Subject

Biology

Class

CBSE Class 12

Pre Boards

Practice to excel and get familiar with the paper pattern and the type of questions. Check you answers with answer keys provided.

Sample Papers

Download the PDF Sample Papers Free for off line practice and view the Solutions online.
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 Multiple Choice QuestionsShort Answer Type

21.

Explain any three advantages that seeds offer to angiosperms.

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22.

Name and explain the role of the inner and middle walls of the human uterus.

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23.

A colour-blind child is born to a normal couple. Work out a cross to show how it is possible. Mention the sex of this child.

672 Views

24.

Mendel published his work on inheritance of characters in 1865, but it remained unrecognized till 1900. Give three reasons for the delay in accepting his work. 

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25.

Women are often blamed for producing female children. Consequently, they are ill-treated and ostracized. How will you address this issue scientifically if you were to conduct an awareness programme to highlight the values involved?

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26.

Name the tropical sugar cane variety grown in South India. How has it helped in improving the sugar cane quality grown in North India?

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27.

Identify ‘a’, ‘b’ and ‘c’ in the following table:


No.

Crop

Variety

Insect Pests

1.

Brassica

Pusa Gaurav

(a)

2.

Flat bean

Pusa Sem 2
Pusa sem 3

(b)

3.

(c)

Pusa Sawani
Pusa A-4

Shoot and fruit borer

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28.

Why are beehives kept in a crop field during flowering period? Name any two crop fields where this is practiced.

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29.

How did the process of RNA interference help to control the nematode from infecting the roots of tobacco plants?


RNA Interference (RNAi) is a gene-silencing process that is used for cellular defense in all eukaryotic organisms. RNAi has been used to control the nematode Meloidegyne incognitia that affects the roots of tobacco plants in the following way:

 Using Agrobacterium vectors, nematode specific genes were introduced in the host plant. The genes were introduced in such a way that it produced both sense and anti-sense RNA in the host cells. The two RNA’s being complementary to each other form a double-stranded RNA dsRNA that initiates RNA interference and silences mRNA that is it inhibits mRNA expression. The nematode is not able to survive in the host which expresses specific interfering RNA and thus the plant is protected from the nematode.

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30.

Explain the process of DNA replication with the help of a schematic diagram.

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