Week 4b: Passive + Active Movement

Question 1

What is diffusion?

Answer 1

Molecules move from regions of high concentrations to low concentration.

Question 2

Diffusion is passive, meaning:

Answer 2

It does not require energy.

Question 3

The greater the difference in concentration,

Answer 3

the steeper the gradient.

Question 4

The steeper the gradient,

Answer 4

the more rapidly diffusion will occur.

Question 5

Diffusion occurs: down or against the gradient?

Answer 5

Down the gradient - from a high concentration to a low concentration.

Question 6

WHhy can only SMALL NON POLAR MOLECULES diffuse across the membrane?

Answer 6

The membrane is made of HYDROPHOBIC lipids.

Question 7

What is osmosis?

Answer 7

The diffusion of water across a semi-permeable membrane, from a low to high concentration.

Question 8

The effect of osmosis can be: (3)

Answer 8

• Hypertonic
• Isotonic
• Hypotonic

Question 9

Hypertonic

Answer 9

A higher solute concentration than the cell

Question 10

Isotonic

Answer 10

Same solute concentration as the cell

Question 11

Hypotonic

Answer 11

A lower solute concentration than the cell

Question 12

Osmotic pressure

Answer 12

Pressure causing water to move in it’s direction

Question 13

Osmosis has a more significant effect on animal cells compared to plant cells. Why?

Answer 13

Animal cells lack a cell wall.

Question 14

If an animal cell loses water:

Answer 14

It will become flaccid/shrivelled

Question 15

If an animal cell gains too much water:

Answer 15

It will swell/burst

Question 16

What is facilitated diffusion?

Answer 16

Diffusion of large and/or polar molecules, which need assistance in moving across the cell membrane

Question 17

Proteins which allow molecules to move along concentration gradients:

Answer 17

• Channel proteins

- Carrier proteins

Question 18

Channel proteins (function)

Answer 18

Provide a pore in the membrane for hydrophilic molecules such as glucose to move through

Question 19

Carrier proteins (function)

Answer 19

Bind to a specific molecule which then changes its shape and release the molecule inside the cell

Question 20

Why does facillitated diffusion not require an input of energy?

Answer 20

The molecules move along their concentration gradient

Question 21

What is active transport?

Answer 21

Movement of solute molecules from a low concentration to a high concentration (against the gradient)

Question 22

Does active transport require energy?

Answer 22

Yes, from ATP

Question 23

How are carrier proteins used in active transport?

Answer 23

Change shape to move molecules

Question 24

The movement of large molecules (ie: proteins) involve:

Answer 24

Membrane bound sacs called vesicles

Question 25

Endocytosis

Answer 25

Large molecules/particles are taken into the cell

Question 26

Phagocytosis (food)

Answer 26

The membrane folds near the particle, enclose it in a vesicle, which breaks away from the membrane and enters the cytoplasm.

Question 27

Pinocytosis (liquid)

Answer 27

A tiny vesicle forms around the liquid at the surface of the cell

Question 28

These processes involve a change in:

Answer 28

Change in shape of the membrane to form a vesicle.

Question 29

Exocytosis

Answer 29

Substances pass out of the cell.

Question 30

Secreted materials produced by the cell are packaged into the vesicle, which then does what?

Answer 30

Migrates and fuses to the plasma membrane. Contents are then released into extracellular fluid.

Question 31

Manufactured material comes from the ___ and packaging occurs in the ____

Answer 31

The ER and the Golgi body

Question 32

Receptor mediated endocytosis

Answer 32

Intake of some substances using receptors.

Question 33

In receptor mediate endocytosis, substance combines with receptor molecules on the outside of the membrane, which causes:

Answer 33

Formation of vesicle which carries the material into the cell