NCERT Class 12 Biology Entrance Exams Questions and Answers

NCERT Class 12 Biology Entrance Exams Questions & Answers NCERT Class 12 Biology QUESTIONS

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:
A Sex-linked recessive.
B Sex-linked dominant
C Autosomal dominant
D Autosomal recessive

Answer: Sex-linked recessive.
72 In a dihybrid cross, if you get 9:3:3:1 ratio it denotes that:
A It is a case of multiple allelism.
B The alleles of two genes are segregating independently.
C The alleles of two genes are interacting with each other.
D It is a multigenic inheritance.

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?
A Inflated pod.
B Yellow colour of pod.
C Green colour of seed.
D Terminal flowers.

Answer: Inflated pod.
74 The bones of forelimbs of whale, bat, cheetah and man are similar in structure, because
A one organism has given rise to another
B they share a common ancestor
C they perform the same function
D they have biochemical similarities.

Answer: they share a common ancestor
75 Analogous organs arise due to
A convergent evolution
B genetic drift
C divergent evolution
D artificial selection

Answer: convergent evolution
76 Which type of selection is industrial melanism observed in moth, Biston bitularia
A Directional
B Artificial
C Stabilising
D Disruptive

Answer: Directional
77 From among the situations given below, choose the one that prevents both autogamy and geitonogamy.
A Monoecious plant bearing unisexual flowers.
B Dioecious plant bearing only male or female flowers.
C Dioecious plant with bisexual flowers.
D Monoecious plant with bisexual flowers.

Answer: Dioecious plant bearing only male or female flowers.
78 Choose the correct statement from the following.
A Cleistogamous flowers always exhibit autogamy.
B Chasmogamous flowers always exhibit geitonogamy.
C Cleistogamous flowers exhibit both autogamy and geitonogamy.
D Chasmogamous flowers never exhibit autogamy.

Answer: Cleistogamous flowers always exhibit autogamy.
79 Autogamy can occur in a chasmogamous flower if
A pollen matures before maturity of ovule.
B ovules mature before maturity of pollen.
C both pollen and ovules mature simultaneously.
D both anther and stigma are of equal lengths.

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
A plant is dioecious and bears only staminate flowers
B plant is dioecious and bears both pistillate and staminate flowers.
C plant is dioecious and bears only pistillate flowers.
D plant is monoecious.

Answer: plant is dioecious and bears only staminate flowers

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