Concept Questions

Take some time to write answers to these questions. If you can answer them, you have a good grasp of the material!

1. Present in outline form the levels of organization in the biosphere. Define the term biome. Compare autotrophs and heterotrophs; producers and consumers. Where in the energy and trophic schemes do decomposers enter? Compare the concepts of habitat and niche using Chlamydomonas (figure 26.1) as an example.

2. Using figure 26.3, point out specific examples of producers; primary, secondary, and tertiary consumers, herbivores; primary, secondary, and tertiary carnivores; and omnivores. What is mineralization, and which organisms are responsible for it?

3. Using specific examples, differentiate between commensalism, mutualism, parasitism, competition, and scavenging.

4. Outline the general characteristics of a biogeochemical cycle. What are the major sources of carbon, nitrogen, phosphorus, and sulfur?

5. In what major forms is carbon found? Name three ways carbon is returned to the atmosphere. Name a way it is fixed into organic compounds. What form is the least available for the majority of living things? Which form is produced during anaerobic reduction of CO₂? Describe the relationship between photosynthesis and respiration with regard to CO₂ and O₂.

6. Tell whether each of the following is produced during the light or dark reactions of photosynthesis: O₂, ATP, NADPH, and glucose. When are water and CO₂ consumed? What is the function of chlorophyll and the photosystems? What is the fate of the ATP and NADH? Compare oxygenic with nonoxygenic photosynthesis.

7. Outline the steps in the nitrogen cycle from N2 to organic nitrogen and back to N2. Describe nitrogen fixation, ammonification, nitrification, and denitrification. What form of nitrogen is required by plants? By animals?

8. Outline the phosphorus and sulfur cycles. What are the most important inorganic and organic phosphorus compounds? How is phosphorus made available to plants? What are the most important inorganic and organic sulfur compounds? What are the roles of microorganisms in these cycles?

9. Describe the structure of the soil and the rhizosphere. What is humus? Compare and contrast root nodules with mycorrhizae.

10. Outline the modes of cycling water through the lithosphere, hydrosphere, and atmosphere. What are the roles of precipitation, condensation, respiration, transpiration, surface water, and aquifers?

11. Map a section through the structure of a lake. What types of organisms are found in plankton? Why is phytoplankton not found in the benthic zone? What would you expect to find there?

12. What causes the formation of the epilimnion, hypolimnion, and thermocline? What is upwelling? In what ways are red tides and eutrophic algal blooms similar and different?

13. Why must water be subjected to microbiological analysis? What are the characteristics of good indicator organisms, and why are they monitored rather than pathogens? Give specific examples of indicator organisms and water-borne pathogens. Describe two methods of water analysis. What are the principles behind the most probable number test? Describe the three phases of sewage treatment. What is activated sludge?

14. Explain the meaning of fermentation from the standpoint of industrial microbiology. Describe five types of fermentations.

15. What is the main criterion regarding the safety of foods? Differentiate between food infection and food intoxication. When are microbes on food harmless? What are the two most common food intoxications? What are the three most common food infections? Summarize the major methods of preventing food poisoning and spoilage.

16. Which microbes are used as starter cultures in bread, beer, wine, cheeses, and sauerkraut? Outline the steps in beer making. List the steps in wine making. What are curds and whey, and what causes them?

17. Describe the aims of industrial microbiology. Differentiate between primary and secondary metabolites. Describe a fermentor. How is it scaled up for industrial use? What are specific examples of products produced by these processes?

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