Biology · Excretory Products and Their Elimination · NEET
No, and this is the trap NEET loves. Excretion removes metabolic wastes made INSIDE the cells (like urea from protein breakdown). Egestion removes undigested food (faeces) that was never absorbed into the body. Faeces is not a true excretory product because it was never part of the cell's metabolism.
Yes. NCERT clearly lists CO2 as an excretory product along with ammonia, urea, uric acid, water and ions. CO2 is a waste of cellular respiration and is removed mainly by the lungs. So excretion is not only about the kidney.
Secretion is the release of a USEFUL substance (like enzymes, hormones or bile) that the body still needs for a function. Excretion is the removal of a HARMFUL or useless waste. Same word ending, opposite purpose.
Wastes like ammonia are very toxic. If they build up they damage cells and disturb the balance of water and ions (homeostasis). Excretion keeps the internal environment steady so enzymes and cells can work normally.
Yes, but only the EXCESS is excreted. The body accumulates extra water and ions (Na+, K+, Cl-, phosphate, sulphate) from food and metabolism. Excretion removes the surplus while keeping the amount the body needs.
Try the real previous-year questions from this chapter — each with the answer and a full solution.
Excretion is the removal of harmful waste substances made by the body's metabolism, such as ammonia, urea, uric acid, carbon dioxide, extra water and extra salts.
The major ones are urea (the main nitrogenous waste), plus carbon dioxide, water and ions. Small amounts of uric acid, creatinine and ammonia are also removed.
Ammonia is the most toxic and needs a large amount of water to be removed. Uric acid is the least toxic and needs the least water. Urea is in between.
The lungs remove CO2 and some water, the liver removes bilirubin, cholesterol and drugs (mostly through bile into faeces), and the skin removes salts and some urea through sweat.
It is the opening concept of the chapter Excretory Products and Their Elimination. Understanding what counts as a waste and how it differs from egestion sets up ammonotelism, ureotelism and the whole nephron topic.
