Tuesday 25 May 2010

Question 1

Cholera bacteria are prokaryotic cells. Give three structures found in prokaryotic cells but not in eukaryotic cells. 3 marks

Answer 1

• Plasmids
• Strands of DNA
• Flagellum

Question 2

Cholera bacteria cause an increase in the secretion of chloride ions into the small intestine. Use your knowledge of water potential to explain how the increased secretion of chloride ions causes diarrhoea. 2 marks

Answer 2

• Lower water potential in the lumen

- Water enters the intestine by osmosis

Question 3

People with diarrhoea suffer fluid loss. They can use oral rehydration solutions (ORS) to replace the lost fluid. The mixture used to make an oral rehydration solution is stored as a powder. The powder can be made into a solution with boiled water.
Why must boiled water be used to make an ORS? 1 mark

Answer 3

• Kills bacteria

- Prevents bacteria from entering the body

Question 4

The mixture used to make the ORS contains glucose. Give one other substance that must be present in the mixture. 1 mark

Answer 4

• Sodium
• ## Potassium