P6 Science SA2 2015 — Raffles Girls | Singapore Past Year Paper

Q: The flowchart below shows how some organisms are classified. Which one of the following correctly identifies questions A and B?

4. A: Does it have feathers? / B: Does it breathe through lungs?. If 'Yes' to Question A leads to Bird, the distinguishing feature must be unique to birds — having feathers (only birds have feathers). For the remaining group, 'No' to Question A leads to Question B; if 'Yes' gives Mammal and 'No' gives Fish, the question must separate mammals from fish — 'Does it breathe through lungs?' (mammals breathe through lungs, fish breathe through gills). Option 4 fits both.

Q: The diagrams below show a fern and a hibiscus plant. Which of the following comparison(s) between the fern and the hibiscus plant is/are correct? A Only the hibiscus plant can bear fruits. B Both the fern and hibiscus plant can make their own food. C Both the fern and hibiscus plant can reproduce from seeds.

3. A and B only. A is correct: hibiscus is a flowering plant that bears fruits while ferns do not bear fruits. B is correct: both are green plants containing chlorophyll, so both make their own food by photosynthesis. C is wrong: ferns do not reproduce by seeds (they reproduce by spores), so only the hibiscus reproduces from seeds. Therefore A and B only.

Q: The diagram below shows the processes involved in the reproduction of a flowering plant. Which of the following correctly identifies processes P, Q and R?

3. P: Pollination / Q: Fertilisation / R: Seed dispersal. The reproduction cycle of a flowering plant proceeds: Germination → Pollination → Fertilisation → Seed dispersal → back to Germination. Following the cycle from Germination: Process P = Pollination, Process Q = Fertilisation, Process R = Seed dispersal. Option 3 matches.

Q: The table below shows the characteristics of organisms A and B. A tick (✓) indicates the presence of the characteristic. Based on the above information, which of the following statement(s) is/are correct? A Both organisms give birth to their young alive. B Organism B lays more eggs than organism A. C Organism A has a 4-stage life cycle while Organism B has a 3-stage life cycle.

2. C only. A is wrong: both organisms lay eggs (tick for 'Lays eggs'), so they do not give birth to live young. B is wrong: the table only shows that both lay eggs, not the number of eggs. C is correct: Organism A has a pupal stage (egg → larva → pupa → adult = 4-stage complete metamorphosis), while Organism B has no pupal stage (egg → nymph → adult = 3-stage incomplete metamorphosis). Therefore C only.

Q: Sophia cut a brightly coloured fruit in half and observed that it contained many seeds as shown in the diagram below. Based only on her observation, which one of the following statements is definitely true about the flower that this fruit has developed from?

1. The flower has many ovules.. Each seed develops from a fertilised ovule. Since the fruit contains many seeds, the flower must have had many ovules. A fruit develops from one ovary, so many ovaries is wrong. The number of pollen grains and the mode of pollination (animal vs wind) cannot be concluded just from observing the seeds. Therefore the flower has many ovules.

Q: Neutering is the process of removing an animal's reproductive organ. This is a safe and quick procedure done by a veterinarian (animal doctor). In some countries, due to the lack of space in animal shelters, millions of stray cats and dogs are killed each year. Which of the following correctly explain how neutering helps to prevent the killing of stray animals? A Neutering of animals enables the animals to reproduce faster. B The ovaries are removed so that fertilisation will not occur in the female body. C The ovaries are removed so that fertilisation will only occur outside the female body. D The testes are removed to prevent the release of male reproductive cells into the female body.

3. B and D only. Neutering reduces stray populations by preventing reproduction. A is wrong (it stops, not speeds up, reproduction). B is correct: removing the ovaries means no egg cells are produced, so fertilisation cannot occur in the female. C is wrong: fertilisation in mammals occurs inside the female body, not outside. D is correct: removing the testes stops sperm (male reproductive cells) being released, so no fertilisation occurs. Therefore B and D only.

Q: The diagram below shows how blood flows through the blood vessels, W, X, Y and Z, in the human body. Four blood samples, P, Q, R and S were taken from the different blood vessels in the above diagram. The following graph shows the amount of oxygen in each of these blood samples. Which one of the following blood samples, P, Q, R or S, was most likely taken from the blood vessel W?

3. R. Blood vessel W carries blood from the lungs to the heart (it points upward into 'lungs'... actually W is the vessel from lungs to heart). W carries oxygen-rich blood that has just been oxygenated in the lungs, so it has the highest oxygen content. From the graph, sample R has the highest amount of oxygen, so W corresponds to R.

Q: Sarah observed three cells and recorded her observations in the table below. A tick (✓) indicates the presence of the cell structure. Which one of the following statements about the cells is correct?

1. Only cells W and Y have fixed shape.. Cell W has a cell wall (plant cell, fixed shape), Cell X has no cell wall (animal cell, no fixed shape), Cell Y has a cell wall (plant cell, fixed shape). (1) Correct: only W and Y have a cell wall, which gives a fixed shape. (2) Wrong: only W has chloroplasts, so cells X and Y cannot carry out photosynthesis — W can. (3) Wrong: the cell membrane controls what enters, allowing only certain substances. (4) Wrong: W and Y are plant cells (have cell walls), X is the animal cell. Therefore statement 1.

Q: The graph below shows how organisms P, Q and R in a habitat are affected when organism F is introduced at point E. Based on the information above, which of the following statement(s) is/are true? A R is eaten by F B F is a food producer. C P and Q compete with each other for food.

1. A only. When F is introduced at E, R decreases (so F likely eats R — A is true). B is wrong: F is introduced into an existing habitat and feeds on R, so F is a consumer, not a food producer. C cannot be concluded: there is no information that P and Q share the same food source, and both rise/behave without evidence of competition. Therefore A only.

Q: The graph below shows the amount of carbon dioxide released into the atmosphere from the burning of fossil fuels since the year 1900. Which one of the following is a consequence of the change in the amount of carbon dioxide released into the atmosphere?

2. Melting of polar ice caps. The graph shows carbon dioxide released has increased over time. More CO₂ traps more heat (greenhouse effect), raising global temperatures, which causes the polar ice caps to melt — a consequence. (1) Wrong: melting ice raises, not drops, sea level. (3) and (4) are causes of increased CO₂, not consequences. Therefore melting of polar ice caps.

Q1 MCQ 2 marks 🖼 Visual

The flowchart below shows how some organisms are classified. Which one of the following correctly identifies questions A and B?

Q2 MCQ 2 marks 🖼 Visual

The diagrams below show a fern and a hibiscus plant. Which of the following comparison(s) between the fern and the hibiscus plant is/are correct? A Only the hibiscus plant can bear fruits. B Both the fern and hibiscus plant can make their own food. C Both the fern and hibiscus plant can reproduce from seeds.

Q3 MCQ 2 marks 🖼 Visual

The diagram below shows the processes involved in the reproduction of a flowering plant. Which of the following correctly identifies processes P, Q and R?

Q4 MCQ 2 marks 🖼 Visual

The table below shows the characteristics of organisms A and B. A tick (✓) indicates the presence of the characteristic. Based on the above information, which of the following statement(s) is/are correct? A Both organisms give birth to their young alive. B Organism B lays more eggs than organism A. C Organism A has a 4-stage life cycle while Organism B has a 3-stage life cycle.

Q5 MCQ 2 marks 🖼 Visual

Sophia cut a brightly coloured fruit in half and observed that it contained many seeds as shown in the diagram below. Based only on her observation, which one of the following statements is definitely true about the flower that this fruit has developed from?

Q6 MCQ 2 marks 🖼 Visual

The diagram below shows part of an island where three types of plants, X, Y and Z, are growing. The diagrams below show the characteristics of fruits A, B, C and D. Which of the following fruits most likely belong to plants, X, Y and Z?

Q7 MCQ 2 marks

Neutering is the process of removing an animal's reproductive organ. This is a safe and quick procedure done by a veterinarian (animal doctor). In some countries, due to the lack of space in animal shelters, millions of stray cats and dogs are killed each year. Which of the following correctly explain how neutering helps to prevent the killing of stray animals? A Neutering of animals enables the animals to reproduce faster. B The ovaries are removed so that fertilisation will not occur in the female body. C The ovaries are removed so that fertilisation will only occur outside the female body. D The testes are removed to prevent the release of male reproductive cells into the female body.

Q8 MCQ 2 marks 🖼 Visual

The diagram below shows how blood flows through the blood vessels, W, X, Y and Z, in the human body. Four blood samples, P, Q, R and S were taken from the different blood vessels in the above diagram. The following graph shows the amount of oxygen in each of these blood samples. Which one of the following blood samples, P, Q, R or S, was most likely taken from the blood vessel W?

Q9 MCQ 2 marks 🖼 Visual

The diagram below shows the different parts of human digestive system. The graph below shows the amount of undigested food in the samples A, B, C and D obtained from different parts of the human digestive system in Diagram 1. Which one of the following correctly matches the parts, P, Q, R and S, in Diagram 1 to the samples A, B, C and D, in the graph?

Q10 MCQ 2 marks 🖼 Visual

Alice placed a partially split celery stalk into two beakers of coloured water as shown below. After half an hour, she cut across the stalks at positions, X and Y, as shown in the diagram below. She observed that the cut sections, X and Y, had coloured dots. Which of the following observations is/are not possible? A All the leaves appeared blue. B All the dots on cut section Y were stained red. C Cut section X had a mixture of red dots and blue dots.

Q11 MCQ 2 marks 🖼 Visual

Sarah observed three cells and recorded her observations in the table below. A tick (✓) indicates the presence of the cell structure. Which one of the following statements about the cells is correct?

Q12 MCQ 2 marks 🖼 Visual

The table below shows the average size of soil particles suitable for growing plants X, Y and Z respectively. Natalie put equal amounts of soil samples, A, B and C, into 3 identical beakers. Then, she poured an equal amount of water into each beaker of soil at the same time. The diagrams below show the set-ups after the water was added. Based on the observations above, which one of the following shows the soil sample that is most suitable for growing plants X, Y and Z respectively?

Q13 MCQ 2 marks 🖼 Visual

The diagram below shows 4 types of organisms living in a pond. A farmer sprayed fertilizer on his vegetable farm which is just next to the pond. The graph below shows the change in the number of the 4 types of organisms living in the pond over one month due to the runoffs and soil erosion from the fertilised vegetable farm during raining seasons. Based on the information above, which one of the following statements is correct?

Q14 MCQ 2 marks 🖼 Visual

The diagram below shows a food web in a community. Which one of the following correctly identifies organisms W, X, Y and Z?

Q15 MCQ 2 marks 🖼 Visual

The graph below shows how organisms P, Q and R in a habitat are affected when organism F is introduced at point E. Based on the information above, which of the following statement(s) is/are true? A R is eaten by F B F is a food producer. C P and Q compete with each other for food.

Q16 MCQ 2 marks 🖼 Visual

Susan recorded some information about the feet of birds X and Y as shown below. • Bird X has muscular and powerful feet with sharp and curved claws to grab its prey firmly. • Bird Y has webbed feet with a large surface area to help it paddle through water efficiently. The diagrams below show different types of feet, A, B, C and D. Which one of the following correctly matches the feet to birds X and Y?

Q17 MCQ 2 marks 🖼 Visual

The graph below shows the amount of carbon dioxide released into the atmosphere from the burning of fossil fuels since the year 1900. Which one of the following is a consequence of the change in the amount of carbon dioxide released into the atmosphere?

Q18 MCQ 2 marks 🖼 Visual

Jasmine collected four beakers of water from four ponds E, F, G and H. Using the set-up below, she measured the amount of light that passed through each beaker of pond water using a light sensor. Jasmine presented her results on a graph as shown below. Which one of the following pond water would be most suitable for fully submerged plants to grow well in?

Q19 MCQ 2 marks 🖼 Visual

Siti was given a beaker containing a mixture of four substances P, Q, R and S. These substances cannot be dissolved in water. A tick (✓) indicates the presence of the property. Based only on the above information, which two substances will Siti not be able to separate?

Q20 MCQ 2 marks 🖼 Visual

Megan placed an empty bottle with two holes at points P and Q into a basin of hot water as shown below. Which of the following would Megan observe? A The cap popped out. B Air entered the bottle through P. C Water entered the bottle through Q.

Q21 MCQ 2 marks 🖼 Visual

At 30°C, substance Z has a definite volume and does not take the shape of the container. However, at 200°C, substance Z can be compressed. Which one of the following is most likely the melting point and boiling point of substance Z?

Q22 MCQ 2 marks 🖼 Visual

Vishnu set up four electrical circuits using identical batteries and identical bulbs. The batteries and bulbs are working properly. Which of the following statement(s) is/are correct? A Bulb W is the brightest. B Bulb Z is dimmer than Bulb W. C Bulb Z is brighter than Bulb Y. D Bulb X and Bulb Z have the same brightness.

Q23 MCQ 2 marks 🖼 Visual

Ethan set up the circuit below. Ethan has 3 rods made of iron, copper and plastic respectively. At which position, A, B, C or D, should Ethan place each rod respectively so that only Bulb 2 and Bulb 3 will light up?

Q24 MCQ 2 marks 🖼 Visual

Serene conducted an experiment on springs A and B. She hung different loads one at a time and recorded the length of the spring. Her results are shown in the graph below. Which one of the following statements is true?

Q25 MCQ 2 marks 🖼 Visual

Chloe put four metal rings A, B, C and D through a smooth plastic rod in three different arrangements as shown below. Based on the observations above, which of the following metal rings are definitely magnets?

Q26 MCQ 2 marks 🖼 Visual

Kim Huat threw a ball into the net as shown in the diagram below. Which of the following statement(s) is/are correct? A There are no forces acting on the ball at T. B Kim Huat exerted a force on the ball at P to move the ball. C There is more gravitational force acting on the ball at R than at Q. D The gravitational potential energy of the ball decreases from R to S only.

Q27 MCQ 2 marks 🖼 Visual

Chloe conducted the experiment in a completely dark room as shown below. She exerted a force on toy car X, such that it moved past the finishing line. Chloe repeated the procedure with toy car Y, using the same amount of force. She recorded the amount of light detected by the light sensor over a period of time in the table below. Based on the above results, which of the following statement(s) is/are true? A Toy car X is opaque. B Toy car Y is transparent. C Toy car Y travels at a greater speed than Toy car X.

Q28 MCQ 2 marks 🖼 Visual

Jasmine's mother bought a humidifier which releases tiny water droplets in the form of mist into the air, as shown below. Jasmine advised her mother to switch off the humidifier when she mops the floor. Which one of the following is the correct explanation for switching off the humidifier when mopping the floor?

Q29 MCQ 2 marks 🖼 Visual

David filled 4 containers, P, Q, R and S, with equal amount of water at 75°C. The 4 containers are of the same size and shape but made of different materials. He left the 4 containers on a table in the Science laboratory with a constant room temperature. He recorded the time taken for the water in the containers to reach room temperature in the table below. Based on the results above, which one of the following materials, P, Q, R or S, would be most suitable to make a mug to keep drinks cold for the longest time?

Q30 MCQ 2 marks 🖼 Visual

Prithi released a bob at position A, which moved to position B and then to position C, as shown in the diagram below. Which one of the following graphs correctly shows the change in kinetic energy (KE) and potential energy (PE) of the bob as it moved from B to C?

Q31 Open-ended 3 marks 🖼 Visual

Sally prepared three identical set-ups by burying 20 seeds in the same amount of moist soil. Then she placed the three set-ups at different temperatures. She recorded her observations over a period of 6 days in the table below. (a) Predict the total number of seeds germinated: (i) at 5°C, on Day 3: ____ (ii) at 15°C, on Day 5: ____ (b) Based on the above information, what can Sally conclude about the effect of temperature on germination? The graph below shows the changes in the mass of the seed leaves of a seed during germination. (c) How did the seedling get its food after day 8?

Q32 Open-ended 3 marks 🖼 Visual

Wendy wanted to find out the colour of the flowers that insects X, Y and Z prefer. She used flowers made from different coloured cards. She put 10 drops of sugar solution in the centre of each flower. The flowers were left in the open field. Wendy then counted the number of each type of insects that visited the flowers over 2 hours. The results were recorded in the table below. (a) Based on Wendy's results, which colour attracted most insects? (b) Using the same materials, what could Wendy do to ensure reliability of her results? (c) Wendy also wanted to find out the relationship between the size of the flowers and the number of the insect Z visiting the flowers. Put a tick (✓) beside the variable(s) that should be kept constant to ensure a fair test. (i) Size of flower (ii) Colour of flower (iii) Number of insect Z visiting each flower (iv) Amount of sugar solution added to each flower

Q33 Open-ended 2 marks 🖼 Visual

Cathy prepared three set-ups, P, Q and R, using the same type of plants as shown below. Some roots were removed from the plant in set-up Q while some leaves were removed from the plant in set-up R. Cathy placed all the set-ups in the open field for 4 hours. Which set-up, P, Q or R would she observe the greatest decrease in the water level? Explain your choice clearly.

Q34 Open-ended 2 marks 🖼 Visual

Jack was given two single-celled organisms, X and Y, of the same species. Part P of organism Y has been removed. He observed the organisms for the same period of time and recorded his observations below. (a) Based on Jack's observation above, what can he conclude about the function of part P? (b) Identify one difference between organism X and a leaf cell.

Q35 Open-ended 4 marks 🖼 Visual

The diagram below shows a food web in a certain community. (a) State two benefits that tree Y could provide for animal X. Both animals X and V are found on Tree Y. Animal X lives in a large group but not animal V. (b) What advantage does animal X have over animal V by living in a large group? (c) A disease wiped out the whole population of animal Z. Explain how this would affect the population of animal V.

Q36 Open-ended 3 marks 🖼 Visual

The diagrams below show 2 fishes, A and B. (a) Based on the diagrams above, explain why Fish A is a faster swimmer than Fish B. (Do not compare the texture of the body.) Fish B has a rough, brown-greenish body. Its diet consists of small fish and shrimps. It is normally found among corals, sand and rocks. (b) Explain how having a rough, brown-greenish body helps Fish B in their survival. (c) Fish B is a slow swimmer. Suggest a behaviour of Fish B that can help it to increase its chance of catching its prey.

Q37 Structured 3 marks 🖼 Visual

Jason placed two identical containers, P and Q, on a balance as shown in the diagram below. Jason poured away all the water in both containers. Then he pumped 300 cm³ of air into P and 100 cm³ of air into Q. (a) Describe clearly what Jason would observe of the balance. (b) Give a reason for your answer in (a). (c) Fill in the table below to indicate the final volume of air in both containers.

Q38 Structured 3 marks 🖼 Visual

The diagram below shows a crane that is used to transfer heavy scrap iron from one place to another. When the switch is closed, the electromagnet picks up the scrap iron. The crane will then transfer the scrap iron to another location. When the switch is opened, the scrap iron drops to the ground. (a) Complete the circuit diagram below to show how the electromagnet works, using 2 batteries, 1 switch and wires. An iron rod with a piece of insulated wire coiled around it, which forms part of the circuit, has been drawn for you. (b) Using the same type of batteries, switch, iron rod, wires and circuit arrangement in part (a), suggest 2 ways to enable the electromagnet to attract more scrap iron.

Q39 Structured 3 marks 🖼 Visual

Angie wanted to find out which magnet, X or Y is stronger. She set up the experiment below. (a) Label 'N' for north-seeking pole or 'S' for south-seeking pole in the box in the above diagram. (b) Angie observed that Magnet Y attracted more thumbtacks than Magnet X. She concluded that Magnet Y is stronger than Magnet X. Explain why Angie cannot conclude that Magnet Y is stronger than Magnet X.

Q40 Structured 2 marks 🖼 Visual

Jane's mass is 40kg. The table below shows how much Jane weighs on different planets. (a) Based on the information above, what can Jane conclude about the gravitational force acting on objects on different planets? (b) What is Jane's mass on planet Mars? Give a reason for your answer.

Q41 Open-ended 6 marks 🖼 Visual

Siti wanted to find out if the surface texture of a box affects the time taken for it to slide down a ramp. She pushed 3 boxes, P, Q and R, made of different materials, down a ramp one at a time as shown in the set-up below. Siti recorded her results in the table below. (a) Which box, P, Q or R, is the smoothest? Explain your answer. (b) Siti kept the starting point of the box sliding down the ramp constant in her experiment. How did this make her experiment a fair test? [Continued] The diagram below shows the callus, a layer of hardened skin, on the sole of Siti's foot. Siti wanted to remove the callus by rubbing it with a foot file. Siti has two foot files, X and Y. X has a rougher surface than Y. (c) Which foot file, X or Y, should she use to remove the callus more quickly? Explain your answer.

Q42 Open-ended 2 marks 🖼 Visual

Monica conducted the experiment as shown below. Monica took 2 seconds to move the torch from A to B, and then another 3 seconds to move the torch from B to C. She measured the length of the shadows cast by the iron block at the different positions of the torch. The distance between the torch and the iron block were kept the same at the different positions of the torch. Positions A and C have the same height from the ground. Draw a line graph below to show how the length of the shadow changes when the torch moves from A to B and then to C.

Q43 Open-ended 3 marks 🖼 Visual

Esther noticed that her father poured hot tea from one cup to the other continuously for a few times as shown in the diagrams below. Her father explained that the hot tea will cool down more quickly after it was "pulled" several times. (a) Explain why the hot tea will cool down more quickly this way. Esther carried out another experiment using two cups of hot tea of the same temperature. She had two cubes of ice, X and Y, of the same mass. She placed ice cube X into a cup and crushed ice cube Y before putting it into another cup. (b) Esther observed that the hot tea with crushed ice cube Y cool more quickly than the hot tea with ice cube X. Give a reason for her observations.

Q44 Structured 3 marks 🖼 Visual

Joanna pushed a toy car towards a wooden plank AB as shown in the diagram below. The toy car moved up the plank, stopped at X and then it rolled down the plank. (a) State the energy conversion that took place when the car moved from A to X. [Fill in the two boxes: ____ energy → ____ energy] (b) Explain why the toy car stopped at X clearly. (c) Explain why the toy car rolled down from point X.

P6 Science SA2 2015 — Raffles Girls

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