Question

Describe briefly:
A) Arithmetic Growth
B) Geometric Growth
C) Sigmoid Growth curve
D) Absolute and Relative Growth

Answer 1

Hint: All these notations are part of the topic “Plant Growth and Development”. Although the terms "development" and "growth" are often used interchangeably in conversation, they refer to separate events in the organisation of the mature plant body in a botanical context.

Complete answer:
Arithmetic Growth: After mitosis, one daughter cell begins to divide, while the other cell differentiates and matures to perform unique functions. Elongation of the root at a constant rate is an example. A linear curve is obtained when a graph of length against time is drawn.
Its mathematical expression is as follows:
${L_t} = {L_0} + rt$
Where ${L_t}$is described as length at time $t$ and ${L_0}$ is described as length at time $0$and $r$is described as the rate per unit time.

Geometric growth: The initial growth is slow in this form of growth, which is referred to as the lag phase. Following that, the growth is very fast and exponential. The log or exponential step is the name given to this stage. Both daughter cells (formed after mitosis) continue to divide during this process. The final phase is characterised by a slower rate of development. This occurs as a result of nutrient scarcity. The stationary step is the name given to this stage. A sigmoid curve emerges from the graph of geometric development.
The exponential growth can be expressed mathematically as follows:
${W_1} = {W_0}{e^{rt}}$
Where ${W_1} = $final size,
${W_0} = $Initial size at the beginning of the period,
$r = $growth rate,
$t = $time of growth
$e = $base of natural logarithm

Sigmoid Growth Curve: The sigmoid growth curve is an S-shaped curve on a graph that represents geometric growth. It's shaped like an S, which is a common trait of living organisms in the natural world. It is made up of three phases: lag, log, or exponential phase, and stationary.

Absolute and Relative Growth rates: Absolute Growth Rate: It involves calculating and comparing overall growth per unit of time. Absolute growth occurs when growth is measured in absolute terms, such as length or weight.

Relative Growth Rate: It is the growth of a given system per unit expressed on a common basis, for example, the relative growth rate per unit initial parameter. The word "relative growth" refers to growth that is measured in comparison terms, such as percentage growth.


Note: A fertilised egg grows into a mature tree via development, which is the progression from earlier to later stages of maturation. The permanent change in the size of cells and plant organs caused by cell division and enlargement is referred to as growth.