2)   exploitation
     3)   parasitism
     4)   symbiosis
     (a)  1 and 2
     (b)  4 only
     (c)  3 only
     (d)  2 only
Ans: (c)
287. Which of the following are true about the human heart?
     1) It is a pear shaped, muscular organ.
     2) It lies in the left side of the thoracic cavity.
     3) It lies between the two lungs.
     4) It is enclosed in a bag-like structure called the pericardium.
     (a) 1 and 2
     (b) 2, 3 and 4
     (c) 1, 3 and 4
     (d) 1, 2, 3 and 4
Ans: (d)
288. Which of the following is not in the inner ear?
     (a) Eustachian tube
     (b) Cochlea
     (c) Semicircular canals
     (d) Sacculus
Ans: (a)
289. Which of the following is/are true about stereoscopic vision?
     1) It gives a three-dimensional effect to the object observed.
     2) It helps one to judge distance.
     3) It is well-developed in birds and animals with eyes in the sides of their heads.
     (a) 1 only
     (b) 1 and 2
     (c) 2 only
     (d) 1, 2 and 3
Ans: (b)
290. Which of the following statements is/are true about tears secreted by the glands under the top eyelids?
     1) It contains sodium bicarbonate.
     2) It contains sodium chloride.
     3) It contains an enzyme lysozyme which can destroy bacteria.
     4) It supplies oxygen to the cornea and crystalline lens.
     (a) 1 and 3
     (b) 2, 3 and 4
     (c) 2 and 4
     (d) 1, 2 and 3
Ans: (d)
291. In blue-eyed people the:
     (a) iris has no pigment
     (b) iris has black pigment
     (c) iris has blue pigment
     (d) choroid has blue pigment
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