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Board Paper of Class 12-Science 2017 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 2
    Suggest a method to ensure an anamnestic response in humans.  (1) VIEW SOLUTION
  • Question 3
    State the fate of a pair of autosomes during gamete formation.        (1) VIEW SOLUTION
  • Question 4
    Our government has intentionally imposed strict conditions for M.T.P. in our country. Justify giving a reason.    (1) VIEW SOLUTION
  • Question 5
    Rearrange the human activities mentioned below as per the order in which they developed after the modern Homo sapiens came into existence during ice age:  (1)

    (i) Human settlement
    (ii) Prehistoric cave art
    (iii) Agriculture VIEW SOLUTION
  • Question 6
    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 7
    How do mycorrhizae help the plants to grow better?   (2) VIEW SOLUTION
  • Question 8
    Mention the ploidy of the different types of cells present in the female gametophyte of an angiosperm.  (2) VIEW SOLUTION
  • Question 9
    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 10
    "Growing Spirulina on a large scale is beneficial both environmentally and nutritionally for humans," Justify. VIEW SOLUTION
  • Question 11
    During a fire in an auditorium a large number of assembled guests got burnt beyond recognition. Suggest and describe a modern technique that can help hand over the dead to their relatives.   (3) VIEW SOLUTION
  • Question 12
    (a) What is inbreeding depression?

    (b) Explain the importance of "selection" during inbreeding in cattle. VIEW SOLUTION
  • Question 13
    p2 + 2pq + q2 = 1. Explain this algebraic equation on the basis of Hardy Weinberg's principle. VIEW SOLUTION
  • Question 14
    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 15
    Draw a labelled diagrammatic sectional view of a human seminiferous tubule.        (3) VIEW SOLUTION
  • Question 16
    Parthenocarpy and apomixis have been observed in some plants. Give an example of each. State a similarity and a difference observed between the two processes.   (3) VIEW SOLUTION
  • Question 17
    Describe how do 'flocs' and 'activated sludge' help in Sewage Treatment.  (3) VIEW SOLUTION
  • Question 18
    Explain the role(s) of the following in Biotechnology:

    (a) Restriction endonuclease
    (b) Gel − electrophoresis
    (c) Selectable markers in pBR322 VIEW SOLUTION
  • Question 19
    Why do lepidopterans die when they feed on Bt cotton plant? Explain how does it happen.   (3) VIEW SOLUTION
  • Question 20
    Show with the help of a flow chart only, the life cycle of malarial parasite in humans.  (3) VIEW SOLUTION
  • Question 21
    '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 22
    Write the steps you would suggest to be undertaken to obtain a foreign-gene-product.    (3) 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

    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
  • Question 25
    (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 26
    (a) A capsicum flower has 240 ovules in its ovary. But, it produces a fruit with only 180 viable seeds.  (5)
     
    Explain giving a reason that could be responsible for such a result.

    (b) Describe the development of an endosperm in a viable seed. Why does endosperm development precedes embryo development?

    (c) Give an example of an angiosperm seed that has a perisperm. Name the part the perisperm develops from.
     
    OR

    a) Where in the fallopian tube does fertilization occur in humans? Describe the development of a fertilized ovum upto implantation.

    b) How is polyspermy prevented in humans? VIEW SOLUTION
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