Which phenomenon do bats and dolphins use to find prey?
Answer: C
Bats and dolphins find prey by echolocation. They emit short high-frequency pulses and judge the direction, distance and even the texture of an object from the returning echoes.
A bat can catch a moth in complete darkness this way, and a dolphin can find a fish buried in sand.
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Which is the largest blood vessel in the body?
Answer: A
The aorta is the largest blood vessel, about 2.5 to 3.5 cm across where it leaves the heart.
It carries oxygenated blood from the left ventricle and branches to supply the whole body. The largest vein is the vena cava; alveoli are air sacs in the lung, not vessels at all.
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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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Pollen grains of flowers in which pollination takes place by insects are:
Answer: D
Insect-pollinated flowers have pollen that is rough and sticky, often with spines or a sticky coating, so that it clings to the visiting insect's body.
Wind-pollinated pollen is the opposite: small, smooth, dry and light, produced in enormous quantity so that a little of it reaches a stigma by chance.
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The number of ribs in a human body is _____
Answer: B
The human body has 24 ribs - twelve pairs.
The first seven pairs are true ribs, joined directly to the sternum by cartilage; the next three are false ribs, attached to the cartilage above; and the last two are floating ribs, attached only to the vertebrae.
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There are _____ muscles in the human body
Answer: D
The human body has about 639 skeletal muscles.
They make up roughly 40 per cent of body weight and work in opposing pairs, since a muscle can only pull. The counts differ slightly between sources because some muscles can be regarded as one or as several.
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Newton’s first law is also called
Answer: A
Newton's first law is the law of inertia: a body remains at rest or in uniform motion in a straight line unless acted on by an external force.
Inertia is the property the law describes - the resistance of matter to any change in its state of motion - and it is measured by the body's mass.
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Fat can be separated from milk in a cream separator because of:
Answer: C
A cream separator works by centrifugal force. Spinning the milk at high speed throws the denser skim milk to the outside of the bowl while the lighter fat globules collect nearer the axis, and the two are drawn off separately.
Gravity separates cream too, but far more slowly - the centrifuge does in seconds what standing does in hours.
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Blotting paper absorbs liquids because
Answer: C
Blotting paper absorbs liquid because it has many small pores. The liquid is drawn into them by capillary action, the same effect that raises water in a narrow tube.
The paper is made without sizing, which is what leaves the fibres loose and porous.
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Which of the following is not an allotrope of Carbon?
Answer: C
Glass is not an allotrope of carbon. It is an amorphous solid made chiefly of silicon dioxide.
Diamond, graphite and the fullerenes are all pure carbon in different structural forms, along with graphene, carbon nanotubes and amorphous carbon.
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