PhotosynthesisIB MYP Sciences: Subtopic test

1. 1
   A greenhouse grower in the Netherlands grows tomato plants. The leaves make glucose from carbon dioxide and water using energy from light, in a process that also releases a gas into the greenhouse air.

   (a)

   Which row shows the correct word equation for photosynthesis?

   [1 mark]

   • ACarbon dioxide + water → glucose + oxygen
   • BGlucose + oxygen → carbon dioxide + water
   • CGlucose + water → carbon dioxide + oxygen
   • DOxygen + water → glucose + carbon dioxide

   (b)

   In which part of a plant cell does photosynthesis take place?

   [1 mark]

   • AMitochondria
   • BNucleus
   • CChloroplasts
   • DVacuole

   (c)

   State the role of chlorophyll in photosynthesis.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   Photosynthesis can be summarised by an incomplete symbol equation in which two of the numbers have been left out: ? CO₂ + 6 H₂O → C₆H₁₂O₆ + ? O₂. The glucose produced is used by the plant in several ways.

   (a)

   What numbers should replace the two question marks, in the order they appear in the equation?

   [1 mark]

   • A3 and 3
   • B6 and 6
   • C6 and 12
   • D12 and 6

   (b)

   Which substance is made from glucose and is used to build the cell walls of plant cells?

   [1 mark]

   • AStarch
   • BChlorophyll
   • CProtein
   • DCellulose

   (c)

   State two ways in which a plant uses the glucose made in photosynthesis.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A student wants to find out whether light is needed for photosynthesis. She keeps a geranium plant in a dark cupboard for 24 hours. She then covers one leaf completely with aluminium foil and places the plant in bright light for two days. She removes the covered leaf and an uncovered leaf and tests both for starch. She boils each leaf in water, heats it in hot ethanol, rinses it and adds iodine solution. The uncovered leaf turns blue-black. The covered leaf stays orange-brown.

   (a)

   Describe the purpose of each of the following steps in the starch test: boiling the leaf in water, heating the leaf in hot ethanol, and adding iodine solution.

   [3 marks]

   (b)

   State the conclusion that can be drawn from the results, with an explanation, and evaluate the method by suggesting one limitation and one safety precaution.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A city council in Kenya plans to plant one million trees on degraded land. The council says the trees will absorb carbon dioxide from the air and provide shade. Some local farmers say they need the land to grow food, and the young trees will need watering for several years.

   (a)

   Explain how trees take in carbon dioxide and use it to grow, referring to photosynthesis, its equation and the uses of glucose.

   [6 marks]

   (b)

   Discuss the social, economic and environmental implications of planting one million trees, and justify a conclusion.

   [6 marks]

   Total for question 4: 12 marks

End of questions