Important Questions from Excretory Products and Their Elimination | Class 11 Biology | NEET 2023

There are three forms of nitrogenous wastes excreted by animals namely, urea, ammonia and uric acid. Here is a collection of all important questions that focus on the elimination of such types of waste from organisms.

1. 1. Which form of nitrogenous waste is the most toxic?

(a) Urea

(b) Ammonia

(c) Uric acid

(d) All are non-toxic

Answer: (b)

Explanation: The nitrogen compound in the form of which excess nitrogen is removed from the body is called nitrogenous waste. There are three forms such nitrogen compounds –

1. 1. • Ammonia – most toxic
      • Urea
      • Uric Acid – least toxic
   2. The process by which organisms maintain a constant internal environment is:

(a) Thermoregulation

(b) Hemostasis

(c) Homeostasis

(d) Osmoregulation

Answer: (c)

Explanation: Thermoregulation is the phenomena of maintenance of the body temperature within an optimum range. Hemostasis is a natural physiological process where the body prevents bleeding at the site of injury while maintaining normal blood flow elsewhere. Homeostasis is the process by which organisms maintain a constant internal environment despite changes in the outside environment. Lastly, osmoregulation is the process of maintaining osmotic pressure of fluids and electrolytes in an organism.

1. 1. Column of Bertini is an extension of

(a) medulla into cortex

(b) cortex into medulla

(c) renal pelvis into renal pyramid

(d) renal pelvis into renal cortex

Answer: (b)

Explanation: The kidney is divided into two zones – cortex and medulla. Cortex forms the peripheral zone of the kidneys. The renal cortex extends in between the medullary pyramids as renal columns called columns of Bertini. Renal pelvis is the space where two or three major calyces join.

1. 1. Glomerulus and Bowman’s capsule together constitute

(a) Henle’s loop

(b) collecting duct

(c) juxtaglomerular apparatus

(d) malpighian corpuscle

Answer: (d)

Explanation: Glomerulus and Bowman’s capsule together constitute the malpighian corpuscle, or renal corpuscle or pygmalion corpuscle. The Bowman’s capsule is a cup like sac that is present at the starting of nephrons (structural and functional unit of kidney). Inside the capsule are enclosed a cluster of microscopic blood vessels called glomerulus where waste is filtered from the blood.

1. 1. A minute vessel of the efferent arterioles runs parallel to the Henle’s loop to form

(a) vasa recta

(b) peritubular capillary

(c) malpighian tubules

(d) glomerulus

Answer: (a)

Explanation: Vasa recta are blood capillaries that surround the renal tubule called the loop of Henle in the juxtamedullary nephrons. It is reduced or absent in cortical nephrons.

1. 1. HCO₃^– absorption takes place in

(a) proximal convoluted tubule and distal convoluted tubule

(b) distal convoluted tubule and collecting duct

(c) proximal convoluted tubule and Henle’s loop

(d) Henle’s loop and collecting duct

Answer: (a)

Explanation: The proximal convoluted tubule is:

1. 1. • A highly coiled structure
      • Found next to Bowman’s capsule
      • Involved in absorption of HCO₃^– from filtrate
      • Reabsorbs nearly all the essential nutrients and 70-80% of electrolytes and water

The distal convoluted tubule is:

1. 1. • A highly coiled tubule that opens into the collecting duct
      • Involved in reabsorption of HCO₃^– and conditional reabsorption of water and Na⁺ ions

Henle’s loop is not much involved in the reabsorption of HCO₃^–. Collecting duct reabsorbs a large amount of water.

1. 1. In a healthy individual, an average of ___ blood is filtered by the kidneys per minute.

(a) 1000mL/min

(b) 1100-1200 mL/min

(c) 125mL/min

(d) 1500mL/min

Answer: (b)

Explanation: In a healthy individual, 1100-1200 mL of blood is filtered by the kidneys per minute.

1. 1. Choose the correct option.

(a) A-proximal convoluted tubule, B-Henle’s loop, C-distal convoluted tubule, D-glomerulus, E-collecting duct

(b) A-Henle’s loop, B-glomerulus, C-proximal convoluted tubule, D-distal convoluted tubule, E-collecting duct

(c) A-collecting duct, B-Henle’s loop, C-proximal convoluted tubule, D-distal convoluted tubule, E-glomerulus

(d) A-glomerulus, B-proximal convoluted tubule, C-Henle’s loop, D-distal convoluted tubule, E-collecting duct

Answer: (d)

Explanation: Nephrons are the structural and functional units of the kidney that are found in millions of numbers. It consists of the glomerulus and renal tubule. The glomerulus is a bunch of capillaries formed from the afferent arteriole. The renal tubule consists of proximal convoluted tubule (PCT), Henle’s loop, distal convoluted tubule (DCT), and collecting duct.

1. 1. Counter current mechanism helps in _____ osmolarity towards the inner medulla.

(a) increasing

(b) decreasing

(c) constant

(d) increasing and then decreasing

Answer: (a)

Explanation: According to the countercurrent mechanism, when filtrate flows in the two limbs of Henle’s loop, blood flows through the two limbs of vasa recta in a countercurrent pattern. This countercurrent flow helps in increasing osmolarity towards the inner medulla. Osmolarity gradient varies from 300mOsmo/L in the cortex to 1200 mOsmo/L in the inner medulla. This gradient helps in removing water from the collecting duct, thereby concentrating the urine.

1. 1. Glucose is reabsorbed from glomerular filtrate through

(a) diffusion

(b) active transport

(c) passive transport

(d) osmosis

Answer: (b)

Explanation: The epithelial cells of the renal tubule reabsorbs substances either by active or passive mechanisms. Substances like amino acids, glucose, Na⁺ are reabsorbed by active transport. Substances like nitrogenous wastes and water are reabsorbed passively.

1. 1. Increase in blood flow stimulates certain specific cells of cardiac atria to secrete:

(a) ADH

(b) Renin

(c) Aldosterone

(d) ANF

Answer: (d)

Explanation: Increase in blood volume or blood flow to the atria of the heart can cause the release of peptide hormone called Atrial Natriuretic Factor (ANF). The primary function of ANF is to decrease blood pressure and, in turn, maintain the GFR ( glomerular filtration rate) within normal range.

1. 1. Choose the correct statement(s):

I. Descending limb of Henle’s loop is permeable to water.

II. Ascending limb of Henle’s loop is permeable to electrolytes.

III. Descending limb of Henle’s loop is permeable to electrolytes.

IV. Reabsorption is minimal in Henle’s ascending loop region.

(a) III is true

(b) I and IV are true

(c) I and III are true

(d) I, II and IV are true

Answer: (d)

Explanation: The descending loop of Henle is permeable to water but impermeable to electrolytes. This makes the filtrate concentrated as it moves down the Henle’s loop. The ascending limb is impermeable to water but permeable to electrolytes. Hence, the filtrate gets diluted as it passes the ascending loop region. Reabsorption is minimal in the ascending limb of Henle’s loop.

1. 1. Which of the following is correct with respect to the juxtamedullary nephron?

(a) Henle’s loop is long

(b) Henle’s loop extends deep into the medulla

(c) Both a & b are correct

(d) Henle’s loop is short

Answer: (c)

Explanation: In some of the nephrons, the loop of Henle is very long and runs deep into the medulla. These nephrons are called juxtamedullary nephrons. In the majority of nephrons, the loop of Henle is too short and extends only very little into the medulla. Such nephrons are called cortical nephrons.

1. 1. Juxtaglomerular apparatus is a sensitive region formed at the location of contact of

(a) distal convoluted tubule and efferent arterioles

(b) proximal convoluted tubule and afferent arterioles

(c) proximal convoluted tubule and efferent arterioles

(d) distal convoluted tubule and afferent arterioles

Answer: (d)

Explanation: Juxtaglomerular apparatus (JGA) is a special sensitive region formed by cellular modifications in the distal convoluted tubule and the afferent arterioles at the location of their contact. It improves the efficiency of the formation of urine.

1. 1. During the formation of urine, which among these processes helps in maintaining ionic and acid base balance in body fluids?

(a) Ultrafiltration

(b) Reabsorption

(c) Secretion

(d) Micturition

Answer: (c)

Explanation: The tubular cells secrete certain substances like H⁺, K⁺ and ammonia into the filtrate that helps in maintaining ionic and acid base balance of body fluids.

1. 1. Assertion: Angiotensin II increases GFR.

Reason: It is a powerful vasodilator.

(a) Both the assertion and reason are true and the reason is the correct explanation for the assertion.

(b) Both assertion and reason are true but reason is not the correct explanation for the assertion.

(c) The assertion is true but the reason is false.

(d) The reason is true but the assertion is false.

Answer: (c)

Explanation: A fall in glomerular blood flow or glomerular blood pressure or GFR activates the juxtaglomerular cells to release renin which converts angiotensinogen in blood to angiotensin I and further to angiotensin II. Angiotensin II, being a powerful vasoconstrictor, increases the glomerular blood pressure and thereby GFR.

1. 1. When ADH level decreases in the blood,

(a) volume of urine decreases

(b) volume of urine increases

(c) volume of the urine remains unaffected

(d) sometimes decreases and sometimes increases

Answer: (b)

Explanation: When ADH, or antidiuretic hormone decreases in the blood, kidneys will not reabsorb much water and the volume of urine that is excreted increases.

1. 1. Micturition is

(a) central nervous system initiating the contraction of urinary bladder

(b) process of release of urine

(c) central nervous system initiating the relaxation of urethral sphincter

(d) filtering of blood to remove waste materials that is carried by blood

Answer: (b)

Explanation: The urine formed in the kidneys is transported to the urinary bladder. As the bladder becomes full, the stretch receptors send a message to the central nervous system. The CNS initiates the contraction of the bladder and simultaneous relaxation of urethral sphincter. This coordinated and sustained contraction of the detrusor muscle along with the simultaneous relaxation of the urethra is micturition reflex. This leads to the release of urine from the urinary bladder. This process is called micturition.

1. 1. Accumulation of urea in blood is called

(a) hematuria

(b) pyuria

(c) uremia

(d) ketonuria

Answer: (c)

Explanation: Abnormal functioning of kidneys can lead to accumulation of urea in blood. This condition is known as uremia. This condition can lead to fluid, electrolyte and hormonal imbalances in the body. Patients having uremia can undergo hemodialysis and remove urea from blood.

1. 1. Dialysing fluid has composition same as

(a) water

(b) plasma

(c) blood

(d) plasma without nitrogenous waste

Answer: (d)

Explanation: A hemodialysis unit contains a coiled cellophane tube (dialyzer) with the dialysing fluid. Dialysing fluid is similar to blood plasma in composition except for the nitrogenous waste. Due to the concentration gradient between blood and dialysing fluid, nitrogenous wastes move from plasma to the dialysing fluid. The purified blood is transferred back to the patient’s body.

Visit BYJU’S for more important updates on NEET.

Recommended Video:

Also See:

• MCQ on Regulation of Gene Expression in Eukaryotes
• Important Notes of Biology for NEET: Human Health and Disease
• Heterotrophic Bacteria