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Evolution

Short Answer Type

91. Try to trace the components of human evolution.

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Long Answer Type

92. Briefly state the major theories of origin of life. Which one of them has scientific basis ?

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93. State the hypothesis of Oparin and Haldane about the primeval earth condition. What do you understand by Haldane’s hot, dilute soup ? State its significance.

Alexander I. Oparin (1894-1980), a Russian biochemist and J.B.S. Haldane (1892-1964), a British scientist have put forward the concept of abiogenesis. According to Oparin and Haldane primeval earth had reducing condition and atmosphere is free from oxygen. Oxygen remained bound in H₂0 and metallic oxides on the surface of rocks and its particles. The early gas cloud was rich in hydrogen, in the form of methane (CH₄) and ammonia (NH₃) and water (H₂0). The organic molecules formed due to atmospheric reaction accumulated slowly and gradually in sea and constitute what is called 'Hot, dilute soup'.

Significance of hot dilute soup. Thus conditions of reducing nature are unable to oxidize these organic compounds which form the basis of life.

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94.

Summarise Miller's simulation experiment for organic synthesis. Comment on its efficacy.

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95.

Using internet and discussing with your teacher, trace the evolutionary stages of any one animal say horse.

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Short Answer Type

96. What is variation ? Name the basic processes that cause variation among organisms. Discuss the role of migration in evolution.

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Long Answer Type

97.

Define genetic drift, founder effect and genetic bottleneck?

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98. What is natural selection in modern terms ? Elucidate the three different effects of natural selection on variation.

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99. Describe present day concept of evolution.

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Short Answer Type

100.

State the advantages that the erect posture and large brain gave to the humans over other primates.

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