Describe a hypothetical situation in which two isolated human populations evolve very different muscle fiber composition
In other words, what environmental conditions or food-gathering strategies might cause a prevalence of one fiber type (fast-twitch versus slow-twitch) to be more adaptive than another?
What will be an ideal response?
One might suggest that slow-twitch fibers are adaptive for hunters that used distance running to chase down prey that were fast but easily winded. In contrast, if prey animals were relatively slow moving, human hunters with lots of fast-twitch fibers might eat well and pass on their genes.
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What may result if the pharyngoesophageal sphincter does not function properly?
A) Food will cause the esophagus to collapse. B) Food will bypass the esophagus. C) Food will be swallowed much faster. D) Food cannot enter the esophagus.
Which of the following cells may eventually become spermatozoa?
a) Sertoli cells b) Sustentacular cells c) Spermatogonia d) Chief cells e) Speciation cells
Blood glucose levels are kept fairly steady in healthy people through the action of the hormones insulin and glucagon. Insulin decreases blood glucose by promoting glucose uptake by cells, whereas glucagon increases blood glucose by promoting release of glucose from cells. Describe these hormone actions as simple reflex pathways, identifying the stimulus, integrating center, efferent pathway, and response.
What will be an ideal response?
Which of the following organs can store glycogen?
A. spleen and pancreas B. kidney and adrenal gland C. large and small intestines D. liver and muscles E. stomach and pancreas