Which of these is a proper contrast between birds and mammals?
a) Birds, unlike mammals, require no parental care.
b) Birds have air sacs in addition to lungs; mammals have no air sacs.
c) Birds are egg laying; no mammals lay eggs.
d) Birds are ectothermic; mammals are endothermic.
Answer: b) Birds have air sacs in addition to lungs; mammals have no air sacs.
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Our sense "fullness" after a big meal is due to
A. mechanoreceptors. B. thermoreceptors. C. stretch receptors. D. electromagnetic receptors. E. chemoreceptors.
The best way to reclaim an ecosystem that is extensively damaged is to ____
a. allow natural succession to take over b. remove all predators from the area c. seed the area with a type of grass d. bring in beneficial insects e. implement ecological restoration
Cnidarians have _______
Fill in the blank(s) with the appropriate word(s).
Which one of the following causes transmembrane channels in target cells?
A) granzymes B) hapten C) IL-1 D) IL-2 E) perforin