CBSE Class 12 Biology
CBSE Sample Papers for Class 12 Biology Solved 2016 Set 14
1.Mention the location and function of Sertoli cells found in human males.
2.Through which linkage a phosphate group is linked to 5′ OH of a nucleoside?
3.Plants need help from the animals for pollination and dispersal, in return of which plants provides nectar, pollens and fruits to the pollinators. Justify this statement with the help of an example.
4.Holes in Swiss cheese are produced by the organism known as Propioni bacterium sharmani. State the reason behind this.
5. Calotropis plants are not grazed by goats and other cattle. Explain.
6.State the different number of cells found in the following embryonic stages.
(i) Blastocyst (ii) Morula
(iii) Zygote (iv) Blastomere
7. List the differences between the two different types of seeds on the basis of amount of endosperm.
It is often seen that pollen grains are produced in the enormous quantity in maize. Justify.
8. Select the enzyme used to unwind the DNA strands for the formation of a replication fork.
9. Ravi and his group was impressed by the scientific process of plant tissue culture being explained by their teacher. They got excited and decided to try to grow the plant artificially. Mention any two advantages of this technique.
10. Biomolecules such as DNA and protein does not exhibit biological activity in their anhydrous condition. Explain.
11. Define ‘floes’ and mention their role in effluent treatment as well as their ultimate fate in the sewage treatment tank.
12. Draw a neat and labelled diagram of a sectional view of human ovary highlighting various stages of follicles growing in it.
13. Nikita was worried about the hike in the prices of the crop food in the market. She asked reason for this to the owner of the super market. He told her prices are such high because these are genetically modified crops. What according to you are the GM Crops? Are they much beneficial for human health? If yes, give reasons.
14. DNA, a nucleic acid found in human beings and many other organisms is considered to be more stable genetic material than RNA found mainly in viruses etc. Justify.
15. (i) List any two situations, when a medical doctor would recommend injection of
pre-formed antibodies into the body of a patient. Name this kind of immunisation and mention its advantages.
- Name the kind of immunity attained when instead of antibodies, weakened antigens are introduced into the body.
- What are primary lymphoid organs present in humans?
- Explain the functions of lymphoid organs.
16. Ecology itself tells about the interactions among different organisms and its physical environment.
Different levels of organisations thus, combined together to form complete ecology. Mention four different levels of organisation concerned with ecology in detail.
17. Write short notes on the following
(i) Effect of scarcity of water on adaptations of animals.
(ii) Adaptations of desert plants and animals.
(iii) Importance of light to plants.
(iv) Smaller animals are rarely seen in polar regions.
(v) Behavioural adaptations in animals
- (i) Both grasshopper and Drosophilla said to show the phenomenon of male heterogamety? Justify with a cross.
(ii) Define female heterogamety with the help of examples.
19. Anthropogenic action can hasten the evolution. Explain with the help of a suitable example.
20. Can you suggest a method to remove oil (hydrocarbon) from seeds based on your understanding of rDNA technology and chemistry of oil?
21. The Mediterranean Orchid, Ophyrs employs sexually deceit to get its flower pollinated. Explain the statement given.
22. The length of a food chain in an ecosystem is generally limited to 3-4 trophic levels. Justify the statement with a suitable example.
23. Two generations of Ankita’s family were the carriers of an autosmal linked disorder called haemophilia. Ankita was disturbed about her brother’s wife as she was planning to conceive a baby. Suggest a way to Ankita and her family so that they can find out whether the coming child may also become be a sufferer of the disease or not. Also give the importance of such analysis.
24.How does a breeder ensures the process of cross pollination in economically important bisexual flower?
Continuous self pollination results in inbreeding depression in plants. Describe any three devices by which cross pollination is encouraged by nature.
25. Draw a labelled diagram of an anther lobe at microspore mother cell stage. Mention the role of different wall layers of anther.
State the different stages of orgenesis in humans starting from foetal life till its completion. When and where in the body is orgenesis completed?
26.(i) Process of DNA replication occurs in small replication forks, not in its entire length. Give reason.
- State the importance of the origin of replication in a fork.
- Replication of DNA is never continuous along the length of the replication fork, it moves continuously and discontinuously both. Justify the statement.
- EcoRI is a restriction endonuclease. How is it named so? Explain.
- Write the sequences of DNA bases that the enzyme recognizes. Mention the point at which the enzyme makes a cut in the DNA segment.