Biology Delhi Set 1 2015-2016 Science (English Medium) Class 12 Question Paper Solution

According to de-Vries what is saltation?

Excessive nutrients in a fresh water body cause fish mortality. Give two reasons.

Suggest the breeding method most suitable for animals that are below average in milk  productivity.

State a difference between a gene and an allele.

Suggest a technique to a researcher who needs to separate fragments of DNA.

Explain the significance of meiocytes in a diploid organism.

Mention the kind of biodiversity of more than a thousand varieties of mangoes in India represent. How is it possible?

List the events that reduce the Biological Oxygen Demand (BOD) of a primary effluent during sewage treatment.

Discuss the role the enzyme DNA ligase plays during DNA replication.

Name the causative organism of the disease amoebiasis. List three symptoms of the disease.

Identify 'A', 'B', 'C' and 'D' in the given table.
 

Why is breast-feeding recommended during the initial period of an infant's growth? Give reasons.

Give an example of an autosomal recessive trait in humans. Explain its pattern of inheritance with the help of a cross.

Describe the experiment that helped Louis Pasteur to dismiss the theory of spontaneous generation of life.

Plant breeding technique has helped sugar industry in North India. Explain how.

Suggest and describe a technique to obtain multiple copies of a gene of interest in vitro.

What is a GMO?

List any five possible advantages of a GMO to a farmer.

During a school trip to 'Rohtang Pass', one of your classmate suddenly developed 'altitude sickness'. But, she recovered after sometime.
(a) Mention one symptom to diagnose the sickness.
(b) What caused the sickness?
(c) How could she recover by herself after sometime?

How has RNAi technique helped to prevent the infestation of roots in tobacco plants by a nematode Meloidegyne incognitia?

"In a food-chain, a trophic level represents a functional level, not a species." Explain.

Name any two places where it is essential to install electrostatic precipitators. Why is it required to do so?

Mention one limitation of the electrostatic precipitator.

Prior to a sports event blood & urine samples of sports-persons are collected for drug tests.
(a) Why is there a need to conduct such tests?
(b) Name the drugs the authorities usually look for.
(c) Write the generic names of two plants from which these drugs are obtained. 

Describe the experiment that helped demonstrate the semi-conservative mode of DNA replication.

Given below is a list of six micro-organisms. State their usefulness to humans.
(a) Nucleopolyhedrovirus
(b) Saccharomyces cerevisiae
(c) Monascus purpureus
(d) Trichoderma polysporum
(e) Penicillium notatum
(f) Propionibacterium sharmanii

Reproductive and Child Healthcare (RCH) programmes are currently in operation. One of the major tasks of these programmes is to create awareness amongst people about the wide range of reproduction related aspects. As this is important and essential for building a reproductively healthy society.

(a) "Providing sex education in schools in one of the ways to meet this goal." Give four points in support of your opinion regarding this statement.

(b) List any two 'indicators' that indicate a reproductively healthy society.

Explain the post-pollination events leading to seed production in angiosperms.

List the different types of pollination depending upon the source of pollen gain.

Briefly explain the events of fertilisation and implantation in an adult human female.

Comment on the role of placenta as an endocrine gland.

How are the following formed and involved in DNA packaging in a nucleus of a cell?

Differentiate between Euchromatin and Heterochromatin.

Why should we conserve biodiversity ? How can we do it?

Explain the importance of biodiversity hot-spots and sacred groves.

Represent diagrammatically three kinds of age-pyramids for human populations.

How does an age pyramid for human population at given point of time helps the policy-makers in planning for future.