Transport Across The Cell Membrane

Question 1

What does the term semi/selectively permeable mean? Give an example

Answer 1

The cell membrane controls the passage of substances that enter and exit the cell and this is described as semi/selectively permeable

Question 2

Explain the term concentration gradient

Answer 2

The concentration gradient is the difference in concentration that exists between the region of high concentration and a region of low concentration

Question 3

Explain the term passive transport.

Give an example

Answer 3

Diffusion is a form of passive transport because no energy input is needed for diffusion to occur

Question 4

State the definition of osmosis

Answer 4

Osmosis is a special case of diffusion.
It is the movement of water molecules from a region of high water concentration to a region of low water concentration across a selectively permeable membrane

Question 5

Describe the effect of placing an animal cell in concentrated, dilute solutions and water

Answer 5

Concentrated- the water moves out of the cell and the cell shrinks
Dilute- the water moves in both directions and stays the same
Water- the water enters the cells and the cell bursts

Question 6

Describe the effect of placing a plant cell in concentrated, dilute solutions and water (using the words plasmolysed and turgid)

Answer 6

Concentrated- the water moves out the cell and the cell becomes Plasmolysed
Diluted- the water moves in both directions and cell stays the same
Water- the water moves into the cell and it swells and becomes turgid

Question 7

What does plasmolyse mean?

Answer 7

When the vacuole shrinks and the cell membrane pulls away from the cell wall it is called plasmolyse

Question 8

State the definition active transport

Answer 8

Active transport is the movement of icons and molecules across the cell membrane from a low to a high concentration against a concentration gradient

Question 9

State 2 main differences between active transport and diffusion

Answer 9

• active transport requires energy

- active transport is a low to high concentration where as diffusion is a high to low concentration

Question 10

What type of molecules act as carrier molecules?

Answer 10

Proteins

Question 11

Where are the carrier molecules located?

Answer 11

Cell membrane

Question 12

State the components of the cell membrane

Answer 12

Lipids and proteins