Question 1

Oliver observed a group of living things under a microscope over 4 days. Which of the following characteristics of living things did he observe over the 4 days?
A: Living things can grow.
B: Living things need food.
C: Living things can respond.
D: Living things can reproduce.

Accepted Answer

B. A, C and D only. Over the 4 days the number of organisms increased (reproduce - D) and grew larger (grow - A), and they moved toward the light source shone from Day 2 onward (respond - C). Whether they need food cannot be directly observed, so the answer is A, C and D.

Question 2

John made a list of common characteristics observed in reptiles and amphibians, as shown in the table below. Which of the following comparisons of the characteristics between the amphibians and reptiles is/are correct?

Accepted Answer

A. B only. Row A is wrong (adult amphibians breathe through lungs/skin, not gills). Row C is wrong (amphibians lay eggs, they do not give birth). Row B is correct: amphibians have moist skin while reptiles have dry scales. So only B is correct.

Question 3

The diagram below shows a process during a stage in the life cycle of a flowering plant. Which of the following is correct about the process that is taking place at this stage of the life cycle of the flowering plant?

Accepted Answer

C. germination | oxygen | carbon dioxide | light needed: no | warmth needed: yes. The diagram shows a seed sprouting a young root, which is germination. Germination requires water, air (oxygen) and warmth but not light. The seed takes in oxygen and gives off carbon dioxide during respiration. So option C is correct.

Question 4

The diagram shows the human digestive system. In which one of the following parts is water absorbed from the undigested food?

Accepted Answer

B. Q. Water is absorbed from undigested food in the large intestine. Q points to the large intestine, so the answer is Q.

Question 5

The diagram below shows that plant A has climbed around plant B. The stem of plant A was cut off at X. Which one of the following explains what is likely to happen to the part of plant A above X after some time?

Accepted Answer

A. died | has no water to make food. Cutting the stem at X separates the upper part of plant A from its roots, so water can no longer be transported up to the leaves. Without water the leaves cannot carry out photosynthesis to make food, and the part above X dies.

Question 6

Study the table below. (The table shows where air passes through, where air from the surrounding enters, and where gaseous exchange takes place for parts A, B, C and D of the respiratory system, ticked as present.) Which of the following correctly shows the parts labelled, A, B, C and D?

Accepted Answer

C. Diagram 3. From the table: D is where air from the surrounding enters (nose/mouth), B and C are where air passes through (windpipe and bronchi/bronchioles), and A is where gaseous exchange takes place (lungs/air sacs). Diagram 3 labels the parts consistent with these functions.

Question 7

The diagram below shows tree Q at the bottom of a hill. After some time, seedlings of tree Q were found growing on the hill as shown in the diagram above. Which of the following are possible characteristics of the fruits of tree Q?
A: has dry pods
B: has fibrous parts
C: has wing-like parts
D: has fleshy edible parts

Accepted Answer

B. C and D only. The seedlings grew uphill, away from and higher than the parent tree. Wing-like fruits (C) are carried by wind, and fleshy edible fruits (D) are eaten and carried by animals, both of which can move seeds uphill. Dry pods (A) and fibrous fruits (B, water dispersal) could not carry seeds up the hill. So C and D only.

Question 8

Two types of cells are shown below. Study the table below. (The table lists parts A, B, C and D of a cell with their functions: A gives the cells a fixed shape; B controls activities in the cells; C gives the cells a green colour; D controls substances entering the cells.) Which one of the parts labelled, A, B, C or D, and its function is correct for both cells?

Accepted Answer

D. D. The diagram shows a plant cell (left) and an animal cell (right). The cell wall (A, fixed shape) and chloroplast (C, green colour) are found only in plant cells. The nucleus (B) and cell membrane (D) are in both, but B's label points to the membrane region. Part D (cell membrane, controls substances entering the cell) is correctly labelled and present in both cells.

Question 9

Which of the following activities help to keep the environment clean and green?
A: drive to a nearby destination
B: turn unwanted vegetable parts into fertiliser
C: bring your own bag during shopping
D: turn on the air-conditioners all the time

Accepted Answer

A. B and C only. Turning unwanted vegetable parts into fertiliser (B) reduces waste, and bringing your own bag (C) reduces plastic use. Driving short distances (A) and running air-conditioners all the time (D) waste energy and pollute. So B and C only.

Question 10

Yasmeen placed substance X in a glass jar and conducted an experiment as shown below. She then tested the leaf for starch using iodine solution. The result of her experiment is as shown below (the part of the leaf away from the jar turned iodine dark blue, while the part of the leaf inside/near substance X remained yellowish brown). What did substance X do in this experiment?

Accepted Answer

C. absorb carbon dioxide. The part of the leaf exposed to substance X did not make starch (iodine remained yellowish brown), meaning that part could not photosynthesise. Photosynthesis needs carbon dioxide, so substance X must have absorbed the carbon dioxide, depriving that part of the leaf of it.

Question 11

A group of researchers was investigating the changes in the population of land animals in Singapore over a period of 30 years. They noted a decrease in the population of land animals over time. Which of the following factor(s) is/are most likely to have caused the decrease in the population of these animals?
A: deforestation
B: increased sunlight
C: introduction of other animals

Accepted Answer

C. A and C only. Deforestation (A) destroys habitats and food sources, and introduction of other animals (C) brings new predators or competitors. Both reduce the land animal population. Increased sunlight (B) is not a likely cause. So A and C only.

Question 12

Alice studied a community living on a rotting log. She found the following organisms: ants, millipede, mould, toadstool. Which one of the following classification is correct?

Accepted Answer

B. Decomposers: mould, toadstool | Organisms that help decomposers: ants, millipede. Decomposers are fungi: mould and toadstool break down dead matter. Ants and millipede are animals that break the dead matter into smaller pieces, helping the decomposers. So decomposers = mould, toadstool; helpers = ants, millipede.

Question 13

The following diagram shows a food web in a particular habitat. Which of the following organisms are both a prey and predator?

Accepted Answer

C. S and T. An organism that is both prey and predator must have at least one arrow pointing to it (it is eaten) and at least one arrow pointing away from it (it eats another). S is eaten by R and eats U; T is eaten by Q and eats V. Both S and T qualify.

Question 14

The diagram below shows animal X. It has a hard outer covering and lives in the seashore habitat. Which of the following is correct about the function of the parts labelled, A, B, C and D?

Accepted Answer

D. For moving around: B and D | For protection: A and C. Animal X is a crab. The walking legs (B and D) are used for moving around, while the pincers/claws (A) and the hard shell/carapace (C) are used for protection. So moving around = B and D; protection = A and C.

Question 15

The diagram below shows two cardboard boxes, A and B, of the same size but of different thickness. Zachary used box A to send a heavy parcel. He also wrapped it up with a clear plastic as shown in the diagram below (Box A wrapped in clear plastic). Why did Zachary choose box A and wrap it up with clear plastic?

Accepted Answer

C. using box A: stronger | wrapping with plastic: to make it waterproof. Box A is thicker, making it stronger to hold a heavy parcel. Wrapping it in clear plastic makes it waterproof, protecting the cardboard from getting wet. So stronger and waterproof.

Question 16

In an experiment, Yue Ling filled a glass container with marbles until she could not put any more marbles into it. She concluded that there was no more space in the container for her to put anything into it. However, her friend, Sally said that she was wrong. How could Sally prove that Yue Ling was wrong?
A: shake the container of marbles
B: heat up the container of marbles
C: pour sand into the container of marbles
D: pour water into the container of marbles

Accepted Answer

D. A, C and D only. There are still air spaces between the marbles. Pouring sand (C) or water (D) into the container fills those spaces, and shaking (A) settles the marbles to reveal/let more in, proving space exists. Heating (B) does not demonstrate the empty space. So A, C and D only.

Question 17

Which of the following is correct about heat and light?

Accepted Answer

B. Both are forms of energy.. Heat and light are both forms of energy. Only light helps us see; energy is not matter so it cannot be compressed and has no mass or volume. So both are forms of energy.

Question 18

A bimetallic strip is formed by joining two different metals together. The diagrams below show how the strip bends when it is heated. Four metals, A, B, C and D, were used in different combinations to form four bimetallic strips. The diagrams below show how each strip bent when heated equally for 5 minutes. (Strip 1: metal A on top, metal B on bottom; Strip 2: metal D on top, metal A on bottom; Strip 3: metal A on top, metal C on bottom; Strip 4: metal B on top, metal C on bottom.) Based on the information given, which of the following shows metals, A, B, C and D, arranged in the correct order, based on how much the metal had expanded when heated?

Accepted Answer

C. C, B, A, D (least to most). A bimetallic strip bends toward the metal that expands less. Comparing the bends: Strip 1 (A over B) bends toward B, so A expands more than B. Strip 2 (D over A) bends toward A, so D expands more than A. Strip 3 (A over C) bends toward C, so A expands more than C. Strip 4 (B over C) bends toward C, so B expands more than C. This gives the order from least to most: C, B, A, D.

Question 19

Gopal used three wooden frames, P, Q and R, as shown below for an experiment on shadows. (Frame P is a 14 cm square outline, Frame Q is a 14 cm circle, Frame R is a 14 cm cross/plus shape.) He conducted the experiment in a dark room using the following set-up. The shadows formed on the screen are shown below. Which of the following shows the correct positions of the wooden frames for the shadows cast on the screen?

Accepted Answer

B. Frame P: Y | Frame Q: Z | Frame R: X. The combined shadow on the screen shows a square outline (from P), a circle (from Q) and a cross (from R) overlapping. The further a frame is from the screen (nearer the torch), the larger its shadow. The shadow image shows the cross (R) largest, then the square (P), then the circle (Q) smallest, so R is nearest the torch (X), P in the middle (Y) and Q nearest the screen (Z). Hence P=Y, Q=Z, R=X.

Question 20

Study the diagram below. (Ice ⇄ Water ⇄ Water vapour, with arrows P from Ice to Water, R from Water to Ice, Q from Water vapour to Water, S from Water to Water vapour.) P: Melting, Q: Evaporation, R: Freezing, S: Condensation. Based on the diagram above, which of the processes are labelled correctly?

Accepted Answer

B. P and R. P (Ice → Water) is correctly labelled melting, and R (Water → Ice) is correctly labelled freezing. Q is the arrow from water vapour to water, which should be condensation not evaporation, and S is the arrow from water to water vapour, which should be evaporation not condensation. So only P and R are correct.

Question 21

Esther heated some ice in a beaker and recorded the temperature changes over time. Based on the graph above, which of the statements below is correct?

Accepted Answer

A. The ice took 5 minutes to melt completely.. The graph stays at 0°C for the first 5 minutes while the ice melts, then the temperature rises. So the ice took 5 minutes to melt completely. The water reaches boiling point (100°C) at about 20 minutes, not 35, and the flat line at 100°C shows heating continues, so the other options are wrong.

Question 22

Maria conducted an experiment as shown in the diagram below (a solar still: a water trough holding sea water under the sun, with a plastic sheet weighted by a pebble sloping toward a beaker that collected 10 ml of water). What are some of the way(s) to increase the amount of water collected in the beaker?
A: increase the size of the pebble
B: place the set-up in a shaded area
C: reduce the size of the beaker
D: reduce the size of the water trough

Accepted Answer

A. C only. More water is collected if more sea water evaporates and condenses. Increasing the pebble size (A) or shading the set-up (B) would not increase evaporation (shading reduces heat). Reducing the trough size (D) reduces the amount of sea water/surface for evaporation. Only reducing the size of the beaker (C) helps, because a smaller, narrower beaker reduces re-evaporation/loss of the collected water. So C only.

Question 23

Aidan used similar bulbs, batteries and wires to set up four circuits as shown below. In which one of the following circuits will all the bulbs shine the brightest?

Accepted Answer

A. Circuit 1. Bulbs shine brightest when each bulb is connected in parallel directly across the battery, so each gets the full voltage. Circuit 1 has the two bulbs arranged in parallel branches across one battery, giving each bulb the full voltage and the brightest shine.

Question 24

Bryan set up an electric circuit as shown below. (Three parallel branches each with a bulb — B1 with Object A, B2 with Object B, B3 with Object C — and Object D on the main return wire.) Only bulb B2 lit up. What objects were used in the set-up above?

Accepted Answer

C. Object A: eraser | Object B: coin | Object C: marble | Object D: metal ruler. Object D is on the shared return wire, so the whole circuit only works if D is a conductor — D must be the metal ruler. Only B2 lit, so Object B (in B2's branch) must be a conductor (coin), while Object A and Object C must be non-conductors (eraser and marble). This matches: A = eraser, B = coin, C = marble, D = metal ruler.

Question 25

Joel kicks a ball. The diagram shows the path of the ball after he has kicked it. (The ball rises from the ground, reaches the highest point Y, then descends to land at Z.) Which one of the following is correct?

Accepted Answer

D. Kinetic energy from Y to Z: increases | Potential energy from Y to Z: decreases. From the highest point Y down to the ground at Z, the ball loses height so its potential energy decreases, and it speeds up as it falls so its kinetic energy increases. Hence kinetic energy increases and potential energy decreases.

Question 26

The diagram below shows a toy car being pushed on two similar wooden planks. The toy car moved up the plank, stopped at X and then, it rolled down. Which one of the following statements about the movement of the toy car is correct?

Accepted Answer

D. The toy car rolled down as it had gained potential energy while moving to X.. As the car moved up to X it gained height and therefore gained potential energy (its kinetic energy converted to potential energy). At X this stored potential energy was converted back into kinetic energy, causing it to roll down. So option D is correct.

Question 27

Rui En set up an experiment as shown in the diagram below. Magnets A and B are equal in mass and weigh 10 g each. (Magnet B hangs from a spring balance with its N pole facing down; Magnet A stands on an electronic balance with its N pole facing up toward B, so like poles face each other.) Which one of the following is correct about the set-up as shown in the diagram above?

Accepted Answer

B. Position of magnet B: moved upwards | Reading on electronic balance: more than 10. The N pole of magnet B faces the N pole of magnet A, so they repel. The repulsion pushes magnet B upwards (stretching the spring balance) and pushes magnet A downwards onto the electronic balance, so the reading is more than 10 g. Hence B moved upwards and reading is more than 10.

Question 28

Diagram 1 shows object X attached to a spring (the spring stretched to 10 cm, lying horizontally with object X at the end). Diagram 2 shows how object X moved in the direction indicated by the arrow when object Y was brought near to object X (the spring stretched further to 15 cm as X was pulled toward Y). Which of the following statements is correct?

Accepted Answer

C. The elastic spring force increases when Y was brought near to X.. When Y was brought near, object X was pulled toward Y (force of attraction), stretching the spring from 10 cm to 15 cm. The more a spring is stretched, the greater its elastic spring force, so the elastic spring force increased. Option A is wrong (it is attraction, not repulsion), and gravitational force on X does not change.

P6 Science SA2 2019 — Henry Park

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P6 Science SA2 2019 — Henry Park

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