Active transport requires the input of energy into a system so as to move solutes against their electrochemical and concentration gradients. Which of the following is not one of the common ways to perform active transport?
(a) Na+-coupled
(b) K+-coupled
(c) ATP-driven
(d) light-driven
(b) Because K+ is a positively charged ion and the outside of the plasma membrane is positively charged, K+ has a very small electrochemical gradient across the membrane even though its concentration gradient is large. Because there is little net movement across the membrane for K+, it would not make a good source of energy to drive the transport of other molecules against their respective gradients.
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The tough, two-layered sac of connective tissue that holds the heart is called the ________
a. ventricle b. atrium c. myocardium d. pericardium
Darwin’s exposure to Lyell gave him insight on the ____
a. existing evidence from fossils b. record of catastrophic changes that encouraged evolution c. soundness of Lamarck's theories d. enormous lengths of time required for geologic events e. arguments for creationism
What would be the ATP yield for a molecule that is catabolized to form one molecule of pyruvate in a eukaryotic cell?
A. 10 ATP B. 11.5 ATP C. 12.5 ATP D. 25 ATP E. 30 ATP
Why does urine frequently have an acidic pH?
A. The kidneys filter and excrete H+ from the blood. B. The kidneys absorb H+ ions and excrete bicarbonate ions. C. The kidneys produce H+ in the process of filtering the blood. D. The blood has an acidic pH and the kidneys produce urine similar to the pH of the blood. E. There is a high concentration of hydrochloric acid (HCl) in the urine, making it highly acidic.