The diagram given alongside is the longitudinal section of a human kidney. Study the diagram and answer the questions that follow.

(i) Label the parts numbered 1 and 3.

(ii) Name the fluid that passes down from the part numbered as 4. Also write its main nitrogenous constituent.

(iii) Why does part 2 show a striped appearance?

(i) The parts labelled 1 and 3 are:

• 1 → Cortex
• 3 → Pelvis

(ii) The fluid is urine. Its main nitrogenous constituent is Urea.

(iii) Henle's loops and collecting ducts lie in the medulla of kidneys giving it a striped appearance.