Inorganic Ions - Mark Scheme Answers (study Mind)

Question 1

Describe and explain the link between oxygen concentration, rate of respiration and
rate of uptake of potassium ions.

Answer 1

• greater rate of oxygen consumption / leads to greater rate of respiration and
• greater rate of uptake;
• oxygen required for respiration;
• respiration produces ATP / releases energy;
• potassium ions taken up by active transport / against concentration gradient;

Question 2

A high concentration of sodium in the blood can affect blood volume and
cause hypertension.
Use your knowledge of water potential to suggest how high sodium
concentrations in the medicines taken could affect blood volume.

Answer 2

1.(Sodium ions) lower the water potential (of blood);
2. Water would move into the blood by osmosis (from cells/tissue fluid);
3. Increasing the blood volume;

Question 3

Describe the roles of iron ions, sodium ions, and phosphate ions in cells.

Answer 3

Iron ions
1. Haemoglobin binds/associates with oxygen

Sodium ions
2. Co-transport of glucose/amino acids (into cells);
3. (Because) sodium moved out by active transport/Na – K pump;
4. Creates a sodium concentration/diffusion gradient;
5. Affects osmosis/water potential;

Phosphate ions
6. Affects osmosis/water potential;
7. Joins nucleotides/in phosphodiester bond/in backbone of DNA/RNA/in nucleotides;
8. Used in/to produce ATP;
9. Phosphorylates other compounds (usually) making them more reactive;
10. Hydrophilic/water soluble part of phospholipid bilayer/membrane;