Evolution – Origin of Life: NEET MCQs with Answers

15 free questions on Evolution – Origin of Life 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: Origin of Life

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Question 1

Previous-year question
From his experiments, S. L. Miller produced amino acids by mixing the following in a closed flask: [NEET 2020]
  1. CH3, H2, NH4 and water vapour at 800 °C
  2. CH4, H2, NH3 and water vapour at 600 °C
  3. CH3, H2, NH3 and water vapour at 600 °C
  4. CH4, H2, NH3 and water vapour at 800 °C
Show answer
Answer: (D) CH4, H2, NH3 and water vapour at 800 °C
Explanation: Miller created an electric discharge in a closed flask containing methane, hydrogen, ammonia and water vapour at 800 °C. After running the experiment for about a week he recovered amino acids from the condensate.

Question 2

Previous-year question
Following are two statements regarding the origin of life. (A) The earliest organisms that appeared on the earth were non-green and presumably anaerobes. (B) The first autotrophic organisms were the chemoautotrophs that never released oxygen. Which one of the following options is correct? [NEET 2016]
  1. (A) is correct but (B) is false
  2. (B) is correct but (A) is false
  3. Both (A) and (B) are correct
  4. Both (A) and (B) are false
Show answer
Answer: (C) Both (A) and (B) are correct
Explanation: The primitive atmosphere lacked oxygen, so the first organisms were necessarily non-green anaerobic heterotrophs. The earliest autotrophs were chemoautotrophs, which obtained energy from inorganic oxidations and released no oxygen; photoautotrophs came later.

Question 3

Previous-year question
Evolution may best be defined as [AIPMT 1989]
  1. progressive development of a race
  2. history and development of a race along with variations
  3. history of a race
  4. development of a race
Show answer
Answer: (B) history and development of a race along with variations
Explanation: Evolution is the history and gradual development of a race accompanied by heritable variations. The term implies gradual descent with modification and provides the working framework for explaining the diversity of organisms.

Question 4

Previous-year question
The book ‘Origin of Species’ was authored by [AIPMT 1989]
  1. Oparin
  2. Weismann
  3. Lamarck
  4. Darwin
Show answer
Answer: (D) Darwin
Explanation: Charles Darwin published 'On the Origin of Species by Means of Natural Selection' in 1859, based on observations made during the voyage of HMS Beagle. Wallace had reached similar conclusions, and their joint papers on natural selection were presented in 1858.

Question 5

Previous-year question
Which one of the following gases was missing from the earth’s atmosphere when life originated? [AIPMT 1991]
  1. NH₃
  2. H₂
  3. O₂
  4. CH₄
Show answer
Answer: (C) O₂
Explanation: The primitive atmosphere was free of molecular oxygen. It consisted mainly of methane, ammonia, water vapour, hydrogen, nitrogen and some carbon monoxide. Hydrogen, being most abundant and reactive, mopped up all free oxygen to form water.

Question 6

Previous-year question
The earliest organisms on the earth belonged to which nutritional category? [AIPMT 1992]
  1. Chemoautotrophs
  2. Chemoheterotrophs
  3. Autotrophs
  4. Eukaryotes
Show answer
Answer: (B) Chemoheterotrophs
Explanation: The first cells were almost certainly heterotrophs that obtained both energy and building blocks from organic molecules already present in their environment. Since prokaryotes preceded eukaryotes, the earliest prokaryotes must have been chemoheterotrophic.

Question 7

Previous-year question
Identify the correct order in which the following substances made their appearance during the course of evolution of life on the earth. [AIPMT 1996]
  1. Glucose, amino acids, nucleic acids, proteins
  2. Ammonia, amino acids, proteins, nucleic acids
  3. Water, amino acids, nucleic acids, enzymes
  4. Amino acids, ammonia, phosphates, nucleic acids
Show answer
Answer: (B) Ammonia, amino acids, proteins, nucleic acids
Explanation: In the reducing primitive atmosphere hydrogen combined with nitrogen to give ammonia and with oxygen to give water. Ammonia and other simple molecules then gave rise to amino acids, which polymerised into polypeptides and proteins; nitrogenous bases with sugars and phosphates finally produced nucleotides and nucleic acids.
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Question 8

Previous-year question
The very first living forms on the earth are believed to have been [AIPMT 2001]
  1. cyanobacteria
  2. chemoheterotrophs
  3. autotrophs
  4. photoautotrophs
Show answer
Answer: (B) chemoheterotrophs
Explanation: The first cells arose in an ocean already rich in ready-made organic molecules. They simply absorbed these molecules for energy and nutrition and were therefore anaerobic chemoheterotrophs; autotrophic forms evolved much later.

Question 9

Previous-year question
The absence of which one of the following is chiefly responsible for the absence of life on the moon? [AIPMT 2002]
  1. O₂
  2. Water
  3. Light
  4. Temperature
Show answer
Answer: (B) Water
Explanation: Water is the single most essential requirement of life — about 90% of plasma is water and life itself originated in water. Organisms can survive without free oxygen (anaerobes) and over wide ranges of light and temperature, but not without water. The moon has no water, hence no life.

Question 10

Previous-year question
Which one of the following sequences was put forward by Darwin and Wallace to explain organic evolution? [AIPMT 2003]
  1. Variations, natural selection, overproduction, constancy of population size
  2. Overproduction, variations, constancy of population size, natural selection
  3. Variations, constancy of population size, overproduction, natural selection
  4. Overproduction, constancy of population size, variations, natural selection
Show answer
Answer: (B) Overproduction, variations, constancy of population size, natural selection
Explanation: Darwin and Wallace argued that organisms multiply geometrically (overproduction), that individuals of a population differ from one another (variations), that nevertheless population size stays roughly constant over time, and that the best-adapted variants are picked out by nature (natural selection).

Question 11

Previous-year question
According to Oparin, which one of the following gases was absent from the atmosphere of the primitive earth? [AIPMT 2004]
  1. Methane
  2. Oxygen
  3. Hydrogen
  4. Water vapour
Show answer
Answer: (B) Oxygen
Explanation: Oparin held that the primitive atmosphere was strongly reducing. It contained large amounts of H₂, N₂, water vapour, CO₂, CH₄ and NH₃, but free oxygen was absent because the highly reactive and abundant hydrogen atoms combined with every available oxygen atom to form water.

Question 12

Previous-year question
Which one of the following experiments indicated that even the simplest living organisms could not have arisen spontaneously from non-living matter? [AIPMT 2005]
  1. Larvae appeared in decaying organic matter
  2. Microbes did not appear in stored meat
  3. Microbes appeared from unsterilised organic matter
  4. Meat did not spoil when it was heated and kept sealed in a vessel
Show answer
Answer: (D) Meat did not spoil when it was heated and kept sealed in a vessel
Explanation: When meat was boiled and then kept in a sealed vessel it did not putrefy, because heating killed the microbes present and sealing prevented fresh microbes from entering. This classic disproof of spontaneous generation showed that living organisms arise only from pre-existing living organisms.

Question 13

Previous-year question
Which one of the following amino acids was NOT among those synthesised in Miller’s experiment? [AIPMT 2006]
  1. Aspartic acid
  2. Glutamic acid
  3. Alanine
  4. Glycine
Show answer
Answer: (B) Glutamic acid
Explanation: Miller and Urey recovered glycine, alanine and aspartic acid in appreciable amounts from their spark-discharge apparatus. Glutamic acid was not produced in that experiment.

Question 14

Previous-year question
The idea of chemical evolution rests on which of the following propositions? [AIPMT 2007]
  1. Crystallisation of chemicals
  2. Interaction of water, air and clay under intense heat
  3. Effect of solar radiation on chemicals
  4. Possible origin of life by the combination of chemicals under suitable environmental conditions
Show answer
Answer: (D) Possible origin of life by the combination of chemicals under suitable environmental conditions
Explanation: Chemical evolution (a form of abiogenesis) proposes that under the physical conditions of the primitive earth, simple inorganic chemicals combined step by step through a long series of chemical reactions to produce organic molecules and eventually the first living systems.

Question 15

Previous-year question
Which one of the following is NOT a correct feature of protobionts (coacervates and microspheres) as visualised in the abiogenic origin of life? [AIPMT 2008]
  1. They were capable of reproducing themselves
  2. They could selectively separate combinations of molecules from the surroundings
  3. They remained partially isolated from the surroundings
  4. They could maintain an internal environment of their own
Show answer
Answer: (A) They were capable of reproducing themselves
Explanation: Protobionts such as coacervates and microspheres were partially isolated from their surroundings, could maintain an internal environment and could selectively take up combinations of molecules. They could not, however, truly reproduce themselves, since they lacked hereditary material.

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