1. Oxygen built up in the atmosphere approximately 2 billion years ago and

A. destroyed ozone forming more oxygen.

B. occurred due to carbon dioxide being split by lightning strikes.

C. could not have occurred without the oxygen coming from outer space.

D. occurred because aerobic organisms required the oxygen.

E. helped to form the ozone layer that is so important to life today.

2. Which form of bacterial cells is rod shaped?

A. vibrios

B. bacilli

C. rhodius

D. cocci

E. spirilla

3. Most bacteria are

A. chemoautotrophs.

B. symbionts.

C. heterotrophs.

D. photoautotrophs.

E. microbial predators.

4. Rickettsias belong to which major group of bacteria?

A. spirochetes

B. Archaea

C. cyanobacteria

D. viruses

E. proteobacteria

5. What term is used to indicate a characteristic that is shared and inherited from a common ancestor?

A. homologous trait

B. cladistic trait

C. outgroups

D. derived trait

E. analogous trait

6. In bacteria, the cell wall is composed mainly of

A. peptidoglycans.

B. various polysaccharides.

C. glycoproteins.

D. lipids.

E. proteins.

7. Eukaryotic cells are thought to have

A. evolved before prokaryotic cells.

B. first appeared with tough cell walls.

C. first appeared as parts of multicellular organisms.

D. developed when mitochondria grew much larger in size that they had been previously.

E. appeared about 2.1 billion years ago.

8. Kelps are a form of what group of protists?

A. dinoflagellates

B. water molds

C. slime molds

D. brown algae

E. ciliates

9. Atmospheric chemists think that Earth's first atmosphere

A. consisted of carbon in the form of carbon monoxide.

B. was very similar to today's atmosphere.

C. contained no oxygen atoms.

D. consisted of carbon in the form of carbon dioxide.

E. contained nitrogen in the form of ammonia and nitrogen gas.

10. Prions are composed of

A. DNA, RNA, and protein.

B. RNA.

C. protein.

D. DNA and protein.

E. DNA.

11. Endospores form

A. to produce two offspring from every one parental cell.

B. as a means of genetic recombination.

C. when the environmental conditions are favorable.

D. in response to adverse conditions.

E. during binary fission.

12. Paleontologists have found fossils dating back 3.6 billion years. These closely resemble

A. fungi.

B. small invertebrate animals.

C. today's simplest plants.

D. nothing alive today.

E. blue-green algae present today.

13. What is the main difference between protists and bacteria?

A. Bacteria have DNA, protists do not.

B. Protists cannot cause infections, bacteria can

C. Protists are unicellular, bacteria are multicellular.

D. Protists have a nucleus, bacteria do not

E. Bacteria are always gram-negative, protists are gram-positive

14. All but one of the following are false regarding protists. Identify the true statement. Most protists are single-celled organisms; some are multicellular.

A. Protists have cell walls composed mainly of peptidoglycans.

B. Protists are prokaryotic.

C. Protists do not have the ability to move on their own.

D. All protists are single-celled organisms.

15. Of the following, which kingdom contains the most diversity in terms of DNA sequences?

A. Protista

B. All of these are approximately equivalently diverse.

C. Fungi

D. Animalia

E. Plantae

16. The Cambrian Explosion provided a wealth of fossil remains for scientists to uncover. Many of the animals from this time period had tough skins or shells. This would

A. allow the animals to move into different environments easily.

B. make these animals more desirable to predators.

C. be a disadvantage for these organisms and lead to their death and fossil formation.

D. protect the animal from osmotic pressure.

E. protect the animal from predators.

17. Some bacteria can form resting structures called ___________ that can withstand extremes in temperature, moisture, and radiation.

A. prions

B. symbionts

C. capsids

D. viroids

E. endospores

18. During which geological era did Pangea break apart?

A. Cenozoic

B. Paleozoic

C. Archean

D. Mesozoic

E. Proterozoic

19. When taxonomists classify organisms using a phylogenetic approach, they are most concerned with

A. derived traits.

B. outgroups.

C. ancestral traits.

D. cladists.

E. ingroups.

20. The endosymbiont hypothesis suggests that the mitochondria of eukaryotic cells are descended from captured

A. eukaryotic algae.

B. chemoautotrophic bacteria.

C. cyanobacteria.

D. aerobic bacteria.

E. archaebacteria.