3.1.8 Inorganic ions

Question 1

Free inorganic ions can play very important roles in the body.
- Describe how iron ions carry oxygen to where it is needed in the body.
[3 marks]

Answer 1

• Iron ions are a key component of haemoglobin.
• The iron ions in haemoglobin bind to oxygen.
• The haemoglobin is transported around the body in red blood cells.

Question 2

Free inorganic ions can play very important roles in the body.
- Explain the role of phosphate ions in providing energy for cellular reactions.
[2 marks]

Answer 2

• Phosphate ions form the phosphate groups of ATP.

- Breaking the bonds between the phosphate groups in ATP releases energy.

Question 3

How are hydrogen ions related to the pH of an environment?

Answer 3

pH is calculated based on the concentration of hydrogen ions (H⁺) in the environment. The more H⁺ present, the lower the pH.

Question 4

What are inorganic ions?

Answer 4

Ions which don’t contain carbon; each ion has a specific role, depending on its properties.

Question 5

Why are iron ions an important part of haemoglobin?

Answer 5

Fe²⁺ binds to the oxygen in haemoglobin. When oxygen is bound, the Fe²⁺ ion temporarily becomes an Fe³⁺ ion, until oxygen is released.

Question 6

What is the role of sodium ions?

Answer 6

Sodium ions help transport glucose and amino acids across membranes (and into a cell) via co-transporters.

Question 7

How are phosphate ions an essential component of ATP and DNA?

Answer 7

• A phosphate group is formed when a phosphate ion (PO₄³⁻)is attached to another molecule.
• The bonds between phosphate groups store energy in ATP.
• The phosphate groups in DNA and RNA allow nucleotides to join up to form the polynucleotides.