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.
Advertisement

 Multiple Choice QuestionsShort Answer Type

21.

With the help of any two suitable examples explain the effect of anthropogenic actions on organic evolution.

944 Views

22.

(a) Why is human ABO blood group gene considered a good example of multiple alleles?

(b) Work out a cross up to F1 generation only, between a mother with blood group A (Homozygous) and the father with blood group B (Homozygous). Explain the pattern of inheritance exhibited.

746 Views

23.

Describe the structure of a RNA polynucleotide chain having four different types of nucleotides.

695 Views

24.

Differentiate between inbreeding and outbreeding in cattle. State one advantage and one disadvantage for each one of them.

965 Views

Advertisement
25.

(a) Why are the fruit juices bought from market clearer as compared to those made at home?

(b) Name the bioactive molecules produced by Trichoderma polysporum and Monascus purpureus.

495 Views

26.

(a) Why are transgenic animals so called?

(b) Explain the role of transgenic animals in

(i) Vaccine safety

(ii) Biological products with the help of an example each.

840 Views

27.

How have human activities caused desertification? Explain. 

768 Views

28.

How does algal bloom destroy the quality of a fresh water body? Explain.

697 Views

Advertisement
Advertisement

29.

Explain mutualism with the help of any two examples. How is it different from commensalism?


Mutualism is the interaction which confers benefits on both the interacting species.

For example:

i. Lichens represent an intimate mutualistic relationship between a fungus and photosynthesizing algae or cyanobacteria in which the fungus provides protection to the algae or cyanobacteria and the algae and cyanobacteria provide food to the fungus.

ii. Mycorrhizae are associations between fungi and roots of higher plants. Fungi help the plant in the absorption of essential nutrients from the soil while the plant, in turn provides the fungi with energy-yielding carbohydrates.

In commensalism the interaction where one species is benefitted and the other is neither benefitted nor harmed is called commensalism.

 Species            Species                 Name of interaction

A                             B

+                             +                            Mutualism

+                             0                            Commensalism
721 Views

Advertisement

 Multiple Choice QuestionsLong Answer Type

30.

(a) Draw a diagrammatic sectional view of a mature anatropous ovule and label the following parts in it:

(i) that develops into seed coat.

(ii) that develops into an embryo after fertilization.

(iii) that develops into an endosperm in an albuminous seed.

(iv) through which the pollen tube grains entry into the embryo sac.

(v) that attaches the ovule to the placenta.

(b) Describe the characteristic features of wind pollinated flowers.
2116 Views

Advertisement