Cell Exchange Materials

Question 1

Define homeostasis

Answer 1

When body systems work together to ensure that the cellular environment is kept constant

Question 2

What’s the name of the diagram that demonstrates the membrane structure?

Answer 2

Fluid mosaic model

Question 3

Why is the cell membrane said to be fluid?

Answer 3

Because the molecules that make up the membrane constantly change position.

Question 4

What is the main structure of the membrane

Answer 4

Phospholipid molecules, which are lipid molecules containing a phosphate group. The phospholipids are arranged in 2 layers - bilayer

Question 5

List the 4 functions of the cell membrane

Answer 5

Physical barrier, regulation of the passage of materials, sensitivity and support.

Question 6

List the main membrane proteins

Answer 6

carrier proteins and channel proteins

Question 7

Name the 3 basic processes that result in transport of materials in/out of the cell and whether they’re passive or active.

Answer 7

Diffusion - passive
Carrier-mediated (requires special proteins) passive or active
Vesicular - active

Question 8

What is concentration gradient?

Answer 8

The difference in concentration that brings about diffusion is called CG/diffusion gradient.

Question 9

What is facilitated diffusion?

Answer 9

A passive process in which substances move with the concentration gradient from high to low concentration with the help of transport proteins.

Question 10

What are carrier proteins? Give an example.

Answer 10

It is a protein that carries molecules across the plasma membrane, rather than opening through a channel.
eg. glucose

Question 11

What are channel proteins? Give examples.

Answer 11

Molecules that diffuse through channels in the plasma membrane.
eg. water and ions

Question 12

What are words that describe the cell membrane and why do you say this?

Answer 12

• plasma membrane
• bilayer (comprised of 2 layers of phospholipids)
• semi permeable (allows molecules to pass through the membrane and restricts the movement of others)

Question 13

What increases the rate of diffusion?

Answer 13

• an increase in the concentration gradient
• an increase in temperature
• a decrease in the size of diffusing particles

Question 14

Explain what is happening when a substance is being trapped against a concentration gradient.

Answer 14

Substances will be transported from an area of low concentration to high concentration.

Question 15

List and explain 2 factors that affect a cells ability to absorb substances into it.

Answer 15

SA:volume ratio - If the SA is not large enough to allow chemical reactions to occur, substances cannot be absorbed.

Concentration gradient - if the concentration gradient is high, it will increase the rate of absorption