Transport Across Cell Membranes

Question 1

What is the cell membrane composed of?

Answer 1

Lipid and protein.

Question 2

Is the cell membrane fully permeable or selectively permeable?

Answer 2

Selectively.

Question 3

A difference in concentration of a substance is a c………… g…………?

Answer 3

Concentration gradient

Question 4

When a substance does not require additional energy for the movement of its molecules along the concentration gradient from a high concentration to a low concentration, this is called?

Answer 4

Passive transport

Question 5

Give 2 examples of passive transport.

Answer 5

Diffusion

Osmosis

Question 6

Describe diffusion.

Answer 6

Diffusion is the movement of substances from a high concentration to a low concentration down a concentration gradient.

Question 7

Give 3 examples of substances that enter most cells by diffusion?

Answer 7

Oxygen
Glucose
Amino acids

Question 8

Give 2 examples of substances that leave most cells by diffusion.

Answer 8

Carbon dioxide

Urea

Question 9

Why is diffusion important to cells?

Answer 9

It helps to provide the cell with raw materials and it helps to remove waste products.

Question 10

What is Osmosis?

Answer 10

Osmosis is the movement of water from a region of high water concentration to a region of low water concentration through a selectively permeable membrane.

Question 11

What could happen to an animal cell place in a high concentration of water than what is in its cell.

Answer 11

It could absorb too much water through osmosis and burst.

Question 12

What could happen to an animal cell that is placed in a lower level of concentration that what is in the cell?

Answer 12

It can lose the water fro, the cell via osmosis and shrink.

Question 13

Describe the word turgid.

Answer 13

When a plant cell becomes swollen with a full vacuole resulting from water intake due to osmosis.

Question 14

When a plant cell takes up too much water by osmosis it is called…..

Answer 14

Turgid

Question 15

When a plant cell is placed in too little water it will lose water via osmosis and become…..

Answer 15

Plasmolysed

Question 16

Describe the term plasmolysed.

Answer 16

Plasmolysed is the term used to describe a cell in which the vacuole has shrunk due to water loss, causing the cell membrane to pull away from the cell wall.

Question 17

Describe the term Active Transport.

Answer 17

Active transport is the movement of molecules from a region of low concentration to a region of higher concentration, against the concentration gradient.

Question 18

What does active transport require to allow membrane proteins to move molecules against the concentration gradient?

Answer 18

Additional energy,

Question 19

What is a lipid?

Answer 19

Fat or oil with molecules composed of fatty acids and glycerol.

Question 20

Restricted response questions

Name 2 substances present in cell membranes. (2 marks)

Answer 20

Lipids

Proteins

Question 21

Give 2 passive processes by which substances pass through membranes.

Answer 21

Diffusion

Osmosis

Question 22

State the difference between an active and a passive process.

Answer 22

Active processes require energy

Passive ones do not

Question 23

State on difference between osmosis and diffusion.

Answer 23

Osmosis only involves water and occurs through membranes

Question 24

Give the meanings of the following terms:
A) turgid
B) plasmolysed

Answer 24

Turgid - plant cells stretched full of water

Plasmolyse - plant cells shrunken

Question 25

Give an example of a situation in which cells use active transport.

Answer 25

Plant roots taking up irons from their environment

Nerve cells transporting potassium and sodium

Question 26

State what is meant by a concentration gradient.

Answer 26

The difference in concentration between two areas

Question 27

Extended response question

Describe the process of diffusion 2 marks

Answer 27

Passive movement of molecules; from a region of high concentration to a region of lower concentration

Question 28

Describe the role of protein molecules in osmosis and active transport. 2 marks

Answer 28

In osmosis they allow the passage of water molecules through pores; in active transport they act as carriers.

Question 29

Extended response question

Explain what would happen to a piece of potato tissue placed into a beaker of pure water for 2 hours. 3 marks

Answer 29

Potato would gain water by osmosis; because concentration of water outside greater than inside; cells would swell up; become turgid and no more water would enter.

Question 30

Extended response question

Explain why immersing a single animal cell in sea water might kill it. 3 marks

Answer 30

Cell would loose waster by osmosis because the water concentration is greater than the outside water concentration; cells would shrink; cell functions would be damaged.

Question 31

What does ATP stand for?

Answer 31

Adenosine triphosphate - a substance that transfers chemical energy in cells.

Question 32

What type of ions does a nerve cell have on the inside.

Answer 32

High concentration of potassium ions.

Question 33

What type of ions does have a nerve cell have on the outside?

Answer 33

High concentration of sodium ions.

Question 34

What do nerve cells have to pump sodium ions out of the cells and potassium ions in the cells?

Answer 34

Use Sodium - potassium pumps.The energy involved is allowing these pumps to work is called ATP.