1 Cell Biology - Cell Transport

Question 1

Define ‘diffusion’.

Answer 1

Net movement of particles from an area of high to low concentration (down concentration gradient)

Question 2

What does it mean by ‘net movement’?

Answer 2

Overall movement: particles can move in any direction, but generally speaking, most of the particles are moving in one particular direction, hence ‘net’ movement

Question 3

State three factors that affect the rate of diffusion.

Answer 3

Concentration gradient, temperature, surface area

Question 4

How does concentration difference affect the rate of diffusion?

Answer 4

Higher conc difference/Steeper conc gradient –> faster diffusion

Question 5

Explain why a higher temperature results in faster diffusion.

Answer 5

More kinetic energy, particles move around more

Question 6

Name a substance that diffuses into our cells for use.

Answer 6

Oxygen, glucose

Question 7

Name a substance that diffuses out of our cells to be removed.

Answer 7

Carbon dioxide, urea

Question 8

Name a structure in the body that is adapted to increase diffusion rate.

Answer 8

Alveoli, villi

Question 9

Define ‘osmosis’.

Answer 9

Net movement of water molecules down the water concentration gradient through a partially permeable membrane

Question 10

Define ‘dilute’.

Answer 10

A solution with a high water conc, but low solute conc

Question 11

Define ‘concentrated’.

Answer 11

A solution with a low water conc, but high solute conc

Question 12

What are partially permeable membranes?

Answer 12

Membranes that only allow some types of substances to pass through

Question 13

What is an isotonic solution?

Answer 13

A solution with the same solute conc as the cell

Question 14

What is a hypertonic solution?

Answer 14

A solution with a higher solute conc than the cell

Question 15

What is a hypotonic solution?

Answer 15

A solution with a lower solute conc than the cell

Question 16

If a cell is in a hypertonic solution, water will ___ (enter/leave) the cell.

Answer 16

Leave

Question 17

If a cell is in a hypotonic solution, water will ___ (enter/leave) the cell.

Answer 17

Enter

Question 18

What will happen to an animal cell if it is in a hypertonic solution?

Answer 18

Water leaves cell –> shrivelled

Question 19

What will happen to an animal cell if it is in a hypotonic solution?

Answer 19

Water enters cell –> burst

Question 20

Why do animal cells burst in hypotonic solutions?

Answer 20

No cell wall

Question 21

What will happen to a plant cell if it is in a hypertonic solution?

Answer 21

Water leaves cell –> plasmolysed

Question 22

What will happen to a plant cell if it is in an isotonic solution?

Answer 22

No net water movement –> flaccid

Question 23

What will happen to a plant cell if it is in a hypotonic solution?

Answer 23

Water enters cell –> turgid

Question 24

What does ‘plasmolysed’ mean?

Answer 24

The cell membrane becomes detached from cell wall

Question 25

Why does the potato skin needs to be removed before putting the potato cylinders into the solutions?

Answer 25

Skin is impermeable

Question 26

How do we calculate % change in mass?

Answer 26

(final mass - intial mass)/initial mass x 100

Question 27

Define 'active transport'.

Answer 27

Movement of particles against the concentration gradient (low to high) using energy in the form of ATP

Question 28

Explain the importance of active transport in plants.

Answer 28

Root hair cells carry out AT to absorb mineral ions effectively in dilute soil

Question 29

Explain the importance of active transport in animals.

Answer 29

Cells in gut lining does AT to absorb glucose effectively from the bloodstream

Question 30

State one adaptations cells may have if they need to carry out active transport.

Answer 30

Lots of mitochondria for respiration for energy

Question 31

How does active transport differ from diffusion and osmosis?

Answer 31

AT uses energy, D and O do not

Question 32

State two differences beween diffusion and osmosis.

Answer 32

D: Any particles, does not need a membrane; O: Water specific, needs partially permeable membrane

Question 33

State the relationship between size and surface area to volume ratio.

Answer 33

The bigger the size, the smaller the SA:V

Question 34

Describe three adaptations of exchange surfaces.

Answer 34

Large SA, thin membrane/surface, ability to maintain high conc difference

Question 35

How are alveoli adapted for efficient gaseous exchange?

Answer 35

Large SA, thin membrane (short diffusion distance), rich blood supply (maintain steep conc gradient)

Question 36

How are plant roots adapted for efficient water and mineral absoprtion?

Answer 36

Large SA (root hairs), transpiration stream

Question 37

How does stomata help maintain efficient gas exchange in leaves?

Answer 37

Allow gases to move in and out of leaf, maintaining steep concentration gradient