https://www.khanacademy.org/science/cambridge-o-level-biology-cie/x2a084a90105205d2:excretion/x2a084a90105205d2:principles-of-excretion/v/nitrogenous-wastes-excretion 2026-04-29T11:20:48.686238051Z Nitrogenous wastes - Excretion Nitrogenous wastes Khan Academy Pakistan video https://cdn.kastatic.org/googleusercontent/ZCdwTudJg6e6n-P2gsaUborP4izvMsGo71pvEVlX9dNYWcLXcP7VHkWpn2grt4TUP1KoJLQP9NswyHBuBLSFTBw Nitrogenous wastes - Excretion Nitrogenous wastes https://cdn.kastatic.org/ka-youtube-converted/wSwA2B9S-ao.mp4/wSwA2B9S-ao.mp4 501 Principles of Excretion