2.3 | Cell Requirements | Year 11 HBIO

Question 1

What’s another name for the cell membrane?

Answer 1

The plasma membrane.

Question 2

What does the cell membrane do?

Answer 2

It encloses the contents of the cell and controls what is able to enter and leave.

Question 3

Why is the cell membrane thin?

Answer 3

It allows for diffusion to readily occur.

Question 4

What is the cell membrane made of?

Answer 4

A phospholipid bilayer.

Question 5

Define selective permeability.

Answer 5

Where some substances can go through a membrane easier than others.

Question 6

What are phospolipid molecules made of?

Answer 6

Lipid molecules containing a phosphate group.

Question 7

Which substances can’t diffuse through the cell membrane and why?

Answer 7

Most water-soluble substances.

(excl. Oxygen and Carbon Dioxide)

Question 8

List 3 functions of the cell membrane.

Answer 8

• It acts as a physical barrier.
• It regulates the passage of substances.
• It supports the cell.

Question 9

Define macromolecule.

Answer 9

A very large molecule important to biological processes.

Question 10

Give an example of a macromolecule.

Answer 10

Protein.

Question 11

What do transport proteins do?

Answer 11

Regulate the movement of water-soluble substances in and out of the cell.

Question 12

What are the two types of transport proteins?

Answer 12

• Channel proteins (aka ion channels)
• Carrier proteins

Question 13

What is the function of a channel protein?

Answer 13

To provide a channel for water-soluble substances to cross the cell membrane.

Question 14

What is the function of a carrier protein?

Answer 14

To allow certain specific substances to cross the cell membrane.

(Carrier-mediated transport)

Question 15

What’s the difference between channel proteins and carrier proteins?

Answer 15

One creates open channels that allow for facilitated diffusion

The other binds to molecules and changes shape to deliver it across the membrane.

Question 16

What is passive transport?

Answer 16

The transport of substances in and out of the cell without the use of energy.

Question 17

Give an example of passive transport.

Answer 17

Diffusion.

Question 18

What is active transport?

Answer 18

The movement of substances in and out of a cell with energy.

Question 19

What is facilitated diffusion?

Answer 19

The process where proteins allow diffusion of molecules, bypassing the membrane.

Question 20

What is facilitated transport?

Answer 20

Where proteins (channel and carrier) allow molecules to be transported across the membrane.

Question 21

What are the types of active transport?

Answer 21

• Facilitated transport
• Vesicular transport

Question 22

What is diffusion?

Answer 22

The tendency for particles to move from an area of higher contentration to an area of lower concentration.

Occurs in gases and liquids

(Diffusion is passive, meaning it does not use energy.)

Question 23

Define permeable.

Answer 23

(of a membrane) allowing substances to pass through

Question 24

Define Osmosis.

Answer 24

The diffusion of water across a selectively permeable membrane.

(Like diffusion, osmosis is passive, meaning it does not use energy.)

Question 25

Define hypotonic.

Answer 25

having a lower solute concentration

Question 26

Define hypertonic.

Answer 26

Having a higher solute concentration.

Question 27

Define isotonic.

Answer 27

An area of water with an even distibution of water molecules.

(e.g. after diffusion has finished)

Question 28

Give an example of a non-permeable substance.

Answer 28

Sucrose.

Question 29

What happens if a cell is inside a hypotonic solution?

Answer 29

The cell will become lysed and expand due to osmosis.

Question 30

Which molecules can’t fit into protein channels?

Answer 30

Large (macro)molecules.

(e.g. Glucose)

Question 31

What is a diffusion/concentration gradient?

Answer 31

The difference in concentration between the area of high concentration and the area of lower concentration.

Question 32

What is an example of active transport?

Answer 32

The Na/K (sodium-potassium) pump.

(extra information)

Question 33

Define vesicular transport.

Answer 33

The movement of substances in vesicles into, out of, or within the cell.

(VT is active, meaning it uses energy.)

Question 34

What are the types of vesicular transport?

Answer 34

Endocytosis and exocytosis

Question 35

What is endocytosis?

Answer 35

The process of taking liquids into the cell by vesicular transport

Question 36

What are the two different types of endocytosis?

Answer 36

• Phagocytosis
• Pinocytosis

Question 36

Explain endocytosis.

Answer 36

• The cell membrane folds around a droplet of external substance
• It then pinches off and forms a vesicle within the cell.

Question 36

Define Phagocytosis.

Answer 36

When endocytosis brings a solid into the cell.

Question 37

Define Pinocytosis.

Answer 37

When endocytosis brings a liquid into the cell.

Question 38

What is exocytosis?

Answer 38

When the contents of a vesicle within the cell is passed back outside the cell.

Question 39

Explain the process of exocytosis.

Answer 39

• A vesicle inside the cell contacts the cell membrane and fuses with it.
• The contents of the vesicle are then blown back out into the extracellular fluid.