NCERT Class 11-Biology: Chapter –19 Excretory Products and Their Elimination Part 4

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Question 12:

Sort the following into actively or passively transported substances during reabsorption of GFR. glucose, aminoacids, nitrogenous wastes, Na+, water

Answer:

Actively transported: Glucose, amino acids,

Passively transported: Nitrogenous wastes and water

Reabsorption of water also occurs passively in the initial segments of the nephron. The ascending limb is impermeable to water but allows transport of electrolytes actively or passively.

Question 13:

Complete the following:

a. urinary excretion = tubular reabsorption + tubular secretion –

b. Dialysis fluid = Plasma–

Answer:

a. urinary excretion tubular reabsorption tubular secretion – Glomerular filtration.

Tubular reabsorption: Tubular reabsorption is the process by which the nephron removes water and solutes from the fluid from the tubules (pre-urine) and returns the same to the blood which is circulating.

Tubular secretion: It is secretion of H⁺ and NH₄⁺ from the blood into the tubular fluid that helps to keep blood pH and maintain osmolality.

b. Dialysis fluid = Plasma– nitrogenous wastes

Nitrogenous wastes: Any metabolic waste product that contains nitrogen is called nitrogenous wastes.

Question 14:

Mention the substances that exit from the tubules in order to maintain a concentration gradient in the medullary interstitium.

Answer:

The substances that exit from the tubules in order to maintain a concentration gradient in the medullary interstitium are urea and sodium chloride.

Urea is a breakdown protein of amino acid metabolism which is freely filtered at the glomerulus. The high osmolality of the renal medullary interstitium provides a concentration gradient needed for water reabsorption to occur.

Question 15:

Fill in the blanks appropriately

Answer:

(a) Urea

(b) Carbon dioxide

(c) bile, drugs

(d) Sterols, hydrocarbons

Short Answer Type Questions

Question 1:

Show the structure of a renal corpuscle with the help of a diagram.

Answer:

Question 2:

What is the role played by Renin-Angiotensin in the regulation of kidney function?

Answer:

The Juxtaglomerular (JG) apparatus has a regulatory role to play.

When there is a fall in glomerular filtration rate (GFR), they activate the JG cells to release renin which gets converted to angiotensinogen in blood to angiotensin I and further to angiotensin II. Angiotensin II, is a powerful vasoconstrictor that increases the GFR.

Angiotensin II is also responsible for activating the adrenal cortex to release Aldosterone which causes reabsorption of Na+ and water from the distal parts of the tubule leading to an increase in blood pressure and GFR.

This mechanism is known as the Renin-Angiotensin mechanism that regulates the kidney function.

The juxtaglomerular apparatus is a structure formed by the distal convoluted tubule and the glomerular afferent arteriole.