Homeostasis (waste products)

Question 1

What is excretion?

Answer 1

the removal of waste substances produced in metabolic reactions.

Question 2

What substances does urea aim to excrete from the body?

Answer 2

• Water
• Nitrogenous substances
• Salts

Question 3

Explain what urea is and how it is excreted: (5)

Answer 3

Urea is a waste substance produced in the liver and is excreted by the kidneys as urine to remove excess amino acids from our body
Amino acids as deaminated in the liver
The amine group from the amino acid is removed from the molecule
This forms the nitrogenous substance ammonia which is highly toxic so is converted into urea, a less toxic substance
The rest of the molecule can be converted into other stores or substances or used in respiration.
The urea travels into the blood to be filtered out by the kidneys, creating urine which we excrete.

Question 4

State and describe the process involved in the production of urea:

Answer 4

Deamination is when the amine group is removed from the amino acid molecule, forming highly toxic ammonia which is quickly converted into less toxic urea.

Question 5

How does our body increase our water content?

Answer 5

drinking
eating
respiration

Question 6

How does our body decrease our water content?

Answer 6

urine
egestion
sweating
breathing

Question 7

Explain why it is important for our body to remove CO₂ from our body:

Answer 7

High levels of CO₂ causes the pH of our blood to drop (become more acidic) which can denature enzymes effecting our metabolic reactions.

Question 8

Explain why it is important for our body to remove excess amino acids from our body:

Answer 8

When our liver deaminates excess amino acids, it forms ammonia which converts into urea, both are toxic substances that poison our body.