The embryonic heart starts beating as blood begins to flow through chorionic vessels at approximately ________ of development
A) day 3
B) day 12
C) week 2
D) week 3
E) the second trimester
Answer: D
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In albinism, ________ is lacking.
A) melanin B) keratin C) carotene D) keratinocytes E) collagen
Why is vasodilation prominent in the skin when a person increases physical activity?
A. It increases delivery of nutrients to the skin to induce sweating. B. Because skeletal muscles are close to the skin, they receive the oxygen via diffusion. C. Heat is dissipated across the skin from the blood to help cool the body. D. Exercise produces metabolites that induce vasodilation.
Linoleic acid and linolenic acid are examples of
A) transport proteins. B) lipoproteins. C) essential fatty acids. D) essential amino acids. E) vitamins.
A drop of dilute ammonium Hydroxide (NH4OH) is placed on one slide containing a large number of swimming paramecium. Under this condition, which of these behaviors of the paramecia will be observed?
a. They will eventually all swim toward the ammonium hydroxide b. They will show no net change in behavior to the ammonium hydroxide c. The will be instantly killed by the ammonium hydroxide d. They will eventually all swim away from the ammonium hydroxide