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Bioassay

Bioassay is a test that uses living things to measure how strong a substance is.

Think of it this way

You have three glasses of water on a counter. Each glass has a different amount of a mystery liquid added. You drop seeds into each glass and watch how many sprout. The glass where the most seeds sprout shows you the right amount of the substance.

Explaining bioassay by grade level

You can plant seeds in cups with plain water and salty water. The seeds in too much salt do not sprout. The more salt you add, the worse the seeds grow. The seeds show you how bad the salt is.

Projects that explore bioassay

Lettuce Seeds as a Salt Toxicity Bioassay

Lettuce seeds make surprisingly capable test organisms. You expose them to different doses of salt, then measure two responses: whether they sprout and how long their roots grow. As concentrations rise, fewer seeds germinate and roots grow shorter — a dose-response pattern that reveals how harmful a substance is to living tissue. That predictable, measurable response is exactly what turns this into a true bioassay, where a living organism's reaction tells you how strong or toxic a substance really is.

Hard