Key Area 2- Transport Across The Cell Membrane

Question 1

What is the cell membrane made of

Answer 1

• Proteins
• phospholipids

Question 2

Why are cell membranes describes as selectively permeable?

Answer 2

It is described as selectively permeable as it lets some small substances pass through it but not others

Question 3

What is diffusion

Answer 3

The movement of molecules down a concentration gradient from a higher to lower concentration. No energy is required.

Question 4

Why is diffusion important to the cells

Answer 4

To gain raw materials for respiration and photosynthesis. To remove waste products

Question 5

What is osmosis?

Answer 5

Osmosis is the movement of water molecules from a higher water concentration to a lower water concentration through a selectively permeable membrane

Question 6

What is concentration gradient?

Answer 6

The gradual difference in concentration from a region of higher concentration to a region of lower concentration.

Question 7

What happens when you put a plant cell in strong salt solution

Answer 7

The water moves from an area of higher water concentration inside the cell, to an area of lower concentration outside the cell. The cell becomes plasmolysed

Question 8

What happens to a plant cell in weak solute

Answer 8

Water moves from an area of higher water concentration outside the cell, to an area of lower water concentration inside the cell. The cell becomes turgid.

Question 9

What happens to an animal cell in strong solute

Answer 9

Water moves from an area of higher water concentration inside the cell, to an area of lower water concentration outside the cell. The cell will shrink.

Question 10

What happens to an animal cell placed in weak solute

Answer 10

Water moves from an area of higher water concentration outside the cell, to an area of lower water concentration inside the cell. The cell will burst.

Question 11

What is active transport

Answer 11

active transport requires energy for membrane proteins to move molecules and ions against the concentration gradient from an area of lower concentration to an area of higher concentration

Question 12

What does it mean if a plant cell is places in isotonic solution

Answer 12

Isotonic means that’s the solution has the same water concentration inside the cell. There will be no net movement of molecules