The kidneys filter the blood - AQA - GCSE Biology - Question 6 - 2023 - Paper 2

Protein: The molecules are too large to pass through the filter.

To find the volume of water reabsorbed into the blood, subtract the volume of water lost in urine from the volume of water filtered from blood:

Volume reabsorbed = Water filtered from blood - Water lost in urine

Volume reabsorbed = 160.0 dm³ - 1.9 dm³ = 158.1 dm³.

A kidney transplant may be better because it generally provides a more permanent solution compared to dialysis, which is a continual treatment.

Supporting Points for Transplant:

• Cheaper in the long term, saving £18,000 in the first year and £30,000 over subsequent years compared to the cost of dialysis.
• No restrictions on lifestyle and no need for regular hospital visits.
• Reduced risk of infection from dialysis procedures.

Counterpoints for Transplant:

• Risk of rejection and the need for long-term immunosuppressant drugs.
• Potential complications like damage from anesthesia.
• A sense of uncertainty regarding the lifespan of the transplanted kidney (approximately 10 years).

In conclusion, while the transplant offers numerous benefits, potential risks and lifestyle changes must be considered.

The total cost of a kidney transplant over the first 5 years can be calculated as follows:

• First year: £17,000
• Next four years: 4 × £5,000 = £20,000

Total cost = £17,000 + £20,000 = £37,000.