Growing more crops Edexcel International GCSE Biology revision
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In plain words
A glasshouse is a way of giving plants a perfect summer all year. Inside, a grower can control everything photosynthesis depends on: warmth, light and carbon dioxide. Outside, the battles are for nutrients and against pests.
Three things to know
- Glasshouses and polythene tunnels raise crop yields by keeping plants warm, sheltered and well lit. Burning fuel inside adds both warmth and carbon dioxide, so photosynthesis is faster.
- Fertilisers add mineral ions, such as nitrates for making proteins, so crops grow bigger.
- Pests can be controlled with pesticides (quick, but may kill other species and build up in food chains) or with biological control, which uses a natural predator (longer-lasting and with no chemicals, but slower and it never kills every pest).
Tips and tricks
- In a glasshouse, more carbon dioxide and more warmth both speed up photosynthesis, as long as there's enough light.
- Compare pesticides with biological control point for point: speed, effect on other species, how long it lasts.
It lands in your notebook with its questions as flashcards.
Growing more crops: 5 questions and answers
These are the quiz’s questions. Do the quiz first, then come back here for the ones that got you.
Why is the temperature raised in a glasshouse?
Enzymes work faster when it is warmer.
Which gas is added to glasshouses to increase yield?
It is a raw material for photosynthesis.
What is biological control?
Ladybirds eating aphids is an example.
What is a disadvantage of pesticides?
They can also build up in food chains.
What do plants use nitrate ions for?
Proteins are needed for growth.
Quiz
5 questions
Tap an answer and you’ll see straight away whether it’s right, and why.
Worksheet
3 questions, 8 marks. Write your answers on paper, then check them.
Growing more crops
Edexcel International GCSE Biology 4BI1 · 8 marks · papermunch.org
Name ______________________________ Date ______________
Explain how a glasshouse increases the yield of a crop.[3]
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It keeps the temperature higher, so photosynthesis and growth are faster. Carbon dioxide can be added (for example by burning fuel), increasing the rate of photosynthesis. Light, water and pests can also be controlled.
Explain why farmers add nitrate fertiliser to soil.[2]
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Plants need nitrate ions to make amino acids and proteins for growth. Adding them increases the crop yield.
Give one advantage and one disadvantage of biological control compared with using pesticides.[3]
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Advantage: no chemicals, so other species are not harmed and nothing builds up in food chains; or its effect lasts longer. Disadvantage: it is slower, or it does not kill all the pests, or the control organism may itself become a pest.
Answers: Growing more crops
- 1. It keeps the temperature higher, so photosynthesis and growth are faster. Carbon dioxide can be added (for example by burning fuel), increasing the rate of photosynthesis. Light, water and pests can also be controlled.
- 2. Plants need nitrate ions to make amino acids and proteins for growth. Adding them increases the crop yield.
- 3. Advantage: no chemicals, so other species are not harmed and nothing builds up in food chains; or its effect lasts longer. Disadvantage: it is slower, or it does not kill all the pests, or the control organism may itself become a pest.