Zoology MCQs for NEET — Practice Questions with Answers

The NCERT text defines GFR as: 'The amount of the filtrate formed by the kidneys per minute is called glomerular filtration rate (GFR). GFR in a healthy individual is approximately 125 ml/minute, i.e., 180 litres per day!'

The NCERT text states: 'Glomerulus is a tuft of capillaries formed from afferent arterioles, fine branches of renal artery.'

The NCERT text states: 'GFR in a healthy individual is approximately 125 ml/minute, i.e., 180 litres per day!'

The NCERT text mentions the filtrate's composition as 'that of plasma except the nitrogenous wastes.' It also implicitly states that protein-free fluid is filtered in the exercise question 3(c) 'Protein-free fluid is filtered from blood plasma into the Bowman’s capsule.'. Hence, proteins are excluded from the filtrate. While nitrogenous wastes are present in the filtrate, they are not 'excepted' from plasma to form the filtrate, rather, proteins are. The context talks about the filtrate being like plasma, implying large molecules like proteins are excluded.

The NCERT text states: 'JGA is a special sensitive region formed by cellular modifications in the distal convoluted tubule and the afferent arteriole at the location of their contact.'

The NCERT text states: 'A fall in GFR can activate the JG cells to release renin which can stimulate the glomerular blood flow and thereby the GFR back to normal.'

The context explicitly states: 'HL primarily helps to maintain osmolar gradient (300 mOsmolL –1 -1200 mOsmolL –1 ) within the kidney interstitium.' It also mentions, 'A counter current mechanism operates between the two limbs of the loop of Henle and those of vasa recta...The Henle’s loop and vasa recta play a significant role in this.' This mechanism is key to producing concentrated urine.

The text states: 'The flow of filtrate in the two limbs of Henle’s loop is in opposite directions and thus forms a counter current. The flow of blood through the two limbs of vasa recta is also in a counter current pattern.' This opposing flow is the definition of a countercurrent mechanism.

The NCERT text mentions: 'Electrolytes and urea are retained in the interstitium by this arrangement (counter current mechanism).'

Though not explicitly stated in a single sentence, the text implies this: 'The filtrate gets concentrated as it moves down the descending limb but is diluted by the ascending limb.' And it emphasizes the role of 'electrolytes' in the interstitium maintained by the countercurrent. The general knowledge (and implied by context) of nephron function is that the descending limb is permeable to water, and the ascending limb is impermeable to water but actively transports solutes.