Evolution – Biological Evolution and Mechanism of Evolution: NEET MCQs with Answers

15 free questions on Evolution – Biological Evolution and Mechanism of Evolution for NEET (UG), starting with previous-year NEET and AIPMT questions. Try each one, then tap Show answer for the answer and a short explanation.

Syllabus covered: Biological Evolution and Mechanism of Evolution: Darwin’s contribution, Modern Synthetic theory of Evolution; Mechanism of evolution- Variation (Mutation and Recombination) and Natural Selection with examples, types of natural selection;

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Question 1

Previous-year question
(NEET 2017 Delhi) Artificial selection to obtain cows yielding higher milk output represents:
  1. Stabilising selection (stabilises this character)
  2. Directional selection (pushes mean in one direction)
  3. Disruptive selection (splits population)
  4. Stabilising followed by disruptive
Show answer
Answer: (B) Directional selection (pushes mean in one direction)
Explanation: Selection for higher milk = directional selection (shifts mean up).

Question 2

Previous-year question
(NEET 2018) According to Hugo de Vries, the mechanism of evolution is:
  1. Multiple-step mutations
  2. Saltation
  3. Phenotypic variations
  4. Minor mutations
Show answer
Answer: (B) Saltation
Explanation: De Vries proposed saltation (single-step large mutation) as the mechanism.

Question 3

Previous-year question
(NEET 2019) In a species, 97% of newborns with weight between 3–3.3 kg survive, whereas 99% of newborns with weight 2–2.5 or 4.5–5 kg die. Which type of selection is taking place?
  1. Directional Selection
  2. Stabilising Selection
  3. Disruptive Selection
  4. Cyclical Selection
Show answer
Answer: (B) Stabilising Selection
Explanation: Eliminating both extremes (and favoring the mean) is stabilising selection.

Question 4

Previous-year question
(NEET 2019) Variations caused by mutation, as proposed by Hugo de Vries, are:
  1. Random and directional
  2. Random and directionless
  3. Small and directional
  4. Small and directionless
Show answer
Answer: (B) Random and directionless
Explanation: De Vries described mutations as random and directionless.

Question 5

Previous-year question
(NEET 2020) Which refer to correct examples of organisms which have evolved due to changes in environment brought about by anthropogenic action? A. Darwin's Finches; B. Herbicide-resistant weeds; C. Drug-resistant eukaryotes; D. Man-created breeds of domesticated animals like dogs.
  1. A and C only
  2. B, C and D only
  3. Only D
  4. Only B
Show answer
Answer: (B) B, C and D only
Explanation: Herbicide-resistant weeds, drug-resistant eukaryotes, and dog breeds are all human-induced; Darwin's Finches are natural.

Question 6

Previous-year question
(NEET 2022) Natural selection where more individuals acquire specific character value other than the mean character value leads to:
  1. Random change
  2. Stabilising change
  3. Directional change
  4. Disruptive change
Show answer
Answer: (C) Directional change
Explanation: Directional selection shifts the mean away from its original value.

Question 7

According to Darwin's theory of natural selection, which of the following is directly favoured by nature in a population?
  1. Large, sudden mutations that produce a new species in a single step
  2. Characters acquired by an individual through repeated use of an organ during its lifetime
  3. The species as a whole, regardless of the variation among its members
  4. Individuals carrying heritable variations that improve their survival and reproduction
Show answer
Answer: (D) Individuals carrying heritable variations that improve their survival and reproduction
Explanation: Darwin held that members of a population vary, and those whose heritable variations suit the environment leave more offspring. Fitness therefore refers to reproductive success of individuals. Inheritance of acquired characters was Lamarck's idea, and sudden large mutations were stressed by de Vries, not Darwin.
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Question 8

The process by which one or more new species arise from an existing species is called
  1. Adaptation
  2. Genetic drift
  3. Speciation
  4. Hybridisation
Show answer
Answer: (C) Speciation
Explanation: Speciation is the formation of new, reproductively isolated species from a pre-existing species. Genetic drift is a chance change in allele frequency, and adaptation and hybridisation do not by themselves mean the origin of a new species.

Question 9

Mutations contribute to evolution mainly by
  1. removing all differences among individuals of a species
  2. keeping offspring exactly identical to their parents
  3. producing new variations in a population
  4. preventing the formation of new species
Show answer
Answer: (C) producing new variations in a population
Explanation: Mutations are changes in the DNA that create new alleles and hence new variations in a population. Natural selection and other forces act on this variation, which can lead to new species over time.

Question 10

Darwin's theory of natural selection could NOT explain which of the following?
  1. Why organisms produce more offspring than can survive
  2. The observation that members of a species differ from one another
  3. How heritable variations are passed from parents to offspring through genes
  4. Why better-adapted individuals leave more progeny
Show answer
Answer: (C) How heritable variations are passed from parents to offspring through genes
Explanation: Darwin observed variation, overproduction and survival of the fitter individuals, and built natural selection on these. He did not know the mechanism of inheritance or the role of genes, so the passing of variations through genes was outside his theory.

Question 11

Read the statements about natural selection.
(a) It acts on heritable variations already present in a population.
(b) Individuals with useful variations tend to leave more offspring.
(c) It produces new variations on demand to suit a changing environment.
Which statements are correct?
  1. (a) and (b) only
  2. (c) only
  3. (a), (b) and (c)
  4. (b) and (c) only
Show answer
Answer: (A) (a) and (b) only
Explanation: Natural selection works on heritable variations that already exist, and individuals with better adaptive ability leave more progeny. It does not create variations to order; new variations arise by chance through mutation and recombination.

Question 12

The idea that heritable variations which let a few individuals use resources better will allow those individuals to reproduce more and leave more progeny, so that the population changes over generations, was put forward by
  1. Thomas Malthus
  2. Hugo de Vries
  3. Charles Darwin
  4. Jean-Baptiste Lamarck
Show answer
Answer: (C) Charles Darwin
Explanation: This was Darwin's key insight: heritable variations that make resource use better let only those individuals reproduce and leave more progeny, and over many generations the population characteristics change. Lamarck spoke of use and disuse of organs, de Vries of large sudden mutations, and Malthus wrote on human population growth.

Question 13

In a population of seed-eating birds, a long drought leaves only very small soft seeds and very large hard seeds. Birds with the smallest and the largest beaks leave the most offspring, while birds with medium beaks leave the fewest. If this continues for many generations, how will beak size be distributed in the population?
  1. A single peak that gets narrower around the original mean
  2. A single peak that shifts towards larger beaks
  3. Two peaks, with medium-sized beaks becoming the least common
  4. A flat distribution in which all beak sizes become equally common
Show answer
Answer: (C) Two peaks, with medium-sized beaks becoming the least common
Explanation: Selection here favours both extremes of the range at once, which is disruptive selection. Individuals near the mean contribute fewest offspring, so the middle of the distribution falls and two peaks form. A narrowing peak would mean stabilising selection, and a peak shifting one way would mean directional selection.

Question 14

Read the two statements on the overuse of pesticides. Statement I: Resistant pest varieties can become common in a time scale of months or years rather than centuries. Statement II: The pesticide acts on each individual pest and creates a resistance trait in it because the pest needs one.
  1. Statement I is false but Statement II is true
  2. Statement I is true but Statement II is false
  3. Both statements are false
  4. Both statements are true
Show answer
Answer: (B) Statement I is true but Statement II is false
Explanation: Heavy use of chemicals selects resistant varieties over a short time scale, which makes this a clear example of evolution by human action. The chemical does not produce resistance out of need. Resistant individuals that arise by chance survive and leave more offspring, so their proportion increases. The idea of a trait appearing through need is Lamarckian, not natural selection.

Question 15

In an industrial area, smoke once darkened tree trunks and killed the lichens on them. After strict smoke control, lichens return and the bark looks pale again. What change is most likely in the local peppered moth population over later generations?
  1. Dark-winged moths turn white during their own lifetime to match the lighter bark
  2. The proportion of the two forms stays fixed, as selection acted only during the smoky years
  3. The proportion of dark-winged moths rises further, as birds cannot see them on pale bark
  4. The proportion of white-winged moths rises, as predators now pick off more of the conspicuous dark-winged moths
Show answer
Answer: (D) The proportion of white-winged moths rises, as predators now pick off more of the conspicuous dark-winged moths
Explanation: Moths that blend into the background escape predatory birds, so background colour decides which form survives better. On lichen-covered pale bark the white-winged form is camouflaged and the dark form stands out. Selection therefore favours the white-winged moths, reversing the earlier trend. Individual moths do not change colour; the proportions in the population change.

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