genetics chapter 3

25. Two gene loci, A and B, assort independently, and alleles A and B are dominant over alleles a and b. What is the probability of producing an AaBb zygote from a cross AaBb × AABB? a. 1/4 b. 1/2 c. 1/16 d. 9/16 e. 1 (100%)

a

30. In a cross between AaBbCcDdEe and AaBbccDdee, what proportion of the offspring would be expected to be A_bbC_ddE_? (A_ means AA or Aa.) a. 3/256 b. 3/32 c. 3/16 d. 3/8 e. 3/4

a

17. Which of the following crosses would produce a 3:1 ratio of phenotypes in the next generation? a. AA × AA b. AA × aa c. Aa × Aa d. Aa × aa e. aa × aa

c

18. Freckles are caused by a dominant allele. A man has freckles but one of his parents does not have freckles. What is his genotype? a. Homozygous dominant b. Homozygous recessive c. Heterozygous d. Heterologous e. Homologous

c

19. Freckles are caused by a dominant allele. A man has freckles but one of his parents does not have freckles. The man has fathered a child with a woman that does not have freckles. What is the probability that their child has freckles? a. 1/4 b. 1/3 c. 1/2 d. 2/3 e. 3/4

c

12. Honeybees have a haplo-diploid sex determination system where females develop from a fertilized egg (they are diploid, having one allele from the female queen and one allele from the male), and males develop from unfertilized eggs (they are haploid, having only one allele from the queen). Assuming that the queen is heterozygous for a particular gene, what is the probability that a female will inherit the recessive allele from her mother? What is the probability that a male will inherit a recessive allele from his mother? a. The probability that a daughter will inherit a recessive allele from her mother is 50%; the probability that a son will inherit a recessive allele from his mother is 50%. b. The probability that a daughter will inherit a recessive allele from her mother is 50%; the probability that a son will inherit a recessive allele from his mother is 100%. c. The probability that a daughter will inherit a recessive allele from her mother is 100%; the probability that a son will inherit a recessive allele from his mother is 50%. d. The probability that a daughter will inherit a recessive allele from her mother is 100%; the probability that a son will inherit a recessive allele from his mother is 100%. e. The probability that a daughter will inherit a recessive allele from her mother is 0%; the probability that a son will inherit a recessive allele from his mother is 100%.

a

14. A couple has six daughters and is expecting a seventh child. What is the probability that this child will be a boy? a. 1/2 b. 1/4 c. 1/16 d. 1/64 e. 1/128

a

2. Genes come in different versions called a. alleles. b. loci. c. genotypes. d. chromosomes. e. genomes.

a

22. Two gene loci, A and B, assort independently, and alleles A and B are dominant over alleles a and b. What is the probability of producing an AB gamete from an AaBb individual? a. 1/4 b. 1/2 c. 1/16 d. 9/16 e. 1 (100%)

a

34. Round seeds (R) is dominant to wrinkled seeds (r), and yellow seeds (Y) is dominant to green seeds (y). A true-breeding pea plant with round and yellow seeds is crossed to a true-breeding plant with wrinkled and green seeds. The F1 progeny are allowed to self-fertilize. What is the probability of obtaining a yellow seed in the F2? a. 3/4 b. 1/16 c. 9/16 d. 3/16 e. 1/2

a

4. Gregor Mendel carried out a cross between two pea plants by taking pollen from a plant that was homozygous for round seeds and dusting the pollen onto the stigma of a plant homozygous for wrinkled seeds. Which of the following would be the reciprocal cross that Mendel had carried out for this experiment? a. Homozygous round stigma pollinated with homozygous wrinkled b. Homozygous round stigma pollinated with heterozygous wrinkled c. Heterozygous round stigma pollinated with homozygous wrinkled d. Homozygous wrinkled stigma pollinated with homozygous round e. Homozygous wrinkled stigma pollinated with homozygous wrinkled

a

7. In Mendel's peas, purple flower color is dominant to white. From which of the following descriptions can you not infer the genotype completely? a. Purple b. White c. Pure-breeding purple d. Heterozygous e. More than one of the above

a

8. Which of the following was not one of Mendel's conclusions based on his monohybrid crosses? a. Genes are carried on chromosomes. b. Alleles exist in pairs. c. Alleles segregate equally into gametes. d. Alleles behave as particles during inheritance. e. One allele can mask the expression of the other allele.

a

1. Why was the pea plant an ideal plant for Mendel to use? a. Generation time that is several years b. Simple traits that are easy to identify c. Low numbers of offspring produced d. Expensive and time-consuming to grow e. All of the above

b

11. In poodles, black fur is dominant to white fur. A black poodle is crossed with a white poodle. In a litter of four, all of the puppies are black. What is the best conclusion? a. The black poodle is definitely homozygous. b. The black poodle is probably homozygous. c. The black poodle is definitely heterozygous. d. The black poodle is probably heterozygous. e. The genotype of the black poodle cannot be inferred with this information.

b

23. Two gene loci, A and B, assort independently, and alleles A and B are dominant over alleles a and b. What is the probability of producing an AB gamete from an AABb individual? a. 1/4 b. 1/2 c. 1/16 d. 9/16 e. 1 (100%)

b

28. In a cross between AaBbCc and AaBbcc, what proportion of the offspring would be expected to be A_bbcc? (A_ means AA or Aa.) a. 3/256 b. 3/32 c. 3/16 d. 3/8 e. 3/4

b

33. Round seeds (R) is dominant to wrinkled seeds (r), and yellow seeds (Y) is dominant to green seeds (y). A true-breeding pea plant with round and yellow seeds is crossed to a true-breeding plant with wrinkled and green seeds. The F1 progeny are allowed to self-fertilize. What is the probability of obtaining a wrinkled, green seed in the F2? a. 3/4 b. 1/16 c. 9/16 d. 3/16 e. 1/2

b

15. If an organism of genotype Aa is used for a test cross, what is the genotype of the other individual used in the cross? a. AA b. Aa c. Aa d. The genotype cannot be known e. Either a or b

c

20. In animals, the inability to make the pigment melanin results in albinism, a recessive condition. Two unaffected parents, who have decided to have three children, have a first child that has albinism (genotype aa). What is the probability that the second and third children will also have albinism? a. 1/4 b. 1/2 c. 1/16 d. 9/16 e. 1 (100%)

c

21. The ability to curl one's tongue into a U-shape is a genetic trait. Curlers always have at least one curler parent but noncurlers can have one or both parents who are curlers. Using C and c to symbolize the alleles that control this trait, what is the genotype of a noncurler? a. CC b. Cc c. cc d. Any of the above could be correct.

c

24. Two gene loci, A and B, assort independently, and alleles A and B are dominant over alleles a and b. What is the probability of producing an AABB zygote from a cross AaBb × AaBb? a. 1/4 b. 1/2 c. 1/16 d. 9/16 e. 1 (100%)

c

32. Round seeds (R) is dominant to wrinkled seeds (r), and yellow seeds (Y) is dominant to green seeds (y). A true-breeding pea plant with round and yellow seeds is crossed to a true-breeding plant with wrinkled and green seeds. The F1 progeny are allowed to self-fertilize. What is the probability of obtaining a round, yellow seed in the F2? a. 3/4 b. 1/16 c. 9/16 d. 3/16 e. 1/2

c

36. In dogs, black coat color (B) is dominant over brown (b), and solid coat color (S) is dominant over white spotted coat (s). A cross between a black, solid female and a black, solid male produces only puppies with black, solid coats. This same female was then mated with a brown, spotted male. Have of the offspring from this cross were black and solid, and half of the offspring were black and spotted. What is the genotype of the female? a. BBSS b. BbSS c. BBSs d. BbSs e. bbss

c

37. In dogs, black coat color (B) is dominant over brown (b), and solid coat color (S) is dominant over white spotted coat (s). A cross between a black, solid female and a black, solid male produces only puppies with black, solid coats. This same female was then mated with a brown, spotted male. Have of the offspring from this cross were black and solid, and half of the offspring were black and spotted. Which of the following could be the genotype of the black, solid male? a. BBSs b. BBss c. BbSS d. BbSs e. Bbss

c

39. A space capsule crashes to earth with an alien life form aboard. Two creatures emerge from the capsule, one with green skin and one with yellow skin. The yellow creature soon gives birth to offspring fathered by the green creature, producing 12 green and 8 yellow offspring. Green skin in these diploid creatures is dominant to yellow skin. You are curious to find out if the number of offspring significantly different from expected Mendelian ratios, so you perform a chi-square test. What is the chi-square value for this cross? a. 0.2 b. 0.4 c. 0.8 d. 1.2 e. 1.6

c

40. A chi-square test was performed and indicated that the observed numbers of offspring were significantly different from the expected. Which of the following P-values would support this conclusion? a. 0.995 b. 0.536 c. 0.024 d. 0.752 e. 0.159

c

6. In Labrador retrievers, black coat color is dominant to brown. Suppose that a black Lab is mated with a brown one and the offspring are 4 black puppies and 1 brown. What can you conclude about the genotype of the black parent? a. The genotype must be BB. b. The genotype must be bb. c. The genotype must be Bb. d. The genotype could be either BB or Bb. e. The genotype cannot be determined from these data.

c

9. In Mendel's peas, yellow seeds are dominant to green. A pure-breeding yellow plant is crossed with a pure-breeding green plant. All of the offspring are yellow. If one of these yellow offspring is crossed with a green plant, what will be the expected proportion of plants with green seeds in the next generation? a. 0% b. 25% c. 50% d. 75% e. 100%

c

10. In a cross between pure-breeding tall plants with pure-breeding short plants, all of the F1 are tall. When these plants are allowed to fertilize themselves, the F2 plants occur in a ratio of 3 tall:1 short. Which of the following is not a valid conclusion from these results? a. The allele that produces the tall condition is dominant to the allele that produces the short condition. b. The difference between tall and short stature in these lines is controlled by a single gene pair. c. During production of gametes in F1 plants, the tall and short alleles segregate from each other equally into the gametes. d. The tall and short traits assort independently of each other in this cross. e. Fertilization occurs randomly between gametes carrying the tall and short alleles.

d

16. Which of the following crosses would produce a 1:1 ratio of phenotypes in the next generation? a. AA × AA b. AA × aa c. Aa × Aa d. Aa × aa e. aa × aa

d

26. Two gene loci, A and B, assort independently, and alleles A and B are dominant over alleles a and b. What is the probability of producing an AB phenotype from a cross AaBb × AaBb? a. 1/4 b. 1/2 c. 1/16 d. 9/16 e. 1 (100%)

d

29. In a cross between AABbCcDD and AaBbccdd, what proportion of the offspring would be expected to be A_B_C_D_? (A_ means AA or Aa.) a. 3/256 b. 3/32 c. 3/16 d. 3/8 e. 3/4

d

3. Which of the following statements is true? a. The genotype is the physical appearance of a trait. b. Alleles, genes, and loci are different names for the same thing. c. The phenotype of a dominant allele is never seen in the F1 progeny of a monohybrid cross. d. A testcross can be used to determine whether an individual is homozygous or heterozygous. e. All of these statements are true.

d

31. Round seeds (R) is dominant to wrinkled seeds (r), and yellow seeds (Y) is dominant to green seeds (y). A true-breeding plant with round and yellow seeds is crossed to a true-breeding plant with wrinkled and green seeds. What is the genotype of the F1 progeny? a. RRYY b. RrYY c. RRYy d. RrYy e. rryy

d

35. Round seeds (R) is dominant to wrinkled seeds (r), and yellow seeds (Y) is dominant to green seeds (y). A plant of unknown genotype is testcrossed to a true-breeding plant with wrinkled and green seeds. The offspring produced were 53 round and yellow, 49 round and green, 44 wrinkled and yellow, 51 wrinkled and green. What is the likely genotype of the parent in question? a. RRYY b. RrYY c. RRYy d. RrYy e. rryy

d

13. While doing field work in Madagascar, you discover a new dragonfly species that has either red (R) or clear (r) wings. Initial crosses indicate that R is dominant to r. You perform three crosses using three different sets of red-winged parents with unknown genotype and observe the following data: Cross Phenotypes 1 72 red-winged, 24 clear-winged 2 12 red-winged 3 96 red-winged Which cross is likely to have at least one parent with the genotype RR? a. Cross 1 b. Cross 2 c. Cross 3 d. Crosses 1 and 2 e. Crosses 2 and 3

e

27. Two gene loci, A and B, assort independently, and alleles A and B are dominant over alleles a and b. What is the probability of producing an AB phenotype from a cross aabb × AABB? a. 1/4 b. 1/2 c. 1/16 d. 9/16 e. 1 (100%)

e

38. In dogs, black coat color (B) is dominant over brown (b), and solid coat color (S) is dominant over white spotted coat (s). A cross between a black, solid female and a black, solid male produces only puppies with black, solid coats. This same female was then mated with a brown, spotted male. Have of the offspring from this cross were black and solid, and half of the offspring were black and spotted. What is the genotype of the brown, spotted male? a. BBSS b. BbSS c. BBSs d. BbSs e. bbss

e

5. Which of the following statements is true? a. The probability of a woman giving birth to three girls in a row is 1/8. b. The chi-square test is used to determine if observed outcomes are consistent with expected outcomes. c. The probability of two or more independent events occurring together is calculated by multiplying their independent probabilities. d. Branched diagrams are used for determining probabilities of various phenotypes or genotypes for genetic crosses involving more than one gene pair. e. All of these statements are true.

e