Transport in cells

Question 1

What is diffusion?

Answer 1

The movement of particles from an area of high concentration to an area of low concentration

Question 2

Give some examples of diffusion in a photosynthesising plant cell.

Answer 2

• Carbon dioxide moves into the plant cell by diffusion

- Oxygen moves out of the plant cell by diffusion

Question 3

Give examples of diffusion in the lungs.

Answer 3

• Oxygen diffuses from high concentration in the alveoli to low concentration in the blood (capillaries)
• Carbon dioxide diffuses from high concentration in the blood (capillaries) to low concentration in the alveoli

Question 4

What three things could increase the rate of diffusion (speed)?

Answer 4

• The greater the concentration gradient, the quicker the diffusion
• The higher the temperature, the quicker the diffusion
• The greater the surface area, the quicker the diffusion

Question 5

What is osmosis?

Answer 5

The movement of water molecules across a selectively permeable membrane from an area of high water concentration to an area of low water concentration

Question 6

As an organism grows larger, what happens to their surface area to volume ratio?

Answer 6

Larger organisms have a smaller surface area to volume ratio

Question 7

Cubes can be used to model cells.

What is the surface area to volume ratio of a cube with a side length of 1 cm?

Answer 7

1:6

Question 8

What is the difference between dilute and concentrated solutions?

Answer 8

• Dilute solutions contain a high concentration of water molecules
• Concentrated solutions contain a low concentration of water molecules

Question 9

What happens to a plant cell in pure water?

Answer 9

The cell contents (cytoplasm and vacuole) push against the cell wall and the cell becomes turgid

Question 10

What happens to a plant cell placed in a concentrated solution?

Answer 10

• The cell contents lose water by osmosis
• The vacuole shrinks and the cytoplasm moves away from the cell wall
• The plant cell becomes flaccid
• The plant cell becomes plasmolysed

Question 11

What is active transport?

Answer 11

A process where particles are moved against the concentration gradient (from low concentration to high concentration), which requires energy

Question 12

Give an example of a process that requires active transport in plants.

Answer 12

Root hair cells in plants taking up mineral ions from the soil

Question 13

Give an example of a process that requires active transport in animals.

Answer 13

Glucose molecules moved across the intestine wall and into the blood

Question 14

How is the energy required for active transport obtained?

Answer 14

Through respiration

Question 15

Which method of cell transport requires the release of energy?

Answer 15

Active transport

Question 16

Which method of cell transport involves the movement of water?

Answer 16

Osmosis