A cell wall is a structural layer that surrounds some types of cells, situated outside the cell membrane. It can be tough, flexible, and sometimes rigid. It provides cells with both structural support and protection, and also acts as a filtering mechanism. Cell walls are present in plants, fungi and prokaryotic cells, where a major function is to act as pressure vessels, preventing over-expansion when water enters the cells. Cell walls are absent from mycoplasmas.
Answer:
an experiment
Explanation:
In the personality research methods, an experiment is the method determines the effect of one variable or more variables on the behavior. In personality research methods, we conclude that :
-- it can be stable as well as predictable
-- it is based on the behavior and the personality traits
-- it is resistant to the sudden changes
In exponential growth, the growth rate of population per capita remains the same in spite of the size of the population, thus, resulting in the population to grow faster and faster as it gets bigger. However, in nature, the populations may grow exponentially for certain time duration, and they eventually get restricted due to limited availability of resources.
In the graph, it is evident that from 1950 to 1990 there is exponential growth, signifying that the fish exhibited almost optimal conditions of living. However, in 1990 the population started to decline steadily, demonstrating an extreme lack of resources or enhancement in predatory species.
The fertility rate of 2.1 with which populations are expected to eventually stabilize is known as the long-term replacement rate. In other words, if a nation maintains a fertility rate of 2.1 over a long period of time the population of that nation will eventually stabilize and it will neither grow nor shrink. Immigration allows the people to grow faster than the fertility rate would suggest. Also because of past growth, the population is younger than it would otherwise be. This means that there are more potential mothers and fathers. Only after its residents age can the population of a country stabilize.
