Muhammad Adnan Fazal

PHOTOSYNTHESIS RECOGNISE THAT LIVING THINGS NEED ENERGY FROM RESPIRATION TO CARRY OUT LIFE PROCESSES Why Do Living Things Need Energy? All living things need energy to survive. Energy is used for life processes such as growth, movement, reproduction, and repair. This energy comes from respiration, which is the process of breaking down food to release energy. RECOGNISE THAT THE SUN IS OUR PRIMARY SOURCE OF ENERGY (LIGHT AND HEAT) The Sun: The Primary Source of Energy The Sun provides light and heat to the Earth. Plants use sunlight to make food. Animals depend on plants (directly or indirectly) for their food. Without the Sun, there would be no energy flow in living things. DIFFERENTIATE BETWEEN THE WAYS IN WHICH PLANTS AND ANIMALS OBTAIN ENERGY How Do Plants and Animals Obtain Energy Differently? Organism Way to Obtain Energy Plants Make their own food through photosynthesis using sunlight, water, and carbon dioxide. Animals Cannot make their own food. They eat plants or other animals to obtain energy. INVESTIGATE THE REQUIREMENTS (WATER, LIGHT ENERGY AND CARBON DIOXIDE) FOR PHOTOSYNTHESIS (PRODUCTION OF SUGAR AND OXYGEN). What is Photosynthesis? • Oxygen – released into the air, which animals and humans use for breathing. Rate of Photosynthesis Photosynthesis is affected by 3 factors: light intensity, amount of carbon dioxide and amount of chlorophyll. (i) Explain why different distances of light from the plant affect the amount of water lost. Factors Effect Light Intensity The higher the light intensity, the faster the rate of photosynthesis. Amount of Carbon The higher the amount of carbon dioxide, the faster the rate of Dioxide photosynthesis. Amount of Chlorophyll The higher the amount of chlorophyll, the faster the rate of photosynthesis. Q1 Samy conducted an experiment using the set- ups below. He placed four similar test tubes A, B, C and D in different corners of a dim room. Based on Samy’s experiment, suggest a reason why leaf A is smaller in size than leaf B. [1] (a) The graph shows the amount of water in the test tubes over a period of time. 2016/Booklet B/35 Q2 A greenhouse provides a suitable environment for growing certain crops. A farmer planted some strawberries in his greenhouse. To produce sweet strawberries, he must ensure that the plants get at least 8 hours of sunlight daily. Based on the graph, (i) Explain why different distances of light from the plant affect the amount of water lost. [1] (ii) Which variable, light or wind, has a greater effect on the amount of water lost? Give a reason for your answer. [1] (b) Samy observed that a plant P growing in a sunny area has smaller leaves than the same type of plant growing in a shaded area. (a) Suggest how having at least 8 hours of sunlight daily may help in producing sweet strawberries. [1] (b) In some cold countries, greenhouses are built next to a power station. There are pipes to transport the waste gases and heat produced by the power station to the greenhouses. Suggest one benefit of this arrangement to the environment. [1] 2016/Booklet B/36 Q3 Liwen conducted an experiment using four identical tubes as shown. 2016/Booklet B/37 Q4 Jack grew some seeds of a plant on four trays inside a room. The experimental conditions and results are shown below. After a few hours, a drop of liquid Y was added to each tube. When liquid Y was added, the colour of water changed according to the amount of carbon dioxide present. (a) Each number below represents a different colour. The number for the colour of the water in tube A is 4. Based only on the results shown above, what is the correct conclusion for the germination of the seeds? 1. Light is required 2. Water is required 3. Light, water and air are required 4. Air, water and warmth are required 2017/Booklet A/10 Suggest a number for the colour of the water tubes B and D. [1] Liwen predicted that tube C has more carbon dioxide than tube A. However, her friend Santhi said that this may not be true. Explain why tube C may not have more carbon dioxide than tube A. [2] Q5 A scientist studied the effect of light on plant S. Her observations are shown below. Which of the following will he most likely observe when plant S is grown under different amounts of light? (ii) Insect R eats its way into a tree trunk. This affects the growth of the roots of the tree. Explain why. [1] (c) Plant T grows in a desert. It is able to store air in the leaves. Carl observed the cells of a leaf of Plant T during the day and at night as shown. 2017/Booklet A/13 Based on Carl’s observations, explain how Plant T is adapted for photosynthesis in a desert. [2] Q6 (a) Four parts of a plant are shown below. Draw arrows ( → ) in the diagram below to show how water is transported in a plant. [1] 2017/Booklet B/34 Q7 Liyan wanted to find out whether a type of plant growing in places with different amounts of carbon dioxide will have different number of tiny openings in their leaves. She collected leaves from the same type of plant growing in different places and counted the number tiny openings as shown below. (b) (i) Describe the process of photosynthesis in green plants. [1] Which of the following variables should Liyan keep constant? A size of plant B number of tiny openings in a leaf C amount of carbon dioxide in the air help unripe bananas to ripen more quickly. She has only the items below. She may use some or all of them. D amount of photosynthesis in each plant 1. A only 2. C and D only Item Quantity Ripe Banana 2 Unripe Banana 2 3. A, B and C only 4. A, B and D only Priya used two identical clear containers for her investigation. What item(s) show she put inside 2018/Booklet A/14 Q8 Unripe bananas are green and contain chlorophyll. the container for each set-up? [2] Experimental set-up: Control set-up: 2018/Booklet B/29 Q9 A farmer measured the amount of light entering his greenhouse at four different times of the day. (a) Bananas curve upwards when growing. Suggest a reason why bananas grow upwards. [1] (b) Ripe bananas are yellow and give out gas X. Priya wants to investigate whether gas X will Time Amount of Light (Units) 12 am 25 6 am 50 12 pm 260 6 pm 150 (a) State at which time of the day the rate of photosynthesis is highest. Explain your answer. [1] (b) A greenhouse needs to be kept warm on cold days and cool on hot days. Some greenhouses have pockets of air in their roofs in order not to become too cold or hot. Which of the following correctly shows the amount of carbon dioxide in P and Q throughout the day? Between two sheets of material F is a pocket of air. The volume of each pocket could be changed as air is pumped into and out of the pocket. 2019/Booklet A/11 Kumar predicted that the greater the amount Explain how this set-up uses a property of air to Q11 allow greenhouses to keep warm on a cold day. [2] of carbon dioxide in a town, the fewer the number of tiny openings called stomata found in a plant. 2018/Booklet B/31 Q10 Thomas prepared two similar set-ups, P and Q, as shown in the diagram. He gave both set-ups the same amount of water and placed them in the sun for one day. Which of the following supports his prediction? same area within a garden. The diagram shows the four pots of plants after two weeks. 2019/Booklet A/14 Q12 Four similar pots of plants A, B, C and D, are placed at different places as shown. (a) State which pots must be compared to conclude the effect of each variable on leaf growth. [2] Variable Pots to Compare Type of Soil Availability of Water For these plants to grow well, the soil must be kept wet. Which pot should be watered most often? 1. A 2. B Ravi conducted a second experiment to find how the amount of fertilizer affects leaf growth. He conducted a fair test, planting the same number of plants in five big pots, V, W, X, Y and Z. The pots are filled with garden soil. The results of his experiment are as shown. 3. C 4. D 2019/Booklet A/24 Q13 Ravi wanted to investigate the conditions needed for leaf growth using three types of soil. Four pots of identical plants were placed in the Pot V W X Y Z Amount of Fertiliser(g) 0 5 10 15 20 Average surface area of leaf after two weeks(cm2) 20 30 36 20 (2) Gas Gas (3) Liquid Gas (4) Gas Liquid 14 (b) What can Ravi conclude about the effect of fertilizer on leaf growth? [2] 2020/Booklet A/8 2019/Booklet B/33 Q16 Which of the following do plants need to Q14 carry out photosynthesis? A tiny openings on leaves B chloroplasts C food carrying tubes D water carrying tubes The graph shows the amount of rain in country W every year. 1. A and C only 2. B and D only The table shows some information about the 3. A, B and C only growth of rice and barley. 4. A, B and D only 2020/Booklet A/7 Q15 What is the state of water when it is taken in and when it is given out by a plant? (1) Taken In Given Out Liquid Liquid Rice Barley Time to become Adult Plants (months) 5 4 Amount of rain suitable for growths (Unit) 5 or more 2 or less Which plant(s) can grow in country W? 1. Rice only on its leaves. 2. Barley only 3. Plant P has more openings on the upper surface of its leaves. 3. Both barley and rice 4. Neither barley nor rice 4. Plant P lost water more quickly through the lower surface of its leaves. 2020/Booklet A/9 Q17 Ken has two identical pots of plant P. He placed one plant in a room at 30℃ and the other 2020/Booklet A/11 at 40℃. On each plant, he clipped dry pieces of a Jianxuan placed a plant under the sun for type of paper to the upper and lower surfaces of Q18 a leaf as shown. The paper turns pink when wet. two hours. She wrapped one leaf in a clear plastic bag as shown. The graph shows the time taken for the paper to turn pink. Which graph represents the amount of oxygen in the bag during the two hours? Based on the graph, which statement is a correct conclusion? 1. Plant P at 30℃ lost more water. 2. Plant P at 40℃ has fewer openings 2021/Booklet A/12 Q19 Distance of Container from lamp (cm) Time taken for leaf disc to float to surface (s) 10 8 20 17 30 28 John cut out circular discs of equal size from a leaf. These leaf discs can still carry out their functions as a leaf for some time. (a) Name the process that occurred in the leaf disc. State how this process caused the leaf disc to rise to the surface of liquid Y. [1] (b) Suggest two things John could do to obtain more reliable results. [2] Bubbles were observed under the discs after some time. John recorded the time taken for the disc to float to the surface of liquid Y. (c) John repeated the experiment with water instead of liquid Y. he placed the container 10cm away from the lamp. The leaf disc did not rise to the surface even after 200s. Liquid Y provided the leaf discs with a larger amount of a substance than water. Name the substance. [1] 2021/Booklet B/34 Q20 John studied the leaf characteristics of some plants growing at two heights on a mountain. His results are as shown. John repeated the experiment using fresh sets of liquid Y and leaf discs. He placed the containers at different distances from the lamp and his results are as shown. What conclusion can John make from his study? 1. At 600m, the plants have larger leaves to trap more sunlight. the presence of food. Which of the following shows the correct test results? 2. At 3000m, the plants have waxy leaves to reduce water loss, 3. At 3000m, the plants have thicker leaves to adapt to the cold. 4. The height at which the plants grow does not affect the size and thickness of their leaves. 2022/Booklet A/11 Q21 Ethan conducted an experiment using a plant that has leaves with green and white parts. The plant was kept in the dark to remove all the food from the leaves. Ethan covered parts of leaf K and leaf L with black 2022/Booklet A/13 Q22 George conducted an experiment to investigate the effect of temperature of the surrounding air on the rate of photosynthesis of plant P. The graph shows the result of the experiment. paper strips on both the upper and lower surfaces. He wrapped a plastic bag containing a liquid that absorbs carbon dioxide around K. The plant was then exposed to sunlight. Many tiny openings are found on the underside of leaves of plant P. George measured the size of openings at different temperatures. After a few hours, Ethan removed K and L from the plant and tested the two leaves for Temperature (℃) Average size of openings (unit) 10 1 20 2 30 5 (a) Using the results shown in the graph above, explain how the change in size of openings at higher temperatures help the plant. [2] Michael Above 1500 units increasing the amount of light has no effect on the rate of photosynthesis. Who is/are correct? 1. Sherwin only 2. Michael only 3. Both Sherwin and Michael 4. Neither Sherwin nor Michael (b) State two factors in the surroundings that George should keep constant for his investigation. [2] 2023/Booklet A/10 Q24 2022/Booklet B/34 Jeanie used four similar leaves, A, B, C and D, of the same mass to conduct an experiment: These leaves have more stomata (tiny openings) on Q23 The graph shows how the amount of light affects the rate of photosynthesis. their bottom surfaces than on their top surfaces. Leaves lose water through their stomata. She coated some surfaces of the leaves with oil as shown in the table. Sherwin and Michael made the following statements. Statement Sherwin The rate of Photsynthesis increases when the amount of light increases from 0 to 1500 units. Leaf Treatment A No oil B Oil on bottom surface C Oil on top surface D Oil on top and bottom surfaces After the leaves were left in an open area for an hour, she removed the oil and measured the mass of each leaf. Which shows the mass of the leaves in increasing order? 1. A, B, C, D After some time, he measured the volume of 2. A, C, B, D oxygen collected in the test-tube. Which graph 3. D, B, C, A shows the volume of oxygen collected? 4. D, C, B, A 2023/Booklet A/12 Q25 Water droplets are observed on the surface of leaves in the early morning. This is due to ____________________. 1. The temperature of the surrounding air being lower than that of the leaves 2. Water vapour in the air condensing on the surface of the leaves 3. Water droplets moving out of the tiny openings on the leaves 4. Evaporation of water from the surface of the leaves. 2024/Booklet A/5 Q26 Xuan Shi conducted an experiment using identical bulbs and batteries in a dark room. 2024/Booklet A/13 Raj knows that the amount of light can affect Q27 the size of tiny openings found on leaves. (a) State the function of tiny openings found on leaves. [1] Raj carried out an investigation to find out if pollutant S can also affect the size of tiny openings on leaves in three different towns that are located near one another. His results are shown in the table. Town Percentage of pollutants in the air (%) Average size of tiny openings (units) J 5 3 K 3 5 L 1 6 (b) State the effect of pollutant S on the size of tiny openings. [1] To ensure a fair investigation, the size of the tiny openings on leaves in all three towns was measured at the same time. Explain why. [1] 2024/Booklet B/33