Biology - Unit 3 (Cell movement)

Define diffusion.

It is the net movement of particles from a region of higher concentration to a region of lower concentration down a concentration gradient.

What are some factors that affect diffusion?

surface area, temperature, distance and concentration gradient

How do you describe the movement of molecules in diffusion? Why?

Passive, because no energy is required

State the importance of diffusion.

for obtaining nutrients and for removing metabolic wastes

When does diffusion stop?

When molecules become evenly distributed and reach an equilibrium state

Define osmosis.

It is the net movement of water molecules from a region of higher water potential to a region of lower water potential, through a selectively permeable membrane

Describe an isotonic solution.

There is no net water movement, as the water potential is the same inside and outside the cell.

Describe a hypertonic solution.

It has a lower water potential than the cell, causing water molecules to move out of the cell

What happens to cells in a hypertonic solution?

Animal cells shrink while plant cells get plasmolyzed and become flaccid.

What is plasmolysis?

The detachment of the cell wall and cell membrane

Describe a hypotonic solution.

It has a higher water potential than the inside of the cell, causing water molecules to move into the cell.

What happens to cells in a hypotonic solution?

Animal cells swell and burst while plant cells become more turgid.

State the importance of osmosis.

It is important in the uptake of water for growth in both plant and animal cells and for the support of plant cells through turgor pressure.

Why is energy required in active transport?

carrier proteins require ATP to change the shape of an ion.

Define active transport.

It is the movement of particles from a region of lower concentration to that of a higher concentration through a cell membrane using energy from respiration.

What are the factors affecting active transport?

Concentration of oxygen, temperature, presence of inhibitors, amount of carrier protein and mitochondria

State the importance of active transport.

Ion uptake by root hairs and the glucose uptake by epithelial cells of villi and kidney tubules

Fill: Phagocytosis packages cells into _________ formed from the cell membrane

vacuoles

State the purpose of phagocytosis

For changing the shape of the cell, fusing the cell membrane and for moving the vacuoles