Chapter 18 - Life's Origin And Early Evolution

Question 1

An abundance of ___________ in the atmosphere would have prevented the spontaneous assembly of organic compounds on early Earth.

a. hydrogen
b. methane
c. oxygen
d. nitrogen

Answer 1

c. oxygen

Question 2

The prevalence of iron-sulfide cofactors in organisms supports the hypothesis that life arose ____________.

a. in outer space
b. on tidal flats
c. near deep-sea vents
d. in the upper atmosphere

Answer 2

c. near deep-sea vents

Question 3

Ribosomes can catalyze formation of peptide bonds. This supports the hypothesis that ______________.

a. an RNA would proceed DNA-based genomes
b. RNA can hold more information than DNA
c. the first protists had RNA as their genetic material
d. all of the above

Answer 3

a. an RNA would proceed DNA-based genomes.

Question 4

By one hypothesis, clay ________________.

a. facilitated assembly of early polypeptides
b. was present at hydrothermal vents
c. provided energy for early metabolism
d. all of the above

Answer 4

a. facilitated assembly of early polypeptides

Question 5

The evolution of _________ resulted in an increase in levels of atmospheric oxygen.

a. sexual reproduction
b. aerobic respiration
c. the noncyclic pathway of photosynthesis
d. the cyclic pathway of photosynthesis

Answer 5

c. the noncyclic pathway of photosynthesis

Question 6

Mitochondria most resemble ____________.

a. archaeans
b. aerobic bacteria
c. cyanobacteria
d. early eukaryotes

Answer 6

b. aerobic bacteria

Question 7

What was the energy source of the Miller-Urey simulation of conditions on the early Earth?

Answer 7

electrodes

Question 8

The first sexual reproducers were _____________.

a. archaeans
b. aerobic bacteria
c. cyanobacteria
d. eukaryotes

Answer 8

d. eukaryotes

Question 9

Oxygen released by ___________ accumulated in the atmosphere and produced the ozone layer.

a. archaeans
b. aerobic bacteria
c. cyanobacteria
d. early eukaryotes

Answer 9

c. cyanobacteria

Question 10

What is a rybozyme made of?

Answer 10

RNA

Question 11

A rise in oxygen in Earth’s air and seas put organisms that engaged in __________ at a selective advantage.

a. aerobic respiration
b. fermentation
c. photosynthesis
d. sexual reproduction

Answer 11

a. aerobic respiration

Question 12

Which of the following was not present on earth when mitochondria first evolved?

a. archaeans
b. bacteria
c. protists
d. animals

Answer 12

d. animals

Question 13

Chloroplasts most resemble ___________.

a. archaeans
b. aerobic bacteria
c. cyanobacteria
d. early eukaryotes

Answer 13

c. cyanobacteria

Question 14

Which provides a more stable genome, DNA or RNA?

Answer 14

DNA

Question 15

Arrange these events in order of occurrence, with 1 being the earliest and 6 the most recent.

\_\_\_1
\_\_\_2
\_\_\_3
\_\_\_4
\_\_\_5
\_\_\_6

a. emergence of the noncyclic pathway of photosynthesis
b. origin of mitochondria
c. origin of protocells
d. emergence of the cyclic pathway of photosynthesis
e. origin of chloroplasts
f. the big bang

Answer 15

Arrange these events in order of occurrence, with 1 being the earliest and 6 the most recent.

(f) 1
(c) 2
(d) 3
(a) 4
(b) 5
(e) 6

a. emergence of the noncyclic pathway of photosynthesis
b. origin of mitochondria
c. origin of protocells
d. emergence of the cyclic pathway of photosynthesis
e. origin of chloroplasts
f. the big bang