NEET-Pattern Practice Questions

How to Use This Set

These 40 questions cover the whole of Excretory Products and their Elimination, in roughly the proportion the chapter itself gives each topic. Six of them are the excretory patterns and the invertebrate excretory structures; four are the gross anatomy of the kidney; five are the nephron; six are glomerular filtration and the GFR; seven - the largest single block - are reabsorption, secretion and the tubule segments; four are the counter current mechanism; five are the regulation of kidney function; two are micturition and the composition of urine; and one is the other excretory organs and the disorders. That weighting is not arbitrary. The tubule and its numbers carry this chapter, and a student who can walk the nephron segment by segment and reproduce the volumes, the rates, the percentages and the osmolarities exactly as printed has already earned most of what this chapter is worth.

Sit the whole set in one go, and look nothing up. Answer every question in order, and mark every question where you were choosing between two options rather than certain. Those marked questions, not only the wrong ones, are your revision list afterwards. Check the answers only at the end, and when you check, go back to the segment or the figure rather than to the option - the fix for a wrong answer here is almost always a number you had not fixed in memory or a segment you had put in the wrong place along the tube.

The marking is +4 for a correct answer and -1 for a wrong one, and it is worth doing that arithmetic once. With four options and one of them right, a blind guess wins 4 marks once in every four attempts and loses 1 mark on the other three, so four blind guesses are worth about +1 mark between them - almost nothing, for four questions' worth of time. Cut the options down to two and the same four attempts are worth about +6. So the rule is not "never guess". It is never guess blind, and never spend time on a guess. On this chapter you can usually strike out at least one option at sight, because the wrong options are the other real numbers of the chapter - a different volume, a different percentage, a different osmolarity - and one of them will be a figure that belongs to a completely different quantity. When you can strike one out, take the guess, and take it quickly. If all four numbers still look alike after fifteen seconds, leave it blank and keep the minute.

These are exam-pattern practice questions built on the chapter's recurring core facts. They are not authenticated year-tagged previous-year papers.

Before You Start

Give yourself 40 minutes for the 40 questions.

Strip this chapter down and it is one long tube plus four hormones. The tube runs Bowman's capsule, PCT, descending limb, ascending limb, DCT, collecting duct, renal pelvis, and the four hormones are ADH, renin, aldosterone and ANF. Almost every question in this set is one of those seven stations or one of those four hormones, asked as a value, an address, an order or a direction - what per cent, which segment, which limb, which source, raises or lowers. That has a direct consequence for pacing: most items should take 15 to 25 seconds, and anything that has not come in fifteen seconds is not coming. A figure or a segment you learnt arrives at once or not at all; staring at four percentages will not pull one out. Mark it, move, and come back only if minutes are left over. The exceptions are the arithmetic items - a GFR to be turned into litres per day, a reabsorbed volume to be taken as a percentage, a filtered volume to be set against the cardiac output - and those are worth a full minute each, because they are the ones you can be certain about.

The fastest way into a segment question is to walk the tube in order and stop at the first segment that fits. Do not scan the four options and try to recognise one. Start at Bowman's capsule and go down, saying what each station does, and take the first station that answers the question - the chapter gives each segment one job that no other segment has, so the first fit is the only fit.

• Bowman's capsule - filtration through 3 layers, and almost all the constituents of plasma except the proteins pass through.
• PCT - nearly all the essential nutrients and 70-80 per cent of electrolytes and water; brush border; secretes hydrogen ions and ammonia, absorbs bicarbonate ions.
• Descending limb - permeable to water, almost impermeable to electrolytes; the filtrate gets concentrated going down.
• Ascending limb - impermeable to water, transports electrolytes; the filtrate gets diluted going up; reabsorption is minimum here.
• DCT - conditional reabsorption of sodium ions and water; secretes hydrogen and potassium ions and ammonia.
• Collecting duct - cortex to the inner medulla; large amounts of water reabsorbed to concentrate the urine; passes small amounts of urea into the medullary interstitium.

Three more habits carry this set. 1. For a value question, say the quantity before you look at the numbers - 125 mL per minute is the GFR, 1100-1200 mL per minute is the blood filtered, 180 litres per day is the filtrate, 1 to 1.5 litres per day is the urine, and the options will offer you all four. 2. For a hormone question, name the source before the action - renin from the JG cells, aldosterone from the adrenal cortex, ADH from the neurohypophysis, ANF from the atria of the heart. 3. For a limb question, say water first - the descending limb is the water limb, the ascending limb is the electrolyte limb, and that one word settles the swap that this chapter is built to catch.