The region(s) where a countercurrent mechanism
operates is (are) indicated by
a. A.
b. B.
c. C.
d. D.
e. C and D.
Answer: b
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The respiratory systems of fish and birds are similar in that both______________.
A. utilize air sacs. B. have similar partial pressures of oxygen in the environmental medium. C. have unidirectional flow of the environmental medium over the gas exchange surfaces. D. employ countercurrent exchange.
What is evolution that occurs as a result of chance events?
A) sexual selection B) genetic drift C) gene flow D) population bottleneck
The difference between vertical and horizontal transmission of plant viruses is that vertical transmission is _____
A) transmission of a virus from a parent plant to its progeny, and horizontal transmission is one plant spreading the virus to another plant B) the spread of viruses from upper leaves to lower leaves of the plant, and horizontal transmission is the spread of a virus among leaves at the same general level C) the spread of viruses from trees and tall plants to bushes and other smaller plants, and horizontal transmission is the spread of viruses among plants of similar size D) the transfer of DNA from a plant of one species to a plant of a different species, and horizontal transmission is the spread of viruses among plants of the same species
Hypothesis I: A flavin pigment absorbs blue light; this pigment then activates the proton pump.Hypothesis II: When CO2 concentration rises, a membrane receptor inactivates the proton pump.Which hypothesis is supported by the fact that stomata open when exposed to white light, a mixture of all colors of light?
A. Supports both hypothesis I and II. B. Supports only hypothesis I. C. Supports only hypothesis II. D. Supports neither hypothesis.