50. Tetrodotoxin is a potent poison that
   (a) erodes blood vessels
   (b) blocks conduction of nerve impulses causing respiratory paralysis
   (c) produces damage to the kidneys
   (d) produces intestinal bleeding
Ans: (b)
51. Xerophthalmia is a deficiency disease. Deficiency of _________ causes it.
   (a) vitamin A
   (b) vitamin B
   (c) vitamin C
   (d) vitamin E
Ans: (a)
52. Calcium and phosphorus assimilation will depend on sufficient intake of
   (a) vitamin B complex
   (b) vitamin D
   (c) vitamin A
   (d) vitamin C
Ans: (b)
53. Vitamin D deficiency leads to
   (a) sterility
   (b) pellagra
   (c) rickets
   (d) capillary fragility
Ans: (c)
54. Kwashiorkar is characterised by
   (a) dermatitis, changes in hair pigments and retarded brain growth
   (b) excretion of creatine in excess
   (c) tyrosinosis and alcaptonuria
   (d) None of these
Ans: (a)
55. Kwashiorkar is a deficiency disease
   (a) due to poor intake of proteins
   (b) due to poor intake of carbohydrates
   (c) due to (a) and (b)
   (d) due to poor intake of lipids
Ans: (a)
56. Modern classification of the living world recognise ___________ kingdoms.
   (a) two
   (b) three
   (c) four
   (d) five
Ans: (d)
57. Pearl is secreted by the __________ of the pearl oyster.
   (a) foot
   (b) mantle
   (c) gills
   (d) None of these
Ans: (b)
58. The country where commercial production of cultured pearls is undertaken on large scale is
   (a) India
   (b) Mexico
   (c) Netherlands
   (d) Japan
Ans: (d)
59. Spiders can take only
   (a) solid food
   (b) liquid food
   (c) plant juice
   (d) flesh of dead animals
Ans: (b)
60. Lizards, snakes, crocodiles and turtles belong to the class