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3.1 Origin of Life — Test 2
Q1. Under present-day conditions, the spontaneous origin of life from inorganic molecules is not possible mainly because of:✓ Presence of molecular oxygen
Q2. The first oxygen-evolving organisms on Earth were:✓ Cyanobacteria
Q3. The strongest evidence suggesting that RNA was more ancient than DNA is that RNA:✓ Can act as a catalyst (ribozyme)
Q4. The first organisms to evolve on Earth were most likely:✓ Anaerobic chemoheterotrophs
Q5. According to current understanding, the most probable site for the origin of life was:✓ Deep-sea hydrothermal vents
Q6. Which gas was essentially ABSENT from the atmosphere during the period when life originated?✓ Oxygen
Q7. In the Urey-Miller experiment, the energy source used to drive the synthesis of organic molecules was:✓ Electric spark
Q8. The gases used by Urey and Miller to test the Oparin-Haldane hypothesis were:✓ Hydrogen, methane and ammonia (with water vapour)
Q9. A student set up a Miller-Urey-type apparatus with NH3, CH4, CO and H2 and an electric spark, but obtained no organic molecules. The most likely forgotten essential ingredient was:✓ Water (H2O)
Q10. The biomolecule with the inherent property of self-replication is:✓ Nucleic acid
Q11. The bubble-like structures proposed by Oparin as precursors to cells were called:✓ Coacervates
Q12. In laboratory simulations of the origin of life, the first biomolecules generated were:✓ Amino acids
Q13. After life arose, the main source of the oxygen that later accumulated in the atmosphere was:✓ Photosynthesis
Q14. The first living beings on Earth were anaerobic because:✓ There was no free oxygen in the air
Q15. Chemolithotrophs obtain their carbon from CO2 and their energy from:✓ Inorganic compounds
Q16. Complex eukaryotic cells are thought to have evolved from simpler prokaryotic cells because increased complexity allowed:✓ The ability to attain a larger size and compartmentalisation
Q17. Which statement about the endosymbiotic hypothesis of eukaryotic origin is INCORRECT?✓ Engulfment of a cyanobacterium preceded engulfment of an alpha-proteobacterium
Q18. The correct chronological order of events in the history of life is: (a) prokaryotic cell; (b) eukaryotic cell; (c) natural selection; (d) organic molecules; (e) self-replicating molecule.✓ d → e → c → a → b
Q19. Among the following, the most primitive eukaryotes are considered to be the:✓ Archezoa (amitochondriate protists)
Q20. Match each milestone with its description and select the correct option.✓ A-iii, B-ii, C-iv, D-i