Q: A fossil is found to contain 25% of its original amount of carbon-14. If the half-life of carbon-14 is 5,730 years, approximately how old is the fossil?

$$2 \times 5,730 = 11,460$$ years

Question 1

Which of the following best describes the main finding of the Urey-Miller experiment?

Accepted Answer

It demonstrated that organic molecules could be synthesized abiotically under conditions thought to resemble those of early Earth.

Question 2

Why is RNA considered a better candidate than DNA for the first genetic material in early life forms?

Accepted Answer

RNA can act as a catalyst and self-replicate, allowing for both information storage and enzymatic activity.

Question 3

Which of the following is NOT a property of protobionts?

Accepted Answer

They have a fully functional nucleus.

Question 4

A fossil is found to contain 25% of its original amount of carbon-14. If the half-life of carbon-14 is 5,730 years, approximately how old is the fossil?

Accepted Answer

$$2 	imes 5,730 = 11,460$$ years

Question 5

What was the primary biological consequence of the oxygen revolution caused by cyanobacteria?

Accepted Answer

It led to the extinction of many anaerobic organisms and allowed for the evolution of aerobic respiration.

Question 6

Which evidence supports the endosymbiotic origin of mitochondria?

Accepted Answer

Mitochondria have their own circular DNA similar to that of proteobacteria.

Question 7

Which eon is the most recent in Earth's history?

Accepted Answer

Phanerozoic

Question 8

The Permian extinction, one of the largest in Earth's history, is thought to have been caused primarily by:

Accepted Answer

Massive volcanic eruptions leading to climate change.

Question 9

During which period did the 'Cambrian explosion' of animal diversity occur?

Accepted Answer

Cambrian

Question 10

Which of the following best describes adaptive radiation?

Accepted Answer

The rapid evolution of many diverse species from a common ancestor when new ecological niches become available.

Question 11

Which of the following is an example of heterochrony?

Accepted Answer

A salamander species reaches sexual maturity while still retaining larval features.

Question 12

Which event is most closely associated with the formation of the supercontinent Pangea?

Accepted Answer

The merging of Earth's landmasses due to tectonic plate movements.

Question 13

Which of the following statements about the endosymbiotic theory is FALSE?

Accepted Answer

Mitochondria and chloroplasts are formed by the fusion of two eukaryotic cells.

Question 14

If a rock contains 12.5% of its original carbon-14, how many half-lives have passed since the organism died?

Accepted Answer

$$3$$ half-lives

Question 15

Which of the following is a reason why RNA can undergo natural selection?

Accepted Answer

RNA can fold into different shapes, allowing for functional variation.

Question 16

Which era is NOT part of the Phanerozoic eon?

Accepted Answer

Proterozoic

Question 17

Which period is associated with the explosion of land plants?

Accepted Answer

Silurian

Question 18

Which of the following is NOT evidence supporting the endosymbiotic origin of chloroplasts?

Accepted Answer

Chloroplasts are found in all prokaryotes.

Question 19

A scientist finds a fossil with 6.25% of its original carbon-14. If the half-life of carbon-14 is 5,730 years, how old is the fossil?

Accepted Answer

$$4 	imes 5,730 = 22,920$$ years

Question 20

Which of the following best illustrates the concept of paedomorphosis?

Accepted Answer

An adult organism retaining juvenile features of its ancestors.

Chapter 25: The History of Life on Earth – Study Notes

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