Home / iGCSE Biology (0610)-18.1 Variation – iGCSE Style Questions Paper 2

iGCSE Biology (0610)-18.1 Variation – iGCSE Style Questions Paper 2

IGCSE Biology (0610) Practice Questions Paper 2 - All Chapters

Question

Which letter represents the lag phase in the population graph shown?

▶️ Answer/Explanation
The lag phase is the initial period of a population growth curve where the population size increases very slowly. During this stage, organisms are adapting to their new environment, undergoing intense metabolic activity, and preparing for reproduction rather than actively dividing at a high rate. In the provided sigmoid (S-shaped) growth curve, section A clearly depicts this slow starting phase before the rapid exponential growth seen in section B. As the graph progresses, C represents the deceleration phase, and D represents the stationary phase where the population reaches carrying capacity.
✅ Answer: (A)

Question

What are sources of genetic variation in populations?

(A) meiosis, mutation, random mating
(B) meiosis, random mating, asexual reproduction
(C) mitosis, mutation, random fertilisation
(D) mitosis, random fertilisation, asexual reproduction
▶️ Answer/Explanation

Genetic variation arises from processes that shuffle or change DNA. Meiosis contributes through crossing over and independent assortment, while mutations create entirely new alleles. Random mating ensures diverse combinations of these alleles within a population. In contrast, mitosis and asexual reproduction produce genetically identical clones, which limits rather than increases variation. Therefore, option (A) is the only set containing three genuine sources of diversity.

✅ Answer: (A)

Question

What is a way in which new alleles are formed?

(A) artificial selection
(B) mutation
(C) natural selection
(D) sexual reproduction
▶️ Answer/Explanation

New alleles are created exclusively through mutation, which is a permanent change in the $DNA$ sequence of a gene. While sexual reproduction (D) increases genetic variation by shuffling existing alleles through recombination and independent assortment, it does not create “new” genetic information. Similarly, natural selection (C) and artificial selection (A) only act upon the variations that are already present in a population, favoring certain traits over others. Therefore, mutation is the primary source of all new genetic material and the ultimate driver of evolutionary novelty.

✅ Answer: (B)

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