3.1.7 and 8 water and other ions

Question 1

Give a property of water

Answer 1

polar, solvent, reactive

Question 2

Why is it useful to living organisms that water is polar?

Answer 2

acts as a universal solvent

Question 3

why is it useful to living cells that water is a solvent?

Answer 3

reactions occur faster in solution

Question 4

why is it useful to living cells that water is reactive?

Answer 4

takes place in hydrolysis and condensation reactions

Question 5

name an important ion

Answer 5

hydrogen, sodium, iron, phosphate

Question 6

how do water and ions enter cells?

Answer 6

they can move down a concentration gradient
both move through channel proteins
ions can move against a concentration gradient by active transport

Question 7

3 properties of water that are important in biology

Answer 7

Is a metabolite
Is a solvent
Has a (relatively)high heat capacity
Has a (relatively)largenlatent heat of vaporisation/ evaporation
Has cohesion / hydrogen bonds between molecule

Question 8

give 2 inorganic ions within the human body and describe one function of each?

Answer 8

Fe2+ - in haemoglobin - binds to oxygen in haemoglobin -

Na+ - involved in co-transport of glucose and amino acids into ileum –> blood / cells

Question 9

give 2 properties of water that are important in the cytoplasm of cells.

for each property of water, explain its importance in the cytoplasm?

Answer 9

• polar
• acts as universal solvent
• reactive
• takes place in hydrolysis

Question 10

compare and contrast the processes by which water and inorganic ions enter cells?

Answer 10

• both move down concentration gradient
• both move through protein channels in membrane
• ions can move against concentration gradient by active tranport

Question 11

the movement in woodlice in low relative humidity is an advantage to their survival.

explain how?

Answer 11

• low humidity = more woodlice moving

- inc movement = leave unfavourable enviro –> reduce water loss