1. Kelps are a form of what group of protists?
A) brown algae
B) ciliates
C) dinoflagellates
D) water molds
E) slime molds

2. Oxygen built up in the atmosphere approximately 2 billion years ago and
A) occurred because aerobic organisms required the oxygen.
B) could not have occurred without the oxygen coming from outer space.
C) occurred due to carbon dioxide being split by lightning strikes.
D) helped to form the ozone layer that is so important to life today.
E) destroyed ozone forming more oxygen.

3. Atmospheric chemists think that Earth's first atmosphere
A) was very similar to today's atmosphere.
B) consisted of carbon in the form of carbon monoxide.
C) contained nitrogen in the form of ammonia and nitrogen gas.
D) consisted of carbon in the form of carbon monoxide.
E) contained no oxygen atoms.

4. The endosymbiont hypothesis suggests that the mitochondria of eukaryotic cells are descended from captured
A) archaebacteria.
B) aerobic bacteria.
C) chemoautotrophic bacteria.
D) cyanobacteria.
E) eukaryotic algae.

5. When taxonomists classify organisms using a phylogenetic approach, they are most concerned with
A) ancestral traits.
B) derived traits.
C) outgroups.
D) cladists.
E) ingroups.

6. In bacteria, the cell wall is composed mainly of
A) lipids.
B) proteins.
C) peptidoglycans.
D) glycoproteins.
E) various polysaccharides.

7. Endospores form
A) in response to adverse conditions.
B) when the environmental conditions are favorable.
C) as a means of genetic recombination.
D) during binary fission.
E) to produce two offspring from every one parental cell.

8. Which form of bacterial cells is rod shaped?
A) cocci
B) spirilla
C) rhodius
D) bacilli
E) vibrios

9. Rickettsias belong to which major group of bacteria?
A) Archaea
B) proteobacteria
C) cyanobacteria
D) viruses
E) spirochetes

10. What term is used to indicate a characteristic that is shared and inherited from a common ancestor?
A) analogous trait
B) derived trait
C) cladistic trait
D) ancestral trait
E) homologous trait

11. Some bacteria can form resting structures called ___________ that can withstand extremes in temperature, moisture, and radiation.
A) capsids
B) viroids
C) prions
D) endospores
E) symbionts

12. All but one of the following are false regarding protists. Identify the true statement.
A) All protists are single-celled organisms.
B) Protists are prokaryotic.
C) Most protists are single-celled organisms; some are multicellular.
D) Protists do not have the ability to move on their own.
E) Protists have cell walls composed mainly of peptidoglycans.

13. Eukaryotic cells are thought to have
A) first appeared as parts of multicellular organisms.
B) developed when mitochondria grew much larger in size that they had been previously.
C) first appeared with tough cell walls.
D) appeared about 2.1 billion years ago.
E) evolved before prokaryotic cells.

14. What is the main difference between protists and bacteria?
A) Protists are unicellular, bacteria are multicellular.
B) Bacteria have DNA, protists do not.
C) Protists cannot cause infections, bacteria can
D) Bacteria are always gram-negative, protists are gram-positive
E) Protists have a nucleus, bacteria do not

15. Paleontologists have found fossils dating back 3.6 billion years. These closely resemble
A) small invertebrate animals.
B) today's simplest plants.
C) blue-green algae present today.
D) fungi.
E) nothing alive today.

16. Of the following, which kingdom contains the most diversity in terms of DNA sequences?
A) Fungi
B) Animalia
C) Plantae
D) All of these are approximately equivalently diverse.
E) Protista

17. During which geological era did Pangea break apart?
A) Paleozoic
B) Proterozoic
C) Cenozoic
D) Mesozoic
E) Archean

18. Prions are composed of
A) DNA and protein.
B) DNA.
C) DNA, RNA, and protein.
D) protein.
E) RNA.

19. Most bacteria are
A) photoautotrophs.
B) symbionts.
C) heterotrophs.
D) chemoautotrophs.
E) microbial predators.

20. 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) be a disadvantage for these organisms and lead to their death and fossil formation.
B) make these animals more desirable to predators.
C) protect the animal from predators.
D) protect the animal from osmotic pressure.
E) allow the animals to move into different environments easily.