IB Biology Option F SL

1. Define the terms photoautotroph, photoheterotroph, chemoautotroph and chemoheterotroph. Match up thekeywordtoitsdefinitions and thencopythemintoyournotes. Look thepictures of the bacteria and seeifyou can use thedescriptionsgiventocatergorisethem

3. State on example of a photoautotroph, photoheterotroph, chemoautotroph and chemoheterotroph. Cyanobacteria(also called blue-green bacteria) photosynthesise in a similar way to plants and algae: Carbon dioxide + water -> carbohydrate + oxygen Chloroflexus aurantiacuscan use both dissolved organic matter and light for energy production, but their photosynthesis does not produce oxygen Thiobacillusdenitrificansuses carbon dioxide as a raw material for making organic compounds, but maintain their energy by oxidizing inorganic chemicals such as ammonia and nitrite. Lactobacillus acidophilusobtains its carbon atoms and energy from organic compounds.

4. Compare chemoautotrophs with chemoheterotrophs in terms of energy sources and carbon sources. Draw a table in your notes comparing the two types of microorganism. List similarities and differences

5. Draw and label a diagram of a filamentous cyanobacterium. Contain chlorophyll Contain protective blue and red pigments known as phycobilins Certain strains e.g. Anabaena able to form nitrogen fixation and photosynthesis Nitrogen fixation occurs only inside thick-walled cells called heterocysts (thick walls exclude oxygen which disrupts nitrogenase structure)

6. Explain the use of bacteria in bioremediation of soil and water.Read the information below and summarise each paragraph into no more than 5 short bullet points Pest control – a pest is any organism that people find undesirable. Pest may be controlled chemically, biologically, by cultural methods or by a combination of methods. Bacillus thuringiensis, a bacterium applied as a spray to cabbage plants infected with caterpillars. The bacterium infects and kills the caterpillars without harming other insects. Sewage treatment – sewage passes first through filters which remove solid inorganic matter, and then into primary settlements tanks where organic solids are separated as sludge from the liquid part. The thick sludge is pumped into sludge digestion tanks, where for a period of up to a month, it is digested by anaerobic microorganisms. The liquid sewage is piped into special tanks called activated sludge tanks. These tanks contain aerobic microorganisms which are activated by aeration of the liquid, for example by pumping compressed air through it continuously. The bacteria feed on the organic material in the liquid and the harmful anaerobic bacteria it contains. Cleaning up oil spills – perhaps the best method of dealing with oil spills is by bioremediation. This aims to speed up oil degradation by stimulating naturally occurring bacteria to break down the oil faster. These bacteria use oil as a food source, but they also need oxygen, nitrogen and phosphorus. Oxygen is usually plentiful, but raising levels of nitrogen and phosphorus by applying fertiliser increases the rate at which the bacteria can feed on oil.