British Sign Language Glossaries of Curriculum Terms

BSL Environmental Science Glossary - Active transport definition

Definition: Active transport happens when a lot of energy is used for the uptake of certain minerals or ions. In trees, the root hair cells have lots of minerals, but the earth surrounding it does not have as many minerals as they are more dispersed. So, for the tree to take up the minerals against the concentration gradient (low to high), the cell needs to expend lots of energy for the minerals outside to be taken up from the soil. In humans, the small intestine has blood vessels running alongside, which have lots of minerals. When food is ingested and comes down into the small intestine to be absorbed, the concentration of minerals in the digested food is low compared to that in the blood. The body needs to extract the minerals from the food, but in order to do so, cellular energy is needed to pull the minerals from the food up into the bloodstream. This is active transport, the active uptake of minerals from a low concentration situation to a high concentration situation against the gradient, using cellular energy.