Question 1

In tomato plants, a gene controlling fruit shape has 2 alleles: O (round)  and o (oval) . A gene controlling inflorescence (position of the flowers)  has two alleles: S (simple)  and s (compound) . A pure-breeding plant with oval fruit and simple inflorescence is crossed to a pure-breeding plant with round fruit and compound inflorescence. All the offspring have round fruit and simple inflorescence. The offspring are then crossed to plants with oval fruit and compound inflorescence. The phenotypes of this second generation are
Oval simple 200
Round compound 190
Oval compound 50
Round simple 60.
Which statement about the genes is true?

Accepted Answer

A)   The alleles of one gene assort independently of the alleles of the other gene.
B)   The recombination frequency between the genes is more than 50 per cent.
C)   The gene loci are on separate chromosomes.
D)   The genes show incomplete dominance.
E)   The genes are linked.F) All of the above
G) None of the above

Question 2

Which of the following is a description of codominance?

Accepted Answer

A)   When one allele makes a partially dominant product and another makes none
B)   When two alleles are both non-functional
C)   When a single gene has multiple alleles
D)   When a single gene has more than one dominant allele
E)   All of the options listed here are incorrectF) B) and E)
G) All of the above

Question 3

Red-green colour-blindness in humans is a recessive X-linked trait. A man and a woman with normal vision have a colour-blind son. What is the probability that their next child will also be a colour-blind son?

Accepted Answer

A)   0
B)   1/4
C)   1/2
D)   3/4
E)   3/8F) B) and C)
G) All of the above

Question 4

Haemophilia is a defect in blood clotting. It is a recessive trait that has arisen from a mutation of a gene on the X-chromosome. A boy with haemophilia has parents who have normal blood clotting. If the parents have another child what is the probability it will be normal?

Accepted Answer

A)   0
B)   1/4
C)   1/2
D)   3/4
E)   3/8F) D) and E)
G) A) and B)

Question 5

In a flowering plant, a mutation in a gene controlling flower structure results in flowers with extra petals. A mutation in another gene results in no flowers (flowerless) . Both mutant phenotypes are recessive, and the two genes assort independently. If a plant heterozygous for both mutations self-fertilises, which of the following ratios would you expect in the offspring?

Accepted Answer

A)   9 wild type: 3 extra petals: 3 flowerless: 1 extra petals, flowerless
B)   9 wild type: 3 extra petals: 4 flowerless
C)   9 wild type: 3 flowerless: 4 extra petals
D)   1 wild type: 1 flowerless: 1 extra petals: 1 extra petals, flowerless
E)   1 wild type: 2 extra petals: 1flowerlessF) A) and C)
G) A) and E)

Exam 9: Inheritance

Haemophilia is a defect in blood clotting. It is a recessive trait that has arisen from a mutation of a gene on the X-chromosome. A boy with haemophilia has parents who have normal blood clotting. If the parents have another child what is the probability it will be normal?

Correct Answer
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Correct Answer
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Correct Answer
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Red-green colour-blindness in humans is a recessive X-linked trait. A man and a woman with normal vision have a colour-blind son. What is the probability that their next child will also be a colour-blind son?

Correct Answer
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Which of the following is a description of codominance?

Correct Answer
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Exam 9: Inheritance

Haemophilia is a defect in blood clotting. It is a recessive trait that has arisen from a mutation of a gene on the X-chromosome. A boy with haemophilia has parents who have normal blood clotting. If the parents have another child what is the probability it will be normal?

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Red-green colour-blindness in humans is a recessive X-linked trait. A man and a woman with normal vision have a colour-blind son. What is the probability that their next child will also be a colour-blind son?

Correct AnswerverifiedShow Answer

Which of the following is a description of codominance?

Correct AnswerverifiedShow Answer

Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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