Question 1

Which of the following best explains why genetically identical mice can display different phenotypes when raised in different environments?

Accepted Answer

Environmental factors can influence gene expression, leading to different phenotypes despite identical genotypes.

Question 2

A mutation in which region of a gene is LEAST likely to affect the protein’s amino acid sequence?

Accepted Answer

Promoter region

Question 3

Which of the following statements about Mendel’s First Law (Principle of Segregation) is correct?

Accepted Answer

During gamete formation, the two alleles for a trait separate so that each gamete receives only one allele.

Question 4

In a dihybrid cross involving two genes on different chromosomes, what is the expected phenotypic ratio in the F2 generation according to Mendel’s Second Law?

Accepted Answer

$$9:3:3:1$$

Question 5

Which of the following is a real-world example of codominance?

Accepted Answer

ABO blood type where both A and B alleles are expressed in type AB individuals.

Question 6

A mutation that results in the addition of one nucleotide in a coding sequence is called:

Accepted Answer

Nucleotide insertion

Question 7

Which of the following best describes the structure of DNA in the B form?

Accepted Answer

A right-handed double helix with anti-parallel strands and major/minor grooves.

Question 8

If a person has the genotype BO for the ABO blood group, what is their blood type phenotype?

Accepted Answer

Type B

Question 9

Which of the following is a misconception about mutations?

Accepted Answer

All mutations are bad and detrimental to the organism.

Question 10

What is the molecular basis for the stability of the DNA double helix?

Accepted Answer

Hydrogen bonds between complementary bases and base stacking forces.

Question 11

A diploid individual can carry how many alleles for a single gene?

Accepted Answer

Two

Question 12

Which of the following best describes a frameshift mutation?

Accepted Answer

A mutation caused by insertion or deletion of nucleotides that alters the reading frame of the gene.

Question 13

Why do traits sometimes 'skip a generation' in Mendelian inheritance?

Accepted Answer

Because alleles remain particulate and recessive alleles can be masked by dominant alleles in heterozygotes.

Question 14

Which of the following is true about genes located on the same chromosome?

Accepted Answer

They are linked and do not assort independently, resulting in altered gamete ratios.

Question 15

Which experiment would best determine the degree of genetic contribution to a trait?

Accepted Answer

Raise genetically identical organisms in different environments and compare their phenotypes.

Question 16

Which of the following is NOT a possible consequence of a mutation in a gene’s regulatory sequence?

Accepted Answer

Change in the amino acid sequence of the protein.

Question 17

What is the chemical difference between a nucleoside and a nucleotide?

Accepted Answer

A nucleotide contains a phosphate group, while a nucleoside does not.

Question 18

Which of the following best describes the anti-parallel nature of DNA?

Accepted Answer

The two strands run in opposite directions: one 5' to 3', the other 3' to 5'.

Question 19

Which of the following is a correct statement about the role of topoisomerase in DNA?

Accepted Answer

Topoisomerase relieves supercoiling and strain in DNA by cutting and rejoining the strands.

Genetics Study Notes: Mendelian Principles, Alleles, and DNA Structure

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