Question 1

Which of the following best describes Mendel’s First Law (Law of Segregation)?

Accepted Answer

Alleles for a given trait separate during gamete formation, so each gamete receives only one allele.

Question 2

A heterozygous individual (Aa) is crossed with a homozygous recessive (aa). What is the expected genotypic ratio in the offspring?

Accepted Answer

1 Aa : 1 aa

Question 3

In a dihybrid cross between two heterozygotes (AaBb x AaBb), what is the probability of obtaining an offspring with genotype Aabb?

Accepted Answer

$$ \frac{1}{16} $$

Question 4

A pedigree shows a trait that appears in every generation and affects both males and females equally. Which mode of inheritance is most likely?

Accepted Answer

Autosomal dominant

Question 5

During which phase of meiosis does the cell become haploid?

Accepted Answer

After Meiosis I

Question 6

Which scenario best illustrates incomplete dominance?

Accepted Answer

A red flower and a white flower produce pink offspring.

Question 7

A gene mutation causes both heart defects and limb abnormalities. This is an example of:

Accepted Answer

Pleiotropy

Question 8

Which of the following best describes allelic heterogeneity?

Accepted Answer

Different mutations in the same gene cause the same phenotype.

Question 9

In mammals, sex determination is based on:

Accepted Answer

The presence of a Y chromosome

Question 10

A cell undergoes nondisjunction during Meiosis II. What is the result?

Accepted Answer

Half the gametes are normal, one is missing a chromosome, and one has an extra chromosome.

Question 11

Which chromosomal abnormality involves a chromosome number that is not an exact multiple of the haploid set?

Accepted Answer

Aneuploidy

Question 12

Which type of chromosomal rearrangement can result in an inversion loop during meiosis?

Accepted Answer

Inversion

Question 13

A reciprocal translocation differs from a Robertsonian translocation in that:

Accepted Answer

Reciprocal translocation involves exchange of segments between two non-homologous chromosomes.

Question 14

In a complementation analysis, two mutant strains are crossed and the offspring have a wild-type phenotype. What does this indicate?

Accepted Answer

The mutations are in different genes.

Question 15

A woman is a carrier for an X-linked recessive disorder. If she has a son, what is the probability that he will be affected?

Accepted Answer

$$ \frac{1}{2} $$

Question 16

Which of the following best describes penetrance?

Accepted Answer

The proportion of individuals with a genotype who express the phenotype.

Question 17

In fruit flies (Drosophila), sex is determined by:

Accepted Answer

The ratio of X chromosomes to autosomes

Question 18

A plant with genotype AaBbCc is self-crossed. What is the probability of obtaining an offspring with genotype aabbcc?

Accepted Answer

$$ \frac{1}{64} $$

Question 19

Which of the following is an example of genetic heterogeneity?

Accepted Answer

Mutations in different genes cause the same disease.

Question 20

A branch diagram is used in genetics to:

Accepted Answer

Calculate probabilities of genotypes and phenotypes in complex crosses.

Genetics Exam Study Guide: Mendelian Laws, Chromosome Behavior, and Gene Pathways

Study Guide - Practice Questions