Indicate whether the following compounds are likely to cross a membrane by nonmediated or mediated transport: (a) ethanol, (b) glycine, (c) cholesterol, (d) ATP.

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#Question id: 31079

#Unit 4. Cell Communication and Cell Signaling

The second messenger, which opens calcium ion pores in endoplasmic reticulum and plasma membrane is:

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#Question id: 28313

#Unit 5. Developmental Biology

During acrosome-reacted sperm pathway sperm that have undergone the acrosome reaction bind directly to which of the glycoprotein?

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#Question id: 24460

#Unit 7. System Physiology – Animal

A 25-year-old medical student spent a summer volunteering in the sub-Saharan region of Africa. There he noted a high incidence of people reporting difficulty with night vision due to a lack of vitamin A in their diet. Vitamin A is a precursor for the synthesis of

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#Question id: 11583

#Unit 7. System Physiology – Animal

Use the figure to answer the following question.

In an experiment, rats' ovaries were removed immediately after impregnation, and then the rats were divided into two groups. Treatments and results are summarized in the table. The results most likely occurred because progesterone exerts an effect on the ________.

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#Question id: 2037

#Unit 4. Cell Communication and Cell Signaling

Which of the following complement receptor activate a humoral response by promoting trapping of an antigen-antibody complex?