The Abiotic Environment

The Climate and the physical features of the surroundings are part of the abiotic environment.Physical features  that make up the abiotic environement.Physical features that make up the abiotic environment include;

Light intensity                          ________

Temperature                           ________)__           Determined by Climate

Amount of water available       ________)

Oxygen content

Salinity (salt concentration of soil or water )

pH of solid or water

How do the physical features of the surroundings after organisms ?

The physical features of the surroundings and the nature of the soil determine the types of plants found in a region.Since animals rely directly or indirectly on plants for food , the animals that live in a region are  determined by plants growing in that region.Organisms found in a region are usually adapted to the physical features of their environment.

How does light intensity affect organisms ?

Light intensity affects the distribution and growth of both plants and animals.Green plants exist only where there is an adequate supply of sunlight.Some plants exist only where there is an adequate supply of sunlight.Some plants develop adaptations to reach the light, for example , climbing plants may twine around or grasp a support to pull themselves upwards.However, bright light causes plants stems to grow more slowly.This is why plants growing in the open usually  end up shorter than those in the shade. Certain plants have developed adaptations to block or screen off excessive light.For example, some plants have a dense covering of hairs on the leaf epidermis or a layer of thick walled cells called hypodermis just beneath the epidermis.These adaptations protect the plants by screening off excessive heat and reducing the rate of transpiration.

Many animals need sunlight to see in order to catch their prey or to detect predators.However ,some animals develop special adaptations for living in dark place.For example, bats are specially adapted to move about in dark cave.They locate prey in the dark by bouncing sound waves off objects around them.

How does temperature affect organisms ?

Temperature affects the rate of reactions of enzymes which control metabolic or physiological activities of plants and animals.Most organisms cannot tolerate extremes of temperatures.Temperatures that are too high or too low would kill an organisms.

Many flowering plants are adapted to changing seasons.Such plants are able to survive through a hot and dry season or through a hot and dry season or through winter by storing food in under ground storage organs, shedding leaves to reduce water loss, or forming seeds which are resistant to heat, cold or drought, just before these season arrive.

How does the amount of available water affect organisms ?

No organism can live long without water.Hence , the amount of available water is one of the major factors affecting the number and location of plants and animals in a region.The amount of available water depends on the amount of rain and the pattern in which rain falls throughout the year.

Some organisms are adapted to survive under conditions where there is a limited supply of water.For example,camels are able to survive for many days in the desert without water because they can drink more than 100 liters of water when available , then go for long periods without drinking.Some plants known as xerophytes , are adapted to survive prolonged drought.Xerophytes may show some of these adaptations.

They reduce their rate of transpiration by shedding their young leaves or by developing leaves reduced to spines.

Their stems become fleshly, storing up much water.

The green stems also take over the function of photosynthesis from the leaves.

On the other hand, there are plants that live in water or in very wet places.These are called hydrophytes.Hydrophytes may be completely submerged , for example , Hydrilla ; partially submerged, for example water lily or free floating.

What adaptations do think hydrophytes would have to help them survive in water ?

Mangrove plants, such as Avicennia , have their roots buried in oxygen-poor mud.Special breathing roots called pneumatophores project above the mud surface.Pneumatophores have openings through which oxygen passes downwards to the whole root system.

Aquatic animals also show adaptive features for living in water, such as gills for absorbing oxygen or special structures for swimming.For Example , frogs have webbed toes and fish have fins for swimming.

How does oxygen content affect organisms ?

Most organisms are aerobic, that is , they require oxygen for respiration,They cannot  survive in environments of low oxygen content.However, some aerobic organisms can survive in environments of low oxygen content.This is because they prossess special adaptations for obtaining sufficient oxygen , for example , mangrove plants have pneumatophores.Fish living in water low oxygen content are usually air breathers.They can come to the surface of the water to gulp air.

How does salinity affect organisms ?

The salinity or salt concentration of water is an important factor affecting aquatic organisms.Animals living in seawater tend to lose water by osmosis as sea water contains a higher salt concentration than the cytoplasm of animal cells.Salt water or marine fishes have a water proof coat consisting of closely-fitting scales covered by a slimy mucous material.This reduces the rate  of water loss.

The cytoplasm of the cells of freshwater organisms usually has higher salt concentration that the surrounding water .Hence the water tends to enter these organisms by osmosis.Most freshwater fish possess slimy scaly skins which keep water from entering their cells.

Most aquatic organisms are so highly special that they can only survive in certain habitats.For example, many fresh water animals cannot live in seawater and vice versa.Hence , starfish and corals are only found in the sea.They are not even found in brackish water where freshwater and seawater mix.Hence in Animals and Plants living in brackish water must be adapted to withstand large fluctuations or changes in salt concentration.

How does pH affect organisms ?

The term pH refers to the acidity or alkalinity of a solution.They pH of soil water or the water in fresh water ponds or the sea affects the types of organisms that can live in such environments.Aquatic organisms are sensitive to the pH of the water in which they live and may die if there are drastic or sudden changes in pH.

The BIOTIC ENVIRONMENT

The living or biotic environment comprises all the living organisms that an organism interacts with in its habitat.A habitat is the place where an organisms live.A pond, a stream, a river, a forest, or a desert could be a habitat.

Why do organisms affect other organisms ?

The organisms in any habitat are never completely independent, The life of each organisms depends on and is influenced by , other organisms around  it.We say that organisms are interdependent.

What is an ecological community ?

When the different populations of plants and animals live together and interact within the same environment, they make up an ecological community.The various groups of living organisms in ponds , forests , seashores and oceans are the examples of communities.

The various populations in any community live interdependently.A charge in one population affects the other populations of the community.For example, if the populations of smal; crabs living in the mud of the mangrove community decreases , the populations of mudskippers may also decrease because there is less food for the mudskippers.It is also possible that the mudskippers may begin to feed on more insects and small worms to get enough food.In this case , the populations of insects and small worms to get enough food.In reality, the abiotic and biotic factors in an ecosystems interact with each other in very complicated ways.The relative sizes of the different populations remain constant.This biological balance or equilibrium is like a web - braking a single strand will affect the whole system.

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