NEET Biology Excretory Products and their Elimination Important Questions Set 01

These Class 11 NEET Biology important questions on Excretory Products and their Elimination give 45 questions with step-by-step answers, arranged as very short, short and long answer types, as asked in school and board examinations. They help NEET aspirants revise the definitions, structures, differences and key terms of the chapter.

Very Short Answer Type Questions

Question 1. Mention the role of Henle's loop.
Answer: Henle's loop primarily helps to maintain osmolar gradient (300 mOsmL–1 to 1200 mOsmL–1) within the kidney interstitium.

Question 2. State the three main processes of urine formation.
Answer: Glomerular filtration, reabsorption and secretion.

Question 3. Name the ions/substances secreted by DCT into the filtrate.
Answer: H⁺, K⁺ and NH₃ (ammonia)

Question 4. Where is urine temporarily stored in the human body?
Answer: Urine is temporarily stored in urinary bladder in human body.

Question 5. Name the accessory excretory structures in human body other than kidneys.
Answer: Other than the kidneys, lungs, liver and skin also help in elimination of excretory wastes.

Question 6. Name the substances that are reabsorbed actively during urine formation.
Answer: Substances like glucose, amino acids, Na⁺ etc. in the filtrate are reabsorbed actively.

Question 7. In which part of the uriniferous tubule reabsorption takes place?
Answer: Reabsorption occurs in all parts of uriniferous tubule, i.e., PCT, loop of Henle and DCT.

Question 8. What is the maximum magnitude of osmolarity in the inner medulla of kidney?
Answer: 1200 mOsmL–1

Question 9. Name the hormones responsible for the reabsorption activities in DCT.
Answer: Aldosterone and vasopressin or ADH.

Question 10. In which type of nephron the loop of Henle is very long and runs deep into the medulla?
Answer: Juxta medullary nephron

Short Answer Type Questions

Question 11. What is JGA?
Answer: 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.

Question 12. What is the function of ADH/vasopressin?
Answer: ADH facilitates water reabsorption from latter parts of the tubule. It also cause an increase in blood pressure by its constrictory effects on blood vessels.

Question 13. What do you mean by tubular secretion?
Answer: The phenomenon of secretion of metabolic wastes from peritubular capillaries and interstitial fluid into lumen of nephron is called tubular secretion.

Question 14. How PCT helps to maintain the pH and ionic balance of the body fluids?
Answer: PCT helps to maintain the pH and ionic balance of the body fluids by selective secretion of hydrogen ions, ammonia and potassium ions into the filtrate and by absorption of HCO3– from it.

Question 15. Mention the structures in the human body responsible for regulation of kidney function.
Answer: The functioning of kidneys is efficiently monitored and regulated by hormonal feedback mechanisms involving the hypothalamus, JGA (Juxtaglomerular Apparatus) and to a certain extent, the heart.

Question 16. In which condition ADH or vasopressin is released from neurohypophysis?
Answer: Osmoreceptors in the body are activated by changes in blood volume, body fluid volume and ionic concentration. An excessive loss of fluid from the body can activate these receptors which stimulate the release of ADH or vasopressin.

Question 17. What is the primary function of sweat?
Answer: The primary function of sweat is to facilitate a cooling effect on the body surface. It also helps in the removal of some waste products such as urea, NaCl etc.

Question 18. What are the major nitrogenous wastes excreted by animals?
Answer: Ammonia, urea and uric acid are the major forms of the nitrogenous wastes excreted by the animals.

Question 19. How ammonia is excreted in animals?
Answer: Ammonia, as it is readily soluble in water, is generally excreted by diffusion across the body surfaces or through gill surfaces (in fishes) as ammonium ions.

Question 20. "The composition of glomerular filtrate and urine is not the same." Comment.
Answer: Glomerular filtrate contains all filterable components of blood. It is extremely dilute having both useful (salts, glucose, amino acids) and waste products. Urine is more concentrated solution of nitrogenous wastes and other excess chemicals. It is produced from glomerular filtrate through reabsorption and secretion.

Question 21. How ammonia is excreted in ureotelic animals?
Answer: Ammonia produced by metabolism is converted into urea in the liver of these animals and released into the blood which is filtered and excreted out by the kidneys.

Question 22. What are the excretory structures of annelids and give their function?
Answer: Nephridia are the excretory structures of annelids. They help to remove nitrogenous wastes and maintain a fluid and ionic balance.

Question 23. Sort the following into actively or passively transported substances during reabsorption : Glucose, amino acids, nitrogenous wastes, Na⁺, water.

Answer:

Actively transported : Na⁺, glucose, amino acids

Passively transported : Nitrogenous wastes, water

Question 24. What are the two zones of the kidney? In which zone is the renal pyramid present?

Answer:

There are two zones in kidney :

(i) An outer cortex

(ii) Inner medulla

Renal or medullary pyramids are conical masses projecting into calyces. These are found in medulla region of kidney.

Question 25. Where kidneys are located in man?
Answer: Kidneys are reddish brown, bean-shaped structures situated between the level of last thoracic and third lumbar vertebra close to the dorsal inner wall of the abdominal cavity.

Question 26. State the significance of hilum in a kidney.
Answer: Towards the centre of the inner concave surface of the kidney, a notch is present, called hilum. Ureter, blood vessels and nerves enter into kidney through this notch.

Question 27. What is the functional unit of kidney? How many functional units are found in each kidney?
Answer: Functional unit of kidney is nephron. Each kidney has about one million nephrons.

Question 28. (i) What is renal pelvis in a kidney?
(ii) What are podocytes?

Answer:

(i) A broad funnel shaped space in the kidney, inner to the hilum is called renal pelvis.

(ii) Podocytes are epithelial cells located in the visceral layer of Bowman's capsule.

Question 29. Draw a labelled diagram of malpighian body (renal corpuscle).
Answer: A well-labelled diagram should show these parts: Afferent arteriole; Efferent arteriole; Bowman's capsule; Proximal convoluted tubule.

Question 30. Which segments of nephron are located in cortex and in medulla region of kidney?
Answer: The malpighian corpuscle, PCT and DCT of the nephron are situated in the cortical region of the kidney, whereas the loop of Henle is present in the medulla region.

Long Answer Type Questions

Question 31. What is reabsorption? What all substances are reabsorbed in different parts of tubules?
Answer: The absorption of useful essential substances from glomerular filtrate by epithelium of uriniferous tubules for transfer to interstitial fluid and peritubular capillaries is called reabsorption. Reabsorption occurs by both active and passive processes. Reabsorption in proximal convoluted tubule (PCT) : Nearly all of the essential nutrients, and 70–80 percent of electrolytes and water are reabsorbed by this segment. Reabsorption in Henle's loop : Reabsorption in this segment is minimum. The descending limb of Henle's loop is permeable to water but almost impermeable to electrolytes. The ascending limb of loop of Henle is impermeable to water but allows transport of electrolytes actively or passively. Reabsorption in distal convoluted tubule (DCT) : Conditional reabsorption of Na⁺ and water takes place in this segment. Reabsorption of HCO3– also takes place. Reabsorption in collecting duct : Large amount of water could be reabsorbed. It also allows passage of small amounts of urea into the medullary interstitium to keep up the osmolarity.

Question 32. (i) If the diameter of efferent arteriole is made double than afferent arteriole, then what will be the effect?
(ii) If the prostate gland in old age gets enlarged, what will be the effect on urination?
Answer: (i) Glomerular filtration is based on the narrowness of efferent arteriole as compared to afferent arteriole. If diameter of efferent arteriole is increased, pressure of blood will ultimately decrease, and therefore, glomerular filtration will become slow or be absent.
(ii) Urethra passes through prostate in males. If prostate is enlarged as in old age, urethra gets pressed and urination becomes difficult and painful.

Question 33. How does juxtaglomerular apparatus regulate the kidney function?
Answer: JGA operates multihormonal Renin-Angiotensin-Aldosterone-System (RAAS). The JGA responds to a decrease in blood pressure or blood volume (glomerular blood flow/glomerular blood pressure/GFR) in the afferent arteriole of the glomerulus and can activate JG cells to release an enzyme, renin, into the blood stream. In the blood, renin initiates chemical reactions that convert a plasma protein called angiotensinogen, to a peptide called angiotensin II, which works as a hormone. Angiotensin II increases blood pressure by causing arterioles to constrict. It also increases blood volume in two ways :
(i) By signaling the PCT to reabsorb more NaCl and water.
(ii) By stimulating the adrenal gland to release aldosterone, a hormone that induces the distal parts to reabsorb more Na⁺ and water. This leads to an increase in blood volume and pressure, completing the feedback circuit by supporting the release of renin.

Question 34. (i) How is heart involved in regulation of kidney function?
(ii) Discuss the role of ADH in regulation of kidney function.
Answer: (i) ANF (Atrial Natriuretic Factor) released from heart keeps a check on renin-angiotensin mechanism. An increase in blood flow to the atria of the heart can cause the release of Atrial Natriuretic Factor (ANF) which causes vasodilation and thereby decrease the blood pressure.
(ii) An excessive loss of fluid from the body activates the osmoreceptors which stimulate the hypothalamus to release antidiuretic hormone (ADH) or vasopressin from neurohypophysis. ADH facilitates water reabsorption from latter parts of the tubule, thereby preventing diuresis. It also has constrictory effects on blood vessels which causes an increase in blood pressure thereby increasing glomerular blood flow/GFR.

Question 35. Explain micturition reflex.
Answer: Urine formed by the nephron is ultimately carried to the urinary bladder, where it is stored till a voluntary signal is given by the central nervous system (CNS). This signal is initiated by the stretching of the urinary bladder as it gets filled with urine. In response, the stretch receptors on the wall of the bladder send signals to the CNS. The CNS passes on motor messages to initiate the contraction of smooth muscles of the bladder and simultaneous relaxation of the urethral sphincter causing the release of urine. The process of release of urine is called micturition and the neural mechanisms causing it is called the micturition reflex.

Question 36. Mention the role of skin in excretion.
Answer: The sweat and sebaceous glands in the skin can eliminate certain substances through their secretions, i.e., sweat and sebum respectively. Sweat produced by sweat glands is a watery fluid containing NaCl, small amount of urea, amino acids and glucose etc. Though the primary function of sweat is to facilitate a cooling effect on the body surface. It also helps in the removal of some of the wastes mentioned above. Sebum is a waxy protective secretion to keep the skin oily and this secretion eliminates some lipids, such as waxes, sterols, other hydrocarbons and fatty acids.

Question 37. Write down a note on kidney transplantation.
Answer: If the kidney failure cannot be treated by drugs or dialysis, the patients are advised for kidney transplantation. A donated kidney may come from an anonymous donor who has recently died, or from a living person, usually a relative. The kidney of donor must be a good match for recipient. The more the new tissue from the donor is like the recepient's tissue, the less likely the immune system of the recipient is to reject it. Immune system protects from disease by attacking anything that is not recognised as a normal part of the body. So, the immune system of the recipient will attack a kidney that appears too 'foreign'. Special drugs can help suppress the immune system of the recipient, so it does not reject a transplanted kidney. Modern clinical procedures have increased the success rate of such a complicated technique.

Question 38. (i) Where does selective reabsorption of glomerular filtrate takes place?
(ii) What is the excretory matter in Amoeba?
(iii) Identify the glands that perform the excretory functions in prawn.
(iv) Expand the following :
(a) ANF
(b) ADH
(c) GFR
(d) DCT

Answer:

(i) Selective reabsorption of glomerular filtrate takes place at proximal convoluted tubule (PCT), ascending and descending limb of loop of Henle, distal convoluted tubule (DCT) and collecting duct.

(ii) Excretory matter in Amoeba is ammonia (NH₃).
(iii) Excretory functions in prawn is performed by antennal glands or green glands.

(iv) (a) ANF – Atrial natriuretic factor

(b) ADH – Antidiuretic hormone

(c) GFR – Glomerular filtration rate

(d) DCT – Distal convoluted tubule

Question 39. Explain in brief the tubular secretion, an important step of urine formation.

Answer:

The phenomenon of secretion of metabolic wastes from tubular cells into filtrate is called tubular secretion. It includes excess of K⁺, H⁺ and some wastes like hippuric acid, creatinine, drugs, pigments, toxins etc. It is the only mode of excretion in animals which do not have glomeruli, e.g., desert amphibians, marine fishes. 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.

Tubular secretion in PCT : H⁺, ammonia etc.

Tubular secretion in DCT : K⁺, H⁺ and ammonia (NH₃)

Tubular secretion in collecting duct : H⁺, K⁺

Question 40. Give a diagrammatic representation of a nephron and vasa recta showing counter-current mechanism.

Answer:

Bowman's Afferent capsule arteriole Glomerulus

Efferent H O 2 arteriole NaCl

Cortex

300 200

300 mOsmolL–1 300 300 400 NaCl Outer medulla NaCl NaCl 300 NaCl H2O 400 600 mOsmolL–1 NaCl 400 NaCl 600 H2O 400 H O NaCl 2 H2O

600 600 NaCl 800 600 900 mOsmolL–1 H2O Inner medulla NaCl H O 800 800 2 1000 Urea 900 1000 1000 1200 1200 H2O 1200 mOsmolL–1 Vasa recta Nephron

Diagrammatic representation of a nephron and vasa recta showing counter current mechanism

Question 41. Label the diagram (from A to I) given below.
Answer: A well-labelled diagram should show these parts: A; I; B; C; H D; G E; F; –; Medullary pyramid; Calyx; Renal artery; D; Renal vein; E; Renal pelvis; Ureter; G; Renal capsule; H; Cortex; Renal column.

Question 42. Label the diagram (from A to J) given below.
Answer: A well-labelled diagram should show these parts: A; J B; I C; D; E; F; G; H; –; Adrenal gland; B; Renal artery; C; Renal vein; Kidney; Dorsal aorta; Ureter; Urinary bladder; Urethra; I; Pelvis; J; Inferior vena cava.

Question 43. Label the diagram (from A to J) given below.

Answer:

A well-labelled diagram should show these parts: B; A; J; I; C; D; H; G; E; F; –; Afferent arteriole; Efferent arteriole; Proximal convoluted tubule; Distal convoluted tubule; Collecting duct; Vasa recta; Bowman's capsule; Glomerulus.

Question 44. Give answer in one word.
(i) Presence of glucose in urine
(ii) Presence of ketone bodies in urine
(iii) Accumulation of urea in blood
(iv) Another name of vasopressin
(v) Excretory product from kidneys of reptile.

Answer:

(i) Glycosuria

(ii) Ketonuria

(iii) Uremia

(iv) ADH (Antidiuretic hormone)

(v) Uric acid

Question 45. Describe the structure of a nephron with a well-labelled diagram.

Answer:

Structure of a nephron : Each nephron has two parts – the glomerulus and the renal tubule.

(i) Glomerulus : It is a tuft of capillaries formed by the afferent arteriole which is a fine branch of renal artery. Blood from the glomerulus is carried away by an efferent arteriole.

(ii) Renal tubule : It begins with Bowman's capsule.

Bowman's capsule : It is blind double-walled cup-shaped structure. The two walls of Bowman's capsule are inner visceral and outer parietal.

The visceral layer (inner wall) consists of flat squamous epithelial and specialised podocytes in the remaining part.

The parietal layer (outer wall) consists of flat squamous epithelium. The space between the two layers of Bowman's capsule is called lumen or capsular space.

Glomerulus along with Bowman's capsule is called malpighian body or renal corpuscle.

Proximal convoluted tubule (PCT) : Bowman's capsule leads PCT. It is present in cortex and lined by cuboidal epithelium having brush border. The cells contain abundant mitochondria.

Loop of Henle : It is hairpin loop like tubular part consisting of descending and an ascending limb.

Distal convoluted tubule (DCT) : The ascending limb of Henle's loop continue as DCT.

Collecting duct : The DCTs of many nephrons open into a straight tube called collecting duct.

The efferent arteriole forms a fine capillary network around the renal tubule called peritubular capillaries. A minute vessel of this network runs parallel to Henle's loop forming U-shaped vasa recta.

Efferent arteriole Afferent arteriole

Glomerulus Bowman's capsule Proximal convoluted tubule

Distal convoluted tubule

Descendingof of limb loop Henle Henle's loop Ascendingof limb of loop Henle

Vasa recta Collecting duct