Transport：练习题

Which substance is not primarily transported dissolved in the blood plasma in significant quantities?

A student investigates the rate of transpiration using a potometer. If the wind speed around the leafy shoot is doubled, and all other environmental factors remain unchanged, what immediate effect is expected on the rate of water uptake?

During a specific phase of the cardiac cycle, the ventricles begin to contract. For a brief moment, the pressure in the ventricles is higher than the pressure in the atria but still lower than the pressure in the aorta and pulmonary artery. What is the state of the heart valves during this moment?

Which factor is understood to increase the risk of developing coronary heart disease?

How does an increase in light intensity typically affect the rate of transpiration in a healthy green plant?

Explain why simple, unicellular organisms, such as Amoeba, can rely solely on diffusion for the movement of essential substances in and out of the cell.

Explain the driving mechanism of the transpiration stream in plants, and describe the physical property of water that allows this mechanism to work continuously up the xylem.

Why is the mammalian circulatory system described as a double circulation, and what is the primary advantage of this system over a single circulation?

Explain why simple diffusion is an adequate mechanism for nutrient and waste transport in single-celled organisms, but an inadequate system for large multicellular organisms like humans.

A student uses a potometer to investigate the effect of environmental conditions on the rate of water uptake in a leafy shoot.
(a) Explain how an increase in wind speed increases the rate of transpiration.
(b) Predict and explain the effect of a significant increase in humidity on the rate of movement of the air bubble in the potometer.