When and where do chorionic villi appear in humans? State their

Subject

Biology

Class

CBSE Class 12

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 Multiple Choice QuestionsShort Answer Type

1.

An anther with malfunctioning tapetum often fails to produce viable male gametophytes. Give any one reason.

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2.

Why sharing of injection a needle between two individuals is not recommended?

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3.

Name the enzyme and state its property that is responsible for continuous and discontinuous replication of the two strands of a DNA molecule.

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4.

Identify the examples of convergent evolution from the following:

(i) Flippers of penguins and dolphins

(ii) Eyes of octopus and mammals

(iii) Vertebrate brains
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5.

Write the importance of MOET.

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6.

Why is the enzyme cellulase needed for isolating genetic material from plant cells and not from the animal cells?

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7.

Name the type of biodiversity represented by the following:

(a) 50,000 different strains of rice in India.

(b) Estuaries and alpine meadows in India.

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8.

Write the equation that helps in deriving the net primary productivity of an ecosystem.

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9.

Geitonogamous flowering plants are genetically autogamous but functionally cross-pollinated. Justify.

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10.

When and where do chorionic villi appear in humans? State their function.


Chorionic villi appear on the trophoblast after implantation. Chorionic villi interdigitate with the uterine tissues and jointly forms the placenta which is a structural and functional unit between developing embryo and maternal body.

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