Exctretion and urea formation

Question 1

What is the process of removing toxic waste substances made by cells called?

Answer 1

Excretion

Excretion specifically refers to the removal of waste products from chemical reactions, not undigested food.

Question 2

What is the incorrect term sometimes used for the removal of faeces?

Answer 2

Excretion

The correct term for the removal of faeces is egestion.

Question 3

What are the two primary waste products of respiration?

Answer 3

• Carbon Dioxide
• Water

Carbon dioxide is removed via the lungs in mammals and through leaves in plants.

Question 4

What is the term for the process of breaking down excess amino acids in humans?

Answer 4

Deamination

Deamination is necessary because humans cannot store excess amino acids.

Question 5

Where are excess amino acids filtered into for processing?

Answer 5

Liver

Excess amino acids are filtered into the liver via the hepatic artery and hepatic portal vein.

Question 6

What toxic substance is produced when amino acids are broken down?

Answer 6

Ammonia

Ammonia is highly toxic and must be converted into urea.

Question 7

What is the less toxic chemical that ammonia is converted into?

Answer 7

Urea

Urea is less toxic and can be excreted from the body.

Question 8

How are carbon dioxide and oxygen exchanged in plants?

Answer 8

Through leaves

Both carbon dioxide and oxygen move in and out of the leaves as plants photosynthesize and respire.

Question 9

Which organ removes carbon dioxide from the blood?

Answer 9

Lungs

Carbon dioxide is removed from the blood via the lungs.

Question 10

Where is urea removed from the body?

Answer 10

• Kidneys
• Skin

Urea is excreted from the body through the kidneys and skin.

Question 11

True or False: Faeces consists of waste products from chemical reactions.

Answer 11

False

Faeces consists of undigested food that has not entered cells.