Question 1

The diagram below shows a rotting log habitat. Based only on the diagram above which of the following statements are correct?
A  There is only one community.
B  There are two populations of fungi.
C  There are two populations of plants.
D  There are two populations of insects.

Accepted Answer

C. A, C and D only. All organisms living in one habitat form one community, so A is correct. Only mushrooms (one fungus population) are shown, so B is wrong. Ferns and moss are two plant populations (C correct). Butterfly and ants are two insect populations (D correct). Hence A, C and D.

Question 2

The table below shows 3 organisms grouped according to 2 physical factors, X and Y, that are found in the environment they live in. John found that organism K preferred bright and dry environments. Which of the following best represents physical factors X and Y, and the habitat that organism K can be most likely found in?

Accepted Answer

D. Physical factor X: Moisture, Physical factor Y: Light, Habitat: Desert. Organism K has factor X = Low and factor Y = High. K prefers bright (high light) and dry (low moisture). So Y (High) = Light and X (Low) = Moisture, and a bright, dry habitat is a desert.

Question 3

The diagram below shows the food relationships among organisms found in the desert. The cactus provides shelter for organism B. After hunters have killed most of organism E, the population of organism C still remains constant. How would the population of the cactus and animal B be affected?

Accepted Answer

C. Cactus: Decrease, Organism B: Increase. With E killed, D is eaten less so D increases. More D feeds on the cactus, so the cactus decreases. Since C stays constant and now has more D to eat, it eats less B, so B increases.

Question 4

The diagram below shows a food web. Rahman made three statements about the food web above.
A  There are six food chains.
B  There are five consumers.
C  J is both a prey and a predator.
Which statement(s) is/are correct?

Accepted Answer

D. A, B and C. Producers (no arrows into them) are G and H, so the other five organisms (D, E, F, J, K) are consumers (B correct). J is eaten by K (prey) and eats H (predator), so J is both prey and predator (C correct). Tracing every path from the producers to the apex consumer E gives six food chains (A correct).

Question 5

A type of dolphins was observed to swim around a school of fish and guide them towards a fisherman's boat. The dolphins feed on the small fish that escape from the fisherman's net. Based only on the information above, which one of the following correctly states and explains the relationship between dolphins and man?

Accepted Answer

C. Both man and dolphins benefit — Man can catch more fish and dolphins have food to eat.. The dolphins herd fish toward the boat so the man catches more fish (man benefits), and the dolphins eat the small fish that escape the net (dolphins benefit). It is a mutually beneficial relationship.

Question 6

The diagram below shows insect X which is a plant-eater. Insect X has a large "ant-like" structure on its head. The "ant-like" structure is light and has prickly spikes. Which of the following characteristic(s) help to protect insect X from its predators?

Accepted Answer

D. Bright warning colours: Yes, Wings: Yes, Prickly "ant-like" structure: Yes. Bright warning colours warn predators that it may be dangerous/poisonous, wings let it fly away from predators, and the prickly 'ant-like' structure makes it hard/unpleasant to be eaten. All three protect it.

Question 7

The graphs below show a population of animal W. Animal W eats grass grown at either locations S or K over a period of a year. Based on the information given, which of the following statement is likely to be correct?

Accepted Answer

C. More grass was available at location K than S from months 7 to 9.. Animal W feeds on grass. From months 7 to 9 the population of W is high at location K but low at location S, indicating there was more grass (food) available at K than S during that period.

Question 8

The diagram below shows animal C. The following are adaptations that animal C uses to help it survive in its habitat. Which of these are behavioural adaptations?
A  Shakes its head to communicate.
B  Hibernates when the weather turns cold.
C  Males are more colourful than females to attract mates.
D  Inflates itself in small spaces to avoid being pulled out by its predators.

Accepted Answer

D. A, B and D only. Behavioural adaptations are actions/behaviours: shaking head to communicate (A), hibernating in cold (B), and inflating itself (D). Males being more colourful (C) is a physical/structural adaptation, not behavioural.

Question 9

Which one of the following does not ensure that an organism will survive till adulthood?

Accepted Answer

D. Eggs are not cared for by the adult organism.. Laying eggs in shelter, near food, or in large numbers all increase chances of survival to adulthood. Eggs not cared for by the adult means the young are unprotected, which does not ensure survival.

Question 10

The diagram below shows fish P. Fish P is streamlined, has both eyes on one side of its body. It eats other fish and is often found flat on the seabed covering its body, except its eyes, with sand. Based on the information above, which of the following reasons for fish P's adaptations are correct?
A  Has a streamlined body — Swims quickly to catch its prey
B  Has a sand-coloured body — Blends into its environment to prevent its prey from spotting it
C  Covers its body with sand — Anchors it to the bottom of the sea
D  Has both eyes on one side of its body — Keeps it warm

Accepted Answer

A. A and B only. A streamlined body lets it swim quickly to catch prey (A correct). Its sand colour camouflages it so prey cannot spot it (B correct). Covering its body with sand is for camouflage/ambush, not anchoring (C wrong). Eyes on one side help it see while lying flat, not for warmth (D wrong).

Question 11

Which one of the following is not a method to reduce overfishing?

Accepted Answer

A. Remove predators of the fish.. Imposing fines, catching only larger fish, and restricting fishing areas all reduce overfishing. Removing predators of the fish does not reduce overfishing and would harm the ecosystem.

Question 12

Some scientists studied the effect of carbon dioxide on the number of mosquitoes in country X. These mosquitoes cause the spread of dengue. Based on the graphs above, which of the following could have caused the increase in the number of dengue cases?
A  Increase in deforestation
B  Increase in the usage of fossil fuels
C  Decrease in the use of plastic straws

Accepted Answer

A. A and B only. The graphs show more carbon dioxide raises temperature, and higher temperature increases dengue cases. Deforestation (fewer trees absorbing CO2) and burning more fossil fuels both raise CO2, increasing temperature and dengue cases. Reducing plastic straws does not raise CO2.

Question 13

Jasmyn set up an experiment using similar seeds in a warm room as shown below. In which box(es) could the seed germinate?
box P (clear plastic box): seeds on dry cotton wool.
box Q (wooden box): seeds on damp cotton wool.
box R (clear plastic box): seeds on damp cotton wool.
box S (clear plastic box): seeds on damp cotton wool, has no air.

Accepted Answer

C. Q and R only. Seeds need water, air and warmth (not light) to germinate. Box P has dry cotton wool (no water). Box S has no air. Boxes Q (wooden, damp, has air, warm) and R (damp, has air, warm) provide all conditions, so the seeds germinate in Q and R.

Question 14

Study the table below. The table gives reproductive parts and functions: J = Where eggs are produced; K = To receive the sperm; L = To produce the sperm; M = Where a fertilised egg develops. Which one of the following diagrams has been labelled correctly based on the functions above?

Accepted Answer

C. Diagram with J to ovary, M to uterus (middle), K to bottom. In the female reproductive system, eggs are produced in the ovary (J), sperm is received in the vagina (K), and a fertilised egg develops in the uterus (M). L (produces sperm) is a male part and should not appear. The diagram labelling ovary = J, uterus = M, vagina = K is correct.

Question 15

The table below shows the amount of carbon dioxide found in blood samples collected from blood vessels, A, B, C and D, in the human body. Blood vessel A = low, B = high, C = high, D = low. Which one of the following diagrams correctly identifies blood vessels A, B, C and D?

Accepted Answer

A. lungs–heart: C (heart→lungs), D (lungs→heart); heart–body: B (body→heart), A (heart→body). Blood carrying high CO2 flows from the body to the heart and from the heart to the lungs; blood with low CO2 flows from the lungs to the heart and from the heart to the body. The diagram where B (body→heart) and C (heart→lungs) are high CO2, and A (heart→body) and D (lungs→heart) are low CO2 matches the table.

Question 16

Which of the following correctly describes the functions of the digestive system?
A  To remove water from undigested food
B  To break down food into smaller pieces
C  To transport digested food around the body
D  To break down food into simpler substances

Accepted Answer

D. A, B and D only. The digestive system removes water from undigested food (A), physically breaks food into smaller pieces (B) and chemically breaks food into simpler substances (D). Transporting digested food around the body (C) is the job of the circulatory system, not the digestive system.

Question 17

John cut down a tree to set up a campfire as shown in the diagram below. Which one of the following shows the main energy conversion?

Accepted Answer

C. light energy → potential energy → heat energy + light energy. The Sun gives out light energy, which the tree stores as potential (chemical) energy in the firewood, and burning the firewood releases heat energy and light energy. So light → potential → heat + light.

Question 18

Four similar-sized blocks, P, Q, R and S, were set up as shown below (hung by string from the ceiling). P = 200g (near the ground), Q = 500g (mid-height), R = 200g (mid-height), S = 500g (near the ground). Which one of the following statements is correct?

Accepted Answer

B. Q has the greatest amount of gravitational potential energy.. Gravitational potential energy increases with both mass and height. Q (500g, high) has the greatest mass and a high position, giving it the greatest GPE. R is higher than P (same mass) so R has more, not less, GPE; P and S differ in mass; Q is higher than S, so they are not equal.

Question 19

A marker pen holder with a magnet in it was attached to a whiteboard made of magnetic material. A weight was then added to the holder and the holder started to slide down while still being attracted to the whiteboard as shown in the diagram below. Which of the following forces were present when the holder was sliding down the whiteboard?
A  frictional force
B  gravitational force
C  elastic spring force
D  magnetic force of attraction

Accepted Answer

D. A, B and D only. As the holder slides, friction acts between holder and whiteboard (A), gravity pulls it down (B), and the magnet is still attracted to the magnetic whiteboard (D). There is no spring, so no elastic spring force (C).

Question 20

A very elastic spring of original length 20 cm was hung from a ceiling and came to rest as shown below (extending to 21 cm). Which of the following statement(s) is/are correct about the spring in figure 2 above?
A  Gravitational force has caused the spring to extend.
B  There is less elastic spring force in the spring when it was extended.
C  There is more gravitational force acting on the spring after it was hung from the ceiling.

Accepted Answer

A. A only. The weight (gravitational force) of the spring pulls it down and causes it to extend (A correct). When stretched, the spring has more, not less, elastic spring force (B wrong). The gravitational force on the spring stays the same since its mass is unchanged (C wrong).

Question 21

Ameenah set up the circuit as shown below to test if object R conducts electricity. She then repeated the experiment by replacing object R with object S. The table shows her observations — Object R: Bulb A light up brightly, Bulb B did not light up, Bulb C light up brightly. Object S: Bulb A light up dimly, Bulb B did not light up, Bulb C light up dimly. Based on the observations above, which of the following statements are correct?
A  Object R is a conductor of electricity.
B  Object S does not allow electricity to pass through.
C  There is no electricity passing through the filament of bulb B.
D  Less electricity passes through bulb A than through bulb C in both experiments.

Accepted Answer

B. A and C only. Bulbs lit with object R, so R is a conductor (A correct). Object S also let bulbs light up (dimly), so S does conduct (B wrong). Bulb B never lit in either case, so no current flows through its filament (C correct). Bulbs A and C had the same brightness in each experiment, so equal current passed through them (D wrong).

Question 22

Study the four circuit diagrams below. Which two bulbs would have the same brightness?

Accepted Answer

A. P and Q. Circuit P (multi-cell battery) has two bulbs in series, so each bulb gets half the battery voltage. Circuit Q (same battery) has parallel branches each containing two bulbs in series, so each Q bulb also gets half the battery voltage. Therefore bulbs P and Q have the same brightness.

Question 23

James plugs in many appliances into a single socket as shown in the diagram below. The diagram shows the arrangement of the appliances (X, Y, Z connected in parallel to one socket with a switch and electrical supply). Based on the information above, which of the following statement(s) is/are correct?
A  When the switch is switched off, all the appliances can no longer work.
B  When one appliance fuses, the rest of the appliances will continue to work as electricity can flow through them.
C  When many appliances are connected to one socket, more electricity passes through appliance X than appliance Y.

Accepted Answer

B. A and B only. The switch is in the main line, so switching it off cuts power to all appliances (A correct). The appliances are in parallel, so if one fuses the others still work (B correct). The current through each appliance depends on the appliance, not its position, so X does not automatically get more than Y (C wrong).

Question 24

Jake is in a completely dark room with several objects. Which of the objects below would he be able to see?
A  A mirror
B  A sheet of black paper
C  A sheet of white paper
D  A piece of aluminium foil

Accepted Answer

D. None of the above. We see objects only when light from them enters our eyes. In a completely dark room there is no light at all, so none of the objects (including mirror and foil, which only reflect light) can be seen.

Question 25

Sets of two blocks, A and B, of different sizes were placed side by side. Both blocks A and B are made of the same metal. The temperature of each block at the start of the experiment is indicated in the diagram below. set-up D: block A 50°C, block B 50°C. set-up E: block A 50°C, block B 70°C. set-up F: block A 70°C, block B 50°C. In which of the set-up(s) will the temperature of block B increase immediately after being placed beside block A?

Accepted Answer

B. F only. Heat flows from a hotter object to a cooler one. Block B increases in temperature only when A is hotter than B. This happens only in set-up F (A 70°C, B 50°C). In D both are 50°C (no flow); in E B is hotter, so B loses heat.

Question 26

A sealed plastic bag of air was left on an electronic balance under the sun for 4 hours as shown below (balance reads 15 g at start, ? g at end). Which of the following statements about the set-up at the end of the experiment are correct?
A  The air in the plastic bag expanded.
B  The mass of air in the plastic bag increased.
C  The volume of air in the plastic bag decreased.
D  The reading on the electronic balance remained the same.

Accepted Answer

A. A and D only. Under the sun the air gains heat and expands, so its volume increases (A correct, C wrong). Since the bag is sealed, no air enters or leaves, so the mass stays the same and the balance reading remains 15 g (B wrong, D correct).

Question 27

[Study the diagram (an electromagnet: a coil of wire wound around a rod, connected to a battery, picking up paper clips from a plastic tray).] Which of the following are materials that the rod can be made of?
A  iron
B  steel
C  wood
D  copper

Accepted Answer

A. A and B only. For the rod to become a magnet (electromagnet core) and attract paper clips, it must be made of a magnetic material. Iron and steel are magnetic; wood and copper are not.

Question 28

Abby added an additional battery to the set-up as shown below. She observed that the number of paper clips attracted by the magnetised rod did not increase. Which of the following are possible reasons for her observation?
A  The battery added had no energy.
B  The wire could not conduct electricity.
C  The other paper clips in the tray were made of non-magnetic materials.

Accepted Answer

B. A and C only. If the added battery had no energy, the magnetism would not strengthen, so no more clips are attracted (A possible). If the remaining clips were non-magnetic, they could not be attracted (C possible). The wire must conduct electricity since the rod was still magnetised and held clips, so B is not a valid reason.

P6 Science SA2 2019 — Nanyang

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P6 Science SA2 2019 — Nanyang

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