Board Paper of Class 12-Science 2016 Biology Delhi(SET 3) - Solutions

General Instructions :
(i) There are a total of 26 questions and five sections in the question paper, All questions are compulsory.
(ii) Section A contains question number 1 to 5, Very Short Answer type questions of one mark each.
(iii) Section B contains question number 6 to 10, Short Answer type I questions of two marks each.
(iv) Section C contains question number 11 to 22, Short Answer type II questions of three marks each.
(v) Section D contains question number 23, Value Based Question of four marks.
(vi) Section E contains question number 24 to 26, Long Answer type questions of five marks each.
(vii) There is no overall choice in the question paper, however, an internal choice is provided in one question of two marks, one question of three marks and all three questions of five marks. An examinee is to attempt any one of the questions out of the two given in the question paper with the same question number.

Question 1
State a difference between a gene and an allele. VIEW SOLUTION

Question 2
Suggest the breeding method most suitable for animals that are below average in milk productivity. VIEW SOLUTION

Question 3
Suggest a technique to a researcher who needs to separate fragments of DNA. VIEW SOLUTION

Question 4
Excessive nutrients in a fresh water body cause fish mortality. Give two reasons. VIEW SOLUTION

Question 5
Give an example of a codon having dual function. VIEW SOLUTION

Question 6
Discuss the role the enzyme DNA ligase plays during DNA replication. VIEW SOLUTION

Question 7
Distinguish between the roles of flocs and anaerobic sludge digesters in sewage treatments. VIEW SOLUTION

Question 8

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

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

Crop	Variety	Resistance to disease
$A$	Himgiri	Leaf rust
Cauliflower	Pusa Shubhra	$B$
Brassica	Pusa Swarnim	$C$
Cowpea	$D$	Bacterial blight

VIEW SOLUTION

Question 9
Plants that inhabit a rain-forest are not found in a wetland. Explain. VIEW SOLUTION

Question 10
Angiosperms bearing unisexual flowers are said to be either monoecious or dioecious. Explain with the help of one example each. VIEW SOLUTION

Question 11
What is a GMO? List any five possible advantages of a GMO to a farmer. VIEW SOLUTION

Question 12
Suggest and describe a technique to obtain multiple copies of a gene of interest in vitro. VIEW SOLUTION

Question 13
(a) Name any two fowls other than chicken reared in a poultry farm.
(b) Enlist four important components of poultry farm management. VIEW SOLUTION

Question 14
Why is breast-feeding recommended during the initial period of an infant's growth? Give reasons. VIEW SOLUTION

Question 15
Describe the experiment that helped Louis Pasteur to dismiss the theory of spontaneous generation of life. VIEW SOLUTION

Question 16
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. VIEW SOLUTION

Question 17
Give an example of an autosomal recessive trait in humans. Explain its pattern of inheritance with the help of a cross. VIEW SOLUTION

Question 18
Explain with the help of suitable examples the three different ways by which organisms overcome their stressful conditions lasting for short duration. VIEW SOLUTION

Question 19
How has RNAi technique helped to prevent the infestation of roots in tobacco plants by a nematode Meloidegyne incognitia? VIEW SOLUTION

Question 20
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 VIEW SOLUTION

Question 21
"In a food-chain, a trophic level represents a functional level, not a species." Explain.

OR

(a) Name any two places where it is essential to install electrostatic precipitators. Why it is required to do so?
(b) Mention one limitation of the electrostatic precipitator. VIEW SOLUTION

Question 22
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. VIEW SOLUTION

Question 24
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.

OR

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

(b) Name the scientist who influenced Darwin and how ? VIEW SOLUTION

Question 25
(a) Why should we conserve biodiversity ? How can we do it?
(b) Explain the importance of biodiversity hot-spots and sacred groves.

Or

(a) Represent diagrammatically three kinds of age-pyramids for human populations.
(b) How does an age pyramid for human population at given point of time helps the policy-makers in planning for future. VIEW SOLUTION

Question 26
(a) Explain the post-pollination events leading to seed production in angiosperms.
(b) List the different types of pollination depending upon the source of pollen gain.

Or

(a) Briefly explain the events of fertilisation and implantation in an adult human female.
(b) Comment on the role of placenta as an endocrine gland.
VIEW SOLUTION

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