Biology Delhi Set 3 2015-2016 Science (English Medium) Class 12 Question Paper Solution

State a difference between a gene and an allele.

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

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

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

Give an example of a codon having dual function.

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

Distinguish between the roles of flocs and anaerobic sludge digesters in sewage treatments.

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

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

Plants that inhabit a rain-forest are not found in a wetland. Explain.

Angiosperms bearing unisexual flowers are said to be either monoecious or dioecious. Explain with the help of one example each.

What is a GMO?

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

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

Name any two fowls other than chicken reared in a poultry farm

Enlist four important components of poultry farm management.

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

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

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. 

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

Explain with the help of suitable examples the three different ways by which organisms overcome their stressful conditions lasting for short duration.

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

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

"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.

How would you find genotype of a tall pea plant bearing white flowers? Explain with the help of a cross. Name the type of cross you would use.

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.

Answer the following questions based on Hershey and Chases's experiments:

(a) Name the kind of virus they worked with and why?

(b) Why did they use two types of culture media to grow viruses in ? Explain.

(c) What was the need for using a blender and later a centrifuge during their experiments?

(d) State the conclusion drawn by them after the experiments.

How did Darwin explain adaptive radiation ? Give another example exhibiting adaptive radiation.

Name the scientist who influenced Darwin and how ?

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.

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.