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Board Paper of Class 12-Science 2004 Biology All India(SET 1) - Solutions

General Instructions:
 (i) All questions are compulsory.
(ii) This question paper consists of four sections A, B, C and D.
Section A contains 5 questions of one mark each.
Section B is of 10 questions of two marks each.
Section C is of 10 questions of three marks each and
 Section D is of 3 questions of five marks each.
(iii) There is no overall choice. However, an internal choice has been provided.
(iv) Wherever necessary, the diagrams drawn should be neat and properly labelled.
  • Question 1

    How is haemoglobin differently located in humans and earthworms?

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  • Question 2

    What is apoptosis with reference to ageing?

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  • Question 3

    What are the starting points of a grazing food chain and a detritus food chain respectively?

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  • Question 4

    A cardiologist observed an enlarged QR wave in the ECG of a patient. What does it indicate?

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  • Question 5

    Name the type of cells that produce antibodies.

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  • Question 6

    What is meant by Respiration Quotient (RQ)? When will the value of RQ be l and when will it be less than1?

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  • Question 7

    Explain any two functions of cerebrospinal fluid in humans.

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  • Question 8

    Name the organism that causes Anthrax in cattle. Why does the infected animal die within 2 or 3 days?

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  • Question 9

    Differentiate between quiescence and dormancy with reference to seed germination.

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  • Question 10

    How is our gut lining protected from its own secretion of proteases?

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  • Question 11

    Name the respective mineral nutrient element that

    (i) forms the core constituent of the ring structure of chlorophyll

    (ii) activates carboxylases

    (iii) forms the component of nitrogenase

    (iv) synthesises the middle lamella of plant cells

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  • Question 12

    What is photochemical smog composed of? How does this affect the plants?

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  • Question 13

    Define a portal vein. Explain the functions of such a vein in our digestive system.

    OR

    What is the role of calcium ions in muscle contraction?

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  • Question 14

    Why is aqueous gel applied between the skin and the scan head in sonography during clinical examination? Why is this technique generally preferred to radiography?

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  • Question 15

    Lichen is considered a good example of obligate mutualism. Explain.

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  • Question 16

    Name the T3 and T4 components of the thyroid hormone. Explain their specific action.

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  • Question 17

    Give a schematic representation of nitrogen cycle of a terrestrial ecosystem. Name any two microorganisms involved in it.

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  • Question 18

    Why does the rate of photosynthesis decrease at higher light intensities? What plays a protective role in such situations?

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  • Question 19

    Due to some physiological reasons the blood glucose level of an otherwise normal person has shot up above normal. How will this condition be returned to normal through hormone action?

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  • Question 20

    (i) Give the scientific name of the soil bacterium which produces crystal (Cry) proteins.

    (ii) How are these proteins useful in agriculture?

    (iii) What do the differently written terms “Cry” and “cry” represent respectively?

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  • Question 21

    Draw a labelled diagram to show the impulse conductive system in human heart.

    OR

    Draw a labelled sketch of human urinary system with its associated blood vessels.

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  • Question 22

    List the three prominent theories to explain water translocation in trees. Describe the most accepted theory out of these.

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  • Question 23

    How is an allopolyploid produced’? Explain with an example.

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  • Question 24

    Differentiate between in situ and ex situ approaches of conserving biodiversity.

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  • Question 25

    Trace the development of a mature ovule from a megaspore mother cell.

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  • Question 26

    Where does glycolysis occur in a cell? Explain its different steps.

    OR

    Explain non-cyclic photophosphorylation in plants. Why is this process called so?

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  • Question 27

    Describe oogenesis in human female. What promotes completion of second meiotic division in oogenesis?

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  • Question 28

    Differentiate between inbred line and a hybrid variety of crop. Explain the steps involved in the production of the hybrid variety.

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