According to Central Pollution Control Board [CPCB]
what size (in diameter) of particulate is responsible for causing greater harm to human health ?
AI-generated explanation. Check against your textbook.
Explanation:
PM2.5 (particulate matter with diameter 2.5 ฮผm or less) is most harmful because it can penetrate deep into the lungs and even enter the bloodstream. According to CPCB guidelines, these tiny particles cause greater health effects than larger particles. Thus, option 2 (2.5 micrometers) is correct. Larger particles like 3.0โ4.0 ฮผm (options 1, 3, 4) are more likely to lodge in the nose or throat and are less able to reach deep lung tissues, causing comparatively milder effects.
๐ง Did You Know?
NCERT explains that finer particles, especially PM2.5, pose serious health risks, including respiratory and cardiovascular problems.
๐ก NCERT Memory Line:
PM2.5 refers to particulates with diameter 2.5 ฮผm or less, capable of reaching deep lungs and entering the bloodstream, causing greater health impacts.
The increase in osmolarity from outer to inner medullary interstitium is maintained due to:
I. Close proximity between Henle's loop and vasa recta
II. Counter current mechanism
III. Selective secretion of HCO3- and hydrogen ions in PCT
IV. Higher blood pressure in glomerular capillaries
AI-generated explanation. Check against your textbook.
Explanation:
The osmolarity of the renal medulla increases from outer to inner due to the countercurrent mechanism involving the loop of Henle and the vasa recta. This is achieved mainly because of their close proximity and interaction (I and II). Options III and IV are not the primary reasons for this gradient: III refers to secretion in the proximal convoluted tubule, which relates to acid-base balance, not medullary osmolarity; IV (high glomerular blood pressure) does not establish the medullary osmotic gradient. Therefore, the correct combination is I and II.
๐ง Did You Know?
NCERT explains that the countercurrent mechanism in the loop of Henle and the surrounding vasa recta creates and preserves the medullary osmotic gradient essential for water reabsorption.
๐ก NCERT Memory Line:
Countercurrent mechanism and close interaction of loop of Henle with vasa recta maintain increasing osmolarity from outer to inner medulla.