The disease Goitre is caused in persons who do not have in their diet sufficient
Answer: C
Goitre is caused by a lack of iodine.
Iodine is needed to make thyroxine; without it the thyroid enlarges as it tries to compensate, producing the swelling in the neck. In children the deficiency also stunts growth and mental development, which is why salt is iodised.
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Genes are situated on _________
Answer: A
Genes are situated on chromosomes.
Each chromosome is a single long DNA molecule with its associated proteins, and a gene is a stretch of that DNA. Sutton and Boveri proposed the chromosome theory of inheritance in 1902, and Morgan proved it with Drosophila.
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The study of the way individual traits are transmitted from one generation to the next is called
Answer: D
The study of how traits are transmitted from one generation to the next is genetics.
Mendel founded it with his work on peas; William Bateson coined the name in 1905. Homology and analogy belong to comparative anatomy, ecology to the study of organisms in their surroundings.
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Study of factors connected with the improvement of human race ?
Answer: B
Eugenics is the study of improving the human race by controlling who reproduces.
Galton coined the term in 1883. In the twentieth century it was used to justify forced sterilisation and worse, and it is now wholly discredited. Euthenics, by contrast, seeks improvement through better surroundings.
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Which one of the following air pollution can affect blood stream leading to death ?
Answer: B
Carbon monoxide acts on the bloodstream and can kill.
It binds to haemoglobin about 240 times more strongly than oxygen does, forming carboxyhaemoglobin, so the blood can no longer carry oxygen. Being colourless and odourless it gives no warning.
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Damage to hearing is caused by sounds which exceed
Answer: D
Sound above 120 decibels damages hearing at once.
That is the threshold of pain, comparable to a jet engine at close range. Prolonged exposure above 85 dB damages hearing more slowly, which is why 85 dB is the usual occupational limit.
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How many eyes are found in an earthworm?
Answer: C
The earthworm has no eyes.
Living underground it has no use for them. It detects light through photoreceptor cells scattered in the skin, densest at the front end, which is enough to make it retreat from the surface into its burrow.
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Dicotyledonous weeds are destroyed by a chemical called
Answer: B
Dicotyledonous weeds are killed by 2,4-dichlorophenoxyacetic acid, or 2,4-D.
It is a synthetic auxin that throws the plant's growth into disorder. It is selective because monocots - the cereals - metabolise it quickly, so a cereal field can be sprayed to kill the broadleaved weeds in it.
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Plant have ____ while animals lack it.
Answer: B
Plants have cellulose; animals do not.
It is the polymer of glucose that makes up the plant cell wall and gives it rigidity. Animal cells have no wall at all. Starch, protein and fat occur in both kingdoms.
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Pollination by wind is called
Answer: A
Pollination by wind is anemophily, from the Greek anemos, wind.
Wind-pollinated flowers are small, dull and scentless, with exposed anthers, feathery stigmas and enormous quantities of light dry pollen. Grasses, cereals and most trees of the temperate forest are anemophilous.
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