Biology

Genetics and Evolutionary Biology

1,123 Questions

Genetics and evolutionary biology explain how traits are passed from parents to offspring and how species change over time. Key concepts include genetic drift, inbreeding, and heredity. This topic is fundamental for the biology section of many competitive tests.

Heredity and traitsGenetic variations and driftInbreeding conceptsEvolutionary mechanisms

Genetics and Evolutionary Biology Questions

Multiple choice

Directions: The following question has four choices, out of which ONLY ONE is correct.

What happens to the tyrosinase gene during melanin synthesis in skin of an albino?

  1. An epistatic effect over other genes, so that melanin is not formed

  2. A complementary role, so that melanin formation is affected

  3. Supplementary role, so that melanin is formed and hidden

  4. Modifying role, so that melanin formation is stopped
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

 Epitasis is the inhibition of the expression of one gene by another non-allelic gene

Multiple choice

Which one of the following statements related to gene mutation is correct?

  1. Gene mutation was first reported on Oenothera

  2. Sorghum plant fails to produce chlorophyll due to gene mutation

  3. Gene mutation is otherwise called chromosomal aberration

  4. Gene mutation is genetically significant
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Gene mutation is genetically significant because it's the ultimate source of genetic variation, providing raw material for evolution. Option A is incorrect - first reported by de Vries in Oenothera lamarckiana (1900), but Oenothera is not the first report context. Sorghum chlorophyll mutants exist but are examples, not the defining principle. Gene mutation is distinct from chromosomal aberrations.

Multiple choice

Which one is gene mutation?

  1. Insertion

  2. Duplication

  3. inversion

  4. Translocation
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Insertion is a gene mutation involving the addition of nucleotide(s) into DNA sequence, changing the reading frame. Duplication, inversion, and translocation are chromosomal mutations involving changes to large chromosome segments rather than point mutations.

Multiple choice

Which of the following terms is not correctly defined?

  1. Population bottleneck : A sharp reduction in size of a population due to environmental random events or human activities

  2. Genetic drift : The changes in the frequency of an allele because of linkage with a positively selected allele at another locus

  3. Microevolution : The changes in allele frequencies that occur overtime within a population

  4. Molecular evolution : The change in the sequence composition of cellular molecules such as DNA, RNA, and proteins over long periods of time

  5. Habitat fragmentation : The emergence of discontinuities in an organism's preferred environment causing population fragmentation
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Genetic drift is the change in the frequency of an allele in a population due to random sampling. Genetic hitch hiking refers to changes in the frequency of an allele because of linkage with a positively selected allele at another locus.

Multiple choice

Mutations which occur in nature are called

  1. Lethal mutations

  2. Chromosomal mutations

  3. Point mutations

  4. Spontaneous mutations
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Spontaneous mutations occur naturally without any external artificial intervention. They arise from random errors during DNA replication, spontaneous chemical changes in DNA, or natural background radiation. This distinguishes them from induced mutations caused by mutagens like X-rays or chemicals.

Multiple choice

Which one of the following is a genetically significant mutation?

  1. Somatic mutation

  2. Translocation mutation

  3. Substitution mutation

  4. Inversion
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The question is poorly framed as all mutation types can be genetically significant depending on context. However, the intended answer is likely substitution (point mutation) as it directly alters gene sequences at the molecular level. Somatic mutations (A) are not heritable; translocation (B) and inversion (D) are chromosomal-level changes. Substitution mutations can change protein function and are heritable if they occur in germ cells, making them 'genetically significant' in evolutionary terms.

Multiple choice

Which of the following terms is not correctly defined?

  1. Microevolution: The changes in allele frequencies that occur over time within a population.

  2. Molecular evolution: The change in the sequence composition of cellular molecules such as DNA, RNA, and proteins over long periods of time.

  3. Habitat fragmentation: The emergence of discontinuities in an organism's preferred environment causing population fragmentation.

  4. Genetic drift: The changes in the frequency of an allele because of linkage with a positively selected allele at another locus.

  5. Population bottleneck: A sharp reduction in size of a population due to environmental random events or human activities.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Genetic drift is the change in the frequency of an allele in a population due to random sampling. Genetic hitchhiking refers to changes in the frequency of an allele because of linkage with a positively selected allele at another locus.

Multiple choice

The source of Darwinian variations is

  1. gene mutations

  2. gene recombination

  3. hormones

  4. natural selection
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Gene recombination during sexual reproduction creates new combinations of existing genes, producing variations Darwin observed. While mutations create new alleles, recombination is the primary source of variations in populations. Natural selection acts on variations but doesn't create them.

Multiple choice

Sudden inheritable changes are called

  1. mutations

  2. gene recombinations

  3. continuous variations

  4. acquired variations
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Mutations are sudden, inheritable changes in genetic material. Gene recombination creates variations but is more predictable. Continuous variations are gradual, and acquired variations (Lamarckian concept) are not inheritable in the way Darwin meant.

Multiple choice

For its entry in gene pool, a mutation must occur in

  1. somatic cells

  2. germ cells

  3. plasma proteins

  4. somatic DNA
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Only mutations in germ cells (gametes - sperm and egg) can be passed to offspring and enter the gene pool. Mutations in somatic (body) cells affect only that individual and are not inherited. Plasma proteins are not genetic material.