Subject

biology

Class

CBSE Class 12

Pre Boards

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Sample Papers

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 Multiple Choice QuestionsShort Answer Type

1.

Differentiate between male and female heterogamety.


Male Heterogamety

Female Heterogamety

Males produce two different types of gametes.

Female produce two different types of gametes.

It is found in humans

It is found in birds.

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2.

How has mutation breeding helped in improving the production of mung bean crop ?


Mutational breeding was used to introduce resistance to yellow mosaic virus and powdery mildew in the mung bean crop thus improving the production of the crop. Chemicals and radiation were used to induce mutations in the mung bean crop and the plants with the desirable qualities like resistance to virus were selected.

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3.

State a reason for the increased population of dark coloured moths coinciding with the loss of lichens (on tree barks) during industrialization period in England.


Industrialization led to darkening of the tree trunks due to deposition of smoke and soot and increase in pollution. The dark colored moths were not attacked by the predators as they camouflaged against the dark bark of the trees while the white coloured moths were picked out by the predators. The lichen population also decreased due to the increase in pollution. 

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4.

Many fresh water animals cannot survive in marine environment. Explain.


Fresh water animals cannot survive in marine environment because their body is not adapted to it. When placed in marine environment their body loses water because the surrounding has higher concentration of salt as compared to their body. The loss of water poses difficulty in their survival and may even result in their death.

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5.

Mention a product of human welfare obtained with the help of each one of the following microbes:

 (a) LAB

 (b) Saccharomyces cerevisiae

 (c) Propionibacterium sharmanii

 (d) Aspergillus niger


The products obtained from:

(a)  LAB - Lacto acid bacteria is used in the production of curd from milk.

(b)  Saccharomyces cerevisiae is used for the production of ethanol.

(c)  Propionibacterium sharmanii is used in the production of Swiss cheese.

(d)  Aspergillus niger is used in production of citric acid.

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6.

After a brief medical examination a healthy couple came to know that both of them are unable to produce functional gametes and should look for an ‘ART’ (Assisted Reproductive Technique). Name the ‘ART’ and the procedure involved that you can suggest to them to help them bear a child.


The ART procedure used to help the couple is ZIFT, that is, zygote intrafallopian transfer. In this method, the sperm is collected from the donor male and the ovum from donor female. The sperm and the ovum are fused in the laboratory and developed till 8-cell stage. The 8 cell zygote is then transferred into the fallopian tubes of the mother for further development.

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7.

Name the transcriptionally active region of chromatin in a nucleus.


Euchromatin is the transcriptionally active region of chromatin in a nucleus.

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8.

A geneticist interested in studying variations and patterns of inheritance in living beings prefers to choose organisms for experiments with shorter life cycle. Provide a reason.


A geneticist interested in studying variations and patterns of inheritance in living beings refers to choose organisms for experiments with shorter life cycle because it allows them to study many generations of the organisms in a short span of time.

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9.

Indiscriminate diagnostic practices using X-rays etc., should be avoided. Give one reason.


X-rays are ionizing radiations that have adverse effects like they increase the chances of cancer by causing mutations.

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10.

What is Biopiracy?


Biopiracy is the use of bio-resources by multinational companies and other organisations without proper authorisation from the countries and people concerned without compensatory payment.

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