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(a) A gardener decided to kill the dandelion plants growing in his lawn - Edexcel - GCSE Biology - Question 7 - 2020 - Paper 1
Question 7
(a) A gardener decided to kill the dandelion plants growing in his lawn. The gardener set up a trial to see which concentration of weed killer would kill the most ... show full transcript
Worked Solution & Example Answer:(a) A gardener decided to kill the dandelion plants growing in his lawn - Edexcel - GCSE Biology - Question 7 - 2020 - Paper 1
Step 1
Give one variable the gardener should control when completing this trial.
Answer
One variable that the gardener should control is the amount of light available to each area. Ensuring that all areas receive the same light will help in accurately assessing the effectiveness of the different weed killer concentrations.
Step 2
State and explain the conclusions the gardener can make based on his trial.
Answer
The gardener can conclude that an 80% concentration of the weed killer is the most effective, as it resulted in the total elimination of dandelion plants in those areas within two weeks. This demonstrates that higher concentrations are more effective for killing dandelions compared to lower concentrations, which only reduced the number of plants without completely eradicating them.
Step 3
Explain how plant hormones work as weed killers.
Answer
Plant hormones, such as auxins, can disrupt the normal growth processes of plants. When applied in high concentrations, these hormones can cause uncontrolled growth, leading to wilting and eventual death of unwanted plants, like weeds.
Step 4
Explain how phototropism is controlled in plant shoots.
Answer
Phototropism is controlled by the distribution of auxin, a plant hormone, in response to light. When light shines on one side of a plant, auxin accumulates on the shaded side, promoting growth on that side. This differential growth causes the plant to bend towards the light source, allowing it to maximize light absorption for photosynthesis.