3.1.8 - INORGANIC IONS

Question 1

describe the roles of iron ions, sodium ions, and phosphate ions in cells (5)

Answer 1

iron ions:
1. haemoglobin transports/binds/associates with oxygen

sodium ions:
1. co-transport of glucose/amino acids into cells
2. because sodium moved out by active transport/sodium-potassium pump
3. creates a sodium concentration/diffusion gradient
4. affects osmosis/water potential

phosphate ions:
1. affects osmosis/water potential
2. joins nucleotides/in phosphodiester bonds/in backbone of DNA/ in nucleotides
3. used to produce ATP
4. phosphorylates other compounds making them more reactive
5. hydrophilic part of phospholipid bilayer

Question 2

describe and explain the link between oxygen concentration, rate of respiration and the rate of uptake of potassium ions (4)

Answer 2

1. greater rate of oxygen consumption/leads to greater rate of respiration and greater rate of uptake
2. oxygen required for respiration
3. respiration produces ATP
4. potassium ions taken up by active transport/against concentration gradient

Question 3

explain a property of iron ions that enables these ions to carry out their role in red blood cells (2)

Answer 3

1. is part of haemoglobin
2. so associates with oxygen