BIOLOGY, M1 2020 VCE 4c

The diagram below is a simplified example of a signal transduction pathway. Three steps in the pathway are labelled.

Explain whether the pathway shown is initiated at Step 1 by a hydrophobic molecule or by a hydrophilic molecule. (2 marks)

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→ The molecule must be hydrophilic as it does not pass through the plasma membrane but instead attaches to a receptor protein.

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→ The molecule does not pass through the plasma membrane but instead attaches to a receptor protein.

→ Therefore, the molecule is hydrophilic.