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100 questions in this collection · Page 6 of 10
Question 51 of 100
📘 CLASS XI
Excretory Products And Their Elimination
Analyze the statements below regarding the nervous regulation of the micturition reflex:
I. The stretching of the urinary bladder wall stimulates stretch receptors to send signals to the Central Nervous System (CNS). II. Motor impulses from the CNS cause simultaneous contraction of the urethral sphincter and relaxation of the bladder smooth muscles. III. The voluntary signal to initiate micturition is carried by the somatic nervous system to relax the external urethral sphincter. IV. Micturition is a completely involuntary reflex that cannot be modified by voluntary controls from higher brain centers.
Statement I is correct because stretching of the bladder wall activates stretch receptors that send impulses to the CNS. Statement II is incorrect because motor impulses cause contraction of the bladder smooth muscles and relaxation of the urethral sphincter, not the reverse. Statement III is correct because voluntary control involves relaxation of the external urethral sphincter through the somatic nervous system. Statement IV is incorrect because micturition is under voluntary control in adults.
Question 52 of 100
📘 CLASS XI
Excretory Products And Their Elimination
Consider the following physical and chemical features of normal human urine:
I. The average pH of normal human urine is 6.0, indicating its slightly acidic nature. II. It is a clear, dark brown fluid with a strong ammonia odor immediately upon excretion. III. An adult human excretes approximately 25–30 grams of urea in the urine daily. IV. Various physiological conditions can dynamically alter the characteristics of urine.
Statement I is correct because normal urine is slightly acidic with an average pH of about 6.0. Statement II is incorrect because fresh urine is light yellow with a characteristic odor and does not have a strong ammonia smell immediately after excretion. Statement III is correct because about 25–30 g of urea are excreted daily. Statement IV is correct because urine characteristics vary with physiological and pathological conditions.
Question 53 of 100
📘 CLASS XI
Excretory Products And Their Elimination
Evaluate these statements regarding the excretory roles of sweat and sebaceous glands in the skin:
I. Sweat is a watery fluid secreted by sweat glands containing NaCl, small amounts of urea, and lactic acid. II. The primary, essential physiological function of sweat is the excretion of metabolic nitrogenous wastes. III. Sebaceous glands eliminate sterols, hydrocarbons, and waxes through sebum. IV. Sebum provides a protective oily covering for the skin.
Statement I is correct because sweat contains NaCl, small amounts of urea, and lactic acid. Statement II is incorrect because the major function of sweat is thermoregulation, while excretion is secondary. Statements III and IV are correct because sebaceous glands secrete sterols, hydrocarbons, and waxes in sebum, which forms a protective oily layer over the skin.
Question 54 of 100
📘 CLASS XI
Excretory Products And Their Elimination
Read the statements below regarding the liver as an auxiliary excretory organ:
I. The liver is the largest gland in the human body and is the primary site of urea synthesis. II. Bile secreted by the liver contains substances like bilirubin, biliverdin, cholesterol, degraded steroid hormones, vitamins, and drugs. III. Most of the bile-contained excretory substances are reabsorbed back in the small intestine to conserve nutrients. IV. Bile pigments and degraded hormones are ultimately eliminated from the body along with fecal matter.
Statements I, II and IV are correct. The liver is the largest gland and synthesizes urea from ammonia. Bile contains bilirubin, biliverdin, cholesterol, degraded steroid hormones, vitamins, and drugs. These excretory substances are eliminated mainly with feces. Statement III is incorrect because these waste substances are not reabsorbed for conservation.
Question 55 of 100
📘 CLASS XI
Excretory Products And Their Elimination
Consider the excretory contributions of the human respiratory system based on these statements:
I. The lungs remove massive amounts of carbon dioxide, amounting to approximately 200 mL per minute under resting conditions. II. Water is lost from the respiratory tract in significant quantities daily, primarily as water vapor. III. Nitrogen gas dissolved in blood is actively excreted by alveolar epithelial cells. IV. The lungs play a direct role in the excretion of non-volatile nitrogenous metabolic wastes.
Statements I and II are correct because the lungs eliminate about 200 mL of CO₂ per minute along with considerable water vapor. Statement III is incorrect because nitrogen is not actively excreted by alveolar cells. Statement IV is incorrect because non-volatile nitrogenous wastes are eliminated mainly by the kidneys, not the lungs.
Question 56 of 100
📘 CLASS XI
Excretory Products And Their Elimination
Evaluate the statements below regarding the clinical procedure of hemodialysis:
I. Blood drained from a convenient vein is used for hemodialysis because vein walls are thinner. II. Before passing blood into the dialyser, an anticoagulant like heparin is added. III. The dialysing unit contains a coiled cellophane tube surrounded by a fluid having the same composition as plasma except the nitrogenous wastes. IV. The cellophane membrane of the tube allows macromolecular plasma proteins to pass out easily by active transport.
Statement I is incorrect because blood is withdrawn from a convenient artery, not a vein. Statements II and III are correct because heparin is added before dialysis and the dialysing fluid resembles plasma except that it lacks nitrogenous wastes. Statement IV is incorrect because the semipermeable membrane does not allow plasma proteins or blood cells to pass.
Question 57 of 100
📘 CLASS XI
Excretory Products And Their Elimination
Analyze these statements regarding the pathophysiological conditions of renal failure and its treatments:
I. Malfunctioning of kidneys can lead to accumulation of urea in blood, a condition called uremia, which is highly harmful and can lead to kidney failure. II. In hemodialysis, the cleared blood is pumped back to the body through a convenient vein after adding heparin. III. For patients with acute or chronic renal failure, kidney transplantation is the ultimate method in correction. IV. In kidney transplantation, a functioning kidney is used from a donor, preferably a close relative, to minimize host immune rejection.
Statement I is correct because kidney malfunction causes accumulation of urea in blood (uremia). Statement II is incorrect because anti-heparin, not heparin, is added before returning blood to the patient. Statements III and IV are correct because kidney transplantation is the definitive treatment for severe renal failure and a closely related donor minimizes immune rejection.
Question 58 of 100
📘 CLASS XI
Excretory Products And Their Elimination
Read the statements below regarding excretory disorders such as renal calculi and glomerulonephritis:
I. Renal calculi refer to the stone or insoluble mass of crystallized salts (oxalates, etc.) formed within the kidney. II. Renal calculi are primarily caused by excessive accumulation of water in the medullary pyramids. III. Glomerulonephritis is defined as the inflammation of the renal pelvis and calyces. IV. Glomerulonephritis represents the inflammation of glomeruli of the kidney.
Statement I is correct because renal calculi are stones or insoluble masses of crystallized salts such as calcium oxalate formed in the kidneys. Statement II is incorrect because renal calculi develop due to precipitation of mineral salts, not water accumulation. Statement III is incorrect because inflammation of the renal pelvis is pyelitis, whereas glomerulonephritis specifically involves inflammation of the glomeruli. Statement IV is correct because glomerulonephritis is inflammation of the kidney glomeruli.
Question 59 of 100
📘 CLASS XI
Excretory Products And Their Elimination
Compare the metabolic characteristics of different nitrogenous wastes based on these statements:
I. Ammonia requires the maximum amount of water for its excretion because of its highly toxic nature. II. Urea is about 100,000 times less toxic than ammonia and can be stored in the body temporarily. III. Uric acid is highly soluble in water and is excreted as a concentrated hypertonic aqueous solution. IV. Uricotelic animals lose large amounts of body water to excrete nitrogenous wastes.
Statement I is correct because ammonia is highly toxic and requires large amounts of water for excretion. Statement II is correct because urea is much less toxic than ammonia and can be temporarily stored. Statement III is incorrect because uric acid is almost insoluble in water. Statement IV is incorrect because uricotelic animals conserve water by excreting uric acid as a semisolid paste.
Question 60 of 100
📘 CLASS XI
Excretory Products And Their Elimination
Consider these statements regarding evolutionary variations in animal excretory mechanisms:
I. All vertebrates possess complex tubular kidneys for nitrogenous waste excretion. II. Simple invertebrates completely lack any specialized excretory structures, relying solely on simple diffusion through the skin. III. Nephridia help in maintaining fluid volume and ionic balance in earthworms. IV. Malpighian tubules remove nitrogenous wastes from the hemolymph of insects.
Statement I is correct because vertebrates possess kidneys as excretory organs. Statement II is incorrect because many invertebrates possess specialized excretory organs such as protonephridia, nephridia, or Malpighian tubules. Statement III is correct because nephridia perform excretion and osmoregulation. Statement IV is correct because Malpighian tubules remove nitrogenous wastes from insect hemolymph.