Why dont populations of organisms grow indefinitely

The growth or shrinkage of populations has nothing to do with natural selection, but with the availability of resources, and the ability of organisms to utilize those resources. This is also known as 'carrying capacity'. The natural tendency is for organisms to produce more offspring than the environment can support. So if the environment supports more individuals, then the population will automatically grow.

If conditions change and the environment supports less individuals, then some individuals will starve or be otherwise unable to reproduce. Natural selection, in this case, "determines" which individuals pass, and which do not. Multicellular organisms grow by the process of cell reproduction, which is mitosis followed by cytokinesis. Log in. Study now. See Answer. Best Answer.

Study guides. Genetics 20 cards. What are chromosomes made of. How are mitosis and meiosis similar. What is a gel electrophoresis chamber. In pea plants what are the two alleles for color. Biology 20 cards. Which part of the cell membrane prevents the cell from dissolving in water. What is it called when a molecule uses energy to move across a semipermeable membrane. Why is the phloem in a leaf important to the roots of a plant. What is the name for the protective structure that forms around an embryo.

What is the basic unit of a nucleic acid. Which of the following is an organic molecule. What is the main function of starch in plants. Which type of protein makes up connective tissue. Q: Why don't populations of organisms grow indefinitely? Write your answer Related questions. Why do all populations face limits to growths? Why can a population of organisms not grow indefinitely?

Can one cell grow indefinitely? Why do animal grow until a particular size whereas plants grow all their lives? Increased food production due to improved agricultural practices, control of many diseases by modern medicine and the use of energy to make historically uninhabitable areas of Earth inhabitable are examples of things which can extend carrying capacity. The question is how long will we be able to keep increasing our population on a planet with finite size and resources?

Population Impact Homo sapiens is a species possessing a diversity of individual needs. Thus, sub-populations will have different requirements and different impacts on the environment. For example million vegetarians will have a significantly different environmental impact than million meat-eaters. This can be demonstrated by comparing the affect on water supplies by both sub-populations. About tons of water are needed to produce 1 ton of grain.

Add to this the amount of water that goes into the production of meat, and you can see that meat comsumption places more stress on global water supplies than grain consumption. Although it is difficult to determine the exact human carrying capacity for a country as large and diverse as the U. Consider the information in the list below and decide if the item is an indication that humans may have exceeded their carrying capacity in some regions. Yes No Maybe. Issuance of a fishery management plan by the National Marine Fisheries Service to allow threatened species of sharks to recover.

One of the biological characteristics of populations is that they grow. If their are more births than deaths in a population, it exhibits "exponential growth". This is a growth pattern in which the rate of growth is continuously accelerating, since the number of organisms reproducing continually increases. Populations of bacteria in a test tube or in a potato salad exhibit exponential growth.

Assuming warm temperatures and a cell division rate of once every 30 minutes:. This is why you shouldn't leave your potato salad in the sun and also why an infected wound should not be neglected.

Exponential growth only occurs when there are no limits to growth. There are always limits so exponential growth never continues indefinitely. Deaths eventually increase and births decrease because of "density-dependent" factors or "density-independent" factors.

Density-dependent factors are those that result from the number of individuals in the population. They grow stronger as the population grows. Density-dependent factors include:. Predation and parasitism. Predators and parasites tend to prosper as the numbers of their prey increase.

Density-independent factors that increase the death rate are not influenced by population size. They include:. The carrying capacity is the size of a particular population that can be sustained by a particular environment for a long period of time. It is important to note that the carryng capacity of an environment for a particular population changes if the envrionment changes.

It is not a static parameter. If exponential population growth greatly exceeds the carrying capacity of an environment, a population "crash" results. Exponential growth continues until the population is much larger than the carrying capacity of the environment. At some point, deaths increase rapidly from density dependent factors and the population drops well below the carrying capacity.

In some cases, the population dies out altogether. A test tube of bacteria shows this pattern, getting very dense and then becoming completely clear as the population crashes from accumulated waste. Populations of deer and other mammals have also shown population crashes.

This is a topic of great importance to all of us. At present, the human population of the globe is growing exponentially. Our numbers have tripled in the last hundred years and there are now over 6 billion humans on the planet.