Plant Structures and Their Functions | Edexcel GCSE Biology, Higher tier (1BI0)
Plant Structures and Their Functions
- 138 questions
- 9 subtopics
- Paper 2
- Paper 2
Plant Structures and Their Functions is examined in Paper 2, Biology 2.
It covers photosynthesis and its limiting factors, light intensity and the inverse square law, root hair cells, xylem and phloem, transpiration and translocation, leaf structure, the factors affecting transpiration and the potometer, plant adaptations to extreme environments, and plant hormones and their commercial uses.
Sample questions from Plant Structures and Their Functions
Answer each one closed book first, then open the answer.
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Photosynthesis as an endothermic reaction
Explain why animals depend on photosynthetic organisms for their food.
Show the answer
Animals cannot make their own food, so they must obtain it by eating producers or by eating other animals that ate producers. -
Limiting factors in photosynthesis
Explain why the rate of photosynthesis falls sharply above about 45 °C.
Show the answer
The enzymes controlling photosynthesis denature, so their active sites change shape and can no longer catalyse the reactions. -
Light intensity and the rate of photosynthesis
Describe two ways of improving the quality of results in an investigation of light intensity and photosynthesis.
Show the answer
Repeat each distance at least three times and calculate a mean, and collect the gas in a capillary tube so its volume can be measured precisely. -
Root hair cells, xylem and phloem
Explain how having a thin surface layer helps a root hair cell absorb substances.
Show the answer
The short distance to cross means water and mineral ions enter the cell quickly. -
Transpiration and translocation
Explain how guard cells open a stoma.
Show the answer
The guard cells take in water by osmosis and become turgid, and their change of shape pulls the pore between them open. -
Leaf structure for photosynthesis and gas exchange
Which layer of a leaf contains the most chloroplasts, and why is it positioned where it is?
Show the answer
The palisade mesophyll, which lies just below the upper surface so that its chloroplasts absorb the most light. -
Factors affecting the rate of transpiration
Explain why water uptake is only an estimate of the rate of transpiration.
Show the answer
A small amount of the water taken up is used in photosynthesis and to keep cells turgid, so uptake is slightly greater than the water lost. -
Plant adaptations to extreme environments
Explain how a thick waxy cuticle helps a plant survive where water is scarce.
Show the answer
The thick waterproof layer greatly reduces evaporation of water from the leaf surface.
The 9 subtopics
One subtopic is one session. Work down the list.
| Subtopic | What it covers | Questions |
|---|---|---|
| Photosynthesis as an endothermic reaction | Producers, biomass and why animals depend on photosynthetic organisms, the word and balanced symbol equations for photosynthesis, why it is endothermic, chlorophyll in chloroplasts, where the raw materials come from, and how a plant uses the glucose and oxygen it makes. | 13 |
| Limiting factors in photosynthesis | What a limiting factor is, how light intensity, temperature and carbon dioxide each set the rate of photosynthesis, and reading graphs of rate against light under different conditions. | 14 |
| Light intensity and the rate of photosynthesis | Measuring the rate of photosynthesis in pondweed, the variables and controls in the lamp-distance investigation, improving on counting bubbles, the inverse square relationship and calculating relative light intensity as 1 ÷ distance², why light limits the rate in dim light, and hypotheses, predictions and whether data support them. | 24 |
| Root hair cells, xylem and phloem | How root hair cells absorb water by osmosis and mineral ions by active transport, why salty water makes a plant wilt, how dead, lignified xylem vessels carry water, and how phloem sieve tubes and companion cells use energy to move sucrose up and down the plant. | 15 |
| Transpiration and translocation | Transpiration and the path of water from soil to air, how evaporation pulls water up the xylem, stomata and how guard cells open and close them, wilting, and the translocation of sucrose in the phloem from the leaves to growing regions and storage organs using energy from respiration. | 14 |
| Leaf structure for photosynthesis and gas exchange | How the broad, thin shape and large surface area to volume ratio of a leaf suit it to photosynthesis and gas exchange, the palisade and spongy mesophyll, the waxy cuticle and transparent upper epidermis, stomata on the lower surface, and the xylem and phloem in leaf veins. | 9 |
| Factors affecting the rate of transpiration | How light, wind, temperature and humidity affect water uptake, setting up and using a potometer, why uptake only estimates transpiration, calculating rates per minute, per hour, by volume and per unit of leaf area, and plotting graphs, lines of best fit, gradients, intercepts and y = mx + c. | 24 |
| Plant adaptations to extreme environments | How desert, dry grassland and cold-climate plants reduce water loss with small leaves and spines, thick waxy cuticles, few stomata on the lower surface, stomata opened only at night or sunk in pits and surrounded by hairs, rolled leaves and needle-shaped leaves. | 8 |
| Plant hormones and their commercial uses | Plant hormones and where auxin is made, phototropism and gravitropism and how auxin bends shoots towards light and roots downwards, and the commercial uses of auxins in weedkillers and rooting powder, gibberellins in germination, flowering and seedless fruit, and ethene in ripening fruit. | 17 |
How the guide is worked
Answering a question from memory stores it far better than reading the answer again. The guide runs that as a fixed procedure on one subtopic at a time, about twenty minutes a session.
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Step 1 · Closed book
Cover the answers. Work through one subtopic and write down what you can. Leave blanks where you have nothing.
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Step 2 · Open book
Go back to the top. Read each printed answer and write it out in full, including the ones you had right.
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Step 3 · Closed book again
Same questions, same order, from memory. The gap between pass one and pass three is the session result.
Read the full method, the return schedule and the research behind it.
Nearby topics
Edexcel GCSE Biology, Higher tier Active Recall Guide
Every topic, not just this one. 1,386 questions with their answers.