Which of the following is a physical basis of life ?
Answer: B
Protoplasm is called the physical basis of life - the living substance of the cell, comprising the cytoplasm and the nucleus together.
The term was coined by Purkinje in 1839 and given its famous description by Thomas Huxley. The mitochondrion, ribosome and nucleus are structures within it.
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Spice saffron is obtained from which part of plant-
Answer: D
Saffron is obtained from the stigma of Crocus sativus.
Each flower yields three stigmas, picked by hand, so a kilogram takes about 150,000 flowers - which is why it is the most expensive spice in the world. In India it is grown in the Pampore area of Kashmir.
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Ramapithecus and Cro-Magnon man are considered
Answer: A
Ramapithecus and Cro-Magnon man are regarded as ancestors of modern man.
Ramapithecus, found in the Siwaliks, lived about 12 million years ago; Cro-Magnon man, about 40,000 years ago in Europe, was anatomically modern and made the cave paintings of Lascaux.
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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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Which vitamin is required for the clotting of blood ?
Answer: D
Correct answer: Vitamin K
Vitamin K is needed to synthesise prothrombin and several other clotting factors in the liver. A deficiency prolongs bleeding, which is why newborn infants are routinely given a dose at birth.
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Movement of cell against concentration gradient is called
Answer: B
Movement against a concentration gradient is active transport.
It moves a substance from low concentration to high, so it needs energy, supplied by ATP through carrier proteins. The sodium-potassium pump in every animal cell is the standard example. Osmosis and diffusion both run down the gradient and need no energy.
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Biological control is to check growth of
Answer: D
Biological control means checking one pest by another organism.
A natural enemy - a predator, parasite or pathogen - is introduced against the pest. The ladybird beetle against aphids and Bacillus thuringiensis against caterpillars are examples; it avoids the residues and resistance that chemicals bring.
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Radical vascular bundles are those in which
Answer: D
In a radial vascular bundle the xylem and phloem lie on different radii, alternating around the axis.
This is the arrangement in roots. In stems the two lie on the same radius, phloem outside xylem, forming collateral bundles.
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In which of the following organelles does photosynthesis take place?
Answer: B
Photosynthesis takes place in the chloroplast.
Its thylakoid membranes hold the chlorophyll that captures light, and the stroma around them holds the enzymes of the Calvin cycle that fix carbon dioxide into sugar. A leaf cell may contain fifty or more.
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Which of the following hormones is called the emergency hormone?
Answer: B
Adrenaline is called the emergency hormone.
Released from the adrenal medulla under stress, it speeds the heart, raises blood pressure and blood sugar, widens the airways and diverts blood to the muscles - the fight-or-flight response that prepares the body for sudden effort.
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