Question 1

A couple, both phenotypically normal, have a child with cystic fibrosis, an autosomal recessive disorder. What is the probability that their next two children will both be unaffected by cystic fibrosis?

Accepted Answer

$$0.5625$$

Question 2

Which of the following best explains how meiosis increases genetic diversity in sexually reproducing organisms?

Accepted Answer

By allowing crossing over between homologous chromosomes and independent assortment of chromosomes

Question 3

A geneticist performs a dihybrid cross between two pea plants heterozygous for both seed color and seed shape. What is the expected phenotypic ratio in the F2 generation, and which statistical test would you use to determine if observed data fit this ratio?

Accepted Answer

9:3:3:1; Chi-square test

Question 4

In a human pedigree, a trait appears in every generation and affects both males and females equally. Which mode of inheritance is most likely?

Accepted Answer

Autosomal dominant

Question 5

A fruit fly geneticist observes that crossing two white-eyed flies produces only red-eyed offspring. Which genetic test would best determine if the mutations are in the same gene or different genes?

Accepted Answer

Complementation test

Question 6

Which of the following correctly matches the term with its definition?

Accepted Answer

Chromatid: a single DNA molecule after replication, still attached to its sister

Question 7

A woman with blood type AB and a man with blood type O have children. Which blood types are possible in their offspring?

Accepted Answer

A and B only

Question 8

Which of the following is an example of epistasis?

Accepted Answer

A gene for pigment deposition masks the effect of a gene for pigment color in Labrador retrievers

Question 9

If a plant with genotype $$AaBb is $$self-crossed, what is the probability that an offspring will be homozygous for both genes?

Accepted Answer

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

Question 10

Which of the following statements about the chromosome theory of inheritance is supported by the work of Thomas Hunt Morgan?

Accepted Answer

Genes are located on chromosomes, as demonstrated by the inheritance of eye color in Drosophila

Question 11

A geneticist is studying a gene with three alleles: $$A_1$$, $$A_2$$, and $$A_3. If$$ $$A_1 is a $$loss-of-function allele, $$A_2 is a $$hypomorph, and $$A_3 is $$wild type, which allelic series correctly orders these alleles from least to most functional?

Accepted Answer

$$A_1$$ \u003c $$A_2$$ \u003c $$A_3$$

Question 12

In a species with a ZW sex-determination system, which of the following statements is true?

Accepted Answer

Females are ZW and males are ZZ

Question 13

A cell with a diploid number of 8 undergoes meiosis. How many chromosomes will each gamete contain?

Accepted Answer

4

Question 14

Which of the following best describes the alternation of the eukaryotic genome between diploid and haploid phases?

Accepted Answer

Meiosis reduces the chromosome number from diploid to haploid, and fertilization restores diploidy

Question 15

A researcher observes a 9:7 phenotypic ratio in the F2 generation of a cross. What is the most likely explanation for this ratio?

Accepted Answer

Gene-gene interaction (epistasis) between two genes in the same pathway

Question 16

Which of the following equations represents the binomial theorem as used in calculating probabilities of genetic crosses?

Accepted Answer

$$P = \frac{n!}{x!(n-x)!} p^x q$$^{n-x}$$

Question 17

Which of the following is a likely consequence of nondisjunction during meiosis I in humans?

Accepted Answer

A gamete with two copies of a chromosome and a gamete with none

Question 18

Which of the following best describes heterochromatin?

Accepted Answer

Densely packed, transcriptionally inactive chromatin

Question 19

Which of the following geneticists is best known for discovering the principles of inheritance through experiments with pea plants?

Accepted Answer

Gregor Mendel

Question 20

A man with hemophilia (an X-linked recessive disorder) and a woman who is a carrier have a child. What is the probability that their son will have hemophilia?

Accepted Answer

$$0.5$$

General Genetics: Comprehensive Study Guide

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