Q: A testcross between two Drosophila with different body color and wing shape alleles produces 270 recombinants out of 1000 offspring. What is the recombination frequency, and what does it indicate about the distance between the genes?

$$\frac{270}{1000} \times 100 = 27\%$$, indicating the genes are 27 map units apart.

Question 1

Which of the following best describes epigenetic gene regulation?

Accepted Answer

Stable changes in gene expression that are passed from cell to cell and are reversible, but do not involve a change in the DNA sequence.

Question 2

A female mammal is heterozygous for an X-linked gene. Which of the following best explains why she may be a mosaic for that gene's expression?

Accepted Answer

One X chromosome is randomly inactivated in each somatic cell during early embryonic development.

Question 3

Which of the following is an example of epigenetic inheritance?

Accepted Answer

A DNA methylation pattern established in a parent and transmitted to offspring via the egg or sperm.

Question 4

In four o'clock plants, leaf color is determined by the chloroplast genome. If a variegated female is crossed with a green male, what types of offspring are expected?

Accepted Answer

A mixture of green, white, and variegated offspring.

Question 5

Which of the following statements about mitochondrial inheritance is correct?

Accepted Answer

Mitochondrial genes are typically inherited maternally.

Question 6

A testcross between two Drosophila with different body color and wing shape alleles produces 270 recombinants out of 1000 offspring. What is the recombination frequency, and what does it indicate about the distance between the genes?

Accepted Answer

$$\frac{270}{1000} 	imes 100 = 27\%$$, indicating the genes are 27 map units apart.

Question 7

Which of the following best explains why linked genes do not follow Mendel's law of independent assortment?

Accepted Answer

They are located close together on the same chromosome and tend to be inherited together.

Question 8

Leber’s hereditary optic neuropathy (LHON) is caused by mutations in mitochondrial genes. Which of the following statements is true regarding its inheritance?

Accepted Answer

Only females can transmit the disease to their offspring.

Question 9

Which of the following scenarios is an example of gene linkage affecting inheritance patterns?

Accepted Answer

Two genes located close together on the same chromosome are inherited together more often than not.

Question 10

Which process is responsible for the creation of recombinant (nonparental) types in a genetic cross involving linked genes?

Accepted Answer

Crossing over between homologous chromosomes during meiosis.

Question 11

A calico cat is always female because:

Accepted Answer

X inactivation in heterozygous females produces patches of orange and black fur.

Question 12

Which of the following is NOT a deviation from Mendelian inheritance?

Accepted Answer

Genes assorting independently during meiosis.

Question 13

Which of the following best describes dosage compensation in mammals?

Accepted Answer

Equalization of X-linked gene expression in males and females by inactivating all but one X chromosome in each cell.

Question 14

If a plant requires low levels of FLC gene expression to flower, what epigenetic process allows flowering in spring after winter?

Accepted Answer

Epigenetic silencing of FLC during winter, maintained until spring.

Question 15

Which of the following equations correctly calculates recombination frequency?

Accepted Answer

$$	ext{Recombination frequency} = \frac{	ext{Number of recombinant offspring}}{	ext{Total offspring}} 	imes 100$$

Question 16

Which of the following is true about the inheritance of organelle genomes?

Accepted Answer

Organelle genomes are inherited maternally because the egg provides most of the cytoplasm.

Question 17

A mutation in a mitochondrial gene causes a disease that affects the heart and muscles. Why are these tissues most affected?

Accepted Answer

They rely heavily on ATP produced by mitochondria.

Question 18

Which of the following best explains why exposure to cigarette smoke can lead to cancer but is not considered epigenetic inheritance?

Accepted Answer

The changes are stable and passed from cell to cell, but not inherited by offspring.

Epigenetics, Linkage, and Extranuclear Inheritance (Chapter 18 Study Notes)

Study Guide - Practice Questions

Study Guide - Flashcards