Question 1 Hard
What does a high concentration of auxin do to cell elongation in a root?
Show answer
Answer: inhibits it
- Roots respond the opposite way to shoots.
- Auxin inhibits elongation.
Plant hormones and tropisms: GCSE Combined Science Biology practice questions
A second set of questions on plant hormones and tropisms. They are different from the ones on the topic page. Try each, then open the answer and compare your working.
More questions
Question 2 Hard
Why do auxin weedkillers harm broad-leaved weeds but not wheat?
Show answer
Answer: broad-leaved weeds take up more auxin
- The broad leaves absorb the hormone.
- They grow too fast and die.
Question 3 Hard
How can ethene help supermarkets with fruit?
Show answer
Answer: to ripen fruit
- Fruit is picked unripe.
- Ethene is used to ripen it on arrival.
Question 4 Hard
In a shoot placed on its side, on which side does auxin collect?
Show answer
Answer: the lower side
- Gravity pulls auxin down.
- It collects on the lower side.
Question 5 Easy
Name the type of chemical messenger that controls growth in plants.
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Answer: hormones
- Plants use chemical messengers.
- They are hormones.
Question 6 Easy
Which part of a plant grows towards gravity: the root or the shoot?
Show answer
Answer: root
- Roots grow down into the soil.
- So it is the root.
Question 7 Medium
What name is given to a plant growth response to a stimulus?
Show answer
Answer: tropism
- It is a growth response.
- This is a tropism.
Question 8 Medium
Is the growth of a shoot towards light a positive or a negative response?
Show answer
Answer: positive
- The shoot grows towards the stimulus.
- So it is a positive response.
Quick checks
Short questions with options. Choose one before you open the answer.
Check 1
What is phototropism?
Show answer
The growth of a plant in response to light.
Check 2
What is gravitropism?
Show answer
The growth of a plant in response to gravity.
Check 3
Do shoots grow towards or away from light?
Show answer
Towards it.
Check 4
Do roots grow towards or away from gravity?
Show answer
Towards it.
Check 5
Where is auxin made?
Show answer
In the tips of shoots and roots.
Check 6
Where does auxin collect in a shoot in one-sided light?
Show answer
On the shaded side.
Check 7
What does auxin do to shoot cells?
Show answer
It makes them elongate.
Check 8
What does a high concentration of auxin do in a root?
Show answer
It inhibits elongation.
Check 9
What do gibberellins do?
Show answer
End seed dormancy, promote flowering and increase fruit size.
Check 10
What does ethene do?
Show answer
It controls cell division and fruit ripening.
Check 11
What is rooting powder?
Show answer
A powder with auxin that makes cuttings grow roots.
Check 12
How do auxin weedkillers work?
Show answer
They make broad-leaved weeds grow too fast and die.
Check 13
How can auxin be used to make seedless fruit?
Show answer
It makes fruit grow without pollination.
Check 14
How is ethene used by fruit growers?
Show answer
To control ripening during transport and storage.
Check 15
What is seed dormancy?
Show answer
A stage where a seed does not germinate.
Check 16
Why is it useful for shoots to grow towards light?
Show answer
The leaves can get more light for photosynthesis.
Check 17
What is a hormone?
Show answer
A chemical messenger made in one part of an organism that changes how another part works.
Check 18
What is a tropism?
Show answer
A growth response of a plant to a stimulus.
Check 19
What does a positive tropism mean?
Show answer
Growth towards the stimulus.
Check 20
What does a negative tropism mean?
Show answer
Growth away from the stimulus.
Check 21
Why does a shoot bend towards light?
Show answer
Auxin moves to the shaded side and makes those cells elongate more.
Check 22
Which side of a seedling on its side collects auxin?
Show answer
The lower side.
Check 23
What is germination?
Show answer
When a seed begins to grow into a plant.
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