Excretory System

Question 1

What is excretion

Answer 1

Is the removal of waste products from the body

Question 2

Metabolic reactions

Answer 2

All the reactions taking place in the body

Question 3

Liver

Answer 3

Is not an excretory organ but many waste products are formed in the liver and excreted elsewhere:

Nitrogenous waste:

• urea firmed from excess amino acids
• Uris acid from the breakdown of nucleic acids
• creatinine

Non-nitrogenous waste:

• toxins and drugs
• alcohol

Other excretory products formed in the liver:

• bile pigments formed from breakdown of Reed blood cells
• cholesterol, formed by breakdown of bile salts

Question 4

Excretory organs: 1. Kidney

Answer 4

Excretes all of the nitrogenous waste products formed in the liver
Also excretes non-nitrogenous waste such as carbon dioxide, excess water and ions

Question 5

Excretory organ: 2. Lungs

Answer 5

The carbon dioxide released from cellular respiration is carried to the lungs in the blood and exhaled by the lungs. Also a little water and heat is excreted this way

Question 6

Excretory organ: 3. Skin

Answer 6

Water, salts and a small amount of urea are released by the skin in the form of sweat

Question 7

Excretory organ: 4. Colon/gut

Answer 7

Bile pigments and cholesterol, formed in the liver, pass into the small intestine and are finally excreted from the colon in faeces

Question 8

The 4 excretory organs

Answer 8

1. Kidneys
2. Lungs
3. Skin
4. Gut/colon