Transport across cell membranes

Question 1

What are membranes made of?

Answer 1

Phosopholipids and proteins.

Question 2

What is diffusion?

Answer 2

The movement of substances from a high concentration to a low concentration down a concentration gradient.

Question 3

What kind of process is diffusion (energy)?

Answer 3

A passive process which requires no energy.

Question 4

Why is diffusion important to living cells?

Answer 4

It is the way that substances are moved from cell to cell and between cells and their surroundings.

Question 5

What is: The movement of substances from a high concentration to a low concentration down a concentration gradient?

Answer 5

Diffusion.

Question 6

What is: OSMOSIS?

Answer 6

The movement of water from a high water concentration to a low water concentration through a selectively permeable membrane.

Question 7

What happens in an animal cell during osmosis if there is a higher water concentration (hypotonic solution)?

Answer 7

Water enters by osmosis and the cell burts.

Question 8

What happens in an animal cell during osmosis if there is a lower water concentration (hypertonic solution)?

Answer 8

The cell shrinks and wrinkles. Water is lost by osmosis.

Question 9

Why does osmosis effect plant cells differently?

Answer 9

Because of the presence of a cell wall.

Question 10

What happens in an plant cell during osmosis if there is a higher water concentration (hypotonic solution)?

Answer 10

Water enters by osmosis. The vacuole swells and the cell is turgid.

Question 11

What happens in an plant cell during osmosis if there is a lower water concentration (hypertonic solution)?

Answer 11

Lose water by osmosis. The vacuole shrinks and the membrane pulls away from the cell wall. The cell is plasmolysed.

Question 12

What is: The movement of water from a high water concentration to a low water concentration through a selectively permeable membrane?

Answer 12

Osmosis

Question 13

Explain what kind of cell this happens to: Water enters by osmosis and the cell burts.

Answer 13

In an animal cell if there is a higher water concentration (hypotonic solution).

Question 14

Explain what kind of cell this happens to: The cell shrinks and wrinkles. Water is lost by osmosis.

Answer 14

In an animal cell if there is a lower water concentration (hypertonic solution)

Question 15

Explain what kind of cell this happens to: Water enters by osmosis. The vacuole swells and the cell is turgid.

Answer 15

In an plant cell if there is a higher water concentration (hypotonic solution)

Question 16

Explain what kind of cell this happens to: Lose water by osmosis. The vacuole shrinks and the membrane pulls away from the cell wall. The cell is plasmolysed.

Answer 16

In an plant cell if there is a lower water concentration (hypertonic solution)

Question 17

What is: ACTIVE TRANSPORT

Answer 17

The movement of molecules against a concentration gradient from a region of low concentration to a region of high concentration.

Question 18

What does active transport need to make it happen?

Answer 18

ATP (energy)

Question 19

What do proteins do in the membrane?

Answer 19

In the membrane proteins act as carriers and transport the molecules (and ions) across the membrane.

Question 20

What is an example of active transport?

Answer 20

In nerve cells, sodium is pumped out and potassium is pumped in.

Question 21

What is: The movement of molecules against a concentration gradient from a region of low concentration to a region of high concentration?

Answer 21

Active Transport

Question 22

In the membrane what act as carriers and transport the molecules (and ions) across the membrane?

Answer 22

Proteins

Question 23

What is this an example of: In nerve cells, sodium is pumped out and potassium is pumped in?

Answer 23

Active Transport