NEET Biology Evolution MCQs Set 12

Answer: (c) Big-bang theory

Explanation:
1. The big-bang theory explains the origin of the universe from a single huge explosion.
2. Panspermia deals with the origin of life, and natural selection deals with evolution of species.

Teacher's Note:
1. The universe is about 20 billion years old.

Answer: (d) All of the above

Explanation:
1. The theory of special creation has three parts: organisms were created as they are, diversity has stayed the same, and the earth is only about 4000 years old.
2. All three statements therefore belong to it.

Teacher's Note:
1. Scientific evidence does not support this theory.

Answer: (c) Life came from dead and decaying matter

Explanation:
1. Spontaneous generation (abiogenesis) said that life arises from decaying matter, such as mud giving rise to worms.
2. Life from pre-existing non-living organic molecules is the chemical evolution theory.

Teacher's Note:
1. Louis Pasteur disproved spontaneous generation.

Answer: (a) Louis Pasteur

Explanation:
1. Pasteur used swan-necked flasks and showed that sterilised broth stayed free of life unless exposed to germs.
2. This supported biogenesis, i.e.
3. life comes only from pre-existing life.

Teacher's Note:
1. Oparin and Haldane proposed the chemical origin of life.

Answer: (d) Theory of biogenesis

Explanation:
1. Without entry of germs from outside, no microbes appear in the sterilised meat.
2. Hence life comes only from pre-existing life, which is biogenesis.

Teacher's Note:
1. Abiogenesis would predict spoilage even in a sealed jar.

Answer: (c) Water

Explanation:
1. Life arose in water, where the organic molecules could interact.
2. Early earth had no free oxygen.

Teacher's Note:
1. Water remains the basic requirement for all life.

Answer: (c) II, IV, I, III

Explanation:
1. Simple organic molecules join to form complex organic molecules (macromolecules).
2. These aggregate into protobionts, from which the first true cell-like forms (eobionts) arose.

Teacher's Note:
1. The order is II, IV, I, III.

Answer: (a) Oparin

Explanation:
1. Oparin prepared coacervate droplets in the laboratory as models of protobionts.
2. Miller synthesised amino acids from gases.

Teacher's Note:
1. Pasteur disproved spontaneous generation.

Answer: (d) Chemoheterotrophs, anaerobic

Explanation:
1. Early earth had no free oxygen and plenty of organic molecules, so the first cells were anaerobic heterotrophs.
2. Autotrophs and aerobic organisms came later.

Teacher's Note:
1. Photosynthesis later released oxygen into the atmosphere.

Answer: (c) Stanley Miller

Explanation:
1. Stanley Miller (1953) passed electric discharges through CH4, \( H2 \), NH3 and water vapour and obtained amino acids.
2. This supported the Oparin-Haldane theory.

Teacher's Note:
1. Oparin and Haldane only proposed the idea.

Answer: (b) P-II, Q-III, R-IV, S-I

Explanation:
1. The universe is about 20 billion years old and the earth about 4.5 billion years.
2. The first non-cellular life appeared about 3 bya and the first cells about 2 bya.

Teacher's Note:
1. So P-II, Q-III, R-IV and \( S-I \).

Answer: (d) The first non-cellular forms of life would have been giant molecules like RNA, proteins and polysaccharides

Explanation:
1. Non-cellular life began as giant molecules such as RNA and proteins.
2. Life began about 500 million years after the earth formed, prokaryotes came before eukaryotes, and the early atmosphere lacked oxygen.

Teacher's Note:
1. Only statement \( (d) \) is correct.

Answer: (b) It can explain the origin of life

Explanation:
1. The big-bang theory explains the formation of the universe, galaxies and the solar system.
2. It does not explain how life arose.

Teacher's Note:
1. The origin of life is explained by chemical evolution.

Answer: (b) 800 degrees C

Explanation:
1. Miller kept the spark chamber at 800 degrees \( C \) with electric discharge, using CH4, \( H2 \), NH3 and water vapour.
2. After some days amino acids were found in the condensate.

Teacher's Note:
1. This showed that organic molecules can form from inorganic ones.

Answer: (d) Devonian - fishes and Jurassic - dinosaurs

Explanation:
1. The Devonian is the age of fishes and the Jurassic is the age of dinosaurs.
2. Amphibians dominated the Carboniferous.

Teacher's Note:
1. Link the era with its dominant group.

Answer: (a) Thecodonts

Explanation:
1. Thecodonts were early archosaurs from which dinosaurs, crocodiles and birds descended.
2. Synapsids and pelycosaurs lead to mammals.

Teacher's Note:
1. Archaeopteryx is a bird-like reptile and not the common ancestor.

Answer: (d) Tail in a newborn baby

Explanation:
1. Atavism is the reappearance of an ancestral character that is normally absent.
2. A tail in a human baby is an atavistic feature.

Teacher's Note:
1. The others are vestigial organs, which are present in every individual.

Answer: (c) Potato and ginger

Explanation:
1. Potato and ginger are both modified stems, so they are homologous.
2. Potato (stem) and sweet potato (root) have different origins but similar function, so they are analogous.

Teacher's Note:
1. Analogy means similar function with different origin.

Answer: (a) Petrified fossils

Explanation:
1. Petrified fossils form when minerals replace the organic material, and these are the commonest.
2. Unaltered fossils such as mammoths in ice are rare.

Teacher's Note:
1. Coprolites are fossilised faeces.

Answer: (b) Increase in number of toes

Explanation:
1. From Eohippus to Equus the number of toes decreased from four to one.
2. Height, tooth crown height and brain size increased.

Teacher's Note:
1. So an increasing toe number is not seen.

Answer: (b) Coccyx, nictitating membrane

Explanation:
1. The coccyx (tail bone) and the nictitating membrane (plica semilunaris) are vestigial in humans.
2. Nails and eyelids are fully functional.

Teacher's Note:
1. The vermiform appendix and wisdom teeth are also vestigial.

Answer: (d) 12 billion years

Explanation:
1. The radioactive fraction is \( 1/16 = (1/2)^4 \), so four half-lives have passed.

Teacher's Note:
1. Age = \( 4 \times 3 = 12 \) billion years.

Answer: (b) Three

Explanation:
1. Items \( (a), (b) \) and \( (d) \) have the same origin and so are homologous.
2. Items \( (c) \) and \( (e) \) are analogous, with similar function but different origin.

Teacher's Note:
1. So there are three examples.

Answer: (a) Preserved impressions or hard parts of past organisms

Explanation:
1. Palaeontology is the study of fossils, which are preserved impressions or hard parts of past life.

Teacher's Note:
1. The second option is comparative anatomy, the third biogeography and the fourth embryology.