Quiz: Genetic Mutations and Evolution — 14 questions

1. What is a chromosomal translocation?

A. A change from one amino acid to another

B. A chromosome splitting into two identical copies

C. An exchange of chromosome parts between chromosomes from different pairs

D. A loss of a single nucleotide from a gene

Answer: (C)

Explanation

A translocation is an exchange of chromosome segments between chromosomes from different pairs. It is a structural chromosome mutation, not a point mutation.

2. Which point mutation type changes one base into another base?

A. Insertion

B. Frameshift

C. Deletion

D. Substitution

Answer: (D)

Explanation

A substitution is a point mutation in which one nitrogenous base is replaced by another. Insertions add a nucleotide, and deletions remove one.

3. What chromosomal mutation occurs when a chromosome region is reversed?

A. Inversion

B. Fusion

C. Deletion

D. Trisomy

Answer: (A)

Explanation

An inversion is a rearrangement in which a chromosome segment is reversed in orientation. Unlike deletion, the segment is not lost, just rearranged.

4. What does monosomy mean?

A. A chromosome segment is lost from one chromosome

B. An extra chromosome is present for a given pair

C. More than two complete sets of chromosomes are present

D. Only one chromosome is present instead of two for a given pair

Answer: (D)

Explanation

Monosomy is the condition in which one chromosome is present instead of the usual two for a pair. An extra chromosome would be trisomy, not monosomy.

5. Why do many DNA sequence changes fail to be passed to daughter cells?

A. Because RNA transcription removes damaged bases

B. Because all mutations occur only in gametes

C. Because DNA repair mechanisms correct them before division

D. Because chromosome number changes block inheritance

Answer: (C)

Explanation

DNA repair mechanisms fix many DNA changes before they can be transmitted to daughter cells. The other choices confuse repair with transcription, gamete formation, or chromosome-level mutations.

6. What is an aneuploidy?

A. The presence of more than two complete chromosome sets

B. A change affecting only one nucleotide

C. A chromosome pair with an abnormal number of copies

D. A reversal of a chromosome segment

Answer: (C)

Explanation

Aneuploidy means a chromosome pair does not have the normal number of copies. Polyploidy is different because it involves extra complete sets of chromosomes.

7. In eukaryotic cells, where do transcription and translation occur?

A. Both transcription and translation occur in the cytoplasm

B. Transcription occurs in the cytoplasm and translation in the nucleus

C. Transcription occurs in the nucleus and translation in the cytoplasm

D. Both transcription and translation occur in the nucleus

Answer: (C)

Explanation

In eukaryotes, transcription takes place in the nucleus and translation occurs in the cytoplasm. This separation is a key feature of protein synthesis in these cells.

8. How can polyploidization contribute to speciation?

A. By directly changing one gene so that all offspring are identical

B. By removing all mutations from a population over time

C. By causing individuals with different genome duplications to become reproductively isolated

D. By making meiosis unnecessary in every organism

Answer: (C)

Explanation

Polyploidization can lead to reproductive isolation when individuals with different chromosome-set numbers can no longer interbreed successfully. That isolation can eventually produce a new species.

9. What is polyploidy?

A. Having one extra chromosome in a single pair

B. Having a chromosome segment reversed in orientation

C. Having more than two complete sets of chromosomes

D. Having a mutation that changes one DNA base

Answer: (C)

Explanation

Polyploidy means an organism carries more than two complete chromosome sets. The other options describe aneuploidy, inversion, or a point mutation.

10. Why can a mutation that changes a codon still leave the amino acid sequence unchanged?

A. Because translation reads DNA directly

B. Because every base change creates a stop codon

C. Because codons are made of four bases

D. Because of redundancy in the genetic code

Answer: (D)

Explanation

The genetic code is redundant, so different codons can specify the same amino acid, producing a silent mutation. The other options contradict how codons and translation work.

11. What is transcription in protein synthesis?

A. The copying of proteins into RNA inside the cytoplasm

B. The production of messenger RNA from a gene using DNA information

C. The exchange of chromosome segments during meiosis

D. The production of protein from amino acids using ribosomes

Answer: (B)

Explanation

Transcription is the synthesis of mRNA from a gene using DNA as the template. Translation, not transcription, is the step that produces protein.

12. Which mutation in a germline cell can be passed to offspring and influence evolution?

A. A mutation in a red blood cell after birth

B. A mutation in a skin cell during life

C. A mutation in a germline cell

D. A mutation in a muscle cell during growth

Answer: (C)

Explanation

Only mutations in germline cells can enter gametes and be inherited by the next generation, so they can affect evolution. Somatic-cell mutations stay in the individual and are not transmitted.

13. What is the main reason mutations contribute to genetic diversity over time?

A. They eliminate all differences between individuals

B. They prevent any change from being inherited

C. They create heritable variation in DNA sequences

D. They directly rearrange proteins without changing DNA

Answer: (C)

Explanation

Mutations change DNA sequences, and when those changes are inherited they generate genetic variation over time. DNA repair can correct many changes, but it does not create diversity.

14. Why do mutations matter for evolution?

A. They generate allelic diversity within populations

B. They eliminate the need for heredity

C. They prevent any genetic variation from arising

D. They occur only in body cells and never matter to offspring

Answer: (A)

Explanation

Mutations create new alleles, increasing genetic variation in populations and making evolutionary change possible. The other choices contradict the role of inherited variation.