Minitest 17 - Chapter 19

A. MULTIPLE CHOICE - Answer the following questions on a multiple choice test sheet. Note that you have three points available to you for each question, and may distribute those points any way you feel appropriate. If you think you absolutely know the answer then mark all three with the same letter. If you are unsure of an answer you may distribute your points to as many as three different answers for each question.

1-3. What is not a characteristic of photosynthesis in purple and green bacteria?

a. The presence of bacteriochlorophyll.

b. Photosynthetic oxygen (O2) production.

c. One photosystem.

d. The production of ATP by photophosphorylation.

e. The use of cytochromes as electron carriers.

4-6. Photosynthesis in purple and green bacteria only takes place anaerobically because:

a. O2 drains compounds which are needed as electron donors.

b. O2 drains compounds which are needed as electron acceptors.

c. O2 inhibits the transfer of electrons between electron carriers in the membrane.

d. O2 acts as an uncoupler in these organisms.

e. O2 represses the production of photosynthetic pigments.

7-9. How is the synthesis of bacterial photosynthetic membrane in the purple bacteria dependent upon light intensity?

a. At high light and low intensities there is a high level of pigment and photosynthetic apparatus, i.e. there is a light intensity for minimum photosynthetic apparatus synthesis.

b. At high light and low intensities there is a low level of pigment and photosynthetic apparatus, i.e. there is a light intensity for maximum photosynthetic apparatus synthesis.

b. At high light there is a high level of pigment and photosynthetic apparatus.

c. At low light there is a high level of pigment and photosynthetic apparatus.

d. Synthesis does not depend on light intensity.

10-12. The following conditions would enrich for the presence of what class or microorganisms? - Soil samples are inoculated and grown at an elevated temperature of 42 C, perhaps even preceded by a heat treatment to select for endospores.

a. Purple sulfur bacteria.

b. Non-sulfur purple bacteria.

c. Green sulfur bacteria.

d. Heliobacteria.

e. Aerobic anoxygenic phototrophs.

13-15. The following conditions would enrich for the presence of what class or microorganisms? - Very low levels of Na2S9H2O, vitamins and a non-fermentable organic substrate such as acetate, ethanol or benzoate.

a. Purple sulfur bacteria.

b. Non-sulfur purple bacteria.

c. Green sulfur bacteria.

d. Heliobacteria.

e. Aerobic anoxygenic phototrophs.

16-18. Nonsulfur purple bacteria:

a. Are unable to use sulfide as an electron donor for the reduction of CO2 to cell material.

b. Are killed by concentrations of sulfide that are used by green and purple sulfur bacteria.

c. Are unable to use sulfide as a source of sulfur containing amino acids.

d. Can only use ammonium or nitrate as sources of nitrogen.

e. Are all gram negative rods.

19-21. What is not true about green bacteria?

a. They are morphologically very diverse.

b. There are both green sulfur bacteria and green nonsulfur bacteria.

c. They have Gram-positive members which are able to form endospores, just like Bacillus and Clostridium.

d. Green sulfur bacteria are strictly anaerobic and obligately photoautotrophic.

e. The green nonsulfur or Chloroflexis group is much more nutritionally versatile than the green sulfur bacteria.

22 -24. Autorophy, as in CO2 fixation, in the green sulfur bacteria is unique because:

a. It uses the same Calvin Cycle as found in the cyanobacteria and green plants.

b. It uses a pathway referred to as the "reverse TCA cycle" where CO2 is incorporated into tricarboxylic acids.

c. It involves the incorporation of CO2 into organic material through a reverse pyruvate decarboxylase.

d. It involves several S-C covalent intermediates.

e. There is no such thing, all green sulfur bacteria are heteroorganotrophs.

25-27. What is not true about a consortium:

a. It is a natural assemblage of two or more bacteria.

b. The bacteria in a consortium benefit each other.

c. One of the organisms is usually photosynthetic.

d. It may sometimes be taken for a single organism because it may not be possible to culture the members separately

e. Interactions are usually metabolic, as one member supplies something to another member.

28-30. Given the characteristics shown in Figure 19.15, the body of water being studied must be:

a. Meromictic.

b. Holomictic.

c. A hot spring.

d. Anoxic.

e. Given the data, it is not possible to tell.

B. TRUE-FALSE - Please answer the following questions a=TRUE and b=FALSE

31-33. While the actual absorption spectrum of the bacteriochlorophyll in a cell (in-vivo spectrum) is easier to measure, the absorption spectrum of the pigment in a standard solvent such as methanol is more important to understanding the ecological role the pigment in a given bacterium.

34-36. Color is a good criterion for the identification of isolates as either green bacteria or purple bacteria.

37-39. Heliobacteria are unusual in that they have neither internal photosynthetic membranes like those found in the purple bacteria nor do they have chlorosomes like in the green bacteria,

40-42. In anoxygenic phototrophs, light is used primarily in the generation of ATP, and is not involved in the generation of reducing power as it is in organisms exhibiting oxygenic photosynthesis.

43-45. In a microbial mat containing cyanobacteria, phototrophic purple sulfur bacteria and sulfate reducing bacteria, one would almost always expect to find the photrophic purple sulfur bacteria on the top.