Physical and chemical characteristics of limnetic environment and its relationship with organisms

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An ecosystem is a system formed by a group Of organisms of different species (or biocenosis), The environment in which they live and its physical/chemical characteristics (or biotope) and the interactions that are established Between them. Biocenoses are determined by many factors resulting from:

oThe Characteristics of the biotope.

oThe Actual presence or variations

1.1Environmental factors and their impacts

Environmental factors are all the components of the ecosystem that have an Impact on the biocenosis through their presence or variation. They determine:

oDistribution and composition of the biocenosis: in other words, the type and number of populations.

oHow many organisms are present in eachpopulation.

oAdaptations the organisms exhibit.

1.2Types of environmental factors

oAbiotic factors: physical/chemical components of an ecosystem. (Temperature, Light, water…)

oBiotic factors: refer to the presence and action of living things that Modify the life of others in the community, the interactions produced in the Biocenosis, like the death caused by plagues or the greater efficiency of wolves When they hunt as a pack.

1.3Tolerance ranges and limiting factors

Each specie can live Within a certain range of values for each factor.

oThe Upper and lower limits of this range is called the tolerance limits, and species can not survive above or bellow these Limits.

oThe Different limits of tolerance are the tolerance Range

oThe optimal zone: the range is where the Species survives best and there is the greatest number of individuals.

oThe zone of environmental stress is Where the species survives with difficulty and the number of individuals falls.

 An environmental factor is limiting for a species when Determines the abundance or distribution of the species.


oTemperature: with a few exceptions, living things carry out their Activity at temperature between 0ºC and 50ºC

oAvailability of light: sunlight is essential for all autotrophic organisms To perform photosynthesis. The scarcity or absence of autotrophic organisms Also limits the presence of the organisms that feed on them.

oAvailability of water: water is the most abundant component of living Things and is essential for plants to perform photosynthesis. Without water, The existence of life would be impossible.

1.1Abiotic factors in the earth’s environment

ØTemperature and availability of water: due to the tilt of the Earth, the Suns ‘rays hit in The surface at a more oblique angle as latitude increases. Temperature drops With an increase in latitude, resulting in climate zones:

oEquatorial Zone, or warm climates.

oMiddle Latitudes, or temperate climates.

oPolar Zones, or cold climates.

The Air in the atmosphere heats up in the equatorial zones, causing convection Currents (winds), which lead to:

oBands With high rainfall (at 60º latitude and particularly at the equator).

oBands Of scarce rainfall ( at 30º latitude). This is where many of the planet’s Deserts are found.

ØAvailability of light: its orbit causes the position of the Earth to vary in relation to the Sun. Causes variation in the number of Hours of light a day., with the seasons and latitude.

ØAlterations of general conditions: the conditions described can be altered by:

oAltitude: At the same latitude, altitude will cause the temperature to drop.

oCoastal mountain Ranges: these force the masses of humid sea air to rise their sides. This Causes them to cool and release it as rain or snow. As the air descendant the Other side, it heats up, creating a dry environment.

1.2Life in land environments

Location and general characteristics:

oClimatic conditions determine the distribution of vegetation and the formation of the large terrestrial ecosystems or biomes.


- Maximum in areas with an optimum temperature and availability of light and water (such as in the equatorial zone).

-  Minimum in Deserts and polar zones, where these factors become limiting.

oOrganisms exhibit adaptations. They adapt their Bodies or behavior. They resist the extreme conditions and environmental Variations between day and night.

2.3 some adaptations to land environment

ØTo the availability Of light: plants regulate their biological processes during the Day and night (photoperiodism).There are:

oLong-day plants: flower when there are more than 12 hours of light.

oShort-day plants: flower with less than twelve hours of light.

oNeutral plants: they are not influenced.

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