Transport across the Cell Membrane

Question 1

What is diffusion?

Give an example

Answer 1

Movement of liquids (not water) and gases from a high concentration to a low concentration
E.g. O2 moving into lungs, CO2 diffusing out

Question 2

What is osmosis?

Answer 2

Movement of water from high concentration to low concentration through selectively permeable membrane

Question 3

What is active transport?

Answer 3

Substance moves from low to high concentrations (against concentration gradient) which requires energy

Question 4

Osmosis paragraph where more salt inside cell than outside

Answer 4

• Water moves from outside cell (high concentration) to inside cell (low concentration)
• Through selectively permeable membrane
• Only water moves through gap as salt is too big
• Water moves down the concentration gradient until water concentration equal on both sides
• Water moves in and out at same rate

Question 5

Word to describe concentrated solution

Answer 5

Hypertonic

Question 6

Word to describe dilute solution

Answer 6

Hypotonic

Question 7

Word to describe equal solution

Answer 7

Isotonic

Question 8

Explain difference between osmosis and diffusion. Give an example where process takes place in living things (QWC)

Answer 8

• Diffusion is movement of liquids and gases from high concentration to low concentration
  E.g. Oxygen diffusers out of a leaf (made by photosynthesis) or carbon dioxide diffusing into leaf (for photosynthesis)
• Osmosis is movement of water from high concentration to low concentration
  E.g. Water passing from soil into root hair of a plant

Question 9

Example of active transport

Answer 9

Cells in our kidneys remove chemicals we don’t want to excrete from our urine