Photosynthesis & Leaf Structure

9.The balanced chemical equation for photosynthesis is: 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂. How many molecules of carbon dioxide are required to produce one molecule of glucose?

10.In an investigation of gas exchange using hydrogencarbonate indicator, a leaf in bright light causes the indicator to turn purple. What does this indicate?

11.A student investigates the effect of temperature on photosynthesis. At 35°C, the rate is lower than at 25°C. Which is the most likely explanation?

12.Which of the following leaf structures is mainly responsible for allowing carbon dioxide to enter the leaf?

13.The balanced chemical equation for photosynthesis is: 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂. How many molecules of oxygen are produced for every molecule of glucose?

14.A student investigates the effect of light intensity on the rate of photosynthesis in pondweed. The number of bubbles produced per minute is counted. Which of the following should be kept constant to ensure a fair test?

15.In an experiment to investigate the effect of light intensity on the rate of photosynthesis, a student places pondweed in a beaker of water and counts the number of bubbles produced per minute. Why is a glass tank placed between the lamp and the beaker?

16.A student investigates the effect of carbon dioxide concentration on the rate of photosynthesis using pondweed. Sodium hydrogen carbonate is added to the water to increase carbon dioxide concentration. Which of the following is the most accurate way to measure the rate of photosynthesis?

17.In the starch test on a leaf, why is the leaf boiled in ethanol?

18.A plant is kept in a dark cupboard for 24 hours before an experiment to investigate the need for light in photosynthesis. What is the purpose of this?

19.In an experiment to test whether carbon dioxide is necessary for photosynthesis, a destarched plant is placed in a bell jar with a beaker of sodium hydroxide. After several hours in bright light, a leaf from this plant is tested for starch. What is the expected result and why?

20.A student sets up three boiling tubes containing hydrogencarbonate indicator and a leaf from the same plant. Tube A is placed in bright light, tube B in dim light, and tube C in darkness. After a few hours, the indicator in tube A turns purple. What does this indicate?

21.A gardener finds that increasing carbon dioxide concentration in a greenhouse from 400 ppm to 600 ppm increases the rate of photosynthesis, but further increase to 700 ppm does not increase the rate further. Which factor is most likely limiting the rate at 700 ppm?

22.Which of the following is the correct pathway for carbon dioxide from the atmosphere to a chloroplast in a leaf?

23.A plant is deficient in magnesium. What effect would this have on photosynthesis?

24.In an experiment to test whether carbon dioxide is necessary for photosynthesis, a destarched plant is placed in a bell jar with a beaker of sodium hydroxide. Another destarched plant is placed in a bell jar with a beaker of water. Both are left in bright light for several hours. Which result would be expected?

25.A student investigates the effect of light intensity on the rate of photosynthesis using pondweed. The number of bubbles produced per minute is counted. Which of the following is a valid way to vary light intensity?

26.In an experiment using hydrogencarbonate indicator, a leaf in bright light causes the indicator to turn purple. A leaf in the dark causes the indicator to turn yellow. What does this show?

27.A student sets up three boiling tubes containing hydrogencarbonate indicator and a leaf from the same plant. Tube A is placed in bright light, tube B in dim light, and tube C in the dark. After two hours, the colours are: A = purple, B = red, C = yellow. Which tube shows the greatest net uptake of carbon dioxide?

28.Which of the following is the balanced chemical equation for photosynthesis?

29.A plant is kept in a dark room for 48 hours. A leaf is then partially covered with aluminium foil and the plant is placed in sunlight for 6 hours. The leaf is tested for starch. Which result would be expected?

30.The graph shows the effect of light intensity on the rate of photosynthesis at two different carbon dioxide concentrations. At point X, the rate is the same for both concentrations. What is the limiting factor at point X?

31.A student measures the rate of photosynthesis of pondweed by counting bubbles per minute. At 20°C and high light intensity, the bubble count is 30 per minute. When the temperature is raised to 35°C, the bubble count drops to 15 per minute. What is the most likely explanation?

32.A farmer increases the carbon dioxide concentration in his greenhouse from 400 ppm to 800 ppm. The rate of photosynthesis increases initially but then levels off. Which factor is most likely limiting the rate after the increase?

33.A gardener notices that the leaves of his tomato plants are turning yellow. Which mineral deficiency is most likely?

34.Which of the following is the definition of photosynthesis?

35.Chlorophyll is a green pigment found in chloroplasts that absorbs light energy for photosynthesis.

36.Which of the following is a use of the carbohydrates produced by photosynthesis in plants?

37.A plant is deficient in magnesium. Which of the following is most likely to be observed?

38.Place the following steps for testing a leaf for starch in the correct order: (1) dip leaf in boiling water, (2) cover leaf with iodine solution, (3) place leaf in hot ethanol to remove chlorophyll, (4) kill leaf in boiling water.

39.Match each leaf structure to its adaptation for photosynthesis.

40.Which of the following is NOT a limiting factor for photosynthesis?

41.In bright light, the net gas exchange in a plant is intake of carbon dioxide and output of oxygen.

42.Complete the sentence.

43.In the balanced chemical equation for photosynthesis: 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂. How many molecules of oxygen are produced for every molecule of glucose?