Oxygen built up in the atmosphere approximately 2 billion years ago and
- destroyed ozone forming more oxygen.
- occurred due to carbon dioxide being split by lightning strikes.
- could not have occurred without the oxygen coming from outer space.
- occurred because aerobic organisms required the oxygen.
- helped to form the ozone layer that is so important to life today.
Which form of bacterial cells is rod shaped?
Most bacteria are
- microbial predators.
Rickettsias belong to which major group of bacteria?
What term is used to indicate a characteristic that is shared and inherited from a common ancestor?
- homologous trait
- cladistic trait
- derived trait
- analogous trait
In bacteria, the cell wall is composed mainly of
- various polysaccharides.
Eukaryotic cells are thought to have
- evolved before prokaryotic cells.
- first appeared with tough cell walls.
- first appeared as parts of multicellular organisms.
- developed when mitochondria grew much larger in size that they had been previously.
- appeared about 2.1 billion years ago.
Kelps are a form of what group of protists?
- water molds
- slime molds
- brown algae
Atmospheric chemists think that Earth’s first atmosphere
- consisted of carbon in the form of carbon monoxide.
- was very similar to today’s atmosphere.
- contained no oxygen atoms.
- consisted of carbon in the form of carbon dioxide.
- contained nitrogen in the form of ammonia and nitrogen gas.
Prions are composed of
- DNA, RNA, and protein.
- DNA and protein.
- to produce two offspring from every one parental cell.
- as a means of genetic recombination.
- when the environmental conditions are favorable.
- in response to adverse conditions.
- during binary fission.
Paleontologists have found fossils dating back 3.6 billion years. These closely resemble
- small invertebrate animals.
- today’s simplest plants.
- nothing alive today.
- blue-green algae present today.
What is the main difference between protists and bacteria?
- Bacteria have DNA, protists do not.
- Protists cannot cause infections, bacteria can
- Protists are unicellular, bacteria are multicellular.
- Protists have a nucleus, bacteria do not
- Bacteria are always gram-negative, protists are gram-positive
All but one of the following are false regarding protists. Identify the true statement.
Most protists are single-celled organisms; some are multicellular.
- Protists have cell walls composed mainly of peptidoglycans.
- Protists are prokaryotic.
- Protists do not have the ability to move on their own.
- All protists are single-celled organisms.
Of the following, which kingdom contains the most diversity in terms of DNA sequences?
- All of these are approximately equivalently diverse.
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
- allow the animals to move into different environments easily.
- make these animals more desirable to predators.
- be a disadvantage for these organisms and lead to their death and fossil formation.
- protect the animal from osmotic pressure.
- protect the animal from predators.
Some bacteria can form resting structures called ___________ that can withstand extremes in temperature, moisture, and radiation.
During which geological era did Pangea break apart?
When taxonomists classify organisms using a phylogenetic approach, they are most concerned with
- derived traits.
- ancestral traits.
The endosymbiont hypothesis suggests that the mitochondria of eukaryotic cells are descended from captured
- eukaryotic algae.
- chemoautotrophic bacteria.
- aerobic bacteria.