diffusion/active transport/osmosis

Question 1

diffusion

Answer 1

the net movement of particles from an area of high concentration to an area of low concentration

Question 2

diffusion is passive/active

Answer 2

PASSIVE - requires no energy because it is across the concentration gradient

Question 3

Active transport is…

Answer 3

• AGAINST the conc gradient
• area of lower concentration to an area of higher concentration; opposite way
• uses atp

Question 4

Osmosis is…

Answer 4

The net movement of water molecules across a partially permeable membrane from a region of higher water concentration to a region of lower water concentration

Question 5

Cell membranes allow what to travel through

Answer 5

Smaller molecules eg glucose, amino acids, water and oxygen
NOT big molecules like starch and proteins

Question 6

Name the four factors which influence the rate of movement of substance

Answer 6

• SURFACE AREA TO VOLUME RATIO
  if the surface area to volume ratio is larger than substances will move in and out of the cube faster
• DISTANCE
  cell membranes are very thin because the smaller the distance that substances need to move, the faster the movement in and out of the cells
• TEMPERATURE
  as the particles in a substance get warmer they have more energy so they move faster
• CONCENTRATION GRADIENT
  substances move faster if the concentration between the inside and the outside of the cell is larger

Question 7

Concentration gradient makes which two faster but does not influence the third method?

Answer 7

DOES: diffusion and osmosis
DOES NOT: active transport

Question 8

Full active transport definition

Answer 8

The movement of particles from an area of lower concentration to an area of higher concentration, against a concentration gradient, using energy released during respiration

Question 9

What are the two ways to investigate osmosis in living and non living systems. What are they?

Answer 9

Potato cylinders- living
Visking tubing- non living

Question 10

How do you investigate diffusion in a non living system?

Answer 10

By using PHENOLPHTHALEIN (a pH indicator)
(We’ve seen it in chemistry before)

Question 11

What colour is phenolphthalein in alkaline solutions

Answer 11

Pink

Question 12

What colour is phenolphthalein in acidic solutions?

Answer 12

Colourless

Question 13

Steps to investigate diffusion in agar jelly: (4 steps- p.10)

Answer 13

• MAKE UP agar jelly with phenolphthalein and dilute sodium hydroxide- the jelly will turn pink.
• put some dilute hydrochloride acid in a beaker
• cut cubes from the jelly and put them in the beaker.
• leave the cubes for a while- they will turn colourless

Question 14

Why do the cubes turn colourless?

Answer 14

The acid diffuses into the agar jelly and neutralises the sodium hydroxide.

Question 15

Using agar jelly, how do you investigate the rate of diffusion?

Answer 15

Use different sized cubes of agar jelly and then time how long it takes the cubes to go colourless.
- the cube with the largest SA:V ratio will lose its colour the quickest