Focus on Pharmacology: Essentials for Health Professionals, 3e (Moini) Chapter 3 Pharmacokinetics 1) Simple diffusion involves: A) drugs crossing membranes against their gradient from areas of low concentration to high concentration B) movement of molecules from areas of higher concentration to areas of lower concentration C) a certain carrier protein D) unevenly distributed electrical charges Answer: B Explanation: B) Simple diffusion involves movement of molecules from areas of higher concentration to areas of lower concentration. Over time, drug molecules are inactivated (metabolized) by tissues, and additional doses may be administered to create a continual concentration gradient, from blood to tissue. 2) Which of the following is false regarding plasma membranes? A) They contain two layers of phospholipids. B) They contain cholesterol, carbohydrates, and proteins. C) Their phospholipids have a round head and one tail. D) Cholesterol and phospholipids are essential. Answer: C Explanation: C) Regarding plasma membranes, their phospholipids do NOT have a round head and one tail. While their heads are round and contain the phosphate, they have two tails, which are long-chain hydrocarbons. Other substances embedded in the membrane include cholesterol, carbohydrates, and proteins. 3) An example of a polar molecule is the: A) water molecule B) hydrogen molecule C) sugar molecule D) alcohol molecule Answer: A Explanation: A) A water molecule is an example of a polar molecule, which has unevenly distributed electrical charges. In the water molecule, the negative electrons remain closer, most of the time, near the oxygen atom in comparison to the two hydrogen atoms. Therefore, the area near the oxygen atom is usually negatively charged, whereas the area near the hydrogen atoms is usually positively charged.
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