Biosphere, Ecosystems, and Biological Relationships

Posted on Mar 8, 2025 in Biology

The Biosphere and its Components

The Biosphere is defined as the “layer” or ecosphere that includes all living things on Earth.

Ecosystem: A part or section of the Biosphere formed by all the living things, the physical environment that surrounds them, and their relationships.
Biotope: The abiotic area of the ecosystem (the physical environment and its conditions).
Biocoenosis or Community: The biotic area of an ecosystem, or all the living things of an ecosystem.
Ecology: The branch of Biology that studies the interactions among organisms and their environment.
Biome: A large geographical area with similar climatic conditions, so basically, they have the same type of ecosystems.

A factor is a characteristic or a variable of the ecosystem that influences the ecosystem and determines its characteristics.

Abiotic factors: Variables of the physical environment (biotope). These factors determine the type of species that live in an ecosystem.
Biotic factors: Variables related to the living things (biocoenosis). This is related to the way the different species interact between them, e.g., species fight for resources.

Tolerance limits: The maximum or minimum values of a factor that a species can tolerate.
Limiting factors: The factors that produce a reduction in distribution, growth, or abundance of an organism or species.

Population: A group of organisms of the same species that live in the same area and interact with one another.
Community: All of the populations of different species that live in the same area and interact with each other.

The relationships established between individuals of the same species. For example, two gorillas playing.

Cooperation (+): A positive interaction. This type of interaction produces a benefit both for the individual and the population.
Competition (-): A negative interaction. This type of interaction is produced when organisms fight for a limited resource, and produces a negative effect on individuals.

The relationships established between organisms of different species. For example, a cat eating a mouse.

Predation: A species (the predator) captures and kills the other species (prey) in order to eat.
Parasitism: A species (parasite) benefits from the other species (the host), which is harmed by it. Parasites can be classified as ectoparasites (lives on the host surface) or endoparasites (lives inside the host).

Mutualism: Both organisms benefit from each other, but they can survive in the absence of the other one.
Symbiosis: Both organisms benefit from each other, but neither species can survive if they are separated.
Commensalism: An organism benefits from others; the others are not favored or harmed. Example: scavengers

Inquilinism: An organism uses another as a host or place to live; only one of them is favored, the other is not affected.

Trophic level: The group of organisms that occupy the same level considering the way they obtain food.
Trophic chain: A linear representation that shows the feeding relationships of different trophic levels.