本题目来源于试卷: Form and Function B.1 Carbohydrates & Lipids，类别为 IB生物学
[单选题]
Which of the following is only able to trigger a response in a cell by biaf .htkfh(7 9ond7 7a(oc t 6cp;xcl0gldg0sa r/ing to a receptor in6r70oal(l sct/dap g cxgc70 ; the 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 isged;6g +; r m*a.edfse a peptide hormone, which is polar soe+ms.ad; gd ;e6rg*ef 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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