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

11.

How are productivity, gross productivity, net primary productivity and secondary productivity interrelated?

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12.

Double fertilization is reported in plants of both, castor and groundnut. However, the mature seeds of groundnut are non-albuminous and castor are albuminous. Explain the Post fertilization events that are responsible for it.

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13.

Describe the process of Parturition in humans.

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14.

A teacher wants his/her students to find the genotype of pea plants bearing purple coloured flowers in their school garden. Name and explain the cross that will make it possible.

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15.

A DNA segment has a total of 1000 nucleotides, out of which 240 of them are adenine containing nucleotides. How many pyrimidine bases this DNA segment possesses?

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16.

Draw a diagrammatic sketch of a portion of DNA segment to support your answer.

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17.

Explain adaptive radiation with the help of a suitable example.

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18.

A team of students are preparing to participate in the interschool sports meet. During a practice session you find some vials with labels of certain cannabinoids.

(a) Will you report to the authorities? Why?

(b) Name of a plant from which such chemicals are obtained.

(c) Write the effect of these chemicals on human body.

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19.

Enlist the steps involved in inbreeding of cattle. Suggest two disadvantages of this practice.

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20.

Choose any three microbes, from the following which are suited for organic farming which is in great demand these days for various reasons. Mention one application of each one chosen.

MycorrhizaMonascusAnabaenaRhizobiumMethanobacteriumTrichoderma.


Following three microbes can be chosen for organic farming:

1. Mycorrhiza: It helps in the absorption of phosphorous from the soil.

2. Anabaena: It is involved in the process of nitrogen fixation.

3. Rhizobium: It fixes nitrogen into organic forms, which can be used by the plant as nutrient.

The application of the following are:

1. Monascus:  It is produces Statins that are used commercially as blood-cholesterol lowering agents.

2. Methanobacterium: It is used in the biological generation of methane by anaerobic processes.

3. Trichoderma: It produces cyclosporin A which is used as an immunosuppressive agent.
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