Which among the following statements is not associated with food preservation?
Answer: B
Correct answer: Decreased shelf life
Preservation exists to increase shelf life, so a decrease is the opposite of what is wanted. The other three describe it correctly: preventing decay, sealing against air and organisms, and keeping food for later use.
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In order to take precautionary steps to control dengue, we must take measures to stop the breeding of:
Answer: A
Correct answer: Aedes mosquito
Dengue is transmitted by the Aedes mosquito, which breeds in small collections of clean water - tyres, pots, coolers, roof gutters - and bites by day. Control therefore means emptying such containers rather than spraying open water. Anopheles carries malaria.
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Which among the following pathogens causes cholera?
Answer: A
Correct answer: Bacteria
Cholera is caused by Vibrio cholerae, a comma-shaped bacterium spread through water contaminated with faeces. Its toxin makes the gut pour out water, and it is the resulting dehydration, not the organism itself, that kills - which is why oral rehydration is so effective.
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The bacteria present in the root nodules of pea are
Answer: C
Correct answer: Rhizobium
Rhizobium lives in the root nodules of legumes such as pea, gram and beans, fixing atmospheric nitrogen into a form the plant can use; the plant supplies it with sugars in return. That symbiosis is why legumes enrich the soil and why they are used in crop rotation.
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What is the shape of an amoeba?
Answer: D
Correct answer: No definite shape
An amoeba has no fixed shape: it has no cell wall, and its cytoplasm flows into pseudopodia that it uses to move and to engulf food. Its outline is therefore always changing.
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Penicillium is a
Answer: B
Correct answer: Fungus
Penicillium is a mould, that is a filamentous fungus - the blue-green growth seen on stale bread and citrus fruit. Fleming’s observation that it killed the bacteria around it led to penicillin.
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Which of the following is a disease caused by protozoans?
Answer: C
Correct answer: Malaria
Malaria is caused by the protozoan Plasmodium. Tuberculosis and typhoid are bacterial, and polio is viral.
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Which one of the following is not a fungus?
Answer: C
Correct answer: Chickenpox
Chickenpox is caused by a virus, varicella-zoster. Bread mould, potato blight and mushrooms are all fungi or fungus-like organisms.
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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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Which of the following diseases is spread by bacteria?
Answer: A
Correct answer: Tuberculosis
Tuberculosis is caused by Mycobacterium tuberculosis, a bacterium, which is why it can be treated with antibiotics - though a long course of several drugs is needed. Measles, chicken pox and polio are viral.
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