Sunday, January 22, 2017




(1) Fill in the blanks and rewrite the completed statements: [3]

(a) ___________ acid inhibits growth leading to wilting of leaves. (Abscissic)

(b) The organic compounds having double or triple bond in them are termed as _________________   _________________. (unsaturated hydrocarbons)

(c) Lymph flows in _______________ direction. (one)

(2) Write the structural formulae of the following compound.   [1]


(3) Name the mode of reproduction process seen in yeast. [1]

Ans. Budding is the name of the mode of reproduction process seen in yeast.

(B) Choose the correct alternative and rewrite the following: [5]

(1) Fermentation is a type of ____________________

(a) aerobic respiration.

(b) anaerobic respiration.

(c) exothermic reaction.

(d) none of the above.

(2) Some acetic acid is treated with solid NaHCO3, the resulting solution will be _________________

(a) Colourless

(b) blue

(c) green

(d) yellow

(3) Ramesh observed a slide of Amoeba with elongated nuclei. It would represent _______________

(a) Binary fission

(b) Budding

(c) Multiple fission

(d) None of the above.

(4) Twenty dry raisins were soaked in 50 ml of water and kept for one hour at 500 C. Which out of the following is the correct observation?

(a) 8 raisins absorbed water

(b) 18 raisins absorbed water

(c) 15 raisins absorbed water.

(d) All raisins absorbed water.

(5) Iron is _____________________

(a) More reactive than Zn.  

(b) more reactive than Al.

(c) less reactive than Cu.

(d) less reactive than Al.

Q. II. Attempt the following questions. (any five):  [ 5 x 2 = 10 ]

(1) Gold and silver are used to make jewellery. Give reason.

(2) Explain the following reaction with balanced chemical equation:

Calcium reacts with water.

Ans. Calcium reacts with water with some vigor to produce calcium hydroxide solution and sets free hydrogen gas. Resulting solution is warm.

Ca + 2H2O --------> Ca(OH)2 + H2(g)

(3) Write any two physical properties of Ethanol.

Ans. (i) It is an inflammable volatile liquid.

(ii) It is soluble in water as well as in organic solvents.

(iii) Ethanol is a colourless liquid.

(iv) It has a pleasant odour.

(v) Its boiling point is 780 C.

(vi) It freezes at - 1140 C.

(4) Roots of plants grow away from light. Give scientific reasons.

(5) In which livings, female decides the sex? Give two examples.

Ans. Living beings in which females decide the sex of the offspring are, birds and moths and butterflies.

(6) Give the molecular and structural formulae of Benzene.

Q. III. Answer the following questions (any five) : [5 x 3 = 15]

(1) What do you mean by vestigial structures? Name four vestigial organs found in man.

(2) State Darwin’s theory of evolution.

(3) Draw a diagram of longitudinal section of a flower and label the following parts.

(a) Petal (b) Ovary (c) Anther (d) Sepal.

(4) Explain the following terms:

(a) Reproduction

(b) Vegetative propagation.

(c) Pollination.

(5) Write the names and functions of three parts of human nervous system in which it is divided.

Ans. The names and functions of three parts of human nervous system and their functions are as follows:

(a) CNS: The central nervous system.
(b) PNS: The peripheral nervous system.
(c) ANS: The automic nervous system.

(a) The central nervous system regulates all activities of the body.
(b) The peripheral nervous system.
(c) The autonomic nervous system regulates involuntary organs such as heart, lungs, stomach etc.

(6) Geeta dipped a copper coin in a solution of silver nitrate. After some time she saw the silver shine on the coin. Why? Give the balanced chemical equation for the same and name the type of reaction.

Q. IV. Attempt any one of the following questions. [5]

(1) (a) What is recycling of waste?

Ans. Recycling is a type of green technology that uses old materials to make new products. It is an environment friendly technology.

(b) Give one example of Reuse.

Ans. Water used for washing vegetables, fruits etc. can be collected and resued to water garden plants or potted plants.

(c) Write the advantages of recycling.

Ans. Advantages of recycling:

It conserves energy and raw materials.

It reduces the cost of production.

It saves space used for landfills.

It protects environment by effective handling of waste materials.

(2) (a) List the organs of Human respiratory system.

Ans. The organs of human respiratory system are:

(i) The nose, (ii) pharyns, (iii) larynx (iv) the trachea (v) lungs (vi) diaphragm

(b) Explain ‘inhalation’.

Ans. A human adult at rest, on an average breathes about 12-20 times per minute i.e. 28800 times per day. The mechanism of breathing in human beings involves two processes : Inhalation and Exhalation.
1. Inhalation : When the muscular diaphragm of the body relaxes, volume of the thoracic cavity increases and air pressure inside the cavity decreases. The air from outside enters the lungs through the nostrils and the alveolar sacs are filled with air rich in oxygen.