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B4F Bioenergetics: Foundation Tier Practice

AQA 8461 · Calculator allowed · about 75 minutes

Total Marks

Name: _______________________________ Date: ____ / ____ / ______

Answer ALL questions. Show all your working.

Plants make food by photosynthesis.

(a)Define the term photosynthesis.(1)

(Total for Question 1 is 1 mark)

Photosynthesis happens inside a special part of a plant cell.

(a)Name the organelle where most photosynthesis occurs.(1)

(Total for Question 2 is 1 mark)

Raw materials for photosynthesis are taken from the air and the soil.

(a)State two raw materials (reactants) needed for photosynthesis.(2)

(Total for Question 3 is 2 marks)

Photosynthesis makes substances that help plants grow.

(a)State two products of photosynthesis.(2)

(Total for Question 4 is 2 marks)

Write a simple word equation for photosynthesis.

(a)Write the word equation for photosynthesis.(2)

(Total for Question 5 is 2 marks)

Chlorophyll is important for capturing light.

(a)State the role of chlorophyll in photosynthesis.(1)

(Total for Question 6 is 1 mark)

Light is one factor that affects the rate of photosynthesis.

(a)Explain why a plant's rate of photosynthesis falls if it is kept in the dark.(2)

(Total for Question 7 is 2 marks)

A student measured the increase in mass of a potted plant after two weeks under bright light. The mass increased by 8.0 g over 4 days when conditions were stable.

(a)Calculate the average increase in mass per day in grams per day. Show your working.(2)

(Total for Question 8 is 2 marks)

Carbon dioxide concentration usually affects photosynthesis.

(a)Predict what will happen to the rate of photosynthesis if the carbon dioxide concentration around a plant is increased (all other conditions unchanged).(1)

(Total for Question 9 is 1 mark)

Which factor would be limiting if a plant is grown in dim light but with plenty of water and carbon dioxide?

(a)Name the limiting factor in this situation.(1)

(Total for Question 10 is 1 mark)

A required practical uses pondweed to measure oxygen production as a measure of photosynthesis. The apparatus includes a cut piece of pondweed, a water-filled tube to collect gas bubbles and a lamp at a fixed distance.

(a)Give two variables that should be kept the same (controlled) during this investigation.(2)

(Total for Question 11 is 2 marks)

During the pondweed experiment, a student notices the number of bubbles varies a lot between repeats.

(a)Suggest one improvement to reduce random variation in the number of bubbles counted.(1)

(Total for Question 12 is 1 mark)

Respiration also involves gases.

(a)State which gas is used in aerobic respiration and which gas is produced.(1)

(Total for Question 13 is 1 mark)

A plant absorbs 30 J of light energy and stores 9 J as chemical energy in glucose during photosynthesis.

(a)Calculate the efficiency of the plant at storing light energy as chemical energy. Show your working and give the answer as a percentage.(2)

(Total for Question 14 is 2 marks)

A student recorded bubbles of oxygen produced by pondweed at different light intensities. The data are: light intensity 20 -> 4 bubbles per minute; 40 -> 8; 60 -> 12; 80 -> 16.

(a)Estimate the number of bubbles per minute at light intensity 50 by interpolation. Show a short calculation.(2)

(Total for Question 15 is 2 marks)

Farmers use methods to increase photosynthesis in greenhouses to raise crop yield.

Explain how a farmer could increase the rate of photosynthesis in a greenhouse to increase crop yield. In your answer include at least three different changes the farmer could make, how each change increases the rate of photosynthesis, and one reason why a farmer might not use a particular change.

(Total for Question 16 is 6 marks)

Mark scheme · B4F Bioenergetics: Foundation Tier Practice

Question 1

(a) B1 the process by which plants use light energy to make glucose from carbon dioxide and water, oe
(a) Answer: The process by which plants use light energy to make glucose from carbon dioxide and water.

Question 2

(a) B1 chloroplast cao
(a) Answer: Chloroplast

Question 3

(a) B1 carbon dioxide
(a) B1 water
(a) Answer: Carbon dioxide and water.

Question 4

(a) B1 glucose
(a) B1 oxygen
(a) Answer: Glucose and oxygen.

Question 5

(a) M1 gives reactants and products in the correct order with light energy present
(a) A1 carbon dioxide + water -> glucose + oxygen cao
(a) Answer: carbon dioxide + water -> glucose + oxygen

Question 6

(a) B1 absorbs light energy (to drive photosynthesis) cao
(a) Answer: Absorbs light energy for photosynthesis.

Question 7

(a) M1 states that less light means less energy available for the reactions
(a) A1 rate falls because the light-dependent stage cannot proceed as quickly, so less glucose and oxygen are produced, oe
(a) Answer: With less light there is less energy for the light-dependent reactions, so the rate of photosynthesis falls and less glucose and oxygen are produced.

Question 8

(a) M1 substitutes: rate = 8.0 g / 4 days
(a) A1 2.0 g per day cao
(a) Answer: 2.0 g per day

Question 9

(a) B1 rate will increase (until another factor becomes limiting) cao
(a) Answer: The rate will increase, until another factor becomes limiting.

Question 10

(a) B1 light (intensity) cao
(a) Answer: Light intensity

Question 11

(a) B1 temperature, oe
(a) B1 distance between lamp and pondweed or light intensity (if lamp distance fixed then light intensity), oe
(a) Answer: Temperature and distance between lamp and pondweed (light intensity).

Question 12

(a) B1 repeat the measurement more times and take an average, oe
(a) Answer: Repeat the measurement several times and use the average.

Question 13

(a) B1 oxygen used and carbon dioxide produced, oe
(a) Answer: Oxygen is used and carbon dioxide is produced.

Question 14

(a) M1 substitutes into efficiency = (useful energy out / total energy in) x 100, i.e. (9 / 30) x 100
(a) A1 30% cao
(a) Answer: 30%

Question 15

(a) M1 uses linear relation: between 40 and 60 intensity the bubbles go from 8 to 12 so slope = (12-8)/(60-40) = 4/20 = 0.2 bubbles per intensity unit
(a) A1 gives 10 bubbles per minute cao
(a) Answer: 10 bubbles per minute

Question 16

Level 3 (5-6): Detailed explanation. Offers at least three valid methods, links each method to how it increases rate of photosynthesis, and gives a valid reason why a method might not be used; explanations are clear and linked to biology terms such as light intensity, carbon dioxide concentration, temperature and limiting factor.
Level 2 (3-4): Partial explanation. Describes two or three methods with correct but limited explanation of how they increase photosynthesis and may include one valid limitation or drawback.
Level 1 (1-2): Basic statements. Mentions one or two relevant methods with little or no explanation of how they increase photosynthesis and no real evaluation of drawbacks.
Indicative content:
- Increase light intensity using artificial lamps so more light energy is available to drive photosynthesis; increases rate when light is limiting.
- Enrich carbon dioxide concentration in the greenhouse so more CO2 is available as a raw material for photosynthesis; increases rate until another factor is limiting.
- Raise temperature to the plant's optimum so enzymes involved in photosynthesis work faster; be careful as too high temperature denatures enzymes so there is a limit.
- Ensure adequate water supply so stomata remain open and water is available as a raw material for photosynthesis; without water photosynthesis stops.
- Use pest and disease control to keep leaves healthy so photosynthetic surface area is not reduced.
- Possible drawbacks: cost of electric lighting or CO2 enrichment; risk of increased disease at higher humidity or temperature; environmental or safety concerns with CO2 use.

Bioenergetics: Foundation Tier Practice - Worksheets, Questions and Revision