GCSE Biology Photosynthesis questions by topic

Complete the sentences about photosynthesis.

1. (a)Carbon dioxide and __________ combine to make glucose.[1]
2. (b)The gas released is __________.[1]
3. (c)The reaction takes place in organelles called __________.[1]
4. (d)Photosynthesis is __________ because it takes in energy from light.[1]

A student counts bubbles from pondweed at two lamp distances.

1. (a)Calculate the mean bubble rate at 20 cm.[2]
2. (b)State the trend between distance and rate shown by the data.[2]

Match each glucose fate to its description.

1. (a)The insoluble storage carbohydrate made from glucose.[1]
2. (b)The strong wall material made from glucose chains.[1]
3. (c)The ions absorbed from soil and combined with glucose to make amino acids.[1]
4. (d)The process that releases energy from glucose.[1]

A greenhouse grower burns paraffin heaters overnight.

1. (a)Name the gas released by burning paraffin that helps photosynthesis.[1]
2. (b)Explain why the heater also raises the rate.[1]
3. (c)State one cost of using the heaters.[1]

This question is about the photosynthesis word equation.

1. (a)Name the two raw materials photosynthesis needs.[1]
2. (b)Name the two products of photosynthesis.[1]
3. (c)Name the organelle where photosynthesis happens.[1]
4. (d)State what kind of energy photosynthesis takes in.[1]

A student tests a leaf for starch using iodine.

1. (a)Why is the leaf first boiled in water?[1]
2. (b)Why is the leaf then heated in ethanol, with the tube standing in hot water?[1]
3. (c)What result shows that starch is present?[1]
4. (d)Why was the plant kept in the dark for 48 hours before the experiment?[1]

Explain how the three limiting factors control the rate of photosynthesis.

1. (a)Explain the effect of light intensity and when it stops limiting.[2]
2. (b)Explain the effect of carbon dioxide concentration.[2]
3. (c)Explain the effect of temperature across the full range.[2]

Describe the pondweed required practical and how its results are made reliable.

1. (a)Describe how the rate is measured and how distance is changed.[3]
2. (b)State three control variables and why one matters.[3]

(Higher) A lamp gives an intensity of 800 arbitrary units at 10 cm from a shoot.

1. (a)Calculate the intensity at 20 cm.[2]
2. (b)Calculate the intensity at 40 cm.[2]
3. (c)State the relationship between distance and intensity shown by your answers.[1]

This question is about the uses of glucose in a plant.

1. (a)List three fates of glucose.[3]
2. (b)Explain why storage is as starch rather than glucose.[2]

Pondweed shoots were grown under four conditions, and the oxygen-bubble rates were measured.

1. (a)Identify the limiting factor in the dim-light condition.[1]
2. (b)Identify the limiting factor in the cold condition.[1]
3. (c)Identify the limiting factor in the normal-air condition.[1]
4. (d)Explain why raising carbon dioxide benefits growers whose plants are otherwise warm and brightly lit.[2]

A pondweed shoot was moved to different distances from a lamp, with the water kept at 22 °C throughout and sodium hydrogencarbonate added to the water.

1. (a)Describe the pattern in the results.[2]
2. (b)Explain why doubling the distance divides the rate by about four.[2]
3. (c)State two variables the student controlled.[2]

Interpret this data from a pondweed investigation.

1. (a)Describe and explain the trend.[3]
2. (b)Name the limiting factor between 10 and 40 cm and justify your choice.[2]
3. (c)Suggest one improvement to make the rate differences easier to detect.[2]

Evaluate the grower’s decision to install high-pressure sodium lighting in a 1-hectare greenhouse.

1. (a)Present the benefits, costs and a justified conclusion.[6]

Explain how a plant’s glucose production and use are balanced over a day and across seasons.

1. (a)Write a full explanation covering day–night balance and seasonal storage.[6]

A student’s pondweed data show a rate of 50 bubbles per minute at 10 cm, 49 at 20 cm, and 48 at 30 cm, but the beaker water was noticeably warmer after the 30 cm trial.

1. (a)Explain why the temperature change could affect the validity of the results.[2]
2. (b)Describe how the student should modify the apparatus to remove this problem.[2]
3. (c)State the variable the student should record to confirm the temperature stayed constant.[1]

(Higher) Two lamps of equal output illuminate identical shoots at 15 cm and 45 cm.

1. (a)Calculate the relative intensity at 45 cm compared with 15 cm.[3]
2. (b)Predict and explain the bubble-rate ratio you would expect between the two shoots.[2]

Explain how the glucose made in photosynthesis becomes the biomass a food chain depends on.

1. (a)Describe three ways a plant uses glucose to build new material.[3]
2. (b)Explain the role of nitrate ions taken up from the soil.[2]
3. (c)Explain why the biomass built this way matters to the rest of a food chain.[1]