Correct Answer - d
Growth at a cellular level, is principally a consequence of increase in the amount of protoplasm. Growth is, measured by a variety of parameters such as (i) Increase in legth, e.g., stem, root, pollen tube. (ii) Increase in volumne e.g., fruits. (iii) Increase in area, e.g., leaves (iv) Increase in diameter, e.g., tree trunks, fruits (v) Increase in fresh or dry weight. One single maize root apical meristem can give rise to more than 17,500 new cells per hour, whereas cells in a watermelon may increase in size by upto 3,50,000 times. In the former, growth is expressed as increase in cell number, the latter expresses growth as increase in size of the cell.
