Question 1

Which of the following best describes the main purpose of meiosis in sexually reproducing organisms?

Accepted Answer

To reduce the chromosome number by half, creating haploid gametes

Question 2

A human karyotype reveals 47 chromosomes with three copies of chromosome 21. What is the most likely diagnosis?

Accepted Answer

Down syndrome (Trisomy 21)

Question 3

During which phase of meiosis does crossing over occur, and what is its significance?

Accepted Answer

Prophase I; it increases genetic variation among gametes

Question 4

If a mutation changes the DNA sequence from GAA to GAG, but both code for glutamic acid, what type of mutation is this?

Accepted Answer

Silent mutation

Question 5

Which of the following best explains why gametes are haploid?

Accepted Answer

So that fertilization restores the diploid number in the zygote

Question 6

A mutation causes an mRNA codon to change from UAU (tyrosine) to UAA (stop codon). What is the result?

Accepted Answer

A nonsense mutation

Question 7

Which of the following is a physical mutagen that can cause mutations in DNA?

Accepted Answer

Ultraviolet (UV) light

Question 8

What is the result of non-disjunction during meiosis?

Accepted Answer

Gametes with abnormal numbers of chromosomes

Question 9

Which of the following equations correctly represents the chromosome number in human somatic and gamete cells?

Accepted Answer

$$2n = 46 in $$somatic cells; $$n = 23 in $$gametes

Question 10

A frameshift mutation is most likely to result from which of the following?

Accepted Answer

An insertion or deletion of a nucleotide

Question 11

Which process ensures that all somatic cells in the human body have the same chromosome number as the original zygote?

Accepted Answer

Mitosis

Question 12

Which of the following best describes homologous chromosomes?

Accepted Answer

Chromosomes that are the same length, centromere position, and carry genes for the same traits

Question 13

Which event during meiosis increases genetic diversity by creating new combinations of alleles?

Accepted Answer

Random alignment of homologous chromosomes during metaphase I

Question 14

A karyotype is most useful for which of the following purposes?

Accepted Answer

Identifying chromosomal abnormalities such as extra or missing chromosomes

Question 15

Which of the following best explains why a child can inherit a genetic disorder even if neither parent shows symptoms?

Accepted Answer

The disorder is due to a new mutation in the gametes

Question 16

Which of the following is true about autosomes in humans?

Accepted Answer

There are 44 autosomes in human somatic cells

Question 17

If a sperm cell contains 22 autosomes and a Y chromosome, what type of offspring could result if it fertilizes an egg?

Accepted Answer

A male child (XY)

Question 18

Which of the following best describes the difference between a missense and a nonsense mutation?

Accepted Answer

A missense mutation changes an amino acid, while a nonsense mutation introduces a stop codon

Question 19

Which of the following equations correctly represents the relationship between diploid and haploid chromosome numbers in humans?

Accepted Answer

$$2n = 46$$, $$n = 23$$

Question 20

Which of the following scenarios is most likely to result in a frameshift mutation?

Accepted Answer

A single nucleotide is inserted into the DNA sequence

Meiosis, Karyotyping, and Mutations: A Study Guide

Study Guide - Practice Questions