Transport in cells 2.0

Question 1

what will happen to the size of animal cells due to osmosis? and why?

Answer 1

• they will change size and shape when put into solutions that are at a different concentration to the cell contents.
• since they do not have a cell wall

Question 2

in animals, what must be kept within strict limits? why?

Answer 2

• the concentration of body fluids, blood plasma and tissue fluid
• If cells lose or gain too much water by osmosis, they do not function efficiently.

Question 3

why do scientists use percentiles?

Answer 3

to divide a set of data into 100, and look to see where the data lie within these divisions.

Question 4

equation for order rank (for a percentile):

Answer 4

order rank = (percentile/ 100) x number of entries in a set

Question 5

what is a median in percentiles?

- what is the 75th percentile?

Answer 5

• this is the 50th percentile: the point in a set of data where 50 per cent of the data fall above this value, and 50 per cent below it.
• where 75 percent of the data fall below this value.

Question 6

how are substances transported along concentration gradients?

Answer 6

-substances are transported passively down concentration gradients.

Question 7

what is active transport?

what does this process require?

Answer 7

• a process that is required to move molecules against a concentration gradient ( from a low to a high concentration).
• the process requires energy.

Question 8

how do plants take up minerals?

how does this relate to active transport?

Answer 8

• ions are moved into root hairs, where they are in a higher concentration than in the dilute solutions in the soil.
• active transport then occurs to allow the plant to take the nutrients it needs for the soil around it.

Question 9

describe the process of diffusion of glucose molecules into the blood of animals: (3)

Answer 9

• glucose molecules have to be moved across the gut wall into the blood.
• glucose molecules in the intestine might be in a higher concentration than in the intestinal cells and blood
• it will diffuse from high concentration in the intestine to a lower concentration in the blood. which doesn’t require energy.

Question 10

describe the process of active transport in the glucose molecules of animal cells: (3)

Answer 10

• there will be times when glucose concentration in the intestine might be lower.
• in this case, movement of glucose involves active transport.
• process requires energy produced by respiration.

Question 11

outline the substances transported and energy needed for diffusion:

Answer 11

substances: carbon dioxide, oxygen, water, food substances, wastes
energy required: none

Question 12

outline the substances transported and energy needed for osmosis:

Answer 12

substances: water

energy requirement: none

Question 13

outline the substances transported and energy needed for active transport:

Answer 13

substances: Mineral ions into plant roots. Glucose from the gut into intestinal cells, from where it moves into the blood
energy required: yes