Subject

Biology

Class

CBSE Class 12

Pre Boards

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Sample Papers

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 Multiple Choice QuestionsShort Answer Type

1.

Mention one application for each of the following : (a) Passive immunization (b) Antihistamine (c) Colostrum (d) Cytokinin-barrier


(a) Passive Immunization : - When ready made antibodies are introduced into the body, it is called as passive immunization. It provides quick immune response in body.
(b) Anti Histamines : - These are the chemicals which are given against allergic reactions.
(c) Colostrum : - It is the yellow fluid produced during the initial days of lactation. It is rich in antibodies and is necessary to develop resistance in a new born baby.
(d) Cytokinin-Barrier : - is Interferon. These are the glycoproteins which protect non-infected cells from further viral infection.

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2.

Name the type of cross that would help to find the genotype of a pea plant bearing violet flowers.


Test Cross

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3.

An electrostatic precipitator in a thermal power plant is not able to generate high voltage of several thousands. Write the ecological implication because of it.


It will not be able to remove particulate matter present in the exhaust of thermal power plants & hence cannot control pollution.

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4.

A herd of cattle is showing reduced fertility and productivity. Provide one reason and one suggestion to overcome this problem.


The cattle's productivity is decreased due to inbreeding depression. A single outcross i.e. breeding with animals of same breed but should not have common ancestors on either side upto 4-6 generations can restore its fertility.

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5.

A pollen grain in angiosperm at the time of dehiscence from an anther could be 2-celled or 3-celled. Explain. How are the cells placed within the pollen grain when shed at a 2-celled stage ?


In majority angiosperms, pollens are released in 2-celled stage whereas in other species, the generative cell divides into 2 male gametes & forms 3-celled stage. When the pollen grain is shed at 2-celled stage - it has two unequal cells - bigger vegetative cell and smaller generative cell.

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6.

State two postulates of Oparin and Haldane with reference to origin of life.


Oparin and Haldane proposed that life originated from pre-existing non-organic molecules and the diverse organic molecules were formed from these inorganic constituents by chemical evolution

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7.

List four benefits to human life by eliminating the use of CFCs .


(1) Ozone depletion will be prevented.
(2) Green house effect will be controlled
(3) Global warming will be controlled.
(4) It will prevent old climatic changes that takes place due to rise in temperature.

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8.

Name the microbes that help production of the following products commercially : (a) Statin (b) Citric acid (c) Penicillin (d) Butyric acid


(a) Statin : - Monascus purpureus (fungus)
(b) Citric acid : - Aspergillus niger (fungi)
(c) Penicillin : - Pencillium notatum (fungi)
(d) Butyric acid : - Clostridium butylicum (Bacteria)

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9.

What are Cry genes ? In which organism are they present ?


Cry genes codes for a toxin which is poisonous to some insects thus giving resistant to the plants. They are present in bacterium Bacillus thuriengiensis.

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10.

Differentiate between the genetic codes given below : (a) Unambiguous and Universal (b) Degenerate and Initiator


(a) Unambiguous and Universal : - Unambiguous : - The code is specific, i.e. one codon codes for only one amino acid. Universal : - The code is same in all organisms. (b) Degenerate and Initiator : - Degenerate : - When an amino acid is coded by more than one codon, it is said to be degenerate. Initiator : - AUG is an initiator codon i.e. it initiates the translation process & also codes for methionine.

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