Question 1 Hard
Which process is reduced when a plant has damaged leaves? Give one word.
Show answer
Answer: photosynthesis
- Leaves make food.
- So photosynthesis falls.
Plant disease and plant defences: GCSE Combined Science Biology practice questions
A second set of questions on plant disease and plant defences. They are different from the ones on the topic page. Try each, then open the answer and compare your working.
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Question 2 Hard
A fungus makes black spots on rose leaves and stems. Name the disease.
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Answer: rose black spot
- The fungus makes dark spots.
- It is rose black spot.
Question 3 Hard
Bark has layers of dead cells. State what this defence is called: physical or chemical.
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Answer: physical
- It is a barrier.
- So it is physical.
Question 4 Hard
Why is magnesium shortage a problem for a plant? Give the process that is reduced.
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Answer: photosynthesis
- Magnesium makes chlorophyll.
- Without it photosynthesis falls.
Question 5 Easy
Name one pest that damages plants by feeding on them.
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Answer: aphid
- Some small insects feed on plants.
- An aphid is one.
Question 6 Easy
What do farmers add to soil to supply mineral ions?
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Answer: fertiliser
- Soil can run short of mineral ions.
- Farmers add fertiliser.
Question 7 Medium
Which part of a plant cell is hard to break through and works as a physical barrier?
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Answer: cell wall
- It is a strong outer layer made of cellulose.
- It is the cell wall.
Question 8 Medium
A plant makes poisons that stop animals eating it. Is this a physical, chemical or mechanical defence?
Show answer
Answer: chemical
- The plant makes a substance.
- So it is a chemical defence.
Quick checks
Short questions with options. Choose one before you open the answer.
Check 1
Name four signs of plant disease.
Show answer
Stunted growth, spots on leaves, decay and discolouration.
Check 2
How can a gardener identify a plant disease?
Show answer
A gardening manual or website, a laboratory, or a testing kit.
Check 3
What do plant testing kits use?
Show answer
Monoclonal antibodies.
Check 4
What are nitrate ions needed for?
Show answer
To make amino acids and proteins.
Check 5
What happens if a plant lacks nitrate?
Show answer
Growth is stunted.
Check 6
What are magnesium ions needed for?
Show answer
To make chlorophyll.
Check 7
What happens if a plant lacks magnesium?
Show answer
The leaves turn yellow. This is chlorosis.
Check 8
What is chlorosis?
Show answer
Yellowing of leaves due to a lack of chlorophyll.
Check 9
Name three physical plant defences.
Show answer
Cellulose cell walls, a waxy cuticle and layers of dead cells such as bark.
Check 10
Name two chemical plant defences.
Show answer
Antibacterial chemicals and poisons.
Check 11
Name two mechanical plant defences.
Show answer
Thorns and hairs, or leaves that droop or curl when touched.
Check 12
What is mimicry in plants?
Show answer
Looking like something harmful to avoid being eaten.
Check 13
Why does disease reduce plant yield?
Show answer
Less photosynthesis happens, so there is less growth.
Check 14
What is an aphid?
Show answer
A pest insect that feeds on plants.
Check 15
What do fertilisers supply?
Show answer
Mineral ions such as nitrate and magnesium.
Check 16
What is stunted growth?
Show answer
Growth that is smaller than normal.
Check 17
Why does knowing the cause of a plant disease help?
Show answer
It tells you which treatment to use, such as a fungicide for a fungus.
Check 18
Where do plants take in mineral ions from?
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From the soil, through the roots.
Check 19
What do plants make from nitrate ions?
Show answer
Amino acids, which are built into proteins.
Check 20
What do plants make from magnesium ions?
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Chlorophyll.
Check 21
Why do leaves turn yellow when a plant lacks magnesium?
Show answer
It cannot make enough chlorophyll, the green pigment.
Check 22
What is mimicry in a plant, and why does it help?
Show answer
Looking like something harmful, so animals avoid eating it.
Check 23
What is a waxy cuticle?
Show answer
A waxy layer on a leaf that stops pathogens and water getting in.
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