Back to the full dot-point answer
SingaporeCombined ScienceQuick questions
Biology: Cells and Human Physiology
Quick questions on Diffusion, osmosis and active transport explained: O-Level Combined Science
6short Q&A pairs drawn directly from our worked dot-point answer. For full context and worked exam questions, read the parent dot-point page.
What is diffusion?Show answer
Diffusion is the net movement of particles from a region of higher concentration to a region of lower concentration, down a concentration gradient, until they are evenly spread. It happens because particles move randomly. No energy from the cell is needed. Oxygen diffuses into cells and carbon dioxide diffuses out this way.
What is osmosis?Show answer
Osmosis is the net movement of water molecules from a region of higher water concentration (a more dilute solution) to a region of lower water concentration (a more concentrated solution), through a partially permeable membrane. The membrane lets water through but not the larger dissolved particles. Osmosis is how water enters and leaves cells.
What is active transport?Show answer
Active transport is the movement of particles against a concentration gradient, from lower to higher concentration. Because this is "uphill", it requires energy from respiration (ATP). Cells doing a lot of active transport have many mitochondria. Root hair cells absorbing mineral ions, and the gut absorbing glucose, use active transport.
What is q1?Show answer
Define osmosis. [2 marks]
What is q2?Show answer
State one similarity and one difference between diffusion and active transport. [2 marks]
What is q3?Show answer
Explain why a red blood cell bursts when placed in pure water but a plant cell does not. [2 marks]
Have a question we have not covered?
This dot-point answer is short enough that we have not extracted many short questions yet. Read the full dot-point answer or ask Mo, our study assistant, in the chat for follow ups.