With the help of suitable diagram describe the logistic population growth curve.
Solution and Explanation
The logistic population growth curve is commonly observed in yeast cells that are grown under laboratory conditions. It includes five phases: the lag phase positive acceleration phase exponential phase negative acceleration phase and stationary phase.
(a) Lag phase: Initially the population of the yeast cell is very small. This is because of the limited resource present in the habitat.
(b) Positive acceleration phase: During this phase the yeast cell adapts to the new environment and starts increasing its population. However at the beginning of this phase the growth of the cell is very limited.
(c) Exponential phase: During this phase the population of the yeast cell increases suddenly due to rapid growth. The population grows exponentially due to the availability of sufficient food resources constant environment and the absence of any interspecific competition. As a result the curve rises steeply upwards.
(d) Negative acceleration phase: During this phase the environmental resistance increases and the growth rate of the population decreases. This occurs due to an increased competition among the yeast cells for food and shelter.
(e) Stationary phase: During this phase the population becomes stable. The number of cells produced in a population equals the number of cells that die. Also the population of the species is said to have reached nature's carrying capacity in its habitat.
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Concepts Used:
Organisms and Populations
Organisms:
An attached living system that lives in an environment is commonly known as an organism. These organisms are able to retain certain behaviors and structures. Some examples of organisms are plants, animals, bacteria, fungi, and humans. A group of these organisms leads to the formation of a population. The collection of the population forms a community that assists in the operation of ecosystems.
Each and every organism has the ability to adapt itself to various conditions of the environment. This capacity of organisms is due to their genetic variations. It is due to this only that their probability of survival get increases. For instance, camels adapt themselves to survive in desert areas and polar bears adapt to the extreme cold conditions or situations through their dense fur coat.
Populations:
A collection of organisms or individuals of a species that live, at a specific time, in a geographical area that is well-defined and capable of interbreeding is described as a population.
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