5P – Ecological interactions

Supporting article P: Ecology: Where we see how biotic and a-biotic factors co-exist


ECOLOGY: The study of how living things interact with each other and with their environment

A species is a group of organisms that are physically similar and can
reproduce with each other to produce fertile offspring.
One member of a species is a organism.
All the members of one species in a particular area are referred to as a population.
All populations that live together in an area make up a community.
The community and abiotic factors together form an ecosystem.

All the living and nonliving things that interact in a geographic area make up an ecosystem.. An organism must obtain food, water, shelter, and other things necessary to live, grow, and reproduce. The place where an organism lives is called its habitat.



Biotic Factors
The living parts of an ecosystem are called biotic factors.
Biotic factors are nonliving physical features that include:
1. Living organisms.
2. Parts of once living organisms
3. Their waste
4. Their presence

Abiotic Factors
The nonliving parts of an ecosystem are called abiotic factors.
Abiotic factors are nonliving physical features that include:
1. Atmosphere—the air that surrounds Earth
a) oxygen
2. Water—the major ingredient of the fluid inside the cells of all organisms
3. Soil—a mixture of mineral and rock particles, the remains of dead organisms, water, and air
4. Sunlight—the source of energy for most life on Earth
5. Temperature is affected by latitude; areas closer to the equator are warmer than areas farther from the equator.
a) Most organisms’ body temperatures should stay within the range of 0°C to 50°C for survival
6. Elevation—distance above sea level that affects temperature, wind, and soil
7. Climate—an area’s average weather conditions over time, including temperature, precipitation, and wind
For most living things, temperature and precipitation are the most important factors.

Population density is the number of individuals in a specific area. Population density is calculated by dividing the number of individuals in the population by the total area. The result tells how many individuals there are per unit area.
The major way in which new individuals are added to a population is through the birth of new offspring.
The birth rate of a population is the number of births in a certain amount of time.
The major way that individuals leave a population is by dying.. If the birth rate is greater than the death rate, the population will generally increase in size..
A limiting factor is an environmental factor that prevents a population from increasing. Some limiting factors for populations are food, space, and weather conditions.
The largest population that an environment can support is called the carrying capacity.

Interactions among organisms
There are three major types of interactions among organisms:
1. competition
2. predation
3. symbiosis.

Competition is the struggle between organisms to survive in a habitat with limited resources.

Predation is an interaction in which one organism kills and eats another organism.
The organism that does the killing is the predator. the organism that is killed is the prey.

Symbiosis is a close relationship between two species that benefits at least one of the species.
The three types of symbiotic relationships are
1. Commensalisms
2. Parasitism.
3. Mutualism
Mutualism is a relationship in which both species benefit.
Commensalism is a relationship in which one species benefits and the other species is neither helped nor harmed.
Parasitism involves one organism living on or inside another organism and harming it.
• Parasite – The organism that benefits from the relationship.
• Host the organism the parasite lives on or in.