Differentiate between the following pairs on the basis of what is mentioned in the brackets:
Osmosis and Active Transport (Substances undergoing movement)
Topic: Osmosis and active transport
Answer
In OSMOSIS it is the SOLVENT — WATER — that moves, through a selectively permeable membrane.
In ACTIVE TRANSPORT it is the SOLUTE — dissolved MINERAL IONS and molecules such as glucose and amino acids — that is moved, using energy from ATP.
The brackets ask about the SUBSTANCES MOVING, so that must be the basis: WATER in osmosis, SOLUTES in active transport.
The other differences are worth a row each but are not what was asked.
WHY PLANTS NEED ACTIVE TRANSPORT: soil often contains a LOWER concentration of a mineral than the root cell already holds. Diffusion would move the mineral OUT of the root. Active transport is the only way to go on absorbing it — and it is why root cells are rich in mitochondria, which supply the ATP.
| Point of difference | Osmosis | Active transport |
|---|---|---|
| Substance moving | Water (the solvent) | Mineral ions and solutes |
| Direction | Down the concentration gradient | Against the concentration gradient |
| Energy | Not required (passive) | Required, from ATP |