Excretion

Insects excrete uric acid because it is less toxic and conserves water. This is particularly beneficial for insects living in dry environments, as they need to minimize water loss.

Oxygen produced during photosynthesis is released into the atmosphere through tiny pores called stomata, located on the surface of leaves.

Nephrons filter blood through the glomerulus, where small molecules like water, salts, urea, and glucose pass into the Bowman’s capsule. This filtrate is then processed in the tubules, where essential substances are reabsorbed, and waste products are concentrated into urine.

Urea is formed in the liver through the urea cycle when excess amino acids are broken down. The nitrogen from amino acids is converted into ammonia, which is toxic. The liver converts ammonia into urea, which is less toxic and can be safely excreted by the kidneys.

The main excretory products in humans are urea, excess salts, water, and nitrogenous waste. Urea is produced by the liver during the breakdown of proteins and is excreted in urine.