Definition: A protective substance that exists in the serum or other bodily fluid and is capable of killing microorganisms; complement.

Alright class, settle down now, let’s take a look! Today we’re tackling a word with a fascinating role – “complement.” The dictionary gives us a good starting point: "A protective substance in your blood..." Think of it this way, like a superhero team, you see? 'Complement' means a group that works together perfectly. Specifically, when we talk about biology and the body, it refers to a system – a very clever one! It’s a collection of proteins floating around in your blood, serum, or other bodily fluids. They don’t just sit there; they're active ! These proteins work together to defend you against invaders – nasty little microorganisms like bacteria and viruses. They “complement” each other, meaning one protein triggers another, building up a powerful defense force. It’s like a chain reaction of protection! So, it kills those germs, keeps you safe and sound, that's the complement's profound sound! Do you have any questions about this amazing system? Let's discuss!