NEET Biology Excretory Products and their Elimination Important Questions Set 02

These Class 11 NEET Biology important questions on Excretory Products and their Elimination give 20 questions with step-by-step answers, arranged as very short, short and long answer types, taken from a model test paper. They help NEET aspirants revise the definitions, structures, differences and key terms of the chapter.

Very Short Answer Type Questions

Question 1. Which limb of loop of Henle is impermeable to water?
Answer: Ascending limb of loop of Henle.

Question 2. Name the part of the uriniferous tubule (nephron) which is influenced by ADH.
Answer: Distal convoluted tubule.

Question 3. What is Malpighian body?
Answer: Glomerulus and Bowman's capsule are collectively called malpighian body.

Question 4. Where do the nephrons discharge their filtrate?
Answer: Collecting duct

Question 5. Where is urea formed in the human body?
Answer: Liver

Short Answer Type Questions

Question 6. Both the thin and thick segments of the ascending limb of Henle's loop transport NaCl out to the interstitial fluid. What is the difference in their respective mode of transport?

Answer:

From thin segment of ascending limb of loop of Henle – By diffusion (passive transport).

From thick segment of ascending limb of loop of Henle – By active transport.

Question 7. Name the basic nitrogenous waste of birds. In what form it is eliminated from the body? What is the advantage of such type of excretion?
Answer: Uric acid, in the form of pellet or paste; conservation of water.

Question 8. (i) What is loop of Henle?
(ii) How does a shark differ from a teleost fish in the chemical nature of nitrogenous excretory wastes?

Answer:

(i) Loop of Henle is hairpin like tubular part of nephron that lies between PCT and DCT and it dips into renal medulla.

(ii) Shark excretes urea as nitrogenous waste, while teleost fish excrete ammonia.

Question 9. Which layers form filtration membrane?

Answer:

Filtration membrane is formed by three layers :

(i) The endothelium of glomerular blood vessels.

(ii) The epithelium of Bowman's capsule.

(iii) A basement membrane between these two layers.

Question 10. Name the excretory organs present in the following animals.
(i) Earthworm
(ii) Man
(iii) Flatworm
(iv) Branchiostoma

Answer:

Question 11. Only land animals excrete nitrogenous waste as uric acid. Give scientific reason.
Answer: It is so because land animals live in conditions of water scarcity and uric acid can be excreted in nearly solid form thereby conserving body water.

Short Answer Type Questions

Question 12. What happens to the walls of distal convoluted tubule (DCT) of a nephron when vasopressin is released into the blood stream?
Answer: Vasopressin is also called antidiuretic hormone (ADH). It decreases the loss of water in the urine by increasing the reabsorption of water in the distal convoluted tubule.

Question 13. (i) Which enzyme converts angiotensinogen into angiotensin I?
(ii) Where urine is temporarily stored in the human body?
(iii) How much amount of urea is excreted out per day by an adult human?

Answer:

(i) Renin

(ii) Urinary bladder

(iii) On an average, 25–30 g of urea is excreted out per day by an adult human.

Question 14. What is the source of renin? When it is released? Give its function.
Answer: Renin is secreted by Juxtaglomerular cells (JG cells) of Juxtaglomerular apparatus (JGA). It is secreted when there is fall in glomerular blood flow/glomerular blood pressure/GFR. Renin converts angiotensinogen in blood to angiotensin I.

Question 15. (i) State the characteristics of urine in Diabetes mellitus.
(ii) What is the average pH of urine formed in an adult human?

Answer:

(i) Urine of a person suffering from diabetes mellitus show presence of glucose (Glycosuria) and ketone bodies (Ketonuria).

(ii) The average pH of urine is 6.0.

Question 16. Name the parts which play an important role in counter current mechanism. Why have birds and mammals evolved counter current mechanism to excrete hypertonic urine?

Answer:

Loop of Henle and vasa recta play an important role in counter current mechanism.

Birds and mammals, being terrestrial animals, have to conserve water. Therefore, they have developed counter current mechanism to excrete hypertonic urine from their bodies.

Question 17. Write down the functions of following :
(i) Urinary bladder
(ii) Ureter
(iii) Urethra

Answer:

(i) Urinary bladder : It temporarily stores urine.

(ii) Ureter : Conduct urine from kidney to urinary bladder.

(iii) Urethra : It conducts urine in female and both urine and semen in male.

Long Answer Type Questions

Question 18. Fill in the blanks with appropriate words :
(i) Glomerulonephritis is the inflammation of _______ of kidney.
(ii) Malfunctioning of kidneys can lead to accumulation of _______ in blood, a condition called _______.
(iii) _______ is the largest gland of our body.
(iv) The amount of filtrate formed by the kidneys per minute is called _______.
(v) _______ is the functional unit of kidney.

Answer:

(i) Glomeruli

(ii) Urea, uremia

(iii) Liver

(iv) Glomerular filtration rate (GFR)

(v) Nephron

Question 19. Draw a diagram of nephron and label the following parts.
(i) Afferent arteriole
(ii) Efferent arteriole
(iii) Glomerulus
(iv) Bowman's capsule
(v) Malpighian body
(vi) Descending limb of loop of Henle
(vii) Ascending limb of loop of Henle
(viii) Vasa recta
(ix) Proximal convoluted tubule
(x) Distal convoluted tubule
Answer: A well-labelled diagram should show these parts: Efferent arteriole; Afferent arteriole; Glomerulus; Malpighian body/; Renal corpuscle; Bowman's capsule; Proximal convoluted tubule; Distal convoluted tubule; Cortex; Descendingof of limb; Medulla loop Henle; Henle's loop; Ascendingof limb of loop Henle; Vasa recta; Collecting duct.

Question 20. Explain in brief the mechanism of urine formation.

Answer:

Urine formation involves three main processes : (i) Glomerular filtration, (ii) Reabsorption and (iii) Secretion.

(i) Glomerular filtration : The first step in urine formation is the filtration of blood, which is carried out by the glomerulus and is called glomerular filtration. On an average, 1100–1200 mL of blood is filtered by the kidneys per minute which constitute roughly 1/5th of the blood pumped out by each ventricle of the heart in a minute. The glomerular capillary blood pressure causes filtration of blood through three layers, i.e., the endothelium of glomerular blood vessels, the epithelium of Bowman's capsule and a basement membrane between these two layers. The epithelial cells of Bowman's capsule called podocytes are arranged in an intricate manner so as to leave some minute spaces called filtration slits or slit pores. Blood is filtered so finely through these membranes, that almost all the constituents of the plasma except the proteins pass into the lumen of the Bowman's capsule. Therefore, it is considered as a process of ultrafiltration.

The amount of filtrate formed by the kidneys per minute is called glomerular filtration rate (GFR). GFR in a healthy individual is approximately 125 mL/minute, i.e., 180 litres per day.

The kidneys have built-in mechanisms for the regulation of glomerular filtration rate. One such efficient mechanism is carried out by juxtaglomerular apparatus (JGA). JGA is a special sensitive region formed by cellular modifications in the distal convoluted tubule and the afferent arteriole at the location of their contact. A fall in GFR can activate the JG cells to release renin which can stimulate the glomerular blood flow and thereby the GFR back to normal.
(ii) Reabsorption : A comparison of the volume of the filtrate formed per day (180 litres/day) with that of the urine released (1.5 litres), suggest that nearly 99 percent of the filtrate has to be reabsorbed by the renal tubules. This process is called reabsorption. The tubular epithelial cells in different segments of nephron perform this either by active or passive mechanisms. For example, substances like glucose, amino acids, Na⁺, etc., in the filtrate are reabsorbed actively, whereas the nitrogenous wastes are absorbed by passive transport. Reabsorption of water also occurs passively in the initial segments of the nephron.

(iii) Secretion : During urine formation, the tubular cells secrete substances like H⁺, K⁺ and ammonia into the filtrate. Tubular secretion is also an important step in urine formation as it helps in the maintenance of ionic and acid-base balance of body fluids.