★ Must-know
📌 Excretion is the removal of metabolic waste from an organism, whereas secretion is the release of useful substances such as enzymes or saliva from cells or glands.
The main human excretory waste products are:
The lungs excrete carbon dioxide and water vapour produced by cellular respiration in exhaled air.
The kidneys excrete urea from deamination of excess amino acids in the liver, together with excess mineral salts and water, in urine.
Further detail
Excretion removes metabolic waste, whereas secretion releases useful substances.
1. Regarding excretion and waste products, which statements are correct?
2. Concerning the distinction between excretion and secretion, select the correct statements:
3. Which statements accurately identify organs and their excretory products?
What distinguishes excretion from secretion in organisms?
Excretion removes metabolic waste, secretion releases useful substances.
What are the main human excretory waste products?
Carbon dioxide, water, bile pigments, urea, and mineral salts.
Which substances do the lungs excrete in exhaled air?
Carbon dioxide and water vapour.
What waste does the kidney excrete in urine?
Urea, excess mineral salts, and water.
From where is urea in urine produced?
From deamination of excess amino acids in the liver.
What does the skin excrete in sweat?
Mineral salts, traces of urea, and water.
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