Chapter 18 — Origin and Evolution of Life: Multiple Choice Questions
1. The theory that life arose from non-living matter through chemical evolution is called ______.
Answer
(a) Theory of special creation (b) Biogenesis (c) Chemical theory of origin of life (d) Panspermia
✅ Answer: (c) Chemical theory of origin of life
ExplanationThe Oparin-Haldane hypothesis (1920s) proposes that life originated from simple inorganic molecules through a series of chemical reactions on primitive Earth (abiogenesis). The Miller-Urey experiment (1953) provided experimental support by producing amino acids from inorganic molecules.
2. Who proposed the Theory of Natural Selection?
Answer
(a) Jean-Baptiste Lamarck (b) Charles Darwin (c) Gregor Mendel (d) Louis Pasteur
✅ Answer: (b) Charles Darwin
ExplanationCharles Darwin (with Alfred Russel Wallace) proposed the theory of Natural Selection in "On the Origin of Species" (1859). Key idea: Survival of the fittest — individuals best adapted to their environment survive and reproduce, passing on their favourable traits to offspring.
3. The Miller-Urey experiment produced ______.
Answer
(a) DNA (b) Amino acids (c) Proteins (d) Cell organelles
✅ Answer: (b) Amino acids
ExplanationStanley Miller and Harold Urey (1953) combined H₂, CH₄ (methane), NH₃ (ammonia), and H₂O (water) in a closed system and applied electrical sparks (simulating lightning). After one week, they found amino acids (organic molecules, building blocks of proteins) — supporting Oparin's hypothesis.
4. The concept that evolution occurs by the inheritance of acquired characteristics was proposed by ______.
Answer
(a) Darwin (b) Mendel (c) Lamarck (d) De Vries
✅ Answer: (c) Lamarck
ExplanationJean-Baptiste Lamarck's theory of evolution (1809) proposed: 1. Use and disuse: Organs that are used become stronger; unused organs weaken. 2. Inheritance of acquired characteristics: Traits acquired during lifetime are passed to offspring.
Example: Giraffes stretched their necks to reach leaves → longer necks passed to offspring. Lamarckism was largely disproved. Darwin's natural selection replaced it.
5. Homologous organs are those that have ______.
Answer
(a) Same function, different structure and origin (b) Same structure and origin, different function (c) No function (d) Same function and same origin
✅ Answer: (b) Same structure and origin, different function
Explanation
- Homologous organs: Same structure/origin (anatomically similar), different functions. Evidence for divergent evolution. Examples: Human arm, bat wing, whale flipper, horse leg — all have same bone arrangement (humerus, radius, ulna, carpals) but serve different purposes.
- Analogous organs: Different structure/origin, same function. Evidence for convergent evolution. Examples: Wings of birds and wings of insects.
6. Vestigial organs are ______.
Answer
(a) Organs that are fully functional (b) Organs that are newly formed (c) Non-functional organs remaining from ancestors (d) Organs of parasites
✅ Answer: (c) Non-functional organs remaining from ancestors
ExplanationVestigial organs are reduced, non-functional structures that were functional in ancestors. Evidence for evolution.
Examples in humans:
- Appendix (vermiform appendix)
- Ear muscles (we can't move our ears)
- Coccyx (tailbone — remnant of a tail)
- Wisdom teeth
- Body hair
7. The age of fossils can be determined by ______.
Answer
(a) Radio carbon dating (b) X-ray diffraction (c) Electron microscopy (d) Mass spectrometry only
✅ Answer: (a) Radio carbon dating
ExplanationRadiocarbon dating (C-14 dating) uses the known half-life of C-14 (5730 years) to date organic fossils up to ~50,000 years old. For older rocks, uranium-lead dating or potassium-argon dating are used. These techniques allow scientists to determine fossil ages accurately.
8. Industrial melanism in peppered moths is an example of ______.
Answer
(a) Mutation (b) Natural selection (c) Lamarckism (d) Genetic drift
✅ Answer: (b) Natural selection
ExplanationBefore industrial revolution, white moths (light coloured) were camouflaged on lichen-covered trees; black moths were eaten by birds. After industrialisation, soot blackened trees → black moths were now camouflaged; white moths were eaten more. Black moths became dominant. This demonstrates natural selection in action over a short time period.
9. The human population in which variation arises spontaneously without any specific cause is due to ______.
Answer
(a) Mutation (b) Hybridisation (c) Natural selection (d) Adaptation
✅ Answer: (a) Mutation
ExplanationMutations are spontaneous, random changes in the DNA sequence. They are the ultimate source of all genetic variation in a population. Mutations can be caused by radiation, chemicals (mutagens), or errors in DNA replication. Most mutations are neutral or harmful; rarely beneficial.
10. Fossils are found in ______.
Answer
(a) Igneous rocks (b) Metamorphic rocks (c) Sedimentary rocks (d) All types of rocks
✅ Answer: (c) Sedimentary rocks
ExplanationFossils are found almost exclusively in sedimentary rocks (formed by layering of sediments like sand, clay, silt). Organisms get buried in sediment and over millions of years their remains are preserved as fossils. Igneous rocks (from volcanic activity) and metamorphic rocks (from heat/pressure) destroy organic remains.
Quick Revision
| Concept | Key Fact |
|---|
| Oparin-Haldane hypothesis | Life from inorganic molecules (abiogenesis) |
| Miller-Urey experiment (1953) | Produced amino acids from inorganic compounds |
| Darwin's Natural Selection | Survival of the fittest; published 1859 |
| Lamarck's theory | Use/disuse + inherited acquired characters (largely disproved) |
| Homologous organs | Same structure, different function (e.g., vertebrate forelimbs) |
| Analogous organs | Different structure, same function (e.g., wings of birds/insects) |
| Vestigial organs | Non-functional remnants (e.g., appendix, coccyx) |
| Fossils in | Sedimentary rocks |
| C-14 dating | For organic fossils up to ~50,000 years |
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