Prions contain
A. DNA only.
B. protein only.
C. RNA only.
D. DNA, RNA, and protein.
B. protein only.
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Whose work with fruit flies presented the first clear evidence that the genes determining Mendelian traits reside on chromosomes?
A. Thomas Hunt Morgan B. Gregor Mendel C. Karl Correns D. Walter Sutton
Which of the following would decrease mean arterial pressure?
A) increase in total peripheral resistance B) increase in arteriole diameter C) increase in heart rate D) increase in venous return E) increase in stroke volume
Leptin is a circulating hormone that is produced by fat cells and plays a role in body metabolism and obesity. It normally binds to receptors in the brain and inhibits appetite. Studies have demonstrated that when obese mice that are leptin deficient are injected with leptin they quickly lose their excess weight. Interestingly, however, many overweight people have high levels of leptin in their bloodstream. Why do you think that the high levels of leptin in obese individuals are insufficient to curb their appetite?
A. In obese people with high levels of leptin, the leptin is a non-functional second messenger. B. The form of leptin released by obese people may lack protein kinase activity. C. Obese people who have high levels of leptin may have a leptin receptor with decreased sensitivity. D. Paracrine signaling may be disrupted in obese people with high levels of leptin.
In the term trace element, the adjective trace means that
A) the element is required in very small amounts. B) the element can be used as a label to trace atoms through an organism's metabolism. C) the element is very rare on Earth. D) the element enhances health but is not essential for the organism's long-term survival.