Why haven't humans evolved a resistance to the common cold?
A) Colds are effectively killed by antibiotics, so there's no need.
B) Cold viruses haven't been in existence long enough to exert selective pressure.
C) Colds are not serious enough to remove nonresistant variants from the population.
D) We could evolve resistance if we stopped taking so many over-the-counter medications for colds.
C
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Which of the following is NOT a function of the integumentary system?
A. Defense against pathogens B. Fluid transport C. Supporting the weight of body structures D. Protection from dehydration E. Regulation of body temperature
In describing the initiation and transmission of action potentials in neurons, it would be INCORRECT to say that
A. the rate of transmission of an action potential is directly related to the diameter of the axon. B. information about the intensity of a stimulus is conveyed by changes in the size of the action potential generated. C. the resting potential is maintained by differential ion permeabilities and the sodium-potassium pump. D. a stimulus to the neuron can either depolarize or hyperpolarize the neuronal membrane.
All deserts have which of the following in
common? a. low rainfall amounts b. uniformly high temperature c. sand d. sparse vegetation e. large leafy plants
Which of the following statements is FALSE? Saturated fats _____
A) are more common in animals than in plants B) have many double bonds in the carbon chains of their fatty acids C) usually solidify at room temperature D) contain more hydrogen than unsaturated fats that consist of the same number of carbon atoms