Excretory Products and their Elimination is a compact Human Physiology chapter with clear facts and fixed numbers. This excretory system NEET PYQ analysis shows which parts of the nephron NTA keeps asking about, the values you must remember, and the hormone pathway that appears in paper after paper.

For the full physiology plan, see our complete Human Physiology guide. This article gives you the chapter-level detail.

Want to test yourself first? Solve the Excretory Products and their Elimination PYQs for free, then use this guide to fix the gaps.

Why This Chapter Is Reliable Marks

NEET usually asks one to two questions from this chapter. Most are direct NCERT facts: which segment does what, which hormone acts where, and a few numbers.

Diagrams matter here, especially the nephron and the counter-current system. Our guide to memorising NCERT Biology diagrams helps with those. See every Biology unit in our full Biology chapter list.

Excretory System NEET PYQ Analysis: The Repeated Question Types

When you sort a decade of NEET biology PYQs from this chapter, five question types cover almost everything.

Question type	Frequency	What it tests
Functions of nephron segments	Most frequent	PCT, loop of Henle, DCT, collecting duct
Hormonal regulation	Very frequent	ADH, renin–angiotensin, aldosterone, ANF
Counter-current mechanism	Very frequent	Role of Henle’s loop and vasa recta
Nitrogenous wastes	Regular	Ammonotelic, ureotelic, uricotelic animals
Numbers and disorders	Regular	GFR, urine output, uremia, renal calculi

For a quick warm-up before the full set, try these five quick physiology practice questions.

Nitrogenous Wastes and Excretory Structures

Type	Main waste	Examples
Ammonotelic	Ammonia	Bony fishes, aquatic amphibians, aquatic insects
Ureotelic	Urea	Mammals, many terrestrial amphibians, marine fishes
Uricotelic	Uric acid	Reptiles, birds, land snails, insects

Ammonia is the most toxic and needs the most water. Uric acid is the least toxic and needs the least.

Excretory structures across animals are also asked: flame cells in Platyhelminthes, nephridia in earthworms, Malpighian tubules in insects and green glands in crustaceans. These link back to our Animal Kingdom PYQ patterns article.

Nephron Structure: What Each Segment Does

Segment	Key function
Glomerulus and Bowman’s capsule	Ultrafiltration of blood
PCT	Reabsorbs 70–80% of electrolytes and water; all glucose and amino acids
Descending limb of Henle’s loop	Permeable to water, almost impermeable to electrolytes
Ascending limb of Henle’s loop	Impermeable to water, transports electrolytes out
DCT	Conditional reabsorption of Na⁺ and water; secretes H⁺ and K⁺
Collecting duct	Reabsorbs large amounts of water to concentrate urine

Numbers to remember:

• Each kidney has about 1 million nephrons
• Glomerular filtration rate (GFR) is about 125 mL per minute, or 180 litres per day
• About 99% of the filtrate is reabsorbed
• Urine output is about 1 to 1.5 litres per day

Juxtamedullary nephrons have a long loop of Henle that runs deep into the medulla. Cortical nephrons have a short one. Filtration depends on blood pressure, which our circulation chapter PYQ patterns article covers.

The Counter-Current Mechanism

The loop of Henle and the vasa recta run in opposite directions. This counter-current mechanism builds an osmolarity gradient in the medulla, from about 300 mOsmol/L in the cortex to about 1200 mOsmol/L in the inner medulla.

NaCl and urea maintain this gradient. It lets the collecting duct draw water out, so humans can produce urine that is about four times more concentrated than the initial filtrate.

Hormonal Regulation of Kidney Function

Hormone	Source	Effect
ADH (vasopressin)	Released from the posterior pituitary	Increases water reabsorption in the DCT and collecting duct
Renin	JG cells of the kidney	Converts angiotensinogen to angiotensin I
Angiotensin II	Formed from angiotensin I	Raises blood pressure; triggers aldosterone release
Aldosterone	Adrenal cortex	Increases Na⁺ and water reabsorption
ANF	Atria of the heart	Lowers blood pressure; opposes the renin–angiotensin system

A fall in blood pressure or GFR activates the JG cells. ANF does the opposite and causes vasodilation.

Worked PYQ-Pattern Questions

Q1. Which part of the nephron is impermeable to water? (a) PCT (b) Descending limb of Henle’s loop (c) Ascending limb of Henle’s loop (d) Collecting duct

Answer: (c). The ascending limb moves electrolytes out but does not let water follow.

Q2. What is the glomerular filtration rate in a healthy adult?

Answer: About 125 mL per minute, which equals about 180 litres per day.

Q3. On which parts of the nephron does ADH act?

Answer: The DCT and the collecting duct. A deficiency of ADH leads to diabetes insipidus, with large volumes of dilute urine.

Q4. Which of these animals is uricotelic? (a) Frog (b) Rohu (c) Pigeon (d) Human

Answer: (c) Pigeon. Birds excrete uric acid to conserve water.

Q5. Which cells release renin?

Answer: The juxtaglomerular (JG) cells. Renin converts angiotensinogen into angiotensin I.

Common Traps in This Chapter

• Swapping the permeability of the descending and ascending limbs
• Saying ADH is produced by the posterior pituitary (it is made in the hypothalamus and released from the posterior pituitary)
• Mixing up 125 mL per minute with 180 litres per day
• Thinking ANF raises blood pressure
• Calling marine fishes ammonotelic (NCERT lists them as ureotelic)

Practise Every Excretory System PYQ

This excretory system NEET PYQ analysis gives you the tables and numbers. Practice makes them automatic. Every previous year question from this chapter is available chapter-wise, free:

👉 Solve all Excretory Products and their Elimination NEET PYQs

Draw the nephron once from memory before each practice set, and label what each segment reabsorbs.

Conclusion

This chapter rewards students who know the nephron segment by segment. Use this excretory system NEET PYQ analysis to master the segment functions, the osmolarity gradient, the hormone pathway and the key numbers. Then practise until each fact comes to mind as soon as you see the question.

❓ FAQ

Q: How many questions come from the Excretory System in NEET? A: Usually one to two questions, mostly on nephron functions, hormonal regulation and the counter-current system.

Q: What is the most important topic in this chapter? A: The functions of each nephron segment are the most tested, followed by hormonal regulation through ADH, renin, angiotensin and aldosterone.

Q: What is the normal GFR? A: About 125 mL per minute in a healthy adult, which adds up to about 180 litres per day.

Q: Which part of the loop of Henle is permeable to water? A: The descending limb is permeable to water. The ascending limb is impermeable to water but transports electrolytes.

Q: How should I revise this chapter for NEET? A: Use an excretory system NEET PYQ analysis to list the repeated facts, learn the nephron diagram, and solve past questions chapter-wise.

Q: Where can I practise Excretory System NEET PYQs for free? A: You can solve every previous year question from this chapter for free using the practice link in this article.