Topic 5 - Kidneys and Kidney Treatment

Question 1

Three examples of substances removed from the body in urine.

Answer 1

Excess water
Ions
Urea

Question 2

How is urea formed? (4 marks)

Answer 2

Amino acids can not be stored by the body and it is too big to be filtered out by the body.
Amino acids are broken down into fats and carbohydrates in a process called deamination in the liver.
This produces ammonia as a waste product which is toxic to the body.
Ammonia is converted to urea.
Urea is a waste product that is filtered out of the blood by the kidney and excreted in urine.

Question 3

What happens in the kidneys during filtration.

Answer 3

The kidneys selectively absorb substances in blood that are in excess as it passes through the kidneys.

Question 4

Two molecules reabsorbed into the blood during selective reabsorption.

Answer 4

Water

Glucose

Question 5

Two reasons why you may lose more water in the body during exercise.

Answer 5

Sweat glands produce sweat which evaporates to release heat to its surroundings. The sweat contains water which is lost from the body.
You breath more often so water is lost as a waste product from increased aerobic respiration.

Question 6

Explain what would happen for the uptake of water by cells in the body if the ion content of the body was incorrect. (3 marks)

Answer 6

There is a concentration imbalance between water and ions.
This could affect the amount of water being absorbed or released from the cells via osmosis through a partially permeable membrane.
This would cause cells to damage as they undergo lysis or plasmolysis.

Question 7

Explain how the liver and kidneys respond to eating food high in protein. (4 marks)

Answer 7

In the liver, excess protein is converted to carbohydrates and fats in a process known as deamination.
Deamination produces ammonia which is a toxic waste product.
Ammonia is then converted to urea.
Urea is filtered out of the blood by the kidney and excreted in urine.