NCERT Class 12 Biology Entrance Exams Questions and Answers
71 If a genetic disease is transferred from a phenotypically normal but carrier female to only some of the male progeny, the disease is:
Answer: Sex-linked recessive.
72 In a dihybrid cross, if you get 9:3:3:1 ratio it denotes that:
Answer: The alleles of two genes are segregating independently.
73 Which of the following traits studied by Mendel in garden pea is a dominant trait?
Answer: Inflated pod.
74 The bones of forelimbs of whale, bat, cheetah and man are similar in structure, because
Answer: they share a common ancestor
76 Which type of selection is industrial melanism observed in moth, Biston bitularia
77 From among the situations given below, choose the one that prevents both autogamy and geitonogamy.
Answer: Dioecious plant bearing only male or female flowers.
78 Choose the correct statement from the following.
Answer: Cleistogamous flowers always exhibit autogamy.
79 Autogamy can occur in a chasmogamous flower if
Answer: both pollen and ovules mature simultaneously.
80 dicotyledonous plant bears flowers but never produces fruits and seeds. The most probable cause for the above situation is
Answer: plant is dioecious and bears only staminate flowers