Practice Questions

Correct: Evidence from chemical evolution and laboratory experiments supports the formation of organic molecules before living cells. A: Contradicts evolutionary theory. C: Spontaneous generation has been disproved. D: Oxygen inhibits, rather than promotes, prebiotic synthesis. Concept: Modern scientific view of the origin of life.

Correct: Without an ozone layer, intense UV radiation reached Earth's surface and acted as an energy source. B, C, D: These are unrelated to the absence of ozone at that stage. Concept: Energy sources for chemical evolution.

Correct: The experiment supported one step of the hypothesis, not the entire process of life's origin. A: No living cells formed. C: Amino acids were produced. D: Oxygen was excluded. Concept: Interpretation of experimental evidence.

Correct: Free oxygen was absent; therefore, the earliest organisms were simple anaerobic cells. A, B: Require oxygen. D: Complex eukaryotes evolved much later. Concept: Earliest life forms.

Correct: Protocells showed primitive organization before true cells evolved. A: Photosynthesis evolved later. C: Multicellularity appeared much later. D: Nuclei evolved in eukaryotes. Concept: Protocells.

Correct: Chemical evolution explains the origin of life's building blocks, whereas biological evolution begins after life exists. A, C, D: Scientifically incorrect. Concept: Comparison of evolutionary concepts.

Correct: Oxygen interferes with the formation and stability of organic molecules. A: Opposite of experimental reasoning. B: Oxygen changes reaction conditions. D: Amino acids do not spontaneously become proteins. Concept: Application of experimental evidence.

Correct: Organic molecules collected in ancient oceans where further chemical evolution occurred. A, B, D: These were not proposed as the primary site of accumulation. Concept: Primordial soup hypothesis.

Correct: Oxygen readily oxidizes organic compounds, preventing their accumulation. A, B, D: These conditions favored chemical evolution. Concept: Primitive Earth conditions.

Correct: Lightning, UV radiation, and volcanic heat provided energy for chemical reactions on primitive Earth. A: Incorrect because energy is essential. C: Miller-Urey controlled contamination. D: No living cells were present. Concept: Role of energy in chemical evolution.