At any given point along the length of the gill lamella, how does the po2 of the blood flowing through the blood vessels in the lamella compare to the po2of the water flowing over the gill lamella?

a. the po2 of the blood never exceeds 50 percent of the po2 of the water.
b. the po2 of the blood is variable and cannot be compared to the po2 of the water.
c. the partial pressure of oxygen in the blood is equal to the po2 of the water.
d. the po2 of the blood is higher than the po2 of the water.
e. the po2 of the blood is lower than the po2 of the water.

the correct answer is (

explanation:

answer: - few nutrients

high pressure

low temperatures

explanation: 1. few nutrients:   open-ocean zone is located way far from the land, which is the main source of the essential nutrients.2. high pressure: pressure increases by 1 atmosphere for every 10 meters increase in depth.3. ample sunlight: a large fraction of the sunlight is reflected back to the atmosphere from the sea surface. 4. varying salinity: below the thermocline, the water is isolated from the atmosphere so the salinity remains stable over the year.5. low temperatures:   the temperature of open-ocean zone ranges from a low of -2°c to an average of 17°c

it enhances antibody production by t cells of the adaptive immune system.

hope i'm right

explanation: