Question 1

Which hypothesis suggests that organic molecules necessary for life may have arrived on Earth via meteorites, and what is a major challenge to this hypothesis?

Accepted Answer

Extraterrestrial hypothesis; destruction of molecules by heat and pressure during impact

Question 2

Which of the following is NOT a bias that affects the fossil record?

Accepted Answer

Organisms living inland are more likely to fossilize than those near water

Question 3

Radiometric dating relies on the concept of half-life. If a fossil contains 25% of its original radioactive isotope, how many half-lives have passed?

Accepted Answer

Two half-lives

Question 4

Which of the following best explains why RNA is hypothesized to have been the first self-replicating molecule in early life?

Accepted Answer

RNA can store information, self-replicate, and catalyze reactions

Question 5

Given the following radioisotope decay equation, $$N = N_0$ e$$^{-rac{t}$${	au}}$$, where $$N is $$the remaining isotope, $$N_0 is $$the original amount, $$t is $$time, and $$	au is $$the mean lifetime, which variable would you measure in a fossil to estimate its age?

Accepted Answer

$$N$$, the remaining amount of isotope

Question 6

Which environmental change is most directly associated with mass extinctions and subsequent adaptive radiations?

Accepted Answer

Meteoric impacts causing rapid climate shifts

Question 7

The endosymbiotic theory explains the origin of which eukaryotic cell structures?

Accepted Answer

Mitochondria and chloroplasts

Question 8

Which of the following best describes the sequence of major evolutionary events on Earth?

Accepted Answer

Prokaryotes → Single-celled eukaryotes → Multicellular eukaryotes → Animals → Humans

Question 9

Why does the fossil record tend to underestimate the actual time since a species came into existence?

Accepted Answer

Fossilization is rare and biased toward certain environments and organisms

Question 10

Which process is most likely to compete with polymerization of organic molecules in aqueous solutions, making prebiotic synthesis challenging?

Accepted Answer

Hydrolysis

Question 11

Which of the following is a characteristic of protocells that was critical for the origin of life?

Accepted Answer

Boundary separating internal contents from external environment

Question 12

During which period did the 'Cambrian explosion' occur, and what was its significance?

Accepted Answer

Cambrian; rapid diversification of animal body plans

Question 13

Which developmental process explains why cetaceans (whales and dolphins) do not grow hind limbs, despite having hind limb buds in early embryos?

Accepted Answer

Spatial variation in expression of developmental genes

Question 14

If the half-life of Carbon-14 is 5730 years, how old is a fossil that contains 12.5% of its original Carbon-14?

Accepted Answer

$$5730 	imes 3 = 17190$$ years

Question 15

Which of the following is a reason why DNA eventually replaced RNA as the primary information storage molecule in cells?

Accepted Answer

DNA is less likely to suffer mutations than RNA

Question 16

Which of the following radioisotopes would be most useful for dating a fossil estimated to be 2 billion years old?

Accepted Answer

Potassium-40

Question 17

Which of the following best describes how multicellularity likely evolved?

Accepted Answer

From the aggregation of many individual unicellular organisms or from daughter cells sticking together after division

Question 18

Which of the following is a real-world example of how developmental genes influence evolutionary change?

Accepted Answer

Migration of the nose opening in cetaceans from the end of the snout to the top of the head

Question 19

Which of the following statements about the age of the Earth and the appearance of life is correct?

Accepted Answer

Earth is approximately 4.6 billion years old; prokaryotes appeared around 3.5-4 billion years ago

Origin and History of Life: Biological Diversity (BSC 2011)

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