Which one of the following is correct with reference to haemodialysis?

Options

A. Absorbs and resends excess of ions
B. The dialysis unit has a coiled cellophane tube
C. Blood is pumped back through a suitable artery after haemodialysis
D. Nitrogenous wastes are removed by active transport

Explanation

### Step-by-Step Solution:

1. **Understanding Hemodialysis**: Hemodialysis is a medical procedure used to remove waste products and excess ions from the blood when the kidneys are not functioning properly. It involves filtering the blood through a machine.

2. **Evaluating the Statements**:
- **Statement 1**: "Absorbs and resends excess of ions."
- This statement is incorrect. Hemodialysis does not absorb and resend ions; it removes excess ions and waste products from the blood.

- **Statement 2**: "The dialysis unit has a coiled cellophane tube."
- This statement is correct. The dialysis unit, or dialyzer, uses a semi-permeable membrane (often made of cellophane) to separate blood from the dialysate (washing fluid). This allows for the exchange of waste products and ions.

- **Statement 3**: "Blood is pumped back through a suitable artery after hemodialysis."
- This statement is incorrect. The blood is filtered and then returned to the body, but it does not go back through an artery; rather, it is returned via a venous access point.

- **Statement 4**: "Nitrogenous wastes are removed by active transport."
- This statement is incorrect. The removal of nitrogenous wastes such as urea and creatinine during hemodialysis occurs through passive diffusion, not active transport.

3. **Conclusion**: After evaluating all the statements, the only correct statement regarding hemodialysis is that "the dialysis unit has a coiled cellophane tube."

### Final Answer:
The correct statement with reference to hemodialysis is: **The dialysis unit has a coiled cellophane tube.**

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