Practice Questions

1.Explain why cells must maintain the correct water content.

Cells must maintain the correct water content so they can function properly.
If too much water enters, cells may swell and burst.
If too much water leaves, cells shrink and cannot carry out normal processes efficiently.

2.Describe what happens to excess amino acids in the liver.

Excess amino acids are deaminated in the liver.
This removes the amino (nitrogen) group to form ammonia, which is toxic.
The ammonia is then converted into urea, which is transported to the kidneys and excreted in urine.

3.Describe how kidney dialysis removes urea from the blood.

In dialysis, blood flows past dialysis fluid separated by a partially permeable membrane.
The dialysis fluid contains no urea, so urea moves from the blood into the dialysis fluid by diffusion, down its concentration gradient.
The dialysis fluid is continuously replaced to maintain this gradient.
The cleaned blood is then returned to the body.