Red Swastika School Science Answers Key

Section A (60 marks)
Q No - Ans
01 - 2, 02 - 4, 03 - 3, 04 - 4, 05 - 4
06 - 3, 07 - 1, 08 - 1, 09 - 4, 10 - 1
11 - 2, 12 - 4, 13 - 1, 14 - 2, 15 - 3
16 - 1, 17 - 3, 18 - 4, 19 - 2, 20 - 4
21 - 2, 22 - 2, 23 - 2, 24 - 2, 25 - 3
26 - 4, 27 - 2, 28 - 2, 29 - 2, 30 - 3

Section B (40 marks)

31a - Cell wall
31b -The presence of chloroplasts.

32a -
32b-

33a - B : nutrients / sugar / glucose ; C : water
33b - It breaks down/digests food into simpler substances.
33c - Both provide nutrients for the organisms.

34a - He wanted to find out if an increasing / different / the amount of carbon dioxide would affect the population size of organisms living in the pond.
OR - He wanted to find out if the size of population of organisms living in a pond is affected by the amount of carbon dioxide in the water.

34b - Organism C. Its population size increased when the amount of carbon dioxide increased (1m), showing that they were reproducing due to an increase in rate of photosynthesis / they photosynthesise more (1m).
OR - Organism C. Its population size was the greatest (1m) as it is the food producer / the first organism in the food chain in the community (1m).

35a - Part R
35b - It would swell / become bigger.
OR - It would swell / become bigger and become a fruit. (1m)

36 - He should remove the light bulb from part X and put an equal number of live maggots in both parts. (to respond to moisture)
OR - He should replace the silica gel with moist cotton wool and put an equal number of live maggots in both parts. (to respond to light)

37a- Type of organism Letter(s)
Food producer - A, G
Herbivore - B, F
Carnivore - C, E
Omnivore - D
37b -

38a - Bird P’s beak is for scooping and catching prey in the water while Bird Q’s beak is for tearing the flesh of its prey.

38b - Bird P’s feet would be webbed to enable it to swim in the water to catch its prey while Bird Q’s feet would be sharp and curved to enable it to catch its prey from a distance in the air.

39a - When the conical flask was immersed in the basin of hot water, the air in the conical flask expanded and pushed the two drops of ink towards P and Q.

39b - When the temperature of the water in the basin increases, the time taken for the two drops of ink to reach P and Q decreases.
OR - When the temperature of the water in the basin decreases, the time taken for the two drops of ink to reach P and Q increases.

40a - Melting
40b - Point E. It cooled faster along EF than DE.

41a - 0% -X, Z, 100% - Y
41b - Good conductors of heat / Conductors of electricity: iron grille, aluminium can
Poor conductors of heat / Insulators of electricity: mirror, clear plastic, glass bulb, spectacle lenses, frosted glass, handkerchief, rice paper
OR - Magnetic: iron grille
Non-magnetic: aluminium can, mirror, clear plastic, glass bulb, spectacle lenses, frosted glass, handkerchief, rice paper
OR - Flexible: handkerchief, rice paper
Non-flexible: iron grille, aluminium can, mirror, clear plastic, glass bulb, spectacle lenses, frosted glass
OR - Metals: iron grille, aluminium can
Non-metals: mirror, clear plastic, glass bulb, spectacle lenses, frosted glass, handkerchief, rice paper
OR - Once alive / Biodegradable: handkerchief, rice paper
Never alive / Non-biodegradable: iron grille, aluminium can, mirror, clear plastic, glass bulb, spectacle lenses, frosted glass
(Other classifications: Water and non-waterproof, hard to break and easy to break)

42a - It can cause air/water/land pollution.
Or - Pesticide can be accumulated in the crops and affect its quality and harm the health of the consumer.

42b - Resistance to pests / Pest immunity

43a -
43b - Electricity will flow through the wire and heat up the nichrome wire, causing the paper spiral to spin.

44a - Any number between 6 and 9 i.e. 7 or 8
44b - Fewer fish was needed to be thrown into the sea as during high tide, the water level is higher and so the boat can float more easily.

45a - Iron / Steel / Nickel / Cobalt / Lodestone
45b - Bar P is made of a magnetic material (1/2m) and is attracted to the magnet. Magnetism is able to pass through glass (1/2m) which is not a magnetic material.
OR -Bar P is attracted to the magnet (1/2m). Magnetism is able to pass through glass (1/2m) which is not a magnetic material.
(if answer to (a) is lodestone)

46a - It tilted downwards to Container P. There are two holes in Container Q. Hence, the water in Q flows out at a faster rate (1m) than P, making Container Q lighter than P (1m).

46b- Move Container P nearer to the centre of the balance.
OR- Move Container Q further away from the centre of the balance.
OR - Move the string nearer to P.