BALANCE OF NATURE
THE NATURAL ENVIRONMENT
- The natural environment is made up of all living and
non – living thing that occur naturally on earth, it includes; air, water,
animals, plants, micro – organism, stones, cloud and rock soil.
IMPORTANCE
OF THE NATURAL ENVIRONMENT
1) It is a
source of food for organisms.
2)
Provides shelter and security for organisms.
3) It
provides an appropriate setting for organism to reproduce and increase in
number
4) It
allows living and non – living things to interact.
THE
COMMONS TERMS IN STUDYING THE NATURAL ENVIRONMENT
BIOTIC
FACTORS: Are all the living components of
the environment. They are plants, animals and micro – organisms
ABIOTIC
FACTORS: Are the non – living components of
the environment e.g. light, water, rocks and soil.
ECOLOGY – Is the branch of biology that deals with the study of the
relationship between living things and their natural environment
POPULATION – Is the total number of a certain species of organisms in
a community. Example; number of frogs in a pond
COMMUNITY – This refers to the populations of different organisms
living in a specific area called a habitat. Example a grass land
community could include grass, acacia trees, lions, antelope, giraffe and
cheetah.
HABITAT – Is a specific area with a specific set of conditions that
is appropriate for a certain community and where the community ties or it is
the home of living organisms. Example; tropical rain forest, a desert, a swamp,
a pond, a grassland and ocean
ECOSYSTEM – This is a natural unit made up of living and non – living
thing whose interactions lead to a self – sustaining system
- An ecosystem is made up of communities.
BIOTIC
FACTORS
Biotic
factors are the living components in the environment. They can either be
population factors or community factors.
1. POPULATION
FACTORS – This include:
i)
Population density – The number of organisms in a given area
ii)
Dispersion – the geographical distribution of organism in an area
iii) Age
structure – the distribution of population according to age
iv) The
ratio of males to female
v) The
number of births
vi) The
number of deaths
vii)
Population growth – The rate of growth at which the number of organism is
increasing
2. COMMUNITY
FACTORS – This includes food chains and food webs,
- These
are feeding relationships that represent the flow of energy and recycling of
nutrients in a community.
ABIOTIC
FACTORS
These are
non – living components of the environment. They can be climatic, soil or
geological.
CLIMATIC
FACTORS
1. Temperature;
is the degree of heat in a place
-
Organisms adapt to the temperature in their habitats in various ways.
Example
some plants shed their leaves or roll them when it is very hot so as to avoid
excessive loss of water
- Animal
in very cold place has extra fat for insulation
2. Light:
it is obtained from the sun
- It
affects opening of stomata
- It is
important during photosynthesis
Example
some animal hunt in bright daylight (e.g. hawks) while others hunt at dark or
dawn when there is dim light (e.g. lions) and others hunt at night (e.g. owls
and bats)
3. Wind:
It increases the rate of water evaporation from water bodies as well as for
living organism
- Wind is
important in the formation of rain and the disposal of some plant seed.
4. Atmospheric
pressure: when atmosphere pressure is high concentration of oxygen and
carbon dioxide are also become high so the threaten of gaseous exchange and
respiration is high. The opposite is also true. This affects the distribution
of both plants and animals.
5. Water
serves as habitat for a large variety of organism. Water serves as solvent
a medium of transportation and a temperature regulatory.
AQUATIC
FACTORS
These are
factors that affect water bodies and life in water
- Salinity:
This is the quantity of salts dissolved in water.
- Aquatic plants have roots that
absorb mineral salts and water depending on the concentration in the plant
cells
- Some aquatic organisms are adapted
to live in fresh water habitat while others live in salt water habitants.
2. WAVE ACTION: It is
important for organism to live in artificial zone. These organism are covered
by water during high tide and low tide
- Such organism includes shrines,
different types of sea weeds, crabs and prawns.
SOIL FACTORS
1. Soil texture – this refers to the
size of soil particles.
- Soil texture affects drainage of
the soil, fertility and distribution of plants.
2. Soil composition: This is the
proportion of components of soil including mineral salts, Air and micro –
organism, water and remains of living things
- These components affect soil
fertility and hence plant growth.
3. SOIL PH: This is the degree of
acidity or alkalinity of soil
- Different types of plants grow
into soil with different PH value. Example; tomato and pineapple grow in slight
acidic soil while onions and cabbage prefer slightly alkaline soil.
GEOLOGICAL FACTORS
- These are factors concerned with the features of the
land surface.
(i) ALTITUDE – Is the height above
sea level
- At high altitudes, atmospheric
pressure, temperature and oxygen concentration are lower while the rain fall
are higher compared to low altitude. This affects distribution of both plants
and animal.
(ii) GEOLOGICAL SUBSTRATUM – refers
to the various types of rocks that disintegrate to form the soil in an area.
The chemical composition of the rocks is reflected in the chemical composition
of the soil, this determines soil PH and fertility.
(iii)SLOPE – refers to gradient of
land. Slope can be steep, moderate or gentle. Soil erosion is highest in steep
slopes and lowest in gentle slope, soil erosion removes top soil making the
soil less fertile. This interferes with plant growth.
Interaction of living and non-living
things
The interaction of biotic and
abiotic components "of the environment is important for the completion of
natural cycles such as the water cycle, the carbon cycle and the nitrogen
cycle.
The water cycle
Water cycle refers to how water
circulates in the environment. Movement of water in the environment occurs as
shown in the figure below:
Precipitation
In the water cycle:
(i) Groundwater and run-off (water
from rain) flow into streams and rivers,
(ii) The streams and rivers flow
into lakes and oceans
(iii) Water evaporates into the
atmosphere from water bodies such as oceans and lakes and from plants through
transpiration
(iv)The evaporated water
precipitates to form water vapor. Water vapor condenses to form clouds
(v) Wind causes clouds to move, for
example from above the ocean to above the land.
(vi) Rain falls and is absorbed by
plants or forms groundwater and run-off. The cycle thus begins again.
Forests act as water catchment areas
and prevent excess loss of water from the land. Wetlands, such as swamps and
marshes, help to control flooding and are also important for water
purification.
The carbon cycle
Carbon cycle refers to a biochemical
cycle in the environment where by carbon dioxide is taken up from the
atmosphere and incorporated into the plant tissues during photosynthesis.
Carbon cycle
Carbon dioxide from the atmosphere
is absorbed by plants and used for photosynthesis. These plants serve as food
for herbivores, which are in turn eaten by carnivores.
When plants and animals die,
microorganisms cause decomposition and carbon dioxide is released into the
atmosphere.
The remains of plants and animals
after millions of years result in the formation of fossil fuels such as coal,
natural gas and oil. When these fuels are burnt, they release carbon dioxide
into the atmosphere.
Respiration of living things also
releases carbon dioxide into the atmosphere. The carbon dioxide is absorbed by
plants and then the cycle starts again.
The nitrogen cycle
Nitrogen cycle refers to a
biochemical cycle in the environment whereby nitrates in the soil are taken up
by plant roots and may pass along food chains into animals absorb it in this
form. It must first be converted into either nitrates or ammonium compound.
Figure below shows the nitrogen cycle.
- Nitrogen-fixing bacteria in the root nodules of legumes
plant carry out fixation by converting atmospheric nitrogen to nitrates.
- Lightning converts atmospheric nitrogen into nitrates.
The nitrates get into the soil and are later absorbed by
plants.
Plants use nitrogen compounds to produce plant proteins.
Plants are eaten by animals. Animals use the nitrogen to produce animal
proteins. When plants and animals die, decomposers such as bacteria and
fungi feed on them. The decomposers release ammonia gas (NH3)
which contains nitrogen. The ammonia is converted into nitrites and then
nitrates by bacteria. Denitrifying bacteria release nitrogen from nitrates
back into the atmosphere.
INTERACTION
AMONG LIVING ORGANISM
The relationship among organisms in
the environment can be explained in the form of predation, competition and
symbiosis.
PREDATION – This happens when one organism captures, kills and feeds
on another in order to get nutrients. Example cats eat mice and sharks eat fishes.
COMPETITION – This is a relationship where organisms both need the same
limited environment resources for survival. Examples lions and leopards both
hunt antelope and zebra. Hence lions and leopards are competitors. Organism
from the same places can also be competitors, Example cow competing for grass
SYMBIOSIS – This is a relationship whereby there is a close
association between organisms. This association could take various forms, such
as mutualism, commensalism, Neutralism, syn-necrosis, amensalism and
parasitism.
MUTUALISM – This is the relationship in which two organisms benefit
each other. Example: The rhizobium bacteria in the root nodules of legumes
convert nitrogen into nitrates for use by the plant. The bacteria get
protection and nutrients from the plants.
COMMENSALISM – This is interaction that is beneficial to one organism and
is neutral to the other organism. Example when a bird builds a nest in a hole,
in a tree.
PARASITISM – In this association one organism benefits while the others
is harmed. Example: Plasmodium that causes malaria in human beings.
FOOD CHAINS AND FOOD WEBS
Food chains and food webs show the
flow of nutrients and energy among organisms in the environment.
- Each organism in a food chain or food web represents a
trophic level a food chain.
- Trophic level -
is a position that organism occupies in food chain or food web.
- Examples; producers like green plants, primary
consumers like herbivores and secondary consumers like carnivores
PRODUCERS: These are organisms that can manufacture their own food
example: green plants and photosynthesis bacteria, this is the first trophic
level.
- Producers
are eaten by primary consumers
- Primary consumers are mostly herbivores such as
rabbits, cows, buffaloes, wild beasts, goat and sheep.
- Primary consumers form the second trophic level.
SECONDARY
CONSUMERS:
These form
the third trophic level.
- They feed on primary consumers
- They are mostly carnivores such as – domestic
cats, dogs, hyenas, lions, leopards and cheetahs.
- This level can be followed by tertiary consumers which
feed on secondary consumer then quaternary consumer feed on tertiary
consumers.
DECOMPOSERS
These are
organisms that decompose dead organic matter
- This is the final trophic level.
- These organisms feed on dead matter and break it down
there by facilitating decomposition.
- The two main decomposers are the saprophytic fungi
and saprophytic bacteria.
- The relationship between organisms at different trophic
levels can be presented diagrammatically as follows;
FOOD CHAINS- a food chain is a linear relationship among the organisms of
a community in which each organism feeds on the one preceding it.
- It presents energy flow from one trophic level to the
next.
- Each organism feeds on therefore derives energy from
the proceedings one in return it is eaten by the other and therefore
provides energy for the one following it.
- The arrows indicate the direction of energy flow
Example of
food chain:
FOOD WEBS
A food web refers to the several food
chains interlinking together(A network of food chain).
- Most herbivores consume more than one kind of plants
and omnivores consume more than one kind of plant and animal and the
decomposer consume more than one kind of herbivore
Example
of food web
SIGNIFICANCE OF FOOD CHAINS AND FOOD
WEBS
i) Food chains and food webs
facilitate the flow of energy in the environment.
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