Board Paper of Class 12-Science 2015 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
Name the transcriptionally active region of chromatin in a nucleus. VIEW SOLUTION

Question 2
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. VIEW SOLUTION

Question 3
What is Biopiracy ? VIEW SOLUTION

Question 4
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. VIEW SOLUTION

Question 5
Indiscrimate diagnostic practices using X-rays etc., should be avoided. Give one reason. VIEW SOLUTION

Question 6
Differentiate between 'ZZ' and 'XY' type of sex-determination mechanisms. VIEW SOLUTION

Question 7
An infertile couple is advised to adopt test-tube baby programme. Describe two principle procedures adopted for such technologies. VIEW SOLUTION

Question 8
Many fresh water animals can not survive in marine environment. Explain.

OR

How are productivity, gross productivity, net primary productivity and secondary productivity interrelated ? VIEW SOLUTION

Question 9
Enumerate four objectives for improving the nutritional quality of different crops for the health benefits of the human population by the process of "Biofortification". VIEW SOLUTION

Question 10
Mention a product of human welfare obtained with the help of each one of the following microbes :
(a) LAB
(b) Saccharomyces cerevisiae
(c) Propionibacterium shermanii
(d) Aspergillus niger VIEW SOLUTION

Question 11
Describe the process of Parturition in humans. VIEW SOLUTION

Question 12
Describe the development of endosperm after double fertilisation in an angiosperm. Why does endosperm development preceeds that of zygote ? VIEW SOLUTION

Question 13
Explain the interpretation of Charles Darwin when he observed a variety of small black birds on Galapagos Islands. VIEW SOLUTION

Question 14
A teacher wants his/her students to find the genotype of pea plants bearing purple coloured flowers in their school garden. Name and explain the cross that will make it possible. VIEW SOLUTION

Question 15

(a) A DNA segment has a total of 2,000 nucleotides, out of which 520 are adenine containing nucleotides.
How many purine bases this DNA segment possesses ?

(b) Draw a diagrammatic sketch of a portion of DNA segment to support your answer.
VIEW SOLUTION

Question 16
Recombination DNA−technology is of great importance in the field of medicine. With the help of a flow chart, show how this technology has been used in preparing genetically engineered human insulins. VIEW SOLUTION

Question 17
Draw a labelled sketch of sparged-stirred-tank bioreactor. Write its application. VIEW SOLUTION

Question 18
Following the collision of two trains a large number of passengers are killed. A majority of them are beyond recognition. Authorities want to hand over the dead to their relatives. Name a modern scientific method and write the procedure that would help in the identification of kinship. VIEW SOLUTION

Question 19

A team of students are preparing to participate in the interschool sports meet. During a practice session you find some vials with labels of certain cannabinoids.

(a) Will you report to the authorities? Why?

(b) Name of a plant from which such chemicals are obtained.

(c) Write the effect of these chemicals on human body.
VIEW SOLUTION

Question 20

Many plant and animal species are on the verge of their extinction because of loss of forest land by indiscriminate use by the humans. As a biology student what method would you suggest along with its advantages that can protect such threatened species from getting extinct ?

OR

"Determination of Biological Oxygen Demand (BOD) can help in suggesting the quality of a water body." Explain.
VIEW SOLUTION

Question 21
Enlist the steps involved in inbreeding of cattle. Suggest two disadvantages of this practice. VIEW SOLUTION

Question 22
Choose any three microbes, from the following which are suited for organic farming which is in great demand these days for various reasons. Mention one application of each one chosen.

Mycorrhiza; Monascus; Anabaena; Rhizobium; Methanobacterium; Trichoderma. VIEW SOLUTION

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