Chap.3 - Movement into and out of Cells

Question 1

Diffusion

Answer 1

The net movement of particles from a region of higher concentration to a region of lower concetration, as a result of their random movement.

Question 2

Where does energy for diffusion come from?

Answer 2

From the kinetic energy of random movement of molecules and ions.

Question 3

Factors that Affect Rate of Diffusion

Answer 3

• Surface Area: larger surface area -> faster rate of diffusion
• Temperature: higher temperature -> faster rate of diffusion because particles have more energy, meaning there are more collisions between particles
• Concetration Gradient: steeper gradient -> faster rate of diffusion
• Distance: farther distance -> slower rate of diffusion

Question 4

What is a solution made from?

Answer 4

• Solute: dissolves in the solvent
• Solvent: a liquid in which the solvent dissolves in

Question 5

Universal Solvent

Answer 5

Water

Question 6

Osmosis

Answer 6

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.

Question 7

How do water molecules diffuse?

Answer 7

Down a water potential gradient from a region of higher water potential to a region of lower water potential.

Question 8

Partially Permeable Membrane

Answer 8

Allows small molecules such as water to pass through but not large solute molecules.

Question 9

How are plants supported?

Answer 9

They are supported by the pressure of water inside the cells pressing outwards on the cell wall, giving the cell its rigid, rectangular shape.

Question 10

Turgidity (water goes into cell)

Answer 10

• A plant is placed in water.
• The molecules diffuse into the cells across the water potential gradient.
• The cell swells up, and as the water pushes against the cell wall turgor pressure builds up.
• The cells stiffens and becomes turgid.

Question 11

Plasmolysis (water goes out of cell)

Answer 11

• Cell is placed into concentraed sugar/salt solution
• Water passes out of the cell
• Cell is no longer stiff, becomes flaccid, and as the vacuole shrinks the cytoplasm starts to move away from the cell wall.
• Cells become plasmolysed.

Question 12

Why osmosis is important?

Answer 12

To maintain turgor in the cells.

Question 13

Active Transport

Answer 13

The movement of particles through a cell membrane from a region of lower concentration to a region of higher concentration (against a concentration gradient), using energy from respiration.

Question 14

Why is active transport important?

Answer 14

To maintain the proper concentrations of ions and molecules, and enables root hair cells to take up ions.

Question 15

Protein Carriers

Answer 15

Move molecules or ions across a membrane during active transport.