

4. In the fruit fly Drosophila, the allele for normal body (B) is dominant to the allele for hairy body (b). When two normal-bodied fruit flies were mated, they produced 81 hair-bodied flies and 319 normal-bodied flies. The genotypes of the parents are most likely

(A) BB × bb

(B) BB × Bb

(C) Bb × Bb

(D) Bb × bb

(E) bb × bb

5. If a coin is tossed three consecutive times, what is the probability of getting three heads?






Directions: Each group of questions consists of five lettered headings followed by a list of numbered phrases or sentences. For each numbered phrase or sentence, select the one heading that is most closely related to it and fill in the corresponding oval on the answer sheet. Each heading may be used once, more than once, or not at all in each group.

Questions 6–9

(A) Phenotype

(B) Codominance

(C) Heterozygous

(D) Dihybrid cross

(E) Monohybrid cross

6. Alleles for two different traits are present in a single organism

7. The functional manifestations of gene activity in an organism

8. When an individual equally expresses both alleles

9. A cross involving two unlinked pairs of alleles