3 interactive concept widgets for Excretory Products and Their Elimination. Drag any slider, change any number, and watch the formula and the answer update live. Built so you understand how each NEET problem actually works, not just the final number.
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A labelled nephron with cortex and medulla regions and seven clickable parts (glomerulus, Bowman capsule, PCT, Loop of Henle, DCT, collecting duct, JGA).
A labelled nephron with cortex and medulla regions. Click any pin or chip to see what each part does and the NEET fact tested about it.
Glomerulus
Tuft of capillaries inside the Bowman capsule. Site of glomerular filtration. Blood enters via the afferent arteriole (wider) and leaves via the efferent arteriole (narrower). This difference keeps the glomerular pressure high.
NEET fact
Glomerular filtration pressure is about 55 mm Hg. Afferent arteriole is wider than efferent.
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The three steps of urine formation in order: filtration, reabsorption, secretion. See input, output and the NEET facts for each step.
Click any of the three steps (Filtration, Reabsorption, Secretion) to see where it happens, what goes in, what comes out, and the NEET fact tested about it.
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Input
Whole blood
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Output
Glomerular filtrate: 125 mL per minute (about 180 L per day)
Glomerular Filtration
Where
Glomerulus and Bowman capsule
What happens
Blood at high pressure (about 55 mm Hg) is forced through the filtration membrane. Water and small solutes (Na+, K+, glucose, amino acids, urea, vitamins) enter the Bowman capsule as glomerular filtrate. Blood cells and plasma proteins stay in the blood.
NEET fact
GFR is about 125 mL/min. Almost all of this is reabsorbed; only about 1 to 1.5 L per day becomes urine.
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Side-by-side comparison of ammonotelic, ureotelic and uricotelic animals: toxicity, water needed, examples and why each group evolved its mode.
Side-by-side comparison of the three nitrogenous excretion strategies with toxicity, water cost, example animals and the reason each group evolved its mode.
Feature
Ammonotelic
Ureotelic
Uricotelic
Main waste
Ammonia (NH3)
Urea ((NH2)2CO)
Uric acid
Toxicity
Very high
Moderate (much less toxic than ammonia)
Low
Water needed
Very high (about 300 to 500 mL of water per gram of N excreted)
Moderate (about 50 mL of water per gram of N excreted)
Very low (almost no water; passed as a near-solid paste)
Ureotelic: example animals
Why this mode?
Urea is made from ammonia in the liver (urea cycle). It is much less toxic than ammonia, so it can be stored briefly in blood. Suits animals that have access to some water but not unlimited amounts.
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