Question 1

Which hypothesis about the origin of organic molecules on early Earth was directly tested by the Miller-Urey experiment, and what was the main result?

Accepted Answer

Reducing atmosphere hypothesis; formation of amino acids and precursor molecules

Question 2

Why is the prebiotic synthesis of polymers considered unlikely in aqueous solutions, and what alternative environment was proposed to facilitate polymerization?

Accepted Answer

Because hydrolysis competes with polymerization; clay surfaces with cations were proposed to facilitate polymerization

Question 3

Which of the following is NOT a characteristic of a protobiont?

Accepted Answer

Ability to photosynthesize

Question 4

What is the central dogma of molecular biology, and which process is represented by the equation $$	ext{DNA} ightarrow 	ext{RNA} ightarrow 	ext{Protein}$$?

Accepted Answer

Transcription and translation

Question 5

Which molecule is believed to have been the first macromolecule in protobionts, and why?

Accepted Answer

RNA, because it can store information, self-replicate, and act as an enzyme

Question 6

Chemical selection in the RNA world is best described as:

Accepted Answer

A process where RNA molecules with advantageous mutations increase in number due to their catalytic abilities

Question 7

Which of the following best explains why DNA eventually replaced RNA as the primary information storage molecule?

Accepted Answer

DNA is more stable and allows RNA to focus on catalytic functions

Question 8

Radiometric dating relies on measuring the amount of a radioisotope and its decay product in rock. If the half-life of uranium-235 is 704 million years, what fraction of the original uranium-235 remains after 1.408 billion years?

Accepted Answer

$$\frac{1}{4}$$

Question 9

Which environmental change during Earth's history was most directly responsible for the evolution of aerobic respiration?

Accepted Answer

Increase in atmospheric oxygen due to cyanobacteria photosynthesis

Question 10

The endosymbiotic theory for the origin of eukaryotes proposes that:

Accepted Answer

Eukaryotes evolved from a symbiotic relationship between two prokaryotic cells

Question 11

Which period is characterized by the abrupt increase in diversity of animal species known as the 'Cambrian explosion'?

Accepted Answer

Cambrian Period

Question 12

What adaptation allowed early land plants to colonize terrestrial environments during the Silurian Period?

Accepted Answer

Development of external cuticle to prevent drying out

Question 13

Which event marks the boundary between the Paleozoic and Mesozoic eras?

Accepted Answer

The Permian mass extinction

Question 14

During which period did the first known bird, Archaeopteryx, appear?

Accepted Answer

Jurassic Period

Question 15

Which of the following is a plausible explanation for the mass extinction at the end of the Cretaceous Period?

Accepted Answer

Large meteorite/asteroid impact and/or volcanic eruptions

Question 16

Which eon is characterized by the emergence of prokaryotic cells and anaerobic life forms?

Accepted Answer

Archaean Eon

Question 17

What is the significance of stromatolites in the fossil record?

Accepted Answer

They are layered structures formed by cyanobacteria, providing evidence of early autotrophic life

Question 18

Which domain is most closely related to Eukarya according to phylogenetic analysis?

Accepted Answer

Archaea

Question 19

Which period saw the emergence of hominoids, including humans and their recent ancestors?

Accepted Answer

Tertiary Period

Question 20

Which of the following best describes the process of mass extinction?

Accepted Answer

A dramatic environmental change that affects many species, leading to widespread extinction

The History of Life on Earth: Origin, Evolution, and Major Transitions

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