In plant body, the water and minerals are transported by _______
Answer: D
Water and minerals are transported by the xylem.
Its tracheids and vessels are dead, hollow, lignified cells forming continuous tubes from root to leaf. Water is drawn up by the pull of transpiration, helped by the cohesion between water molecules.
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Which of the following plays an important part in photosynthesis?
Answer: A
The chloroplast carries out photosynthesis.
Its thylakoid membranes hold the chlorophyll that captures light, and the surrounding stroma holds the enzymes that fix carbon dioxide into sugar. A leaf cell may contain fifty or more.
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Branch of biology in which we study about relationship between living and their environment
Answer: C
Ecology studies the relationship between living things and their environment.
Ernst Haeckel coined the word in 1866 from the Greek oikos, household. It covers populations, communities and ecosystems, and the flow of energy and cycling of matter through them.
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The protoplasm of a child is exactly the same as that of its
Answer: D
A child's protoplasm is identical only to that of an identical twin.
Identical twins arise from a single fertilised egg that splits, so they carry exactly the same genes. A child receives half its genes from each parent and so is identical to neither.
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The insects do not have blood pigments because
Answer: B
Insects have no blood pigment because their blood has no respiratory function.
Oxygen reaches the tissues directly through a branching system of air tubes, the tracheae, which open at the spiracles. The haemolymph carries food and waste but no oxygen, so it needs no carrier.
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Organisms that feed on the excreta of other organisms are called
Answer: C
Organisms that feed on the droppings of others are coprophagous, from the Greek kopros, dung.
Dung beetles and many termites and rodents are coprophagous. Rabbits eat their own soft pellets to extract nutrients released by the second passage through the gut.
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In which of the following mammals estrous cycle is absent ?
Answer: D
The monkey has no oestrous cycle - primates have a menstrual cycle instead.
In an oestrous cycle the unfertilised endometrium is reabsorbed and the female is receptive only at oestrus. In a menstrual cycle it is shed with bleeding, and the female may be receptive throughout.
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The technique of DNA fingerprinting in human was developed for first time by _________
Answer: B
Alec Jeffreys developed DNA fingerprinting, at Leicester in 1984.
He found that certain repeated sequences vary in number between individuals, giving each person a unique pattern. It was first used in 1986 to clear an innocent suspect and convict the real murderer.
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Organisms which synthesise their own food are called
Answer: A
Organisms that make their own food are autotrophs.
Photoautotrophs, such as green plants and cyanobacteria, use light; chemoautotrophs, such as the nitrifying bacteria, use energy from oxidising inorganic compounds. Everything else in the food chain depends on them.
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Which one of the following strongly threatens biodiversity?
Answer: C
The greatest threat to biodiversity is the destruction of natural habitats and vegetation, and jhum cultivation.
Habitat loss accounts for the great majority of extinctions: a species with nowhere to live cannot survive however well protected in law. Shifting cultivation on shortened cycles clears forest faster than it can regrow.
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