3. 1. 8 Inorganic ions

Question 1

Where do inorganic ions occur?

Answer 1

Inorganic ions occur in solutions in the the cytoplasm and body fluids of organisms.

Question 2

Are inorganic ions found in high or low concentrations?

Answer 2

Some are found in high concentrations and others in very low concentrations.

Question 3

describe the role of ions in hydrogen ions and pH.

Answer 3

The pH is a measure of the concentration of hydrogen ions; higher H+ ions=lower pH and vise versa. A pH of 1 represents a H+ concentration of 0.1 mol/dm3

Question 4

Describe the role of iron ions as a component of haemoglobin.

Answer 4

• Haemoglobin is a large protein that carries oxygen around the body in RBC
• It’s made up of 4 different polypeptide chains each with Fe2+ in the centre
• Fe2+ binds to oxygen
• When oxygen is bound, Fe2+ temporarily becomes Fe3+

Question 5

Describe the role of sodium ions in the co-transport of glucose and amino acids.

Answer 5

• Na+ ions actively transported out of epithelial cells
  through a protein carrier molecule
• 3Na+ ions transported out of epithelial cells into bloodstream in exchange for 2K+ ions
• Movement gives higher concentration of Na+
  in lumen of intestine rather than inside of the cell
• This maintains concentration gradient
• Na+ moves down concentration gradient using a co-transport protein. Both Na+ and glucose bind to it
• 2Na+ and glucose must bind before being transported across the membrane.
• Glucose moves into blood plasma using facilitated diffusion and a uniporter

Question 6

Describe the role of phosphate ions as components of DNA and ATP.

Answer 6

• It’s the bonds between phosphate groups that store energy in ATP.
• The phosphate groups in DNA and RNA allow nucleotides to join up to form polynucleotides.

(when a phosphate ion is attached to another molecule, it’s known as a phosphate group)