Name the part of lens through which a ray of light passes without suffering any deviation.
7. What is the function of galvanometer in a circuit?
OR
What is the principle of an Electric Motor?
8. Draw the magnetic field lines around a straight current carrying conductor?
9. Veins are thin walled and have valves? Justify.
10. How is the wall of small intestine adopted for performing the function of absorption of food?
OR
Out of a goat and a tiger, which one will have a longer small intestine? Justify your answer.
11. Explain how ozone being a deadly poison can still perform an essential function for our
environment.
OR
Give reasons why a food chain can not have more than four trophic levels.
12. Identify the poles of the magnet in the given figure:-
13. State the role of pancreas in digestion of food.
For questions no. 14, 15 and 16, two statements are given, one labelled Assertion(A) and other
labeled Reason (R) . Select the correct answer to these questions from the codes (a), (b), (c) and
(d) as given below:
(a) Both A and R are true but R is correct explanation of the assertion.
(b) Both A and R are true but R is not correct explanation.
(c) A is true but R is false.
(d) A is false but R is false.
14. Assertion: After white washing the walls, a shiny white finish on walls is obtained after two or
three days.
Reason :Calcium oxide reacts with carbon dioxide to form Calcium Hydrogen Carbonate which
gives shiny finish.
15. Assertion : Food chain is responsible for the entry of harmful chemicals in our bodies.
Reason : The length and complexity of food chain vary greatly.
OR
Assertion : Greater no. of individuals are present in lower trophic level.
Reason :The flow of energy is unidirectional.
16. Assertion : A geneticist crossed a pea plant having violet flowers with a pea plant with white
flowers, he got all violet flowers in first generation.
Reason : White colour gene is not passed on to next generation.
Question no.17 contains five sub-parts. You are expected to answer any four sub-parts.
17. Read the following and answer any four question from 17(I) to 17(V):
All living cells require energy for various activities. This energy is available by the breakdown of
simple carbohydrates either using oxygen or without using oxygen.
(I) – Energy in the case of higher plants and animals is obtained by- (a) Breathing, (b) Tissue
respiration, (c) Organ respiration, (d) Digestion of food.
(II) – The graph below represents the blood lactic acid concentrate of an athlete during a race of
400 and shows a peak at point D
Answers
Optical centre
Name the part of a lens through which a ray of light passes without suffering any deviation. Answer: Optical centre.
7. Galvanometer, instrument for measuring a small electrical current or a function of the current by deflection of a moving coil. The deflection is a mechanical rotation derived from forces resulting from the current.
OR
The principle of an electric motor is based on the current carrying conductor which produces magnetic field around it. A current carrying conductor is placed perpendicular to the magnetic field so that it experiences a force.
8. The Magnetic field lines around a straight conductor carrying current are concentric circles whose centres lie on the wire. The direction of magnetic field lines can be determined using Right-Hand Thumb Rule.
9. Veins collect the blood from different organs and bring it back to the heart. The blood is no longer under pressure so, the walls are thin with valves to ensure that blood flows only in one direction.
10. The small intestine has millions of tiny finger-like projections called villi. These villi increase the surface area for more efficient food absorption. Within these villi, many blood vessels are present that absorb the digested food and carry it to the bloodstream.
OR
Herbivores eat only green leaves and thus it is difficulties for them digest,so goat as longer small intestine. goat requires long small intestine to digest the cellulose which it gets from the plant it feeds on . Tiger need smallest small intestine so that the meat can be easily digest.
11. Ozone layer is deadly poisonous because it is combination of 3 oxygen atoms which make it highly reactive which is not good for our body system and it is essential because it shields the surface of the earth from the entry of UV rays from the sun which can harm us by causing skin burnings and skin cancer.
OR
Food chains are limited to 4 trophic levels because less and less energy is available at higher trophic levels
12. DON;T KNOW THIS
13. During digestion, your pancreas makes pancreatic juices called enzymes. These enzymes break down sugars, fats, and starches. Your pancreas also helps your digestive system by making hormones. These are chemical messengers that travel through your blood.
(B)