unit 3 bio - movement into and out of cells

What is diffusion?

The net movement of particles from a region of higher concentration to a region of lower concentration, down a concentration gradient, due to random movement

Where does the energy for diffusion come from?

From the kinetic energy of random movement of molecules and ions

How do substances move into and out of cells?

By diffusion through the cell membrane

Why is diffusion important in living organisms?

It allows exchange of gases (like O₂ and CO₂) and solutes for processes such as respiration and waste removal

What factors affect the rate of diffusion?

Surface area, temperature, concentration gradient, and distance

What is the role of water as a solvent in organisms?

It helps in digestion, excretion, and transport of substances

What is osmosis?

The net movement of water molecules from a region of higher water potential (dilute solution) to a region of lower water potential (concentrated solution) through a partially permeable membrane

How does water move in and out of cells?

By osmosis through the cell membrane

What is a partially permeable membrane?

A membrane that allows only certain small molecules (like water) to pass through

How can osmosis be investigated?

Using materials like dialysis tubing or potato strips in solutions of different concentrations

What happens to plant cells in pure water?

They become turgid due to water entering the cell

What happens to plant cells in a concentrated solution?

They become flaccid or plasmolysed due to water leaving the cell

What supports a plant cell’s structure?

The pressure of water inside the cell pressing outwards on the cell wall (turgor pressure)

Why is osmosis important to organisms?

It controls water uptake and loss, maintaining cell function and hydration

What is active transport?

The movement of particles through a cell membrane from a region of lower concentration to a region of higher concentration, using energy from respiration

Why is active transport important?

It allows cells to absorb ions and molecules even when they are in lower concentration outside the cell

How does active transport occur?

Protein carriers in the cell membrane move molecules or ions using energy