Question 1

Which of the following best describes incomplete dominance?

Accepted Answer

The heterozygote phenotype is intermediate between the two homozygotes.

Question 2

In a cross between two heterozygous violet-fruited plants (Pp), what is the expected phenotypic ratio in the F2 generation?

Accepted Answer

$1:2:1$ (purple:violet:white)

Question 3

Which statement about penetrance is correct?

Accepted Answer

Penetrance is the proportion of individuals with a genotype that show the expected phenotype.

Question 4

A lethal allele in mice causes death when homozygous. If two heterozygous yellow mice ($Yy$) are crossed, what proportion of the surviving offspring will be yellow?

Accepted Answer

$2/3$

Question 5

In a population of ducks, three alleles ($M^R$, $M$, $m^d$) control coat color. If a restricted ($M^R M^R$) duck is crossed with a mallard ($M M$), what proportion of the F1 will be mallard?

Accepted Answer

$1/4$

Question 6

Which blood type genotype exhibits codominance?

Accepted Answer

$I^A I^B$

Question 7

In peppers, two loci ($Y$ and $C$) interact to produce fruit color. What is the phenotype of a $yycc$ plant?

Accepted Answer

Cream

Question 8

Which genetic phenomenon is described when one gene masks the effect of another gene at a different locus?

Accepted Answer

Epistasis

Question 9

In Labrador retrievers, which genotype will result in a yellow coat color?

Accepted Answer

$B_ee$ or $bbee$

Question 10

A cross between $WWYY$ (white squash) and $wwyy$ (green squash) produces $WwYy$ (white squash). What is the role of the $W$ allele?

Accepted Answer

It is dominant and inhibits pigment production.

Question 11

Which phenotypic ratio is indicative of duplicate recessive epistasis?

Accepted Answer

$9:7$

Question 12

If two homozygous mutant parents are crossed and the F1 offspring are wild-type, what does this indicate?

Accepted Answer

The mutations are at different loci.

Question 13

Which inheritance pattern is demonstrated when the phenotype of the progeny is determined by the genotype of the mother, not its own genotype?

Accepted Answer

Genetic maternal effect

Question 14

A plant with genotype $AaBb$ produces pigment only if both $A$ and $B$ are dominant. What is the expected phenotypic ratio in the F2 generation for pigment production?

Accepted Answer

$9:7$

Question 15

Which of the following is an example of pleiotropy?

Accepted Answer

A single gene affects both eye color and wing shape in fruit flies.

Question 16

How many genotypes are possible for a polygenic trait controlled by 2 loci, each with 2 alleles?

Accepted Answer

$9$

Question 17

Which of the following best describes cytoplasmic inheritance?

Accepted Answer

Traits are typically inherited from the egg cell and can be identified by reciprocal crosses.

Question 18

Genomic imprinting results in:

Accepted Answer

Only one functional copy of a gene due to epigenetic silencing.

Question 19

A breeder crosses a yellow Labrador ($B_ee$) with a brown Labrador ($bbE_$) and all puppies are black. What is the most likely genotype of the parents?

Accepted Answer

$BbEe$ (black)  BbEe$ (black)

Question 20

A summer-squash plant producing disc-shaped fruit is crossed with a plant producing long fruit. All F1 are disc-shaped. F2 progeny are 430 disc-shaped, 287 spherical, and 46 long. What is the most likely mode of inheritance?

Accepted Answer

Two genes with dominant epistasis

Extensions of Mendelian Principles: Gene Interaction, Dominance, and Complex Inheritance

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