Option B, "They need more oxygen to function, so gas exchange needs to increase. "
I think the best answer would be A. since the number of prairie dogs decreased from the picture on the left to the picture on the right. Hope this helped :p
The causitive agent of the cohesion-tension model of xylem transport is transpiration. During the process of transpiration, water vapor is lost from the stomata of the leaf. To replace this water, water from adjacent cells is withdrawn. The water molecules stick together due to cohesion and are transported upwards through the stem in the form of a stream.<span />
Answer:
The return of blood to the heart is assisted by the action of the skeletal- muscle pump. As muscles move, they squeeze the veins running through them. Veins contain a series of one-way valves, and they are squeezed, blood is pushed through the valves, which then close to prevent backflow.
We have an internal skeleton and a grasshopper has an external skeleton.
