To which one of the following types of organism do mushrooms belong?
Answer: C
Correct answer: Fungi
A mushroom is the fruiting body of a fungus. The organism itself is the mycelium spreading through soil or wood; the mushroom appears only to release spores.
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Agar is placed in a petri dish and some soil is sprinkled on the agar. The lid is placed on the petri dish, and it is incubated for two days. After two days, areas of bacteria and fungi are visible on the agar.
What is the name for these areas?
Answer: D
Correct answer: Colonies
Each visible patch is a colony - the descendants of a single cell that landed on the agar and multiplied until the mass became visible. Counting colonies is how bacteria are counted, on the assumption that one colony grew from one organism.
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Which one of the following statements is incorrect?
Answer: B
Correct answer: Bacteria cannot respire.
That statement is false: bacteria do respire, some aerobically and some anaerobically, and some ferment instead. The others are true - bacteria cause a range of human infections, bacteria are used in cheese making, and soil bacteria decompose dead plants and animals.
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Which one of the following acts as a decomposer?
Answer: A
Correct answer: Bacteria
Bacteria are the principal decomposers, breaking down dead organic matter and returning nutrients to the soil. (Fungi and moulds do the same work, and are decomposers too - but bacteria are the answer the question is looking for, being the most numerous and the most versatile.)
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The largest type of microorganism is a
Answer: D
Correct answer: fungus
Fungi are the largest of the microorganisms - many are multicellular, and their mycelia can extend for metres, though the individual structures need a microscope. Bacteria are a few micrometres across and viruses smaller still, measured in nanometres.
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Which one of the following microorganisms is not a virus?
Answer: C
Correct answer: Salmonella
Salmonella is a bacterium, the cause of typhoid and of much food poisoning. Ebola, rhinovirus (the common cold) and influenza are all viruses.
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Dead plants and animals in the soil are broken down into humus by the efforts of
Answer: A
Correct answer: bacteria and fungi in the soil.
Decomposition is the work of both bacteria and fungi. Fungi are particularly good at breaking down tough materials such as cellulose and lignin, and bacteria complete the process - between them turning dead matter into humus and releasing the nutrients it contains. Viruses play no part.
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Tetanus, pneumonia and tooth decay are examples of
Answer: C
Correct answer: bacterial diseases
All three are caused by bacteria: tetanus by Clostridium tetani, pneumonia commonly by Streptococcus pneumoniae, and tooth decay by Streptococcus mutans acting on sugars. Being bacterial, all three can be treated with antibiotics - and tetanus and pneumonia can be vaccinated against.
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Which one of the following is not a beneficial effect of fungi?
Answer: C
Correct answer: They are used to make yoghurt.
Yoghurt is made with bacteria - Lactobacillus and Streptococcus - not with fungi. The other three are genuine benefits: fungi produce antibiotics such as penicillin, they act as decomposers, and they are essential to cheese making.
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Which one of the following microorganisms consists of only one cell?
Answer: B
Correct answer: Bacteria
Bacteria are unicellular: one cell is the whole organism. Bread mould and most fungi are multicellular, and a virus is not a cell at all.
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