Question 1

Why did Gregor Mendel choose pea plants for his inheritance experiments?

Accepted Answer

Pea plants have easily observable traits, can self- or cross-pollinate, and produce many offspring.

Question 2

In a monohybrid cross between two true-breeding pea plants (AA × aa), what is the expected genotype ratio in the F2 generation?

Accepted Answer

$$1\ AA : 2\ Aa : 1\ aa$$

Question 3

A plant with genotype Dd is crossed with a plant with genotype dd. What percentage of the offspring will display the dominant phenotype?

Accepted Answer

$$50\%$$

Question 4

Which of the following best describes the outcome of a test cross between an organism with an unknown dominant phenotype and a homozygous recessive organism?

Accepted Answer

If all offspring show the dominant phenotype, the unknown parent is homozygous dominant.

Question 5

If a parent has genotype GgWw, what are all the possible gamete genotypes produced according to the law of independent assortment?

Accepted Answer

$$GW, Gw, gW, gw$$

Question 6

In a dihybrid cross between two heterozygous parents (GgWw × GgWw), what is the expected phenotypic ratio in the F2 generation?

Accepted Answer

$$9:3:3:1$$

Question 7

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

Accepted Answer

Autosomal dominant

Question 8

Which symbol in a pedigree chart represents a female carrier of an X-linked recessive trait?

Accepted Answer

A half-shaded circle

Question 9

If the probability of inheriting allele G is $$\frac{1}{2}$$ and the probability of inheriting allele W is $$\frac{1}{2}$$, what is the probability of inheriting both G and W together?

Accepted Answer

$$\frac{1}{4}$$

Question 10

Which of the following best defines a complex trait?

Accepted Answer

A trait influenced by multiple genes and environmental factors

Question 11

What is a SNP (Single Nucleotide Polymorphism)?

Accepted Answer

A single base-pair change in the DNA sequence among individuals

Question 12

How are SNPs most commonly identified in the laboratory?

Accepted Answer

By DNA sequencing or microarrays

Question 13

Why must thousands of people be studied in a GWAS (Genome-Wide Association Study)?

Accepted Answer

To detect small genetic effects and avoid random chance

Question 14

If a pedigree shows that only males are affected and there is no father-to-son transmission, what is the most likely inheritance pattern?

Accepted Answer

X-linked recessive

Question 15

Which of the following statements about genetic linkage is correct?

Accepted Answer

Linked genes are inherited together more often than expected by independent assortment.

Question 16

If the recombination frequency between two genes is 10%, what is their map distance?

Accepted Answer

$$10\ 	ext{cM}$$

Question 17

A double crossover event between three genes on a chromosome most often affects which gene?

Accepted Answer

The gene in the middle

Question 18

Which of the following is a correct interpretation of a 9:3:3:1 phenotypic ratio in the F2 generation of a dihybrid cross?

Accepted Answer

Both parents are heterozygous for both traits.

Question 19

In a pedigree, which symbol represents a deceased male?

Accepted Answer

A square with a diagonal line

Question 20

If a SNP is found significantly more often in people with a disease than in healthy controls, what does this suggest?

Accepted Answer

The SNP is likely linked to a gene influencing the disease.

Mendelian Genetics, Pedigrees, and Genetic Mapping: Study Guide

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