本题目来源于试卷: Continuity and Change D.9 Homeostasis，类别为 IB生物学
[单选题]
Which of the following is only able to trigkl b a 9ajtmko1oz-. ;u-d;4oager a response in a cell by br8,3a5w dh .wwosb ;psinding to a receptor in ts s pw,haw;bowd3r8 .5he plasma membrane?
A. Insulin
B. Testosterone
C. Oestradiol
D. Progesterone
参考答案: A
本题详细解析:
Choice A is correct because insulin is a peptide hormone, which is polar so cannot directly pass through the plasma membrane. Instead it binds to receptors in the plasma membrane which triggers intracellular signalling pathways. Choices B, C and D are all incorrect, as they are all non-polar steroids so can diffuse through the plasma membrane and bind directly to receptors inside the cell, affecting gene expression.
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