Which of these is an autotroph?
Answer: B
Correct answer: Algae
An autotroph makes its own food, and algae do so by photosynthesis. Mushrooms and most bacteria absorb organic nutrients, and Cuscuta (dodder) is a parasitic plant with almost no chlorophyll, drawing its food from a host.
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Rhizobium, the organism found in the root nodules of legumes, is a -
Answer: A
Correct answer: Bacteria
Rhizobium is a soil bacterium. It invades the roots of legumes, forms nodules, and fixes atmospheric nitrogen into ammonia the plant can use, taking sugars in return.
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Organisms that take in nutrients from dead and decaying matter are called
Answer: C
Correct answer: Saprotrophs
Saprotrophs feed on dead and decaying matter, secreting enzymes onto it and absorbing the products - the fungi and many bacteria. They are the decomposers, without which nutrients would stay locked in dead material and the cycles of matter would stop.
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The shape of a bacillus is generally
Answer: C
Correct answer: Rod like
A bacillus is rod-shaped. Cocci are spherical, vibrios comma-shaped and spirilla helical.
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Who discovered the process of fermentation?
Answer: B
Correct answer: Louis Pasteur
Louis Pasteur established in the 1850s that fermentation is the work of living microorganisms rather than a purely chemical change. The same investigations gave us pasteurisation and, in time, the germ theory of disease.
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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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Rhizobium bacteria are present in the _____ of leguminous plants.
Answer: A
Correct answer: Roots
Rhizobium lives in nodules on the roots of legumes - peas, beans, gram, groundnut. The nodule is a structure the plant builds around the bacteria, and its pink colour comes from leghaemoglobin, which keeps oxygen away from the nitrogenase that oxygen would destroy.
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Which of these is a saprotroph?
Answer: C
Correct answer: Fungi
Fungi are saprotrophs: they secrete enzymes onto dead organic matter and absorb the digested products. The pitcher plant is an insectivorous autotroph, and Cuscuta is a parasite that feeds on a living host.
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Prokaryotes do not have a
Answer: C
Correct answer: Nuclear membrane
A prokaryote has no nuclear membrane - its chromosome lies free in the cytoplasm as a nucleoid. It does have cytoplasm, ribosomes (of the 70S kind) and a chromosome; what it lacks is that membrane and the other membrane-bound organelles.
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Which of the following does not have the capacity to reproduce outside the host cell?
Answer: D
Correct answer: Virus
A virus has no ribosomes and no metabolism, so it can only replicate inside a living host cell, using the host’s machinery. Bacteria, fungi and algae are complete cells and multiply on their own.
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