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Board Paper of Class 12 2018 Biology - Solutions

This paper comprises TWO PARTS – Part A and Part B.
Answer all questions.
Part A contains one question of 20 marks having four subparts.
Part B consists of Sections A, B and C.
Section A consists seven questions of two marks each.
Section B consists seven questions of three marks each, and Section C consists three questions of five marks each.
Internal choices have been provided in two questions in Section A, two questions in Section B and in all three questions of Section C.

  • Question 1
    (a) Answer the following questions briefly and to the point:
    (i) Give a significant point of difference between Oestrous and Menstrual cycle.
    (ii) Give the biological name of the organism causing typhoid.
    (iii) If the haploid number of chromosomes in a plant species is 20, how many chromosomes will be present in the cells of the shoot tip?
    (iv) Name a plant which flowers every twelve years.
    (v) Name the diagnostic test for AIDS.
    (vi) Name the terminal stage of ageing in the life cycle of plants.
    (vii) Which organisms constitute the last trophic level?
    (viii) What is emasculation?

    (b) Each of the following questions has four choices. Choose the best option in each case:
    (i) Length of the DNA with 23 base pairs is:
    (1) 78.4 Å
    (2) 78.2 Å
    (3) 78 Å
    (4) 74.8 Å

    (ii) Opium is obtained from:
    (1) Papaver somniferum
    (2) Cannabis sativa
    (3) Erythroxylum coca
    (4) Datura metel

    (iii) According to Abiogenesis, life originated from:
    (1) Non-living matter
    (2) Pre-existing life
    (3) Oxygen
    (4) Extra-terrestrial matter

    (iv) The largest unit in which gene flow is possible is:
    (1) Organism
    (2) Population
    (3) Species
    (4) Genes

    (c) Give one significant contribution of each of the following scientists:
    (i) P. Maheshwari
    (ii) E. Wilson
    (iii) M. S. Swaminathan
    (iv) H. Boyer

    (d) Define the following:
    (i) Biopatent
    (ii) Parthenocarpy

    (e) Give a reason for each of the following:
    (i) Pollen grains of wind pollinated flowers are produced in large quantities.
    (ii) Equilibrium of a forest ecosystem can be disturbed by uncontrolled hunting of big predators. VIEW SOLUTION

  • Question 2
    (b) If the mother is a carrier of colour blindness and the father is normal, show the possible genotype and phenotype of the offspring of the next generation, with the help of a punnet square.


    (a) A woman with blood group O married a man with blood group AB. Show the possible blood groups of the progeny. List the alleles involved in this inheritance. VIEW SOLUTION

  • Question 3
    Define life span. Give the life span of an elephant. VIEW SOLUTION

  • Question 4
    Give two characteristic features of each of the following:
    (a) Ramapithecus
    (b) Cro-Magnon man VIEW SOLUTION

  • Question 5
    (a) List any four effects of global warming.


    (b) State any four measures to control noise pollution. VIEW SOLUTION

  • Question 6
    Define BOD. What is its significance in an aquatic ecosystem? VIEW SOLUTION

  • Question 7
    Give one significant difference between each of the following pairs:
    (a) Humoral immunity and cell mediated immunity.
    (b) Benign tumour and malignant tumour VIEW SOLUTION

  • Question 8
    Give four causes of infertility in males. VIEW SOLUTION

  • Question 9
    (a) Draw a labelled diagram of L.S. of human testis.


    (b) Draw a labelled diagram of the mature embryo sac of angiosperms. VIEW SOLUTION

  • Question 10
    Explain gene therapy, with reference to treatment of SCID. VIEW SOLUTION

  • Question 11
    Study the table given below. Do not copy the table, but write the answers in the correct order.
    Scientific Name Commercial Product Use
     (a)______________  Streptokinase  (b) _______________
     Monascus purpureus  (c)_____________  (d)________________
     (e)________________  Lactic acid  (f) ________________

  • Question 13
    Describe the tissue culture technique in plants. VIEW SOLUTION

  • Question 14
    Define the following:
    (a) Spermiogenesis
    (b) Reproductive health
    (c) Amenorrhea VIEW SOLUTION

  • Question 15
    (b) Define the following:
    (i) Hotspots
    (ii) Ramsar Sites
    (iii) Red data book


    (a) Define the following:
    (i) Biodiversity
    (ii) Eutrophication
    (iii) PAR

  • Question 16
    (a) Describe post transcriptional processing of RNA in eukaryotes.


    (b) Describe Avery, McLeod and McCarty’s experiment. State its significance. VIEW SOLUTION

  • Question 17
    (a) Write a short note on Chipko Movement.


    (b) Write a short note on Joint forest management. VIEW SOLUTION

  • Question 18
    (a) What does PCR stand for? Describe the different steps of PCR.


    (b) Give an account of the Blue-White Method of selection of recombinants. VIEW SOLUTION
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