1. Atmospheric chemists think that Earth's first atmosphere

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

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

A) endospores
B) symbionts
C) prions
D) capsids
E) viroids

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

A) slime molds
B) water molds
C) dinoflagellates
D) brown algae
E) ciliates

4.Which form of bacterial cells is rod shaped?

A) rhodius
B) spirilla
C) cocci
D) vibrios
E) bacilli

5.All but one of the following are false regarding protists. Identify the true statement.

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

6.Prions are composed of

A) DNA, RNA, and protein.
B) DNA and protein.
C) DNA.
D) protein.
E) RNA.

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

A) today's simplest plants.
B) blue-green algae present today.
C) small invertebrate animals.
D) nothing alive today.
E) fungi.

8.Most bacteria are

A) symbionts.
B) heterotrophs.
C) microbial predators.
D) chemoautotrophs.
E) photoautotrophs.

9.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) allow the animals to move into different environments easily.
C) protect the animal from osmotic pressure.
D) protect the animal from predators.
E) make these animals more desirable to predators.

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

A) peptidoglycans.
B) proteins.
C) glycoproteins.
D) various polysaccharides.
E) lipids.

11.Rickettsias belong to which major group of bacteria?

A) Archaea
B) spirochetes
C) cyanobacteria
D) proteobacteria
E) viruses

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

A) archaebacteria.
B) chemoautotrophic bacteria.
C) aerobic bacteria.
D) cyanobacteria.
E) eukaryotic algae.

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

A) ancestral traits.
B) outgroups.
C) derived traits.
D) ingroups.
E) cladists.

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

A) cladistic trait
B) ancestral trait
C) derived trait
D) analogous trait
E) homologous trait

15.Endospores form

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

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

A) All of these are approximately equivalently diverse.
B) Fungi
C) Protista
D) Animalia
E) Plantae

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

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

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

A) Protists cannot cause infections, bacteria can
B) Protists have a nucleus, bacteria do not
C) Protists are unicellular, bacteria are multicellular.
D) Bacteria are always gram-negative, protists are gram-positive
E) Bacteria have DNA, protists do not.

19.During which geological era did Pangea break apart?

A) Cenozoic
B) Paleozoic
C) Archean
D) Proterozoic
E) Mesozoic

20.Eukaryotic cells are thought to have

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