Smallest form of bacteria is called-
Answer: B
Cocci are the smallest bacteria in shape and size - spherical cells typically about 0.5 to 1 micrometre across.
Bacilli are rod-shaped, vibrios comma-shaped and spirilla spiral, and all three are longer than a coccus is wide.
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What is the wavelength of visible spectrum?
Answer: C
The visible spectrum runs from about 3900 to 7600 angstrom - 390 to 760 nanometres.
Violet is at the short-wavelength end and red at the long. Below 390 nm is ultraviolet and above 760 nm infrared, neither of which the eye detects.
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The most important ore of aluminium is
Answer: D
Bauxite is the chief ore of aluminium, a mixture of hydrated aluminium oxides.
The oxide is extracted from it by the Bayer process and then reduced to the metal by electrolysis in molten cryolite. Calamine is a zinc ore, calcite calcium carbonate, and galena lead sulphide.
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Which of the following animals have teeth in their stomach?
Answer: B
Crabs have teeth in their stomach. The gastric mill is a set of chitinous plates in the foregut that grinds food after it is swallowed.
Crustaceans have no jaws capable of chewing, so the grinding is done internally, and the mill is worked by muscles attached to the stomach wall.
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How does common salt help in separating soap from the solution after saponification?
Answer: B
Common salt separates soap from the solution after saponification by decreasing the soap's solubility - a process called salting out.
The sodium ions from the salt raise the concentration of sodium in the water, and the soap, being a sodium salt, is forced out of solution and floats to the top as a curd.
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What is the name of the cells in the body that engulf foreign particles like bacteria?
Answer: B
Phagocytes engulf bacteria and other foreign particles, taking them into a vesicle and digesting them with enzymes - a process called phagocytosis.
Neutrophils and macrophages are the main types. Albumin, globulin and fibrinogen are plasma proteins, not cells.
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The wonder pigment chlorophyll is present in
Answer: C
Chlorophyll is carried in the quantosomes, the pigment-bearing units embedded in the thylakoid membranes of the chloroplast.
Each quantosome holds about 230 chlorophyll molecules and is regarded as the physical unit of photosynthesis. Mitochondria, centrosomes and lysosomes contain no chlorophyll.
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Ozone Layer restricts from
Answer: C
The ozone layer blocks ultraviolet radiation.
It absorbs essentially all UV-C and about 90 per cent of UV-B, which would otherwise cause skin cancer and cataracts and damage crops and plankton. Infrared and radio waves pass through it freely.
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Metal used to make wires for safety fuses must have
Answer: C
Fuse wire must have high resistivity and a low melting point.
High resistivity makes it the hottest point in the circuit for a given current, and a low melting point makes it part before the wiring behind it is damaged. A tin–lead alloy meets both conditions.
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The uranium fuel used worldwide is mainly in the form of
Answer: B
Reactor fuel is used mainly as uranium dioxide, UO2, pressed and sintered into ceramic pellets.
The oxide is chosen because it has a very high melting point, about 2,865°C, and is chemically stable under irradiation. UF6 is the gas used in enrichment, not in the reactor.
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