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Board Paper of Class 12-Science 2017 Biology Delhi(SET 2) - 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
    What is "fitness of an individual" according to Darwin?  (1) VIEW SOLUTION
  • Question 3
    Suggest a method to ensure an anamnestic response in humans.  (1) VIEW SOLUTION
  • Question 4
    State the fate of a pair of autosomes during gamete formation.        (1) VIEW SOLUTION
  • Question 5
    Our government has intentionally imposed strict conditions for M.T.P. in our country. Justify giving a reason.    (1) VIEW SOLUTION
  • Question 6
    By taking two examples explain how has bio-fortification helped in improving food quality.  (2) VIEW SOLUTION
  • Question 7
    Plenty of algal bloom is observed in a pond in your locality.   (2)

    (a) Write what has caused this bloom and how does it affect the quality of water.
    (b) Suggest a preventive measure. VIEW SOLUTION
  • Question 8
    How does the application of cyanobacteria help improve agricultural output?  (2) VIEW SOLUTION
  • Question 9
    In a flowering plant a microspore mother cell produces four male gametophytes while a megapore mother cell forms only one female gametophyte. Explain.  (2) VIEW SOLUTION
  • Question 10
    Describe the structure of a nucleosome.  (2)
     
    OR

    Mention the evolutionary significance of the following organisms :

    (a) Shrews

    (b) Lobefins

    (c) Homo habilis

    (d) Homo erectus VIEW SOLUTION
  • Question 11
    During a medical investigation, an infant was found to possess an extra  chromosome-21. Describe the symptoms the child is likely to develop later in the life.          (3) VIEW SOLUTION
  • Question 12
    'in-situ' Conservation can help endangered/threatened species. Justify the statement.     (3)

    OR
     
    Name and describe any three causes of bio-diversity losses. VIEW SOLUTION
  • Question 13
    Difference between an annual and biennial plants. Provide one example of each.  (3) VIEW SOLUTION
  • Question 14
    Draw a labelled diagrammatic sectional view of a human seminiferous tubule.        (3) VIEW SOLUTION
  • Question 15
    A criminal blew himself up in a local market when was chased by cops. His face was beyond recognition. Suggest and describe a modern technique that can help establish his identity.  (3) VIEW SOLUTION
  • Question 16
    p2 + 2pq + q2 = 1. Explain this algebraic equation on the basis of Hardy Weinberg's principle. VIEW SOLUTION
  • Question 17
    Explain the role(s) of the following in Biotechnology:

    (a) Restriction endonuclease
    (b) Gel − electrophoresis
    (c) Selectable markers in pBR322 VIEW SOLUTION
  • Question 18
    Why do lepidopterans die when they feed on Bt cotton plant? Explain how does it happen.   (3) VIEW SOLUTION
  • Question 19
    Write the steps you would suggest to be undertaken to obtain a foreign-gene-product.    (3) VIEW SOLUTION
  • Question 20
    Describe how do 'flocs' and 'activated sludge' help in Sewage Treatment.  (3) VIEW SOLUTION
  • Question 21
    (a) What is inbreeding depression?

    (b) Explain the importance of "selection" during inbreeding in cattle. VIEW SOLUTION
  • Question 22
    A group of youth were having a 'rave party' in an isolated area and was raided by police. Packets of 'smack' and syringes with needles were found littered around.  (3)

    (a) Why is taking 'smack' considered an abuse?

    (b) Write the chemical name of 'smack' and the name of its source plant.

    (c) Syringes and needles used by the youth for taking the drug could prove to be very fatal. Why? VIEW SOLUTION
  • Question 23

    Public all over India is very much concerned about the deteriorating air quality in large parts of North India. Alarmed by this situation the Resident's Welfare Association of your locality organized an awareness programme entitled "Bury not burn". They invited you, being a biology student to participate.     (4)

    (a) How would you justify your arguments that promote burying and discourage burning? (Give two reasons)

    (b) With the help of flow charts, one for each practice depict the chain of events that follow.

    VIEW SOLUTION
  • Question 24
    (a) What is an age-pyramid?

    (b) Name three representative kinds of age-pyramids for human population and list the characteristics for each one of them.
     
    OR

    Discuss the role of healthy ecosystem services as a pre-requisite for a wide range of economic, environmental and aesthetic goods and services. VIEW SOLUTION
  • Question 25
    Read the statement and answer the questions that follow.  (5)

    A flower of brinjal has 520 ovules in its ovary. However, it produces a fruit with only 480 viable seeds.

    (a) What could have prevented the rest of the 40 ovules from maturing into viable seeds? Explain giving a reason.

    (b) Describe the development of a dicot embryo in a viable seed.

    (c) Why certain angiospermic seed albuminous while others are exalbuminous? Explain.
     
    OR

    (a) Name the hormones secreted and write their functions :

    (i) by corpus luteum and placenta (any two).

    (ii) during Follicular phase and parturition.


    (b) Name the stages in a human female where :

    (i) Corpus luteum and placenta co-exist.

    (ii) Corpus luteum temporarily ceases to exist. VIEW SOLUTION
  • Question 26

    State and explain the "law of independent assortment" in a typical Mendelian dihybrid cross.   (5)

    OR

    (a) How do the observations made during moth collection in pre- and post- industrialized era in England support evolution by Natural Selection?

    (b) Explain the phenomenon that is well represented by Darwin's finches other than natural selection.

    VIEW SOLUTION
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