1. Mendel and the Gene Idea
Chapter 14
Mendel and the Gene Idea

2. A couple who are both carriers of the gene for cystic fibrosis have two children who have cystic fibrosis. What is the probability that their next child will have cystic fibrosis? 0%
25%
50%
75%
100%
Answer: 2
Source: Barstow - Test Bank for Biology, Seventh Edition, Question #6

3. A couple who are both carriers of the gene for cystic fibrosis have two children who have cystic fibrosis. What is the probability that their next child will be phenotypically normal? 0%
25%
50%
75%
100%
Answer: 4
Source: Barstow - Test Bank for Biology, Seventh Edition, Question #7

4. In cattle, roan coat color (mixed red and white hairs) occurs in the heterozygous (Rr) offspring of red (RR) and white (rr) homozygotes. When two roan cattle are crossed, the phenotypes of the progeny are found to be in the ratio of 1 red:2 roan:1 white. Which of the following crosses could produce the highest percentage of roan cattle? *
red  white
roan  roan
white  roan
red  roan
All of the above crosses would give the same percentage of roan.
Answer: 1
Source: Barstow - Test Bank for Biology, Seventh Edition, Question #10
Discussion Notes for the Instructor
There are several questions which can be asked to guide the discussion of this question, including:
What genotype produces a “roan” phenotype?
What cross would produce the greatest percentage of this genotype?
What type of inheritance does this show?
Using these questions as an outline, discussion of the choices might look like this:
Choice A, correct; this cross will produce 100% roan offspring
Choice B, roan X roan will produce only 50% roan offspring
Choice C, white X roan will produce only 50% roan offspring
Choice D, red X roan will produce only 50% roan offspring
Choice E, only choice A will produce 100% roan offspring

5. What is the probability that individual C-1 is Ww?
3/4
1/4
2/4
2/3 1
Answer: 5
Source: Barstow - Test Bank for Biology, Seventh Edition, Question #19

6. A woman and her spouse both show the normal phenotype for pigmentation, but both had one parent who was an albino. Albinism is an autosomal recessive trait. If their first two children have normal pigmentation, what is the probability that their third child will be an albino?
1/4
1/2
3/4 1
Answer: 2
Source: Barstow - Test Bank for Biology, Seventh Edition, Question #25

7. In a cross AaBbCc  AaBbCc, what is the probability of producing the genotype AABBCC?
1/4
1/8
1/16
1/32
1/64
Answer: 5
Source: Barstow - Test Bank for Biology, Seventh Edition, Question #33

8. Feather color in budgies is determined by two different genes that affect the pigmentation of the outer feather and its core. Y_B_ is green; yyB_ is blue; Y_bb is yellow; and yybb is white. A green budgie is crossed with a blue budgie. Which of the following results is not possible?
all green offspring
all blue offspring
all white offspring
all yellow offspring
All of the above are possible, but with different probabilities.
Answer: 5
Source: Barstow - Test Bank for Biology, Seventh Edition, Question #35

9. Three babies were recently mixed up in a hospital
Three babies were recently mixed up in a hospital. After consideration of the data below, which of the following represent the correct baby/parent combinations?
Couple #
Blood groups I
A and A II
A and B
III
B and O
Baby # 1 B 2 O 3 AB
I-3, II-1, III-2
I-1, II-3, III-2
I-2, II-3, III-1
I-2, II-1, III-3
I-3, II-2, III-1
Answer: 3
Source: Barstow - Test Bank for Biology, Seventh Edition, Question #49

10. A man is brought to court in a paternity case
A man is brought to court in a paternity case. He has blood type B, Rh positive. The mother has blood type B, Rh negative. Which blood type of a child would exclude the accused from paternity?
AB, Rh negative
B, Rh negative
O, Rh negative
B, Rh positive
None of these choices will exclude.
Answer: 1
Source: Barstow - Test Bank for Biology, Seventh Edition, Question #58

11. You are handed a “mystery’’ pea plant with long stems and axial flowers, and asked to determine its genotype as quickly as possible. You know the allele for long stems (L) is dominant to that for dwarf stems (l) and that the allele for axial flowers (A) is dominant to that for terminal flowers (a). You cross the “mystery” plant with a dwarf stemmed axial flowered plant. If your mystery plant is heterozygous at both loci, what is/are the expected proportion of offspring?
100% long stemmed terminal flowered
100% dwarf stemmed terminal flowered
100% long stemmed axial flowered
50% long stemmed axial flowered, 50% dwarf stemmed terminal flowered
25% long stemmed axial flowered, 25% long stemmed terminal flowered, 25% dwarf stemmed axial flowered, 25% dwarf stemmed terminal flowered
Answer: 5
Source: Campbell/Reece - Biology, Seventh Edition, EOC Process of Science Question

12. You think that two alleles for coat color in mice show incomplete dominance. What is the best and simplest cross to perform in order to support your hypothesis?
a testcross of a homozygous recessive mouse with a mouse of unknown genotype
a cross of F1 mice to look for a 1:2:1 ratio in the offspring
a reciprocal cross in which the sex of the mice of each coat color is reversed
a cross of two true-breeding mice of different colors to look for an intermediate phenotype in the F1
a cross of F1 mice to look for a 9:7 ratio in the offspring
Answer: 4
Source: Taylor - Student Study Guide for Biology, Seventh Edition, Test Your Knowledge Question #11

13. A mother with type B blood has two children, one with type A blood and one with type O blood. Her husband has type O blood. Which of the following could you conclude from this information?
The husband could not have fathered either child.
The husband could have fathered both children.
The husband must be the father of the child with type O blood and could be the father of the type A child.
The husband could be the father of the child with type O blood, but not the type A child.
Neither the mother nor the husband could be the biological parent of the type A child.
Answer: 4
Source: Taylor - Student Study Guide for Biology, Seventh Edition, Test Your Knowledge Question #14

14. The Chromosomal Basis of Inheritance
Chapter 15
The Chromosomal Basis of Inheritance

15. Vermilion eyes is a sex-linked recessive characteristic in fruit flies. If a female having vermilion eyes is crossed with a wild-type male, what percentage of the F1 males will have vermilion eyes? 0%
25%
50%
75%
100%
Answer: e
Source: Barstow - Test Bank for Biology, Seventh Edition, Question #3

16. Barring in chickens is due to a sex-linked dominant gene (B)
Barring in chickens is due to a sex-linked dominant gene (B). The sex of chicks at hatching is difficult to determine, but barred chicks can be distinguished from nonbarred at that time. To use this trait so that at hatching all chicks of one sex are barred, what cross would you make?
barred males  barred females
barred males  nonbarred females
nonbarred males  barred females
nonbarred males  nonbarred females
Answer: b
Source: Barstow - Test Bank for Biology, Seventh Edition, Question #21

17. A recessive allele on the X chromosome is responsible for red-green color blindness in humans. A woman with normal vision whose father is color-blind marries a color-blind male. What is the probability that this couple’s son will be color-blind?
1/4
1/2
3/4 1
Answer: c
Source: Barstow - Test Bank for Biology, Seventh Edition, Question #29

18. An achondroplastic dwarf man with normal vision marries a color-blind woman of normal height. The man's father was six feet tall, and both the woman's parents were of average height. Achondroplastic dwarfism is autosomal dominant, and red-green color blindness is X-linked recessive. How many of their female children might be expected to be color-blind dwarfs? *
all
none
half
one out of four
three out of four
Answer: b
Source: Barstow - Test Bank for Biology, Seventh Edition, Question #32
Discussion Notes for the Instructor
There are several questions which can be asked to guide the discussion of this question, including:
Are these genes linked?
Are the phenotypes of the individual parents useful?
What are the genotypes of the individuals involved?
Using these questions as an outline, discussion of the choices might look like this:
Choice A, in order for all the female offspring to be color-blind the man would have to be color-blind
Choice B, correct
Choice C, since red-green colorblindness is an X-linked recessive the female offspring can only be color-blind if the father is also color-blind
Choice D, since red-green colorblindness is an X-linked recessive the female offspring can only be color-blind if the father is also color-blind
Choice E, since red-green colorblindness is an X-linked recessive the female offspring can only be color-blind if the father is also color-blind
This discussion could be followed by just looking at dwarfism or color-blindness in the male or female offspring.

19. An achondroplastic dwarf man with normal vision marries a color-blind woman of normal height. The man's father was six feet tall, and both the woman's parents were of average height. Achondroplastic dwarfism is autosomal dominant, and red-green color blindness is X-linked recessive. How many of their male children would be color-blind and normal height?
all
none
half
one out of four
three out of four
Answer: c
Source: Barstow - Test Bank for Biology, Seventh Edition, Question #33

20. In cats, black color is caused by an X-linked allele; the other allele at this locus causes orange color. The heterozygote is tortoiseshell. What kinds of offspring would you expect from the cross of a black female and an orange male?
tortoiseshell female; tortoiseshell male
black female; orange male
orange female; orange male
tortoiseshell female; black male
orange female; black male
Answer: d
Source: Barstow - Test Bank for Biology, Seventh Edition, Question #38

21. Red-green color blindness is a sex-linked recessive trait in humans
Red-green color blindness is a sex-linked recessive trait in humans. Two people with normal color vision have a color-blind son. What are the genotypes of the parents?
XcXc and XcY
XcXc and XCY
XCXC and XcY
XCXC and XCY
XCXc and XCY
Answer: e
Source: Barstow - Test Bank for Biology, Seventh Edition, Question #43

22. A color-blind son inherited this trait from his
mother.
father.
mother only if she is color-blind.
father only if he is color-blind.
mother only if she is not color-blind.
Answer: a
Source: Taylor - Student Study Guide for Biology, Seventh Edition, Test Your Knowledge Question #9

23. The Molecular Basis of Inheritance
Chapter 16
The Molecular Basis of Inheritance

24. Tobacco mosaic virus has RNA rather than DNA as its genetic material. In a hypothetical situation where RNA from a tobacco mosaic virus is mixed with proteins from a related DNA virus, the result could be a hybrid virus. If that virus were to infect a cell and reproduce, what would the resulting "offspring" viruses be like?
tobacco mosaic virus
the related DNA virus
a hybrid: tobacco mosaic virus RNA and protein from the DNA virus
a hybrid: tobacco mosaic virus protein and nucleic acid from the DNA virus
a virus with a double helix made up of one strand of DNA complementary to a strand of RNA surrounded by viral protein
Answer: 1
Source: Barstow - Test Bank for Biology, Seventh Edition, Question #4

25. Cytosine makes up 38% of the nucleotides in a sample of DNA from an organism. What percent of the nucleotides in this sample will be thymine? 12 24 31 38
It cannot be determined from the information provided.
Answer: 1
Source: Barstow - Test Bank for Biology, Seventh Edition, Question #16

26. In an analysis of the nucleotide composition of DNA, which of the following is true?
A = C
A = G and C = T
A + C = G + T
A + T = G + C
Both B and C are true
Answer: 3
Source: Barstow - Test Bank for Biology, Seventh Edition, Question #21

27. A space probe returns with a culture of a microorganism found on a distant planet. Analysis shows that it is a carbon-based life form that has DNA. You grow the cells in 15N medium for several generations and then transfer it to 14N medium. Which pattern in this figure would you expect if the DNA were replicated in a conservative manner?
Answer: b
Source: Barstow - Test Bank for Biology, Seventh Edition, Question #24 a. b. c. d. e.

28. In analyzing the number of different bases in a DNA sample, which result would be consistent with the base-pairing rules?
A = G
A + G = C + T
A + T = G + T
A = C
G = T
Answer: 2
Source: Campbell/Reece - Biology, Seventh Edition, EOC Self-Quiz Question #5

29. Imagine the following experiment is done: Bacteria are first grown for several generations in a medium containing the lighter isotope of nitrogen, 14N, then switched into a medium containing 15N. The rest of the experiment is identical to the Meselson and Stahl experiment. Which of the following represents the band positions you would expect after two generations? *
Answer: e
Source: Campbell/Reece - Biology, Seventh Edition, EOC Process of Science Question
Discussion Notes for the Instructor
There are several questions which can be asked to guide the discussion of this question, including:
Which isotope will the new nucleotides contain?
As DNA is being replicated the new backbone (strand) will contain which isotope?
How many templates are formed from one molecule of DNA?
Using these questions as an outline. discussion of the choices might look like this:
Choice A, since the original 14N labeled backbones will act as templates with new 15N nucleotides there should an intermediate band.
Choice B, the intermediate band should have a mass exactly half way between the 14N and 15N marks
Choice C, since there are no new 14N labeled nucleotides there can be no bands that are just 14N
Choice D, since there are no new 14N labeled nucleotides there can be no bands that are just 14N
Choice E, correct

30. You are trying to support your hypothesis that DNA replication is conservative; i.e., parental strands separate; complementary strands are made, but these new strands join together to make a new DNA molecule and the parental strands rejoin. You take E. coli that had grown in a medium containing only heavy nitrogen (15N) and transfer a sample to a medium containing light nitrogen (14N).
Answer: c
Source: Taylor - Student Study Guide for Biology, Seventh Edition, Test Your Knowledge Question #20

31. (cont.) After allowing time for only one DNA replication, you centrifuge a sample and compare the density band(s) formed with control bands for bacteria grown on either normal 14N or 15N medium. Which band location would support your hypothesis of conservative DNA replication?
Answer: c
Source: Taylor - Student Study Guide for Biology, Seventh Edition, Test Your Knowledge Question #20

32. Using the experiment explained in the previous question, which centrifuge tube would represent the band distribution obtained after one replication showing that DNA replication is semiconservative?
Answer: a
Source: Taylor - Student Study Guide for Biology, Seventh Edition, Test Your Knowledge Question #21