Question

Kidneys help to regulate the volume of fluid and various metabolites waste products in the body. Normally, kidney filter about 180 L of fluid daily but the volume actually excreted out is only a litre or two a day. Patients with kidney failures can be saved by dialysis and kidney transplant.

(a) Write the structure and function of Bowman’s capsule.    [1]

(b) Although kidneys filter a large amount (about 180 L daily) of fluids, still the excretion from the body is only about a litre or two. Why?    [1]

(c) What is excretion? Why is it necessary for any living organism?    [2]

OR

(c) State two similarities between lungs and kidneys.    [2]

Answer 1

(a) Structure of Bowman’s capsule:

Bowman’s capsule is a cup-shaped, double-walled structure. It surrounds the glomerulus in the nephron of the kidney. It forms the initial part of the renal tubule.

Function of Bowman’s capsule: It collects the filtrate formed by ultrafiltration of blood in the glomerulus. It allows water and small solutes (like urea, salts, glucose) to pass while retaining blood cells and proteins.

(b) Although about 180 L of filtrate is formed daily, most of it is selectively reabsorbed (water, glucose, ions) back into the blood in the tubules. Hence, only 1-2 L of urine is finally excreted.

(c) Excretion is the process of removal of metabolic waste products (like urea, CO₂, excess salts and water) from the body.
It is necessary to maintain internal balance (homeostasis) and prevent the accumulation of toxic substances, which can harm the body.

OR

(c) Similarities between Lungs and kidneys are:

1. Both help in the removal of waste products from the body (lungs remove CO₂, kidneys remove urea).
2. Both are richly supplied with blood capillaries, allowing efficient exchange and removal of wastes.