Exercise 3.2
Platelets help in blood clotting at the site of the injury.
Not cross-checked
NCERT prints no numerical answer for this exercise, so this working has not been cross-checked against the book.
Blood clots because of platelets, which act at the site of the injury.
Table $\displaystyle 3.3$ pairs the everyday experience — red blood oozing from a small cut — with the observation that a clot forms after some time, and the question "What causes blood to clot?"
The clot plugs the cut so that bleeding stops and germs cannot get in through the wound.
Platelets are one of the formed elements of blood, which together make up \(\displaystyle 45\% \) of its volume; the rest is plasma.