What are Biotic and Abiotic Factors?

The Biotic and abiotic factors Are ecological components or environmental factors that constitute an ecosystem and are important for its operation.

Biotic factors can be defined as the living elements of a ecosystem . Plants, animals (including humans), fungi, bacteria, viruses and protozoa are biotic elements.

Biotic and abiotic factors Meadow before Pico de Orizaba in Mexico.

Abiotic elements are the non-living elements of the ecosystem. Bodies and streams, air, soil and sunlight are abiotic elements.

These elements are decisive in the development of ecosystems, and influence these at different levels. Both biotic and abiotic factors may be limiting factors in nature, these being what limit the excessive growth of populations.

For example, the amount of water in a habitat (abiotic factor) determines the number of species that can live in it.

For its part, predation (biotic factor) limits the number of prey. If the number of prey is low, the number of predators will also decrease. What are Biotic and Abiotic Factors?

Biotic factors

Biotic factors are the living elements of the ecosystem, which are characterized by their ability to be born, grow, reproduce and die. These are plants, animals, fungi, protozoa, bacteria and viruses.

These organisms can be classified into two large groups, depending on the shape of their cells:

- Eukaryotes : If the genetic information is contained in the nucleus of the cell. Such is the case of plants, animals, fungi and protozoa.

- Prokaryotes : If there is not a cell nucleus proper, but the genetic information is dispersed in the cytoplasm. To this group belong the bacteria.

Similarly, living things can be classified according to the number of cells that make them up:

- Unicellular, composed of a single cell . These are microscopic organisms. Bacteria and protozoa are part of this group. Some fungi and algae can also be unicellular.

- Multicellular, composed of two or more cells . Plants, animals and most fungi are multicellular.

Abiotic factors

Abiotic factors are elements of the ecosystem that are not alive. The main abiotic factors are water, soils, oxygen, carbon, temperature and sunlight.


Water is one of the most abundant elements of the Earth and can present in liquid, solid and gaseous state.

In the liquid state, water covers 75% of the Earth. This classification includes rivers, lakes, seas, oceans and groundwater streams.

In solid state, there are glaciers and mountains with perpetual snow.

In the liquid state, there is water vapor. Water in this state is less abundant than in any other state. However, it is important for temperature regulation.


Soils are one of the layers of the earth's crust, which are composed of inorganic elements (rock, water and air) and organic (plant and animal remains that provide nutrients to the soil).


Oxygen makes up 21% of the air on planet Earth. Also, oxygen is in the water.

In addition to this, oxygen combines with other elements to form more complex molecules (such as carbon dioxide, which has two oxygen atoms.

This element is essential for many organisms that perform aerobic respiration.


Living things can survive in temperatures that do not drop many degrees below 0 ° and temperatures no higher than 50 or 55 ° C. This factor conditions the life of ecosystems.

For example, not all animals can adapt to life in the Arctic, since temperatures are very low.


Light is an essential element for the good development of ecosystems. Plants use sunlight to make photosynthesis.

Likewise, the alternation between periods of light and darkness determines the hours of activity of the animals.

Biogeochemical cycles

Some abiotic elements complete cycles that are important for the development of ecosystems, for example, water, oxygen and carbon.

Water cycle

He water cycle Is one of the most well-known biogeochemical cycles. It happens as follows:

- Surface water (from soils, rivers, seas and lakes) and that from the transpiration of animals and plants evaporates and rises into the atmosphere.

- In the atmosphere, the water condenses in small drops, forming clouds. When these clouds have accumulated enough condensed water, the drops fall to the ground in liquid (rain), solid (hail) or semi-solid (snow).

- So, the cycle starts again.

Oxygen Cycle

Oxygen is one of the most important abiotic factors in the ecosystem. Its cycle is developed as follows:

- Plants photosynthesize and release oxygen to the medium (both in the water and in the air)

- This oxygen is captured by aerobics (which oxidize substances to produce energy).

- These organisms breathe oxygen and release carbon dioxide.

- The carbon dioxide is captured by the plants and thus starts the cycle again.

Carbon cycle

Carbon is an element that is present in all living things. The cycle of this element involves many more actions.

- At first, plants consume carbon dioxide to make photosynthesis.

- Herbivorous animals consume plants and thus also consume carbon.

- Carnivores consume herbivores that have already incorporated carbon into their system.

- When animals die, their body is consumed by decomposers, like fungi. In this way, decomposers absorb carbon.

- The carbon remains of certain animals are left in the soil and from there are absorbed by the plants through the roots.

- Both animals, plants and decomposers release carbon dioxide into nature.


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