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Board Paper of Class 12-Science 2015 Biology (SET 1) - 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
    How many chromosomes do drones of honeybee possess? Name the type of cell division involved in the production of sperms by them. VIEW SOLUTION

  • Question 3
    Retroviruses have no DNA. However, the DNA of the infected host cell does possess viral DNA. How is it possible? VIEW SOLUTION

  • Question 4
    Why do children cured by enzyme-replacement therapy for adenosine deaminase deficiency need periodic treatment? VIEW SOLUTION

  • Question 5
    List two advantages of the use of unleaded petrol in automobiles as fuel. VIEW SOLUTION

  • Question 6
    Why do moss plants produce very large number of male gametes? Provide one reason. What are these gametes called? VIEW SOLUTION

  • Question 7
    Select the homologous structures from the combinations given below :
    (i) Forelimbs of whales and bats
    (ii) Tuber of potato and sweet potato
    (iii) Eyes of octopus and mammals
    (iv) Thorns of Bougainvillea and tendrils of Cucurbita

    (b) State the kind of evolution they represent. VIEW SOLUTION

  • Question 8
    (a) Why are the plants raised through micropropagation termed as somaclones ?

    (b) Mention two advantages of this technique. VIEW SOLUTION

  • Question 9
    Explain the different steps involved during primary treatment phase of sewage. VIEW SOLUTION

  • Question 10
    What is mutualism? Mention any two examples where the organisms involved are commercially exploited in agriculture.


    List any four techniques where the principle of ex-situ conservation of biodiversity has been employed. VIEW SOLUTION

  • Question 11
    State what is apomixis. Comment on its significance. How can it be commercially used? VIEW SOLUTION

  • Question 12
    During a monohybrid cross involving a tall pea plant with a dwarf pea plant, the offspring populations were tall and dwarf in equal ratio. Work out a cross to show how it it possible. VIEW SOLUTION

  • Question 13
    Explain the significance of satellite DNA in DNA fingerprinting technique. VIEW SOLUTION

  • Question 14
    What does the following equation represent? Explain

    p2 + 2 pq + q2 = 1 VIEW SOLUTION

  • Question 15
    A heavily bleeding and bruised road accident victim was brought to a nursing home. The doctor immediately gave him an injection to protect him against a deadly disease.

    (a) Write what did the doctor inject into the patient's body.
    (b) How do you think this injection would protect the patient against the disease?
    (c) Name the disease against which this injection was given and the kind of immunity it provides. VIEW SOLUTION

  • Question 16
    Enumerate any six essentials of good, effective Dairy Farm Management Practices. VIEW SOLUTION

  • Question 17
    State the medicinal value and the bioactive molecules produced by Streptococcus, Monascus and Trichoderma.


    What are methanogens ? How do they help to generate biogas ? VIEW SOLUTION

  • Question 18
    Rearrange the following in the current sequences to accomplish an important biotechnological reaction :
    (a) In vitro synthesis of region of DNA of interest
    (b) Chemically synthesised oligonucleotides
    (c) Enzyme DNA-polymerase
    (d) Complementary region of DNA
    (e) Genomic DNA template
    (f) Nucleotides provided
    (g) Primers
    (h) Thermostable DNA-polymerase (from Thermus aquaticus)
    (i) Denaturation of ds-DNA VIEW SOLUTION

  • Question 19
    Describe any three potential applications of genetically modified plants. VIEW SOLUTION

  • Question 20
    How did an American Company. Eli Lilly use the knowledge of r-DNA technology to produce human insulin? VIEW SOLUTION

  • Question 21
    How do snails, seeds, bears, zooplanktons, fungi and bacteria adapt to conditions unfavourable for their survival? VIEW SOLUTION

  • Question 22
    With the help of a flow chart, show the phenomenon of biomagnification of DDT in an aquatic food chain. VIEW SOLUTION

  • Question 23
    Your school has been selected by the Department of Education to organize and host an interschool seminar on "Reproductive Health – Problems and Practices". However, many parents are reluctant to permit their wards to attend it. Their argument is that the topic is "too embarrassing."

    Put forth four arguments with appropriate reasons and explanation to justify the topic to be very essential and timely. VIEW SOLUTION

  • Question 24

    (a) Plan an experiment and prepare a flow chart of the steps that you would follow to ensure that the seeds are formed only from the desired sets of pollen grains. Name the type of experiment that you carried out.

    (b) Write the importance of such experiments.


    Describe the roles of pituitary and ovarian hormones during the menstrual cycle in a human female. VIEW SOLUTION

  • Question 25

    (a) Why are thalassemia and haemophilia categorized as Mendelian disorders ? Write the symptoms of these diseases. Explain their pattern of inheritance in humans.

    (b) Write the genotypes of the normal parents producing a haemophilic son.


    How do m-RNA, t-RNA and ribosomes help in the process of translation ? VIEW SOLUTION

  • Question 26

    (a) List the different attributes that a population has and not an individual organism.

    (b) What is population density ? Explain any three different ways the population density can be measured, with the help of an example each.

    "It is often said that the pyramid of energy is always upright. On the other hand, the pyramid of biomass can be both upright and inverted." Explain with the help of examples and sketches. VIEW SOLUTION
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