Question 1

In snapdragons, flower color is determined by incomplete dominance. If a red-flowered plant ($$R^R) is $$crossed with a white-flowered plant ($$R^r$$), what will be the phenotypic ratio of the F1 offspring?

Accepted Answer

All pink

Question 2

Which equation best represents the classic Mendelian dihybrid ratio for a cross between two heterozygotes ($$AaBb 	imes AaBb$$)?

Accepted Answer

$$9:3:3:1$$

Question 3

A mother has type A blood and her son has type O blood. What are the possible blood types of her son's father?

Accepted Answer

Type A, B, or O

Question 4

Which of the following best describes codominance?

Accepted Answer

Both alleles are expressed equally in the heterozygote

Question 5

In mice, coat color is determined by two genes. The B allele produces black pigment, and the A allele produces agouti. If a mouse is $$bb$$, it is albino regardless of the A allele. What is this an example of?

Accepted Answer

Recessive epistasis

Question 6

A cross between two true-breeding white guinea pigs produces all black F1 offspring. When F1 are crossed, a 9:7 ratio of black:white is observed in F2. What is the best explanation for this result?

Accepted Answer

Two separate gene products are needed for black pigment production

Question 7

Which of the following is an example of a gain-of-function mutation?

Accepted Answer

A mutation that increases the quantity of gene product by affecting regulation of transcription

Question 8

What is the expected phenotypic ratio for a cross between two heterozygous summer squash ($$AaBb 	imes AaBb) $$for fruit color, where dominant allele A produces white fruit, absence of A produces yellow, and $$bb$$ produces green?

Accepted Answer

$$12:3:1$$

Question 9

Which term describes the phenomenon where the physical location of a gene on a chromosome affects its expression?

Accepted Answer

Position effect

Question 10

A man with Duchenne muscular dystrophy, a recessive X-linked disorder, must have inherited the disorder from:

Accepted Answer

His mother

Question 11

Which equation represents the probability of a child being type O if both parents are heterozygous for the A and B alleles ($$I^A i 	imes I^B i$$)?

Accepted Answer

$$1/4$$

Question 12

Which of the following best describes maternal effect inheritance?

Accepted Answer

Phenotype is determined by the mother's nuclear gene products present in the egg

Question 13

In Mirabilis jalapa (four-o'clock plant), leaf color is determined by chloroplast inheritance. If a branch with white leaves is used as the ovule source, what leaf color will the offspring have?

Accepted Answer

All white

Question 14

Which of the following is true about mitochondrial inheritance?

Accepted Answer

Mitochondrial genes are inherited only from the maternal parent

Question 15

A temperature-sensitive mutation in a virus expresses the mutant phenotype at one temperature and wild-type at another. What is the term for the temperature at which the mutant gene product is functional?

Accepted Answer

Permissive condition

Question 16

Which term describes the percentage of individuals with a mutant genotype that actually express the mutant phenotype?

Accepted Answer

Penetrance

Question 17

In Drosophila, the bicoid gene is responsible for anterior development. If a mother is homozygous recessive for bicoid, what will be the phenotype of her offspring?

Accepted Answer

Failure to develop anterior areas regardless of embryo genotype

Question 18

Which of the following best describes heteroplasmy?

Accepted Answer

Presence of a mixture of normal and abnormal mitochondria in a cell

Question 19

Complementation analysis is used to determine:

Accepted Answer

If two mutations are in the same gene

Question 20

Which of the following is an example of a real-world application of gene interaction modifying Mendelian ratios?

Accepted Answer

Inheritance of coat color in mice showing recessive epistasis

Ch 4 Modification of Mendelian Ratios: Extensions and Exceptions to Classical Genetics

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