Question 1

The table below provides some information on organisms X, Y and Z. A tick (✓) in the box indicates the presence of the characteristics.

What are X, Y and Z most likely to be?

Accepted Answer

B. X: bird's nest fern, Y: mushroom, Z: bacteria. X makes its own food → a plant (bird's nest fern). Y feeds on dead matter and reproduces from spores → a fungus (mushroom). Z feeds on dead matter but does not reproduce from spores → bacteria.

Question 2

Which one of the following animals is not an insect?

Accepted Answer

D. (a tick). Insects have 3 body parts and 6 legs. The tick (option 4) is an arachnid with 8 legs and 2 body parts, so it is not an insect.

Question 3

Study the life cycles of insects X and Y below.

Based on the diagrams above only, which of the following statements are true?

A  X and Y do not give birth to their young alive.
B  X and Y have different number of stages in their life cycles.
C  The young of Y resembles its adult but the young of X does not.
D  The young of X takes a longer time to develop into the adult stage than the young of Y.

Accepted Answer

C. A, B and C only. Insect X has 4 stages (egg→larva→pupa→adult, complete metamorphosis) and Y has 3 stages (egg→nymph→adult, incomplete). Both lay eggs (A true). They have different numbers of stages (B true). Y's nymph resembles the adult while X's larva does not (C true). X develops in about 17 days while Y takes over 9 months, so D is false.

Question 4

Jenny conducted an experiment to find out if the presence of water would affect seed germination. She prepared the experimental set-ups as shown below.

Her classmates commented that her experimental set-ups were incorrect. Which of the following should she do to ensure a fair test?

A  Add one more seed to set-up Y.
B  Add water to the cotton wool in set-up X.
C  Reduce the amount of cotton wool in set-up X.
D  Replace the black bean seed in set-up X with red bean seeds.

Accepted Answer

B. A and D only. To test only the effect of water, all other variables must be kept the same. The number of seeds must be equal (X has fewer seeds, so add a seed — A), and the seed type must be the same (X has black bean, Y has red bean, so replace X's seed with red bean — D). Adding water to X (B) would remove the variable being tested.

Question 5

Diagrams 1 and 2 show the reproductive parts of a human and a plant respectively.

Identify the part where the male sex cells are produced in the reproductive system of a human and plant respectively.

Accepted Answer

C. Human: R, Plant: W. In humans the male sex cells (sperm) are produced in the testis, labelled R. In plants the male sex cells (pollen) are produced in the anther, labelled W.

Question 6

The diagrams below show the parts of a river bank. Diagram 1 shows the areas where two different types of plants, A and B, were introduced in 2015, while Diagram 2 shows the same river bank and the growth of the plants in some other areas of the land in 2016.

Based on the diagrams above, which one of the following shows the possible characteristics of the fruits of Plants A and B?

Accepted Answer

D. A: Has fibrous husk, B: Is small and light. Plant A (●) spread downstream along the water, so its fruit is dispersed by water and has a fibrous husk that traps air and floats. Plant B (★) spread to areas all around the bank away from the water, so it is dispersed by wind and its fruit is small and light.

Question 7

Mary heated some water in a beaker until it boiled. The results of her experiment are recorded in the graph below.

Based on the information above, which of the following statements correctly describes what happened to the water at the different stages?

A  Evaporation takes place only from Y to Z.
B  The water in the beaker gained heat energy from W to X.
C  Mary heated the water in the beaker for more than 20 minutes.
D  The water in the beaker started to boil after it had been heated for 18 minutes.

Accepted Answer

B. B only. From W to X temperature rises from 30°C to 100°C, so the water gained heat energy (B true). Evaporation occurs at all temperatures, not only Y to Z (A false). The water boiled at X (9 min), not after 18 min (D false). Heating stopped at Y (18 min) when temperature began to fall, so it was heated for about 18 minutes, not more than 20 (C false).

Question 8

The lungs and heart are two organs in the human body. Which one of the following statements on the function of the lungs or heart is correct?

Accepted Answer

C. The lungs remove carbon dioxide from the body when we breathe out.. The lungs are part of the respiratory system; they take in oxygen and remove carbon dioxide from the body when we breathe out. The other statements wrongly attribute gas exchange or transport functions.

Question 9

The diagram below shows the digestive system of a human body.

Digestion is completed at ____.

Accepted Answer

A. C only. Digestion is completed in the small intestine, labelled C. A is the gullet/oesophagus, B is the stomach/liver region and D is the large intestine where water is absorbed, not where digestion is completed.

Question 10

Peter wanted to find out how the length of the root affected the growth of plants. He planted four similar plants, W, X, Y and Z. He added the same amount of water to the plants. The table shows when each plant was harvested (W on day 10, X on day 20, Y on day 30, Z on day 40). He then recorded the height of the plant, number of leaves and the length of the root as shown in the diagram below.

Based on the information above, which of the following conclusions are correct?

A  As the length of the root increases, the height of the plant increases.
B  As the length of the root increases, the number of leaves increases.
C  The longer the length of the root, the greater the volume of water the plant was able to absorb.

Accepted Answer

A. A and B only. The diagram shows that as root length increases (W→Z), both plant height and number of leaves increase, so A and B are valid conclusions. The volume of water absorbed was not measured (the same amount of water was added), so C cannot be concluded from the data.

Question 11

Study the three cells below.

Which of the following cell parts are found in all three cells?

Accepted Answer

D. cytoplasm, nucleus and cell membrane only. All cells (animal and plant) have cytoplasm, a nucleus and a cell membrane. Only the plant cell has a cell wall, so cell wall is not common to all three.

Question 12

Jack saw two different types of birds, Y and Z. Bird Y was seen feeding in the pond while bird Z was seen feeding on the tree trunk. Bird Y waddled through shallow waters and does not swim. Bird Z perched on the tree trunk and feed on tiny organisms.

Which of the bird feet, A, B, C and D shown below represents the feet of bird Y and Z?

Accepted Answer

A. Bird Y: A, Bird Z: B. Bird Y wades through shallow water without swimming, so it has long, slender, spread-out toes (foot A) to walk on soft ground. Bird Z perches and grips the tree trunk, so it has strong curved gripping claws (foot B). Foot D (webbed) is for swimming and foot C (sharp curved talons) is for a bird of prey.

Question 13

Mary was trapped in a small lift. She started to kick the lift door and shout for help continuously. The graph below shows the percentage of gases in Mary's inhaled and exhaled air at rest.

Which one of the following graphs below shows the percentage of gases in Mary's inhaled and exhaled air after 15 minutes in the lift?

Accepted Answer

C. (graph option 3). After 15 minutes of vigorous activity in a closed lift, the oxygen in the air she inhales has decreased while carbon dioxide has increased. As she breathes faster and uses more oxygen, the difference between oxygen used and carbon dioxide/water vapour produced is reflected in option 3, which shows lower inhaled oxygen and the correct relative changes in exhaled gases.

Question 14

The diagram below shows an aquatic habitat.

Four friends made the following statements about the aquatic habitat.

A  There are a total of two different populations in the aquatic habitat.
B  The fishes and the tadpoles form two communities in aquatic habitat.
C  The tadpoles, fishes and aquatic plans form one community in the aquatic habitat.
D  The tadpoles, fishes and aquatic plants form three different populations in the aquatic habitat.

Which of the above statements is/are correct?

Accepted Answer

A. C only. A community is made up of all the populations living together in a habitat. The tadpoles, fishes and aquatic plants are three populations that together form one community, so C is correct. There are three populations (not two), so A and D are wrong, and the fishes and tadpoles are populations not communities, so B is wrong.

Question 15

The table below shows the changes between the number of moths and the number of trees in the forest over a period of 5 years.

Based on the table above, which of the following reasons possibly explain for the changes in the population of moths and trees over a period of 5 years?

A  The trees provides food for the moths.
B  The number of trees decreased due to a fire in the forest.
C  The number of moths increases faster than the number of trees.
D  As the number of moths decreases, the number of trees increased.

Accepted Answer

B. A and D only. The graph shows that as the moth population rises the tree population falls, and as the moth population falls the trees recover. This means the trees are food for the moths (A) and as the moths decrease the trees increase (D). A forest fire (B) is not supported, and the moths do not increase faster than trees (C is not what the graph shows).

Question 16

The characteristics of a desert frog are listed below:
• feeds in the day
• hides in its burrow at night.
• stays in the burrow when the temperature rises above 40°C.

Which of the following statements explain the above behaviour of the desert frog?

A  Availability of water in the burrow.
B  Availability of prey above the ground in the day.
C  Availability of shelter to hide from predators in the burrow.

Accepted Answer

C. B and C only. The frog feeds in the day because its prey is available above ground then (B), and it hides in the burrow at night and in extreme heat for shelter from predators and harsh conditions (C). Availability of water in the burrow (A) is not indicated by the listed behaviours.

Question 17

Pollution affects the environment. The diagram below shows three points, A, B and C, of the river.

Which points, A, B and/or C will be the most polluted?

Accepted Answer

B. B and C only. Point A is upstream of the farm and factory, so its water is clean. Point B is beside/just after the farm and factory (which release pollutants), and point C is further downstream after the factory but before the treatment plant cleans it, so B and C are the most polluted.

Question 18

Siti set up an experiment to find out if carbon dioxide is needed for photosynthesis. She placed a plant in a dark room for two days and then moved it to the school garden. She inserted one of its leaves, Leaf X, in a conical flask containing a solution that removes carbon dioxide as shown in the diagram below.

After 6 hours, Siti removed leaves X and Y from the plant, discoloured the leaves and then tested them for starch using iodine.

Which one of the following correctly shows the results of Siti's experiment?

Accepted Answer

C. Leaf X: yellowish-brown, Leaf Y: blue-black. Leaf X is in a flask with no carbon dioxide, so it cannot photosynthesise and makes no starch — iodine stays yellowish-brown. Leaf Y is exposed to air with carbon dioxide and light, so it photosynthesises and makes starch — iodine turns blue-black.

Question 19

Marie conducted an experiment using three rods, A, B and C and four bars made of materials W, X, Y and Z. She used each rod to scratch each bar. Her observations are shown in the table below. A tick (✓) indicates the presence of scratch marks on the bar.

Based on Marie's experiment, which material, W, X, Y or Z, is most suitable for making a safety helmet?

Accepted Answer

B. X. A safety helmet should be made of the hardest material — the one that is scratched the least (fewest ticks). Based on the table, material X is the hardest and so is the most suitable for a safety helmet.

Question 20

Germaine poured an equal amount of water into four similar measuring cylinders. She then placed four blocks, W, X, Y and Z, in the cylinders in the following order.

Which of the following statements are definitely correct?

A  The volume of block Z is 5 ml.
B  The volume of block X is 15 ml.
C  The original volume of water was 20 ml.
D  The volume of block W is greater than the volume of block Y.

Accepted Answer

B. B and D only. Cylinder 1 (W): 30 ml. Cylinder 2 (W+X): 45 ml, so X = 15 ml (B). Cylinder 3 (W+X+Y): 40 ml... using the rise readings, block X's volume is 15 ml and block W's volume is greater than block Y's, making B and D correct. The original water volume and Z's exact volume cannot be definitely determined from the given readings.

Question 21

Cheryl has a container filled with a mixture of two substances, X and Y. The table below shows the melting point and boiling point of the substances. Substance X: melting point 217°C, boiling point 700°C. Substance Y: melting point 420°C, boiling point 900°C.

At what temperature should Cheryl heat the mixture such that one substance becomes a liquid and the other substance becomes a solid?

Accepted Answer

A. 300 °C. At 300°C: X is above its melting point (217°C) but below its boiling point (700°C), so X is a liquid. Y is below its melting point (420°C), so Y is still a solid. Therefore 300°C gives one liquid and one solid.

Question 22

Study the circuit diagram below carefully. Materials P, Q and R were connected to the circuit below.

Which one of the following most likely represents the materials, P, Q and R, and the number of bulbs that lighted up?

Accepted Answer

D. P: copper, Q: glass, R: iron, Bulbs lit: 3. For bulbs to light, the materials in their part of the circuit must be conductors. The arrangement that gives a consistent conducting/non-conducting pattern producing 3 lit bulbs is P: copper (conductor), Q: glass (non-conductor), R: iron (conductor). Glass at Q breaks the parallel branch with B2, so the main loop with B1, B3, B4 (through R) lights 3 bulbs.

Question 23

A circuit card with six metal pins, A, B, C, D, E and F, are connected by wires on its underside. It is tested with a circuit tester and the results are recorded below. A and B: no; A and F: yes; B and D: no; C and E: no; D and E: yes.

Which one of the following correctly identifies the circuit card used?

Accepted Answer

C. (card option 3). The bulb lights only when the two pins are connected by a wire. A–F connected (yes) and D–E connected (yes); A–B, B–D and C–E are not connected (no). Option 3, which shows wires joining A to F and A to D (with D to E) but no connection to B or C as tested, matches all five results.

Question 24

Wendy hung four magnets, P, Q, R and S, above a tray of identical iron pins. Her observation is shown below.

Which of the following statements are correct?

A  Magnet S is the strongest magnet.
B  Magnet P is weaker than Magnet R.
C  Magnet R is stronger than Magnet Q.
D  Both Magnets P and Q have the same strength.

Accepted Answer

A. A and B only. The stronger the magnet, the more iron pins it attracts and the higher the pins reach. Based on the heights/number of pins attracted, S is the strongest (A) and P is weaker than R (B). The diagram does not support R being stronger than Q or P and Q having equal strength, so C and D are wrong.

Question 25

Tom is riding on his pogo stick as shown below.

Which of the following statements is/are correct?

A  Gravitational force increases as Tom jumps into the air.
B  There is gravitational attraction between Tom and the Earth.
C  Only elastic spring force is needed for Tom to move over a distance.

Accepted Answer

A. B only. There is always a gravitational attraction between Tom and the Earth (B is correct). Gravitational force does not increase as he jumps up (A is wrong), and both elastic spring force and gravitational force act on Tom, not only the spring force (C is wrong).

Question 26

The diagrams below show four examples of forces in our daily life.
(A) Writing on the white board
(B) A stationary car on level ground
(C) Skateboarding down a ramp
(D) Using tongs to pick up an ice cube

Which of the following has friction acting on it?

Accepted Answer

C. A, C and D only. Friction acts when surfaces are in contact and there is movement or a tendency to move/grip. Writing on a board (A — marker rubs the board), skateboarding down a ramp (C — wheels/board on ramp) and using tongs to grip an ice cube (D — grip friction) all involve friction. A stationary car on level ground (B) has no friction acting on it because it is not moving and has no tendency to move.

Question 27

Study the diagram below. Four children and two of their toys are separated by screens, A, B, C, D and E. Given that the screens are made of different materials,
• Tom is unable to see Alice.
• Lily is unable to see the toy truck.
• Alice can see both the teddy bear and the toy truck.

Based on the information above, which one of the following could possibly be the materials which have been used to make the screens?

Accepted Answer

B. A: wood, B: clear plastic, C: clear glass, D: metal, E: clear plastic. Tom cannot see Alice → screens between them include an opaque screen (A is wood/opaque). Lily cannot see the toy truck → screen between them is opaque (E... and the screens block her view). Alice can see both the teddy bear and the toy truck → screens B and C between Alice and those toys must be transparent (clear plastic/clear glass). Option 2 satisfies all three conditions: A wood (blocks Tom–Alice), B clear plastic and C clear glass (Alice sees both toys), and the opaque/transparent arrangement stops Lily seeing the truck.

Question 28

Gopal always has difficulty separating two metal pails which are stacked together as shown in the diagram below.

Which one of the following ways is the best in separating the two pails easily?

A  Pour hot water into the inner pail.
B  Pour cold water into the inner pail.
C  Place the outer pail in a tub of hot water.
D  Place the outer pail in a tub of cold water.

Accepted Answer

C. B and C. To separate them, the inner pail should shrink (contract) and/or the outer pail should expand. Pouring cold water into the inner pail (B) cools and contracts it, while placing the outer pail in hot water (C) heats and expands it — both increase the gap, making separation easier.

Question 29

Four mugs of hot tea of the same temperature were placed inside four boxes which were made of different materials, P, Q, R and S. The time taken for the hot tea to reach room temperature of 30°C was recorded: P took 25 min, Q took 51 min, R took 38 min, S took 46 min.

Which one of the materials is the most suitable to be used to make a container which can keep a bottle of water cold for the longest time?

Accepted Answer

B. Q. The best insulator is the material that allows heat to flow most slowly — the hot tea took the longest time to cool. Material Q kept the tea hot the longest (51 min), so it is the poorest conductor / best insulator and is most suitable for keeping water cold the longest.

Question 30

Denny was playing on a swing as shown in the diagram below.

Which one of the following statements is true when Denny swung from position A to B and then to C?

Accepted Answer

D. Kinetic energy increased from A to B and decreased from B to C.. B is the lowest point of the swing. From A (high) to B (low), height decreases so potential energy converts to kinetic energy — kinetic energy increases. From B (low) to C (high), the swing rises, so kinetic energy converts back to potential energy — kinetic energy decreases.

P6 Science SA2 2016 — Raffles Girls

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P6 Science SA2 2016 — Raffles Girls

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