ISC Biology 2012 Class-12 Previous Year Question Papers

ISC Biology 2012 Class-12 Previous Year Question Paper Solved for practice. Step by step Solutions with Part-I, and II (Section-A,B). By the practice of ISC Biology 2012 Class-12 Solved Previous Year Question Paper you can get the idea of solving.

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ISC Biology 2012 Class-12 Previous Year Question Papers Solved


-: Select Your Topics :-

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Part-I,

Sections-A, Part- II,

Sections-B, Part- II,


Maximum Marks: 70

Time allowed: Three hours

(Candidates are allowed additional 15 minutes for only reading the paper. They must not start writing during this time)

  • This paper comprises TWO PARTS – Part I and Part II.
  • Part I contains one question of 20 marks having four sub parts.
  • Part II consists of Sections A, and B.
  • Section A contains seven questions of two marks each Section B contains seven questions of three marks each, and
  • Section C contains 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.
  • The intended marks for questions or parts of questions are given in brackets [ ].

Part-I
(Attempt All Questions)

ISC Biology 2012 Class-12 Previous Year Question Papers Solved

Question 1.
(a) Give one difference between each of the following :
(i) Ventricular systole and Ventricular diastole.
(ii) Sertoli cells and Spermatids.
(iii) Dwarfism and Cretinism.
(iv) Antibodies and Interferons.
(v) Glucocorticoids and Mineralocorticoids.

(b) Give reasons for the following :
(i) Nerve impulse travels in one direction.
(ii) Jamming of wooden doors and windows takes place during rainy season.
(iii) A cut plant wilts fast even if its cut end is dipped in water.
(iv) Urine excreted during summer months is hypertonic.
(v) A person has difficulty in focusing on nearer objects, as the age increases.

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(c) Give a scientific term for each of the following:
(i) A single isolated contraction of muscle fibre.
(ii) Inhibition of lateral bud growth by terminal bud.
(iii) Specialised structure through which guttation occurs.
(iv) Development of embryo from the egg without the process of fertilization.
(v) Process of splitting of water molecules during photosynthesis.
(vi) Passing out of urine.

(d) Mention the most significant function of each of the following :
(i) Tapetum cells
(ii) Serotonin
(iii) Lenticels
(iv) Cerebrospinal fluid
(v) Islets of Langerhans
(vi) Bundle sheath

(e) State the most significant contribution of the following scientists :
(i) Hans Berger
(ii) Dixon and Jolly
(iii) J.B. Lamarck
(iv) William Harvey

(e) State the most significant contribution of the following scientists: [2]

(f) Expand the following: [2]
(1) OP
(ii) RuBP
(iii) IBA
(iv) PEP
Answer:
(a)

(i)

Ventricular systole Ventricular diastole
Ventricles contract and the blood flows from ventricles to arteries. Ventricles are relaxed and the blood flows from auricles to the ventricles.

(ii)

Sertoli cell Spermatids
Present in the germinal epithelium of the seminiferous tubules which provides nour­ishment to the developing sperms. Few cells of the germinal epithelium of the seminiferous tubules undergo meiosis to produce spermatids.

(iii)

Dwarfism Cretinism
It is caused due to hyposecretion of growth hormone during childhood. Caused due to malfunctioning of the thyroid gland in infant.

(iv)

Antibodies Interferons
Acts slowly and long-lasting. The action is quick but temporary.

(v)

Glucocorticoids Mineralocorticoids
Influences the metabolism of carbohy­drates, proteins and fats. Affects the transport of electrolyte and absorption of sodium ions by the various parts of the uriniferous tubules.

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(b)

(i) Nerve impulse travels in one direction Since the neurotransmitter is present only in the axon terminal so nerve impulse always travels from the axon terminal of one neurone to the dendrite or cell body of the next neurone.

(ii) Jamming of wooden doors and windows takes place during rainy season The cellulose of the wood absorbs water and swells up. This causes increase in size of doors and windows resulting in jam.

(iii) A cut plant wilts fast even if the cut end is dipped in water As the rate of transpiration is higher than that of the absorption by the cut end, the wilting is fast.

(iv) Urine excreted during summer months is hypertonic During the summer, excessive water is lost as sweating. Urine becomes hypertonic to reduce the loss of water in urine and maintains the osmotic concentration of the blood constant.

(v) A person has difficulty in focusing on nearer objects as the age increases With the advancement of age, the elasticity of the lens decreases. It causes the person difficult to focus the nearer object.

(e)
(i) Single muscle twitch
(ii) Apical dominance
(iii) Hydathodes
(iv) Parthenocarpy
(v) Photolysis
(vi) Micturition

(f)
(i) Tapetum cells: Rich in food materials, surrounds the microspore mother cell and supplies food to the developing spores.
(ii) Serotonin : Acts as a neurotransmitter.
(iii) Lenticels : Allows exchange of gases between the atmosphere and the interior of the cells.
(iv) Cerebrospinal fluid : Forms the protective cushion over the brain and spinal cord against shock and mechanical injury.
(v) Islets of Langerhans: Secrete two hormones –

(a) insulin and
(b) glucagon
(vi) Bundle sheath : Surrounds the vascular bundles in monocot leaf, provides mechanical support.

(e)
(i) hans Berger : First to record EEG
(ii) Dixon and Jolly: Theory of ascent of sap
(iii) J. B Lamarck: Theory of inhentance of acquired characters.
(iv) William Harvey : Discovered closed circulatory system

(f)
(i) OP – Osmotic pressure/potentiaL
(ii) RuBP — Ribulose biphosphate
(iii) IBA – Indole – 3 – butyric acid
(iv) PEP — Phosphoenol pyruvic acid


Section – A Part-II 

(Attempt any three questions)

ISC Biology 2012 Class-12 Previous Year Question Papers Solved

Question 2.
(a) Give any four anatomical differences between monocotyledonous and dicotyledonous leaf. [4] (b) Explain the phases of growth in the meristem of plants. [3] (c) Draw a neat labelled diagram of a matured anatropous ovule before fertilization. [3] Answer:
(a) MonocoG’ledonous/Isobilateral Leaf

  1. Both the surfaces are alike.
  2. Stomata are equally distributed on both sides. Mesophyll undifferentiated.
  3. Vascular bundles are partially or completely surrounded by a sclerenchymatous sheath.
  4. Vascular bundles have phloem on the upper side and xylem on the lower side.

Dicotyledonous/Dorsiven frai leaf

  1. Distinct upper and lower surface.
  2. Stomata are mostly present on the lower side. Mesophyll differentiated.
  3. Vascular bundles has sclerenchymatous patches on the upper side.
  4. Vascular bundles have downward phloem and upward xylem.

(b) Phases of growth in meristem of plant:
(i) Cell formation phase – During this phase meristematic cell divides to form new cells. The newly formed cells are thin wailed.
(ii) Cell enlargement phase – During this phase, the newly formed cells absorb water by osmosis resulting in the increase in turgidity and expansion and dialation of the elastic cell wall.
(iii) Cell differentiation phase – This occurs below the zone of elongation. The thin cell wall grows in thickness and the cells gradually undergoes structural and physiological changes.

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