Question 1

One group of protozoans which are non-motile, produce spores, and have disease-causing species is the ________.

Accepted Answer

Unlike other groups of protozoans, sporozoans are non-motile. They are so-named because they produce spores. Sporozoans include the parasite that causes malaria.

Question 2

You take a large sample of soil and put it all into individual pots. You then divide the pots into two groups: In the first group, every pot of soil has been sterilized, and thus contains no bacteria. In the other group, none of the pots of soil has been sterilized. You plant soybean seeds in all the pots. What would you expect to see as the seeds sprout and grow?

Accepted Answer

Mutualistic, nitrogen-fixing bacteria live in the roots nodules of certain plants, such as soybeans. They reduce atmospheric nitrogen to ammonia, which can be used by plants. Plants are unable to fix nitrogen for themselves.

Question 3

Which archaea use a pigment related to the rhodopsin in our eyes to absorb solar energy and pump chloride ions?

Accepted Answer

Halophilic archaea use a rhodopsin-like pigment to absorb solar energy for pumping chloride. This enables them to survive in extremely salty environments.

Question 4

Penicillin is an antibiotic drug that interferes with cell wall synthesis in bacteria, eventually resulting in cell death. What effect would you predict if you applied penicillin to archaea?

Accepted Answer

Most archaea do have cell walls, but they are not composed of peptidoglycan. Thus, an antibiotic that inhibits peptidoglycan synthesis will not harm archaea.

Question 5

Without bacteria in the environment

Accepted Answer

Bacteria are vital, natural parts of all ecosystems, and are now harnessed by humans to repair damaged ecosystems through bioremediation.

Question 6

In which type of environment would you be most likely to find methanogenic archaea?

Accepted Answer

Methanogens thrive in anaerobic environments, where they produce methane from hydrogen gas and carbon dioxide in order to make ATP.

Question 7

Support for the endosymbiotic hypothesis is provided by all of the following except

Accepted Answer

If certain bacteria were engulfed by primitive and eukaryotic cells and not digested, then they would acquire an extra membrane outside the original bacterial plasma membrane; this would explain the double membrane structure of mitochondria and chloroplasts. Since bacteria have their own genetic material, mitochondria and chloroplasts would be expected, as descendants of free-living bacteria, to have their own DNA and ribosomes. Thus, mitochondria and chloroplasts can carry out their own protein synthesis. The fact that mitochondria and chloroplasts contribute to different metabolic processes (aerobic respiration and photosynthesis) in the cell does not provide direct support for the endosymbiotic hypothesis. However, it does make sense in light of the likely origins of these two organelles: The mitochondria are descendants of aerobic bacteria and the chloroplasts are descendants of cyanobacteria.

Question 8

Which statement about slime molds and water molds is incorrect?

Accepted Answer

Both were once classified as fungi, but are now classified as protists.

Question 9

Bacteria that secrete digestive enzymes into their surroundings in order to decompose nonliving organic matter are called ________.

Accepted Answer

Many chemoheterotrophic bacteria are saprotrophs; they are important decomposers in ecosystems.

Question 10

Which of the following is not a similarity that protozoans have to animals?

Accepted Answer

Because protozoans are eukaryotic chemoheterotrophs, not photoautotrophs, and most have some means of locomotion, they were once classified along with animals.

Question 11

Which statement about bacteria is incorrect?

Accepted Answer

Most bacteria are not pathogenic to humans.

Question 12

Which of these is mismatched?

Accepted Answer

None of the archaea are known to cause disease in humans.

Question 13

A viroid is a naked, infectious _____ molecule.

Accepted Answer

A viroid is a naked, infectious RNA molecule.

Question 14

Which similarity is not shared between algae and plants?

Accepted Answer

Because algae are eukaryotic photoautotrophs, and producer organisms, they were once classified with plants. They do not have locomotion.

Question 15

What evidence supports the idea that archaea are more closely related to eukaryotes rather than to bacteria?

Accepted Answer

Some of the most compelling evidence in support of a close relationship between archaea and eukaryotes is similarity in the means of expressing genetic information. Peptidoglycan is only found in the cell walls of bacteria.

Question 16

As a result of drinking contaminated water, a patient contracts amoebic dysentery. Would an antibiotic drug that inhibits peptidoglycan synthesis be beneficial in treating the amoeba infection?

Accepted Answer

An antibiotic that affects peptidoglycan synthesis would not be effective against amoebic dysentery, because Entamoeba histolytica does not have peptidoglycan, or any kind of cell wall at all. (Radiolarians and foraminiferans are amoeboids with skeletons, not cell walls, of calcium carbonate; however, they do not cause disease.)

Question 17

Algae are commonly grouped by their type of ________.

Accepted Answer

The algae are traditionally classified on the basis of the pigments in their chloroplasts: green algae, red algae, golden-brown algae, and brown algae.

Question 18

The _____ of a virus is enclosed by a _____ capsid.

Accepted Answer

The nucleic acid of a virus is enclosed by a protein capsid.

Question 19

Some species of pathogenic bacteria are able to attack specific tissues in the human body because of

Accepted Answer

Adhesion factors permit a pathogenic bacterium to bind to certain types of cells in the body.

Question 20

Archaea

Accepted Answer

Like all cells, archaea have plasma membranes. Most also have cell walls.

Quiz 17: The Microorganisms: Viruses, Bacteria, and Protists