Question 1

Consider the case of X-linked inheritance of a recessive mutant allele.Among progeny from a cross of an unaffected male and a heterozygous female carrier,

Accepted Answer

In X-linked inheritance, males receive only one X chromosome from their mother and no X chromosome from their father. Therefore, if the mother is a carrier of a recessive mutant allele, half of her sons would receive the mutant X chromosome and show the trait. On the other hand, females receive one X chromosome from their mother and one from their father. If the father is unaffected, none of the daughters would show the trait, but half of them would be carriers.

Question 2

Penetrance and expressivity are related to

Accepted Answer

The answer of Penetrance and expressivity are related to
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Question 3

Wild type fruit flies have red eyes.A white-eyed female fly is crossed with a red-eyed male fly.All of the females from the cross are red-eyed, and all of the males are white-eyed.What type of inheritance pattern is this?

Accepted Answer

This inheritance pattern is indicative of sex-linked recessive inheritance, where the white-eye trait is carried on the X chromosome. Since males only have one X chromosome, they will express the trait if they inherit the recessive allele from their mother (who is a carrier of the trait). Females, on the other hand, would need to inherit the recessive allele from both parents in order to express the trait since they have two X chromosomes.

Question 4

The X7 allele in a species of a plant has 75 percent penetrance for producing red spots and 60 percent penetrance for dwarfism.If these probabilities of penetrance are independent, _______ percent of individuals with the X7 allele will have neither red spots nor will be dwarfs.

Accepted Answer

The probability of not having red spots is 1 - 0.75 = 0.25. The probability of not being a dwarf is 1 - 0.60 = 0.40. The probability of having neither red spots nor being a dwarf is 0.25 * 0.40 = 0.10, or 10%.

Question 5

The genes a, b, and c are different genes that reside on the same chromosome.Genes a and b are 10 cM apart, b and c are 2 cM apart, and a and c are 8 cM apart.What is the order of these genes?

Accepted Answer

The correct order is a, c, b because the distances between the genes add up correctly: a to c is 8 cM and c to b is 2 cM, which together equal the 10 cM distance between a and b.

Question 6

Genes located on mitochondrial DNA are usually inherited

Accepted Answer

Mitochondrial DNA is only passed down from the mother to her offspring. This is because during fertilization, the egg contributes the majority of the cytoplasm, which includes the mitochondria and their DNA. Therefore, all mitochondrial genes are inherited exclusively from the maternal lineage.

Question 7

In tomatoes, tall is dominant to dwarf, and smooth fruits are dominant to hairy fruits.A plant homozygous for both dominant traits is crossed with a plant homozygous for both recessive traits.The F₁ progeny are test-crossed with the following results in the F₂ progeny: 96 tall with smooth fruits; 94 dwarf with hairy fruits; 6 tall with hairy fruits; and 4 dwarf with smooth fruits.These data indicate that the genes are

Accepted Answer

The presence of recombinant phenotypes (tall with hairy fruits and dwarf with smooth fruits) in lower frequencies (6 and 4 out of 200 total) indicates linkage between the genes with a 5 percent recombination frequency (10 recombinants out of 200 total offspring).

Question 8

If bacteria could not undergo conjugation, they

Accepted Answer

Conjugation allows for the transfer of genetic material between bacterial cells, increasing the potential for genetic diversity. Without conjugation, bacteria would have to rely solely on mutations for genetic variation, which may not be as efficient in generating diversity.

Question 9

What is the map distance between two genes with a recombination frequency of 0.08?

Accepted Answer

A recombination frequency of 0.08 corresponds to a genetic distance of 8 cM (centiMorgans), which is the map distance between the two genes.

Question 10

A bacterial cell's genotype can be altered by

Accepted Answer

The answer of A bacterial cell's genotype can be altered...

Quiz 12: Inheritance, Genes, and Chromosomes