The correct answer is d: a
target cell's response is determined by the components of its signal transduction pathways.
The response of a cell to a hormone depends on the cell’s receptor and a signal transduction. When a peptide hormone binds to a receptor on the cell membrane, a second messenger is activated in the cytoplasm. The second messenger has a role of triggering signal transduction leading to the cellular response. Lots of different signal transduction processes (for example, different intracellular proteins) are used to coordinate the behaviour of target cells.
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There’s actually 100 but only 8 of them infect humans
Quiet inspiration is _an active process_, and quiet expiration is _a passive process_.
I believe that is ecology
N colder near the poles go's with maritime/ polar air mass
