"Evolution and Human Welfare" — Practice

Question 1

The Miller-Urey experiment demonstrated the abiotic formation of:
(a) amino acids (b) DNA (c) a living cell (d) proteins

Accepted Answer

(a) amino acids.

Miller and Urey passed an electric discharge through a simulated early-Earth reducing atmosphere (CH₄, NH₃, H₂, water vapour) and obtained amino acids, showing that organic molecules can form abiotically — not that life itself was created.

Question 2

The forelimbs of a human, a bat and a whale, though used for different functions, share the same basic bone arrangement. This is an example of:
(a) homologous organs (b) analogous organs (c) vestigial organs (d) convergent evolution

Accepted Answer

(a) homologous organs.

Same underlying structure (humerus, radius, ulna, carpals), different function (grasping, flying, swimming) — evidence of divergent evolution from a common ancestor.

Question 3

Wings of a butterfly and wings of a bird are an example of:
(a) analogous organs (b) homologous organs (c) vestigial organs (d) connecting links

Accepted Answer

(a) analogous organs.

Completely different structural origin (chitinous exoskeleton vs. bony/feathered limb) serving the same function of flight — convergent evolution, no common ancestry for the wing structure itself.

Question 4

The shift of the peppered moth population toward the dark (melanic) form during industrialisation is an example of:
(a) directional selection (b) stabilising selection (c) disruptive selection (d) genetic drift

Accepted Answer

(a) directional selection.

One extreme phenotype (dark form) was favoured due to better camouflage on soot-darkened trees, shifting the population mean toward that extreme.

Question 5

Human birth weight showing highest survival near the average, with both very low and very high birth weights having higher mortality, illustrates:
(a) stabilising selection (b) directional selection (c) disruptive selection (d) adaptive radiation

Accepted Answer

(a) stabilising selection.

Stabilising selection favours the intermediate/average phenotype and removes both extremes, keeping the population's trait distribution narrow around the mean.

Question 6

In a population of 20,000 individuals, 16% show a recessive phenotype. Assuming Hardy-Weinberg equilibrium, how many individuals are homozygous dominant?

Accepted Answer

q² = 0.16 ⇒ q = 0.4, so p = 1 − 0.4 = 0.6.

Homozygous dominant frequency p² = 0.36. Number = 0.36 × 20,000 = 7,200 individuals.

Question 7

Which of the following is NOT a condition required for a population to remain in Hardy-Weinberg equilibrium?
(a) natural selection acting on the population (b) random mating (c) no mutation (d) large population size

Accepted Answer

(a) natural selection acting on the population.

Equilibrium requires NO natural selection (among other conditions: no mutation, random mating, large population, no gene migration). Any of these being violated causes allele frequencies to change — i.e., evolution.

Question 8

A small group of colonising individuals establishes a new population whose allele frequencies differ, by chance, from the parent population. This is called:
(a) founder effect (b) bottleneck effect (c) gene flow (d) natural selection

Accepted Answer

(a) founder effect.

The founder effect is a form of genetic drift where a small founding group's (chance) allele frequencies diverge from the source population, shaping the new population's gene pool. The bottleneck effect instead refers to a sudden drastic reduction of an EXISTING population.

Question 9

Darwin's finches on the Galápagos Islands, showing diverse beak shapes evolved from a common ancestral finch, illustrate:
(a) adaptive radiation (b) convergent evolution (c) genetic drift (d) gene flow

Accepted Answer

(a) adaptive radiation.

Adaptive radiation is the evolution of different species from a common ancestral stock within a single geographical area, each adapting to a different niche (here, different food sources).

Question 10

Which hominid is recognised as the first confirmed toolmaker in the human evolutionary lineage?
(a) Homo habilis (b) Homo erectus (c) Australopithecus (d) Neanderthal man

Accepted Answer

(a) Homo habilis.

Homo habilis (brain capacity ~650–800 cc) is credited as the first confirmed toolmaker, primarily consuming meat, preceding Homo erectus in the lineage.

Question 11

Antibody-mediated immunity is carried out by:
(a) B-lymphocytes (b) T-lymphocytes (c) macrophages (d) neutrophils

Accepted Answer

(a) B-lymphocytes.

B-lymphocytes differentiate into plasma cells that secrete antibodies into blood and lymph — humoral immunity. T-lymphocytes mediate cell-mediated immunity, directly attacking infected cells.

Question 12

An antibody (immunoglobulin) molecule is structurally composed of:
(a) 2 heavy chains + 2 light chains (b) 4 identical heavy chains (c) 2 heavy chains + 4 light chains (d) 1 heavy chain + 1 light chain

Accepted Answer

(a) 2 heavy chains + 2 light chains.

Each Y-shaped antibody has two identical heavy (H) chains and two identical light (L) chains, linked by disulfide bonds. Five classes exist (IgA, IgM, IgE, IgG, IgD); IgG alone crosses the placenta.

Question 13

HIV, the causative agent of AIDS, primarily infects and destroys:
(a) helper T-lymphocytes (b) B-lymphocytes (c) red blood cells (d) platelets

Accepted Answer

(a) helper T-lymphocytes.

HIV (a retrovirus) infects TH cells; their progressive destruction cripples both cell-mediated and (indirectly) humoral immunity, since TH cells are required to activate B-cells.

Question 14

Elephantiasis (filariasis), caused by Wuchereria bancrofti, is transmitted by:
(a) Culex mosquito (b) Anopheles mosquito (c) Aedes mosquito (d) housefly

Accepted Answer

(a) Culex mosquito.

Filariasis is transmitted by the Culex mosquito. Malaria uses the female Anopheles mosquito; dengue and chikungunya use Aedes — a frequently swapped distractor set in NEET.

Question 15

The spread of cancer cells from their original site to a distant part of the body via blood or lymph is called:
(a) metastasis (b) mutation (c) apoptosis (d) mitosis

Accepted Answer

(a) metastasis.

Metastasis — invasion and spread to distant tissues — is what distinguishes a malignant tumour from a benign one, which stays localised despite also showing uncontrolled cell division.

Practice — "Evolution and Human Welfare"

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