Q.Differentiate between Arithmetic and Geometric growth.

(b) Geometric growth.

When all daughter cells keep dividing, cell (and hence organ) number increases exponentially — this is geometric growth.

Growth in plants can follow an arithmetic pattern, where only one daughter cell after mitosis continues to divide while the other differentiates (giving a linear increase in size, as in a root elongating at a constant rate), or a geometric pattern, where both daughter cells produced by mitotic division continue to divide and redivide. In geometric growth, cell number (and consequently growth) increases exponentially — 1→2→4→8→16, etc. — which is the pattern typically seen during the early, rapid phase of growth (e.g., in a growing seedling or in cells of the exponential/log phase). This exponential increase is characteristic of geometric growth, matching option (b).

The grand period of growth is the sigmoid (S-shaped) curve obtained when growth rate of an organ/organism is plotted against time, showing an initial slow lag phase, a rapid log/exponential phase, and a final slow sta...

Grand period of growth = the characteristic S-shaped growth-rate curve of an organ over time.

When the growth of any plant organ (root, stem, leaf) is measured periodically and plotted against time, the resulting curve is sigmoid in shape and is termed the grand period of growth. It has three distinguishable phases: a lag phase, where growth is initially slow as cells adapt/prepare metabolically; a log (exponential) phase, where growth rate rises sharply and is maximal, cells actively dividing and elongating; and a senescent/stationary phase, where growth rate again slows and eventually plateaus as the organ matures. This universal pattern is used to compare growth rates of different organs or under different environmental conditions.