Exercise 3.1
The red colour of blood is due to haemoglobin, an iron-rich protein in the Red Blood Cells (RBCs). RBCs live for about months and are replaced regularly.
Not cross-checked
NCERT prints no numerical answer for this exercise, so this working has not been cross-checked against the book.
Blood is red because of haemoglobin, an iron-rich protein carried inside the Red Blood Cells (RBCs).
RBCs live for about $\displaystyle 4$ months and are then replaced regularly by newly made ones, so the supply is continuously renewed.
This is why red blood oozes out of even a small cut on the skin.
Blood is a connective tissue — it connects the parts of the body by transporting nutrients, gases and hormones.
Its matrix is watery: plasma makes up \(\displaystyle 55\% \) of the total volume, and the formed elements — RBCs, WBCs and platelets — the remaining \(\displaystyle 45\% \).