Diffusion, Osmosis, and Active Transport in Biology
This page provides an overview of three important biological processes: diffusion, osmosis, and active transport. It also includes information on gas exchange and a practical experiment involving osmosis in potatoes.
Diffusion
Definition: Diffusion is the net movement of particles (gas or liquid) from an area of high concentration to low concentration.
Diffusion plays a crucial role in various biological processes:
- In leaves, it facilitates gas exchange, with carbon dioxide moving in and oxygen moving out.
- In the lungs, oxygen diffuses from the alveoli into the bloodstream.
Example: Gas exchange in leaves and lungs occurs through diffusion.
Osmosis
Definition: Osmosis is the net movement of water across a partially permeable membrane from an area of high concentration to low concentration.
Osmosis is important in various biological contexts:
- It occurs in root hair cells during transpiration.
- Unlike active transport, osmosis does not require energy.
Example: In a potato osmosis experiment, water will move into the potato if the surrounding solution has a higher concentration of water molecules.
Active Transport
Definition: Active transport is the net movement of particles from an area of low concentration to high, against the concentration gradient.
Key points about active transport:
- It requires energy (ATP) as it goes against the concentration gradient.
- Root hair cells in plants use active transport to absorb mineral ions.
- These cells are packed with mitochondria to provide the necessary energy.
Highlight: Both plants and animals use active transport. In plants, root hair cells actively transport mineral ions for absorption.
Root Hair Cell Adaptations
Root hair cells have specific adaptations for their function:
- Large surface area to increase absorption of water and mineral ions.
- Numerous mitochondria to release energy for active transport.
- No chloroplasts, as these cells are underground.
Potato Osmosis Practical
The transcript outlines steps for a potato osmosis experiment:
- Slice potatoes into equal lengths and weigh each piece.
- Record the starting mass and place each piece into solutions with different sugar concentrations.
- Leave the potato pieces in the solutions for an hour.
- Remove them, dry thoroughly, and weigh again.
- Record the end mass to determine which solution is isotonic, hypotonic, or hypertonic.
Highlight: If the solution is isotonic, the weight of the potato would remain the same.
This practical experiment helps students understand the concept of osmosis and how it affects cells in different environments.
