BM - Inorganic Ions

Question 1

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 1

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 2

Role of Iron Ions

Answer 2

1. Haemoglobin binds/associates with oxygen
2. Haemoglobin transports/loads oxygen;

Question 3

Role of Sodium ions

Answer 3

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;

Question 4

Role of Phosphate ions

Answer 4

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;

Question 5

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

Answer 5

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

Question 6

Explain how phosphate ions (PO₄³⁻) contribute to the formation of ATP and DNA.
(4 marks)

Answer 6

• Phosphate ions are part of the structure of ATP (adenosine triphosphate), where three phosphate groups are attached to an adenine base and a ribose sugar.
• The bonds between the phosphate groups (particularly the high-energy bonds) store and release energy during cellular processes.
• Phosphate groups are also part of the nucleotides that form DNA and RNA, contributing to the structure of the nucleic acids.
• The addition of phosphate groups to proteins (phosphorylation) can activate or deactivate enzymes and regulate cell signaling pathways.