Question 1

Which of the following best describes incomplete dominance, as seen in the inheritance of flower color in snapdragons?

Accepted Answer

The heterozygote has a phenotype intermediate between the two homozygotes.

Question 2

A person with genotype $I^A I^B$ for the ABO blood group system will have which blood type, and why?

Accepted Answer

Type AB, because both alleles are codominant and both antigens are expressed.

Question 3

Which of the following is an example of overdominance?

Accepted Answer

A heterozygote for sickle cell anemia ($Hb^A Hb^S$) is resistant to malaria and does not have sickle cell disease.

Question 4

A mutation that results in a complete loss of function of a gene is called:

Accepted Answer

Null mutation

Question 5

In rabbits, the dominance series for coat color alleles is $C > c^{ch} > c^h > c$. Which genotype would result in a Himalayan rabbit?

Accepted Answer

$c^h c$

Question 6

A Manx cat has a genotype $Mm$ for the tail length gene, where $M$ is a dominant lethal allele. What is the expected ratio of tailed to tailless kittens when two Manx cats are crossed?

Accepted Answer

1:2

Question 7

Which of the following best explains incomplete penetrance?

Accepted Answer

Individuals with a disease-causing genotype may not show the disease phenotype due to environmental or genetic factors.

Question 8

A family has several members with Waardenburg syndrome, but the severity of symptoms varies widely. This is an example of:

Accepted Answer

Variable expressivity

Question 9

Which of the following is a real-life example of gene-environment interaction?

Accepted Answer

A person with PKU who avoids phenylalanine in their diet does not develop intellectual disability.

Question 10

Genomic imprinting is best described as:

Accepted Answer

A gene being expressed only from the allele inherited from one parent due to epigenetic modification.

Question 11

Which of the following is an example of pleiotropy?

Accepted Answer

A single gene mutation in chickens causes frizzled feathers, abnormal body temperature, and reduced egg laying.

Question 12

Which of the following best describes recessive epistasis, as seen in Labrador retriever coat color?

Accepted Answer

A recessive allele at one gene masks the expression of alleles at a second gene.

Question 13

A person with genotype $ii$ for the ABO blood group system will have which blood type?

Accepted Answer

Type O

Question 14

Which of the following is NOT a feature of epigenetic inheritance?

Accepted Answer

It involves changes in DNA sequence.

Question 15

A gain-of-function mutation that results in a protein with a new activity is called:

Accepted Answer

Neomorphic mutation

Question 16

Which of the following best describes the concept of a dominance series?

Accepted Answer

A hierarchy of alleles where some are dominant over others, as seen in rabbit coat color.

Question 17

Which of the following is a correct example of codominance?

Accepted Answer

A person with genotype $I^A I^B$ expresses both A and B antigens on their red blood cells.

Question 18

Which of the following scenarios best illustrates variable expressivity?

Accepted Answer

Two siblings with the same mutation in the Waardenburg syndrome gene show different combinations of hearing loss, eye color, and hair color.

Question 19

Which of the following is a real-world example of a lethal mutation?

Accepted Answer

The homozygous dominant genotype (MM) in Manx cats results in embryonic death.

Question 20

Which of the following best describes pleiotropy?

Accepted Answer

A single gene affects multiple, seemingly unrelated phenotypic traits.

Non-Mendelian Inheritance Patterns: Dominance, Mutations, Penetrance, Expressivity, and Gene Interaction

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