Question 1

Which of the following best describes incomplete dominance?

Accepted Answer

The heterozygote expresses a phenotype that is intermediate between the two homozygotes.

Question 2

A cross between a red-flowered plant ($$C^R C^R) $$and a white-flowered plant ($$C^W C^W) $$produces all pink-flowered offspring ($$C^R C^W). If $$two pink-flowered plants are crossed, what is the expected phenotypic ratio in the F2 generation?

Accepted Answer

$$1$$ red : $$2$$ pink : $$1$$ white

Question 3

Which of the following is an example of codominance in humans?

Accepted Answer

ABO blood group, specifically the AB blood type

Question 4

A man with blood type AB and a woman with blood type O have a child. What are the possible blood types of their child?

Accepted Answer

A or B

Question 5

In a dihybrid cross involving two genes with recessive epistasis, what phenotypic ratio is expected in the F2 generation?

Accepted Answer

$$9:3:4$$

Question 6

A cross between two agouti mice ($$A a B b x$$ $$A a B b) $$produces offspring with the following phenotypes: agouti, black, cinnamon, and brown. Which genetic interaction best explains this result?

Accepted Answer

Gene interaction involving two genes affecting coat color

Question 7

Which of the following statements about mitochondrial inheritance is correct?

Accepted Answer

Mitochondrial DNA is inherited exclusively from the mother.

Question 8

A woman with a mitochondrial disease has children with a healthy man. What is the probability that her children will inherit the disease?

Accepted Answer

All children will inherit the disease.

Question 9

Which of the following best describes genomic imprinting?

Accepted Answer

One allele is silenced depending on whether it is inherited from the mother or the father.

Question 10

A child is diagnosed with Prader-Willi syndrome (PWS). Which of the following genetic mechanisms is most likely responsible?

Accepted Answer

A deletion in the paternal chromosome 15 (15q11-13)

Question 11

Which of the following is a likely outcome of histone acetylation?

Accepted Answer

Loosening of chromatin structure and increased gene expression

Question 12

A cross between two yellow mice ($$Yy x$$ $$Yy) $$produces a 2:1 ratio of yellow to non-yellow offspring. What is the most likely explanation for this result?

Accepted Answer

The yellow allele is a dominant lethal allele.

Question 13

Which of the following best explains the Bombay phenotype in humans?

Accepted Answer

A mutation in the H gene prevents the formation of the H antigen, so A and B antigens cannot be produced even if the ABO gene is present.

Question 14

Which of the following is an example of a sex-influenced trait?

Accepted Answer

Pattern baldness in humans

Question 15

A gene shows incomplete penetrance. Which of the following is true?

Accepted Answer

Only some individuals with the genotype express the expected phenotype.

Question 16

Which of the following best describes the effect of temperature-sensitive alleles, as seen in Himalayan rabbits?

Accepted Answer

The allele produces pigment only at lower temperatures, resulting in color at the extremities.

Question 17

If three independently assorting genes each have two alleles, how many different types of gametes can be produced by an individual heterozygous for all three genes?

Accepted Answer

$$2^3 = 8$

Question 18

Which of the following is a key feature of epigenetic inheritance?

Accepted Answer

It involves heritable changes in gene expression without altering the DNA sequence.

Question 19

A researcher performs a chi-square test to compare observed and expected ratios in a genetic cross. Which formula should be used to calculate the chi-square statistic?

Accepted Answer

$$\sum \frac{(O - E)^2$}{E}$$

Question 20

Which of the following is a real-world example of a disease caused by a mutation in mitochondrial DNA?

Accepted Answer

Leber's Hereditary Optic Neuropathy (LHON)

Extension of Mendelian Genetics and Non-Mendelian Genetics

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