The removal of parts of living organisms (explants) for culture in a suitable artificial medium. This may be done to study the growth and development of tissues and organs and how they respond to different nutrient conditions. Explants are often only small segments of tissue, such as leaf discs or meristems. Their placement into or onto the culture medium is termed inoculation by analogy with microbiological techniques. The regenerative capacity of plant explants had led to their use as a means of plant propagation. exponential growth A type of population growth in which the rate of increase in the number of members is proportional to the number present. Exponential growth involves an increasing rate of growth: the more individuals there are, the faster the population in-creases. A graph of number against time in such growth has a J-shaped curve. In practice, exponential growth does not coritinue indefinitely. Other factors (e.g. shortage of food) become important and slow down the growth rate. The resulting curve is S-shaped (sigmoid). See also logarithmic phase. |
