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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Out of 900 reported species of living gymnosperms, conifers are represented by about 500 species, About 2,50,000 species of angiosperms (flowering plants) have also been reported in the world. The vas
Answer: C
Only the conifers match the description.
They are about 500 of the 900 living gymnosperm species, over half the group, while the 250,000 angiosperms make the conifers a small fraction of seed plants as a whole - yet they dominate the northern forests.
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A flower bud which is used as a spice is obtained from
Answer: C
Clove is a dried flower bud, of Syzygium aromaticum, picked before it opens.
Its aroma comes from eugenol, which makes up most of clove oil and is used as a local anaesthetic in dentistry. Cinnamon is bark, cardamom a fruit and coriander a seed.
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Pyorrhoea is a disease of the
Answer: B
Pyorrhoea is a disease of the gums - periodontitis, in which the gum recedes from the teeth and the pockets discharge pus.
It follows untreated gingivitis, destroys the bone supporting the teeth, and is the commonest cause of tooth loss in adults.
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The poison of honey bee is
Answer: C
Bee venom is acidic, with a pH around 5.
Its main component is the peptide melittin. Wasp venom, by contrast, is slightly alkaline - which is the origin of the folk remedy of vinegar for wasp stings and baking soda for bee stings.
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Study of fossils is called
Answer: D
The study of fossils is palaeontology.
It reconstructs the history of life from preserved remains and traces, and supplies the direct evidence for evolution and for the sequence of geological time.
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At which stage of HIV infection does one usually show symptoms of AIDS?
Answer: B
AIDS appears when HIV replicates rapidly in the helper T lymphocytes and destroys them.
The virus can lie latent for years while the CD4 count falls slowly. AIDS is diagnosed when the count drops below 200 per microlitre or an opportunistic infection appears - not on infection itself.
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Lathyrism is caused by excess consumption of.......
Answer: A
Lathyrism is caused by eating too much khesari dal, Lathyrus sativus.
Its neurotoxin, BOAA, damages the motor neurons of the spinal cord and paralyses the legs irreversibly. The pulse is drought-hardy and cheap, so it is eaten most where crops have failed.
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