Q: A couple, both heterozygous for gene B ($$Bb$$), have two children. What is the probability that both children will be carriers (heterozygous)?

$$\frac{1}{2} \times \frac{1}{2} = \frac{1}{4}$$

Question 1

Which statement best describes the Chromosome Theory of Inheritance?

Accepted Answer

Genes are found on chromosomes at specific locations (loci), and each chromosome can carry dozens to thousands of genes.

Question 2

In humans, which chromosome combination determines a male offspring?

Accepted Answer

XY

Question 3

What is the function of the SRY gene (also called TDF) located on the Y chromosome?

Accepted Answer

It initiates male development.

Question 4

Why are X-linked recessive traits, such as red/green color blindness, more commonly observed in males?

Accepted Answer

Males are hemizygous for the X chromosome, so a single recessive allele will be expressed.

Question 5

A female cat is heterozygous for fur color genes located on the X chromosome. What phenomenon explains her tortoiseshell appearance?

Accepted Answer

X inactivation, where one X chromosome is randomly inactivated in each cell, resulting in a mosaic of fur colors.

Question 6

Which chromosomal mutation is defined as having an extra copy of a chromosome, such as trisomy 21 (Down syndrome)?

Accepted Answer

Trisomy

Question 7

What is the cause of aneuploidy, such as trisomy or monosomy, in gametes?

Accepted Answer

Meiotic non-disjunction, where chromosomes fail to separate properly during anaphase I or II.

Question 8

Which of the following is NOT a type of structural chromosomal mutation?

Accepted Answer

Monosomy

Question 9

Transposable elements ('jumping genes') can promote which genetic event during meiosis?

Accepted Answer

Unequal crossover events

Question 10

If a parent cell has 40 chromosomes, how many chromosomes will be in each daughter cell after meiosis?

Accepted Answer

20

Question 11

During which specific phase of meiosis do homologous chromosomes separate?

Accepted Answer

Anaphase I

Question 12

During which phase of meiosis does crossing over occur?

Accepted Answer

Prophase I

Question 13

A test cross between a dihybrid fruit fly (gray body, normal wings) and a double mutant (black body, vestigial wings) produces offspring with mostly parental phenotypes and fewer recombinants. What does this suggest about the genes involved?

Accepted Answer

The genes are linked and located close together on the same chromosome.

Question 14

How is the map distance between two genes on a chromosome calculated in a linkage experiment?

Accepted Answer

By counting the number of recombinant offspring and expressing it as a percentage of the total offspring.

Question 15

What is the maximum map distance (in percent) that can be observed between two genes on the same chromosome?

Accepted Answer

$$50\%$$

Question 16

A couple, both heterozygous for gene B ($$Bb$$), have two children. What is the probability that both children will be carriers (heterozygous)?

Accepted Answer

$$\frac{1}{2} 	imes \frac{1}{2} = \frac{1}{4}$$

Question 17

In a Punnett square for a cross between a homozygous dominant ($$BB) $$and a heterozygous ($$Bb) $$individual, what is the probability that an offspring will be homozygous recessive?

Accepted Answer

$$0$$

Question 18

Which statistical test is used to compare expected genetic ratios to observed ratios in experimental data?

Accepted Answer

Chi square test ($$\$$chi^2$$)

Question 19

If your calculated Chi square value is less than the critical value at $$P=0.05$$, what does this indicate?

Accepted Answer

The difference between expected and observed ratios is likely due to chance, supporting your genetic hypothesis.

Question 20

Which chromosomal abnormality is associated with Turner syndrome?

Accepted Answer

Monosomy X ($$XO)$$

The Chromosomal Basis of Inheritance: Structure, Function, and Genetic Analysis

Study Guide - Practice Questions

Study Guide - Flashcards