Question 1

Study the flowchart below carefully. Which of the following best represents A, B, C and D?

Accepted Answer

B. yeast, bat, damselfly, guppy. A must reproduce asexually (yeast, by budding). C does not give birth to live young (lays eggs → damselfly). Following 'gives birth alive?' → yes → 'is it a mammal?' → yes gives B (bat, a live-bearing mammal); no gives D (guppy, a fish that bears live young but is not a mammal). Only option B fits every box.

Question 2

Four sealed tubes containing aquatic plants and animals were set up as shown below for a month. At the end of the month, only the organisms in set-up Q were alive. What does the results of this experiment show?

Accepted Answer

C. Plants can only make food in the light.. Set-up Q (aquatic plant exposed to light) survived while S (same plant kept in the dark) died. The plant in Q could photosynthesise to make food and release oxygen only because it had light, whereas the plant in the dark could not — showing plants can only make food in the light.

Question 3

The diagram below shows part of the human digestive system. Which of the following takes place at the part labelled A?

Accepted Answer

C. Absorption of digested food. The label A points to the coiled small intestine, where digested food is absorbed into the bloodstream. Digestion starts in the mouth, water removal occurs in the large intestine, and undigested food is stored in the rectum.

Question 4

Study the life cycle of a flowering plant below. A and B represent the different stages of the life cycle. Which one of the following statements about the stages of the life cycle of the plant is true?

Accepted Answer

A. Germination occurs at Stage A.. The cycle runs Adult Plant → A (seed) → B (young plant/seedling) → Adult Plant. Stage A is the seed, which germinates. A seed cannot make food (no leaves), a young plant (B) cannot yet bear flowers/fruits, and no plant survives on only water and carbon dioxide.

Question 5

The diagram shows a coastal area where two types of plants (star-shaped and triangle-shaped) are growing. How are the fruits or seeds of each type of plant most likely dispersed?

Accepted Answer

A. Triangle: Water, Star: Animals. The triangle-shaped plants grow only right along the sea's edge, indicating their fruits/seeds are dispersed by water. The star-shaped plants are spread far and wide across the whole land area, indicating a long-distance mechanism such as animal dispersal rather than short-range splitting action.

Question 6

The diagram below shows some plant cells under a microscope. Which of the following statements is true of Part A or Part B?

Accepted Answer

A. Part A provides the cell with a fixed shape.. Part A points to the cell wall, which gives the plant cell a fixed, regular shape. Controlling what enters/leaves the cell is the cell membrane's job, and controlling cell activities is the nucleus's job.

Question 7

Study the following relationships between A, B and C. A is the father of B. B is the mother of C. C is the brother of D. Given the legend (square = Male, circle = Female), which of the following family trees shows the relationship described?

Accepted Answer

D. Family tree 4. A is a father, so A must be male (square). B is a mother, so B must be female (circle) and a child of A. C is a brother, so C must be male (square) and a child of B. Only family tree 4 shows A as a male square, B as his female-circle child, and C as a male-square child of B who is the brother of D.

Question 8

The diagram below shows a pond community. What is the source of energy for all the organisms in the pond above?

Accepted Answer

A. The sun. The Sun is the ultimate source of energy for all living things. Plants capture the Sun's light energy to make food, and this energy is then passed to animals along the food chain.

Question 9

The table below shows the organisms in different communities (Community X: Clownfish, Sea Anemone, Horseshoe crab; Community Y: Spider, Centipede, Scorpion; Community Z: Pondskater, Tadpole, Dragonfly nymph). Which of the following is correctly classified?

Accepted Answer

B. X: Starfish, Y: Millipede, Z: Water Hyacinth. Community X is a marine (sea) community, Y is a land/soil community of many-legged arthropods, and Z is a freshwater pond community. Starfish (marine), Millipede (land arthropod) and Water Hyacinth (freshwater plant) each fit the correct community, so option B is fully correct.

Question 10

Study the food web in the Arctic region below. How many food chains are there involving the arctic fox?

Accepted Answer

B. Four. The arctic fox eats Hare, Squirrel and Seal. The chains are: Plant→Hare→Arctic Fox; Plant→Squirrel→Arctic Fox; Plankton→Krill→Seal→Arctic Fox; Plankton→Krill→Cod→Seal→Arctic Fox. That gives four food chains.

Question 11

A disease killed the mouse in the food web below. Which of the following graphs would show the immediate change in population of the lion and owl? (Key: dashed line = Owl, solid line = Lion)

Accepted Answer

A. Graph 1. The owl relies on the mouse for food, so when the mouse dies the owl population falls. The lion does not feed on the mouse (it eats goat, jackal and wild cat), so its population stays roughly unchanged. Graph 1 shows the owl (dashed) decreasing while the lion (solid) remains roughly constant.

Question 12

The diagram below shows a simple food chain in a forest ecosystem. A, B, C and D are organisms in the food chain (A → B → C → D). If there was a sudden decrease in the amount of carbon dioxide in the atmosphere, which one of the following groups of organisms, A, B, C or D, would be affected first?

Accepted Answer

A. A. A is the first organism in the chain, so it is the producer (plant). Plants need carbon dioxide for photosynthesis, so a sudden fall in carbon dioxide affects the producer A first.

Question 13

Four organisms are classified as shown below. What do W, X, Y and Z represent?

Accepted Answer

D. W: Yeast, X: Button Mushroom, Y: Onion, Z: Bird's Nest Fern. W is a fungus that reproduces by budding = yeast. X is a fungus that reproduces by spores = button mushroom. Y is a plant that reproduces by seeds = onion. Z is a plant that reproduces by spores = fern (Bird's Nest Fern). Option D matches all four.

Question 14

Below shows stages in the life cycle of a butterfly. At which stage of the life cycle of the butterfly is it most harmful to plants in a garden?

Accepted Answer

C. Y. The cycle runs Adult → X (egg) → Y (larva/caterpillar) → Z (pupa) → Adult. The caterpillar (larva) stage, Y, feeds voraciously on leaves and is therefore most harmful to garden plants.

Question 15

A farmer planted the same number of string bean seedlings in 4 pots. He watered them daily with different amounts of water. He measured the height of the seedlings in each pot after 10 days and plotted their average heights in the bar graph below. The seedlings are considered to have grown well if they have grown at least 15 cm after 10 days. Based on the bar graph, what is the least amount of water to be given to the seedlings per day to ensure that they grow well?

Accepted Answer

C. 60 ml. From the bar graph, 20 ml gives about 8 cm, 40 ml about 14 cm (below 15 cm), 60 ml about 17 cm, and 80 ml about 21 cm. The least amount that reaches at least 15 cm is 60 ml.

Question 16

Study the diagram of the human reproductive system below. Which parts of the reproductive systems shown above produce the sperm and eggs respectively?

Accepted Answer

C. B and C. Sperm are produced by the testes (labelled B in the male system) and eggs are produced by the ovaries (labelled C in the female system), so the answer is B and C.

Question 17

An outer ring of the stem between positions A and B of a plant is removed. The tubes which carry food between positions A and B are removed while the tubes which carry water remain in the stem. After some time, which one of the following diagrams represents the appearance of the stem?

Accepted Answer

A. Diagram 1. Food made in the leaves travels downwards through the food tubes (phloem). With the ring of food tubes removed, food cannot pass the gap and accumulates above the ring, causing the stem to swell above the removed ring. Diagram 1 shows this swelling above the ring.

Question 18

Joshua set up an experiment to count the number of sheets of paper. Position X refers to where the papers are placed. He increased the number of sheets of paper of the same type and recorded his readings in the table below (0 sheets = 80 lux, 1 = 40, 2 = 20, 3 = 10, 4 = 0, 5 = 0). What changes should Joshua make to the set-up if he wants to count up to 6 sheets of the same type of paper?

Accepted Answer

A. Move the torch nearer to the paper.. The reading already drops to 0 lux at 4 sheets, so 4, 5 and 6 sheets cannot be distinguished. Moving the torch nearer to the paper increases the amount of light hitting the sheets, so light can still pass through more sheets and give non-zero readings up to 6 sheets.

Question 19

Two cups of similar shape and thickness, A and B, are hung on a rod. They are balanced when a lit candle is placed under the cup, B. Cup B is made of cardboard. Based on the diagram, which of the following statements is definitely true?

Accepted Answer

D. The cups, A and B, are made of the same material.. Because the cups balance, they have equal mass. Since they also have similar shape and thickness (so similar volume), equal mass and equal volume means they have the same density, which means they are made of the same material.

Question 20

Huiling set up an experiment as shown below. She blew into the rubber tube and made the following observations. A: The water level in the trough rose. B: The water level in the bell jar dropped. C: Bubbles were observed in the water in the bell jar. Based on the above observations, what can Huiling conclude about the property of air?

Accepted Answer

B. Air occupies space.. Blowing air into the bell jar pushes the water in the jar down and the water in the trough up, because the air takes up the space previously occupied by water. This shows that air occupies space.

Question 21

Jamie used similar lengths of cotton thread and silk thread to set up the experiment below. After adding 3 identical weights to each pan, the cotton thread snapped while the silk thread did not. She repeated the experiment twice and obtained the same results. What can Jamie infer from the results of her experiment?

Accepted Answer

C. The silk thread is stronger than the cotton thread.. Under the same load of 3 identical weights, the cotton thread broke but the silk thread did not. This shows the silk thread can withstand a greater pulling force without breaking, meaning it is stronger than the cotton thread.

Question 22

The diagram below shows a torch shining on a ball and a square mirror. Which of the following shows the correct shadow cast on the screen?

Accepted Answer

B. A solid black square. The ball is between the torch and the mirror, and the mirror is between the ball and the screen. The mirror is opaque and reflects the light back toward the torch, so no light reaches the screen in the region behind the mirror. The screen therefore shows a solid dark shadow the shape of the mirror — a black square.

Question 23

Magnet A is hung from a spring as shown in Diagram 1. Object B is then placed on the ground, directly below Magnet A as shown in Diagram 2. Which of the following is a possible explanation for the spring stretching less in Diagram 2?

Accepted Answer

A. Object B repelled Magnet A.. The spring stretches less when there is a smaller downward pull on it. If Object B repels Magnet A, it pushes Magnet A upward, reducing the downward force stretching the spring. Attraction downward would stretch the spring more, and an object cannot change the magnet's actual weight.

Question 24

In which of the following circuits will the bulb light up?

Accepted Answer

A. Circuit 1 (iron cap). For the bulb to light, the circuit must be complete and made of conducting material. Only the set-up using an iron (conductor) cap in a complete loop allows current to flow; plastic caps do not conduct electricity, so those bulbs stay off.

Question 25

Study the table below (Substance R: freezing point 10°C, boiling point 50°C; Substance S: freezing point 35°C, boiling point 110°C; Substance T: freezing point -8°C, boiling point 140°C). Which of the following is true?

Accepted Answer

A. R and S are solids at 0 °C.. A substance is solid below its freezing point. At 0°C, R (freezing point 10°C) and S (freezing point 35°C) are both below their freezing points, so both are solids. Checking the others: at 75°C S is still liquid; at 0°C R is solid; at 125°C S is a gas — so only option A is true.

Question 26

The diagram below shows a pendulum swinging from position A to position C. Which of the following shows the energy conversion of the pendulum swinging from position A to position C?

Accepted Answer

B. A: Gravitational Potential Energy, B: Kinetic Energy, C: Gravitational Potential Energy. A and C are the highest points of the swing where the pendulum is momentarily at rest, so it has maximum gravitational potential energy there. B is the lowest point where the pendulum moves fastest, so it has maximum kinetic energy. Thus A = GPE, B = KE, C = GPE.

Question 27

Study the four circuits A, B, C and D shown below. The bulbs and batteries in the four circuits are identical. Which one of the following statements about the brightness of the bulbs is correct?

Accepted Answer

D. The bulb in circuit D is brighter than each bulb in circuit A.. Circuit A (1 cell, 2 bulbs in series) gives dim bulbs. Circuit D (1 cell, 1 bulb) gives a normally bright bulb. Circuit B (2 cells, 2 bulbs in series) and circuit C (1 cell, 2 bulbs in parallel) give bulbs of normal brightness. So the bulb in D is brighter than each dim bulb in A, making statement D correct.

Question 28

Colette measured the temperature of some boiling water as shown in the diagram below. Colette turned off the flame after 30 minutes. She monitored the temperature of the water for 5 hours before putting the beaker of water in the freezer and left it there for 2 hours for the water to be frozen. Which of the following graphs correctly represent the change of the temperature of the water over this period?

Accepted Answer

A. Graph 1. While boiling (first 30 minutes) the water stays at its high boiling temperature. After the flame is off it cools until it reaches room temperature and then stays constant (a flat plateau) up to 5 hours. In the freezer (5 to 7 hours) it cools further down toward 0°C. Graph 1 shows the high start, a level plateau at room temperature, then a drop to 0°C.

Question 29

Use the flow chart below to identify the forces, X, Y and Z. What could the forces, X, Y and Z be?

Accepted Answer

D. X: Gravity, Y: Magnetism, Z: Elastic Spring Force. X acts from a distance and is only a pull → gravity (weight), which acts at a distance and only pulls. Y acts from a distance but is not only a pull (it can push and pull) → magnetism. Z cannot act from a distance (a contact force) → elastic spring force. Option D fits every branch.

Question 30

Betty conducted an investigation using a bar magnet and some paper clips. She marked different positions on a bar magnet with letters A, B, C and D. She cut the magnet in the middle to form 2 magnets. She counted the number of paper clips that could be attracted to the different positions on the magnets. Which one of the following sets of reading was she likely to obtain for her investigation?

Accepted Answer

C. A:5, B:5, C:5, D:5. Cutting the bar magnet in the middle (between B and C) creates two new magnets: A–B and C–D. Each new magnet has poles at both of its ends, so positions A, B, C and D all become poles. Poles are the strongest parts, so all four positions attract the most (5) paper clips.

P6 Science SA2 2012 — Tao Nan

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P6 Science SA2 2012 — Tao Nan

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