(a)  nucleus
     (b)  mitochondria
     (c)  chloroplast
     (d)  peroxisome
Ans: (c)
451. A married couple adopted a male child. A few years later, twin boys were born to them. The blood group of the couple
     is AB positive and O negative. The blood group of the three sons is A positive, B positive, and O positive. The blood
     group of the adopted son is [CSAT 2011]
     (a) O positive
     (b) A positive
     (c) B positive
     (d) Cannot be determined on the basis of the given data
Ans: (a)
452. When the bark of a tree is removed in a circular fashion all around near its base, it gradually dries up and dies because
     [CSAT 2011]
     (a) Water from soil cannot rise to aerial parts
     (b) Roots are starved of energy
     (c) Tree is infected by soil microbes
     (d) Roots do not receive oxygen for respiration
Ans: (a)