Homeostasis：练习题

Which molecule acts as a second messenger in the signaling pathway that leads to the closure of stomata during times of water stress?

Which part of the nephron is correctly matched with its role in the formation of urine?

A plant is experiencing severe water stress. How does the increase in abscisic acid (ABA) concentration lead to the loss of turgor in guard cells?

Which part of the mammalian kidney is responsible for the formation of glomerular filtrate through the process of ultrafiltration?

Which features of the Bowman’s capsule and its associated blood vessels facilitate ultrafiltration?

In the context of osmoregulation, state the sensor and the effector involved in the negative feedback loop when blood water potential decreases.

Describe the function of aquaporins in the collecting ducts and explain how their density in the luminal membrane is regulated by antidiuretic hormone (ADH).

Describe the cell signalling pathway initiated by glucagon that leads to the amplification of the signal and the eventual breakdown of glycogen in liver cells.

(a) Explain what is meant by the term homeostasis and state its importance in a multicellular mammal.
(b) Define negative feedback and explain how it is used to maintain a stable internal environment.

The maintenance of blood water potential is regulated by the hormone antidiuretic hormone (ADH).
(a) Describe the role of the hypothalamus and the posterior pituitary gland in the control of blood water potential.
(b) Explain the mechanism by which ADH affects the permeability of the collecting ducts, including the role of aquaporins.