Importance of Excreting Waste

Question 1

How Waste is Produced

Answer 1

Body breaks down complex organic compounds into simpler compounds, which are often toxic and harmful for our body

Question 2

Elimination of Wastes

Answer 2

• Lungs eliminate CO2 (CR waste)
• Large intestine eliminates toxic digestive wastes and indigestible material (fibre)
• Liver converts alcohol, heavy metals, hazardous waste from protein catabolism (ammonia) and nucleic acid catabolism (uric acid) into soluble compounds
• Kidney eliminates soluble compounds produced by liver (alcohol, heavy metals, urea, ammonia, uric acid, etc.)

Question 3

Waste from Proteins

Answer 3

Excess proteins get converted to carbs - requires deamination in liver which produces ammonia from amino group (highly toxic)
–> in fish, ammonia constantly expelled through gills, but must be stored in land animals
- Liver combines ammonia with CO2 to produce urea (less toxic)

Question 4

Excretion of Wastes in Unicellular Organisms

Answer 4

Waste is excreted directly into environment –> also have contractile vacuoles that expel excess water to prevent cell from bursting due to osmosis