Growth

Growth is the increase in size of an organism or one of its parts. The study of growth is called developmental biology or embryology. organisms grow throughout their lives, although most grow fastest as embryos or young adults. Growth can be limited by external conditions such as food availability and predation pressure, but ultimately these effects are mediated by internal factors such as nutrient status and hormones.

Growth is a complex process that involves both cell division and the deposition of extracellular matrix (ECM). Cell division increases the number of cells in an organism, while ECM deposition adds to the overall size. In many cases, growth must be coordinated between different tissues in order for the organism to maintain a functional shape; for example, bone must grow faster than cartilage during early development, otherwise the individual will have deformities later in life.

There are two main types of growth: linear and exponential. Linear growth results in a straight line when graphed, while exponential growth produces a curve. Most organisms exhibit exponential growth at some point in their lives; this type of growth allows them to reach a larger size more quickly than if they were growing linearly.
A well-known example of exponential growth is population growth; if left unchecked, population size will increase exponentially until resources are depleted and individuals begin dying from starvation or other causes. This type of population dynamics is often modeled using the logistic equation.

While linear and exponentialgrowth are common, there are also other possibilities. For example, negative allometricgrowth occurs when an organ grows more slowly than the rest of the body; this often happens during periods of drought when food availability is low. Conversely, positive allometricspeeds up organ development relative to overall body size; this often happens during periodsof rapid weight gain such as adolescence