Weekly chapter test: CBSE Class 11

1. A student claims that the loop of Henle in cortical nephrons is responsible for producing highly concentrated urine. What is wrong with this reasoning?

• A. Cortical nephrons lack a loop of Henle entirely
• B. Cortical nephrons have short loops that barely enter the medulla, contributing little to the osmotic gradient
• C. The loop of Henle only secretes urea, not water or salts
• D. Cortical nephrons are located outside the kidney and do not filter blood

2. A farmer observes that a freshwater fish (rohu) and a marine bony fish both live in water, yet their excretory challenges differ. Which statement correctly compares their osmoregulatory strategies?

• A. Both excrete large volumes of dilute urine because water is abundant
• B. Freshwater fish produce dilute urine to expel excess water; marine fish produce small volumes of concentrated urine to conserve water
• C. Both fish are uricotelic because they live in aquatic environments
• D. Marine fish excrete more ammonia than freshwater fish due to higher salt content

3. The juxtaglomerular apparatus (JGA) is a specialised structure that releases renin. Where is the JGA located in the nephron?

• A. At the junction of the loop of Henle and collecting duct
• B. Where the distal convoluted tubule contacts the afferent arteriole of the same nephron
• C. Inside the Bowman's capsule surrounding the glomerulus
• D. At the opening of the collecting duct into the renal pelvis

4. In haemodialysis, blood is passed through a dialyser containing a semipermeable membrane. Which principle allows waste products like urea to move from blood into the dialysing fluid?

• A. Active transport using ATP
• B. Osmosis driven by water potential difference
• C. Diffusion along the concentration gradient
• D. Endocytosis by membrane proteins

5. During a practical, a student argues that tubular secretion is unnecessary because glomerular filtration already removes all wastes. Why is this reasoning incorrect?

• A. Filtration cannot occur without prior secretion in the tubules
• B. Some substances like H⁺, K⁺ and certain drugs are not filtered efficiently and need active secretion
• C. Tubular secretion only adds water, not waste products
• D. Glomerular filtration removes proteins which secretion must return

6. An animal excretes nitrogenous waste mainly in the form of ammonia. What term describes this mode of excretion?

• A. Ureotelism
• B. Uricotelism
• C. Ammonotelism
• D. Aminotelism

7. A biology student claims that birds excrete urea as their main nitrogenous waste because they are warm-blooded like mammals. What is wrong with this reasoning?

• A. Birds actually excrete ammonia, not urea
• B. Birds excrete uric acid to conserve water, which is unrelated to being warm-blooded
• C. Birds excrete urea but convert it to uric acid only during flight
• D. Warm-blooded animals always excrete ammonia

8. Antidiuretic hormone (ADH) primarily acts on which part of the nephron to increase water reabsorption?

• A. Glomerulus
• B. Proximal convoluted tubule
• C. Ascending limb of loop of Henle
• D. Distal convoluted tubule and collecting duct

9. If the PCT failed to reabsorb glucose, what would be the direct consequence for urine composition?

• A. Urine would contain no urea
• B. Glucose would appear in urine in significant amounts
• C. Urine volume would decrease drastically
• D. Urine would become highly acidic

10. During haemodialysis, a patient's blood flows through a dialyser at 200 mL/min. The dialysing fluid contains glucose at 100 mg/100 mL, while the patient's blood has glucose at 100 mg/100 mL. Urea in blood is 80 mg/100 mL, while dialysing fluid has 0 mg/100 mL urea. Which substance will move from blood to dialysing fluid?

• A. Both glucose and urea
• B. Only glucose
• C. Only urea
• D. Neither glucose nor urea