Chapter 18

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

Ribosomes can catalyze formation of peptide bonds. This supports the hypothesis that _____. a. an RNA world preceded 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

The evolution of _____ resulted in an increase in the levels of atmospheric oxygen. a. sexual reproduction b. aerobic respiration c. the noncyclic pathway of photosynthesis d. the cyclic pathway of photosynthesis

Mitochondria most resemble _____. a. archaeans b. aerobic bacteria c. cyanobacteria d. early eukaryotes

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

The first sexual reproducers were _____. a. archaeans b. aerobic bacteria c. cyanobacteria d. eukaryotes

Oxygen released by _____ accumulated in the atmosphere and produced the ozone layer. a. archaeans b. aerobic bacteria c. cyanobacteria d. early eukaryotes

What is a ribozyme made of?

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

Which of the following was not present on Earth when mitochondria first evolved? a. archaeans b. bacteria c. protists d. animals

Chloroplasts most resemble _____. a. archacans b. aerobic bacteria c. cyanobacteria d. early eukaryotes

Arrange these events in order of occurence, with 1 being the earliest and 6 the most recent. 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 1 ____ 2 ____ 3 ____ 4 ____ 5 ____ 6 ____