Question 1

Which of the following best describes a missense mutation?

Accepted Answer

A mutation that changes one amino acid to another by altering a single base pair.

Question 2

A single base substitution at codon #6 in the $\beta$-globin gene changes glutamic acid to valine, causing sickle cell anemia. What type of mutation is this?

Accepted Answer

Missense mutation

Question 3

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

Accepted Answer

Base insertion or deletion

Question 4

A nonsense mutation in a gene will most likely result in:

Accepted Answer

A truncated protein due to a premature stop codon

Question 5

Which of the following best explains why synonymous (silent) mutations are more common at the third position of a codon?

Accepted Answer

The genetic code is degenerate, allowing multiple codons to code for the same amino acid due to wobble at the third position.

Question 6

Which chromosomal abnormality is responsible for non-familial Down Syndrome?

Accepted Answer

Trisomy 21

Question 7

Aneuploidy is most often caused by which cellular process?

Accepted Answer

Non-disjunction during meiosis

Question 8

If a cell has a chromosome number of $2n + 1$, what condition does it exhibit?

Accepted Answer

Trisomy (aneuploidy)

Question 9

Which of the following is an example of polyploidy?

Accepted Answer

A plant cell with three complete sets of chromosomes ($3n$)

Question 10

Tandem duplications most commonly arise from which genetic event?

Accepted Answer

Unequal crossing over during meiosis

Question 11

What is the likely consequence of a frameshift mutation in a protein-coding gene?

Accepted Answer

Alteration of the entire amino acid sequence downstream of the mutation

Question 12

Which equation correctly represents a tetraploid organism?

Accepted Answer

$4n$

Question 13

A mutation that does not change the amino acid sequence of a protein is called:

Accepted Answer

Silent (synonymous) mutation

Question 14

Which of the following best describes the effect of gene duplication on gene expression?

Accepted Answer

It can increase gene dosage, leading to phenotypic variation.

Question 15

Which of the following scenarios would most likely result in a triploid ($3n$) organism?

Accepted Answer

Fusion of a diploid gamete with a haploid gamete

Question 16

Which of the following is NOT a type of molecular mutation?

Accepted Answer

Chromosome duplication

Question 17

A plant with autopolyploidy is likely to exhibit which of the following characteristics compared to its diploid counterpart?

Accepted Answer

Larger fruit size due to increased gene dosage

Question 18

Which of the following best explains the genetic basis of Trisomy 21?

Accepted Answer

An extra copy of chromosome 21 due to non-disjunction

Question 19

Which process is most likely to result in a monosomic zygote ($2n - 1$)?

Accepted Answer

Non-disjunction during meiosis resulting in a gamete missing a chromosome

Question 20

Which of the following statements about gene mutations is correct?

Accepted Answer

Mutations can occur anywhere in a gene sequence and in any cell.

Gene Mutations and Eukaryotic Chromosome Abnormalities: Key Concepts and Mechanisms CH 10 & 11

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