Which is the best example of water regulating an organism’s body temperature?

a jogger sweating after a run

a fish passing water over its gills

a deer taking a drink from a stream

a leaf using water for photosynthesis

A jogger sweating after a run is the best example of water regulating an organism’s body temperature.

Explanation:

When a human being drinks water, the water content increases in the body. After the exercise, the water flows out of the body in the form of sweat and the body cools down as the temperature of body decreases.

That is the amount of excess water content in the body decreases or moves out of the body. Hence, in this manner the body temperature regulates.

A fish breathes with the help of his gills. When the fish gulps water through its mouth it passes through the gills. The oxygen in the water molecules gets absorbed by the gills and moves in the blood stream.

Therefore, the heart distributes oxygen in the body and carbon dioxide is moved from the body to the water. Hence, it does not affect the temperature of the fish.

Whereas a deer taking a drink from a stream is actually drinking to satisfy his thirst. This will again do not have any effect on deer's body temperature.

A leaf using water for photosynthesis will help in the preparation of food for the plant. There will be no effect of water regulation on the plant's body temperature.

Thus, we can conclude that option (a) is the correct answer.

1. the question asks the most appropriate, which seems to rule out "all of the above." your choice appears to be the correct one.

2. the protocol described is good for identifying correlation, but not cause and effect. for cause/effect, you need to devise a protocol that will assign the treatment (or not) to groups that have essentially the same "demographics" with respect to all the other variables. your choice regarding control group seems appropriate. random assignment of treatment (choice d) may be appropriate also. (i think you can argue that b and d are just different descriptions of the same method.)

3. d will randomize the birds, but may not guarantee there are 10 in each group. e will do both, so seems the better choice.

comment on question 2

based on the problem statement, it seems clear that confident, attentive drivers are more likely to use daytime running lights. so, the protocol might need to be devised in such a way that the lights would be turned on or off without the driver's knowledge. (an attentive driver will figure it out.) assigning a confident, attentive driver to a group required to drive without running lights might mess with his/her confidence and attentiveness. you don't want your experiment to do that. (nor do you want the experiment to subject a driver to greater risk of accident as a consequence of driving without running lights.) experiments involving human safety are always problematic.