Answer ALL questions.
Write your answers in the spaces provided.
1 Plants can respond to and use light.
The photograph shows a seedling starting to grow from a germinating seed.
(a) Explain why the seedling needs a s
...
Answer ALL questions.
Write your answers in the spaces provided.
1 Plants can respond to and use light.
The photograph shows a seedling starting to grow from a germinating seed.
(a) Explain why the seedling needs a supply of magnesium ions.
(2)
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(b) Describe the role of IAA (auxin) in the phototropic response of plants.
(4
2 Acetylcholinesterase is an enzyme involved in regulating the transmission of nerve
impulses across some synapses.
(a) Acetylcholinesterase is found on the cell surface membranes of neurones and red
blood cells.
These acetylcholinesterase molecules have different primary structures.
In humans, a single gene codes for acetylcholinesterase.
(i) Explain how a single gene can give rise to acetylcholinesterase molecules with
different primary structures.
(2)
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