What is the function of valves in the heart?
a. to prevent backflow of blood
b. to prevent clot formation
c. to form blood cells
d. to push blood ahead
Ans: a. to prevent backflow of blood
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In the Foofnagle family, the trait of being able to yodel affects members of both sexes in every generation. This trait could be
A) autosomal recessive or autosomal dominant. B) autosomal dominant but not autosomal recessive. C) conclusive or inconclusive. D) caused by something in the environment and not inherited at all.
Amoebas move and feed by using _____.
Fill in the blank(s) with the appropriate word(s).
Most bird species that form flocks show a negative relationship between flock size and individual vigilance (i.e., the larger the flock, the less often an individual lifts its head to scan the surrounding environment). However, some bird species have shown a positive relationship between flock size and individual vigilance. The positive relationship is particularly strong when flocks are space-constrained, such as in small ponds or fields. What is the most likely explanation for this?
A. As flock size increases, the number of "cheaters" increases, so individuals must spend more time scanning for predators. B. As flock size increases, the risk for interference and aggression between members increases, so individuals must scan for both conspecifics and predators. C. As flock size increases, the risk of predation for any given member increases, so individuals must spend more time scanning for predators. D. As flock size increases, mating opportunities decrease, so individuals must spend more time scanning for potential mates.
When the reproductive cells of different species are incompatible and cannot accomplish fertilization,
it is referred to as: a. behavioral isolation. b. gametic isolation. c. hybrid breakdown. d. temporal isolation. e. hybrid sterility.