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Biology – Module 1 – A Local Ecosystem
1. The distribution, diversity and numbers of plants and animals found
in ecosystems are determined by biotic and abiotic factors

Compare the abiotic characteristics of aquatic and terrestrial
environments
An aquatic environment is one that consists in water.
The abiotic characteristics of an aquatic environment include:
o
Viscosity – This refers to the thickness of the medium in which the
environment is located, and its ability to resist internal movement through it.
For example in an aquatic environment, the medium is water. It is much
more difficult to travel through water than it is through air. This is why many
aquatic animals have streamlined bodies so that they can move through the
water easily.
o
Buoyancy – This refers to the upward pressure (or thrust) that is applied on
the organism by its medium. Buoyancy is determined by the density of the
medium and determines the floating ability of an organism. Water provides
sufficient buoyancy for many organisms, eg, the jellyfish. If a jellyfish is taken
out of water and placed on land it will disintegrate by spreading apart. Thus,
the water provides enough buoyancy (pressure) in order to keep the shape of
the jellyfish.
o
Pressure – This is the downward force that is applied on an organism by its
medium. In water, the pressure is dependant on the depth. Organisms that
live at the bottom of the ocean experience the effects of extreme pressure
and they must have specific adaptations that enable them to survive in such
harsh environments.
o
Temperature Variations – Usually in an aquatic environment there are
minimal temperature variations to that compared with terrestrial
environments. The temperature variations also depend on the size of the
body of water; a large body of water will experience much less temperature
variations than a smaller body of water. Also, as depth increases the
temperature of the water decreases.
o
Availability of gases – in water the availability of gases depends on factors
such as temperature, depth and turbulence. Hot water holds much less
oxygen than cold water. The availability of gases also depends on the rate of
diffusion which is much slower in water than it is in air. Also, as the depth of
the water decreases the availability of the gases decreases.
o
Availability of water – In aquatic environments water availability can be a
problem as osmosis occurs. Organisms are suited to a particular type of water
– either fresh water or salt water. If the organism is placed in the wrong type
of water they will die, thus water-availability is an issue. In this scenario, the
salinity of the water is another factor.
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o
Light penetration – Light is only able to penetrate about 100m in oceans
and seas. Thus as the depth increases the light penetration decreases. Light
is essential for all aquatic plants, thus the plants need to have specific
adaptations that allow them to retrieve enough sunlight to survive. The light
penetration is also dependant upon water clarity.
o
Exposure to natural forces – Different aquatic environments are exposed
to different natural forces such as tides, currents, waves etc. Marine
organisms must be adapted to survive in such conditions.
A terrestrial environment is one that consists on land.
The characteristics of a terrestrial environment include:
o
Temperature – There are much larger temperature variations on land rather
than in water. Land organisms must therefore have adaptations to cope with
such large temperature changes.
o
Landscape position – Slope and aspect may affect temperature, water and
light availability as well as impact on soil quality. Run-off and erosion may
also be prominent in particular landscapes.
o
Rainfall and water availability – Water is not freely abundant in land. It
must be sourced from the soil or consumed. Organisms must have
adaptations that allow them to survive using the amount of water available to
them
o
Salinity – Different soils have different salinity levels and only particular
organisms thrive in certain salinity levels. Plants must have adaptations that
enable them to cope with the different levels of salinity.
o
pH (acidity/alkalinity) – Soil pH can vary. Dissolved salts play an
important role in determining the pH of the soil and some plants need to have
a particular pH to survive. Plants need to have adaptations that allow them to
cope with the pH of the soil in their environment.
o
Buoyancy – Air provides minimal buoyancy and therefore land organisms
need to have a skeletal and muscle structures that enable them to support
them.
o
Exposure to natural forces – Wind, rain, floods, droughts, monsoons,
cyclones, storms etc are all part of the terrestrial environment and organisms
need to be able to adapt to most if not all of these forces.
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
Identify the factors determining the distribution and abundance of a
species in each environment
Distribution – refers to the region where an organism is found.
Abundance – refers to the number of individuals in the area and is usually
described as a density.
Aquatic - There are several abiotic factors that affect abundance and distribution
of organisms in aquatic environments including:
o
Pressure Variations – ranging from low pressures in surface waters to
extreme pressure in deep ocean trenches.
o
Light penetration – plants need adequate light for photosynthesis. This is
true in both environments (aquatic and terrestrial). In water the light is only
able to penetrate to a certain depth. Water doesn’t absorb all light. About
30% is reflected off the surface. At certain depths water absorbs different
wavelengths (what we see as colours). Water absorbs the wavelengths that a
majority of plants use for photosynthesis extremely quickly. This means that
as the depth increases not only does the light penetration decrease, the
quality of the light decreases as well.
o
The salt concentration of the water – Marine organisms are suited to a
specific type of water (ranging from the extremely salty Dead Sea to
freshwater which has almost no salt) and if they were to be placed outside
this they would die (due to osmosis)
o
Temperature – The range of temperature is important as well because
organisms prefer to live in certain temperatures ranging from hot springs
through warm tropical seas to freezing Antarctic oceans.
o
Gas Availability – This ranges from small amounts of gas available in
warmer waters to plentiful amounts of gas in turbulent waters of oceans and
cold streams
Terrestrial – There are several abiotic factors that affect abundance and
distribution of organisms in aquatic environments including:
o
Temperature – Most organisms prefer to live between 0 – 45 degrees
o
Soil composition – Many species only prefer specific soil types.
o
Rainfall patterns – Many organisms will only live in areas where the rainfall
is specific to their needs. If the organisms prefers high rainfall and humidity it
will live in areas where these conditions are prominent.
o
Altitude – increasing altitude results in colder temperatures, reduced rainfall
and decreased pressure which are specific factors that affect the abundance
and distribution of the organism.
o
Availability of salts – in the soil there must be specific salts for the plants.
Plants will only thrive if there are those specific salts available.
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There are also other factors that affect distribution and abundance of both aquatic
and terrestrial organisms including:
o
o
o
o
Availability of resources and Limiting factors – A limiting factor is a
single resource that determines the maximum population of a specific species
in that area. In aquatic environments this could be factors such as food
resources. The amount of food available will determine the abundance of the
organism in that environment.
Competition – Competition for resources from both the same species and
other species for specific resources can alter the abundance and distribution
of that aquatic organism in that particular environment.
Predation – This is when one organism consumes another. If a species has
numerous predators in its environment, its abundance and distribution will
fluctuate.
Ability to mate – This refers to the organisms ability to reproduce efficiently.
If the organism reproduces extremely quickly its distribution and abundance
are likely to rise dramatically whereas if it was the opposite the distribution
and abundance will remain steady.
o
Chemical Factors – such as pH of the soil
o
Dynamic Factors – such as wind speed and patterns, wave action. These are
natural factors that will affect the organism and its environment.

describe the roles of photosynthesis and respiration in ecosystems
Photosynthesis is the process by which plants take carbon dioxide and water and
with the use of sunlight convert it into glucose and oxygen.
6H2O + 6CO2
Light
C6H12O6 + 6O2
Photosynthesis is significant in any ecosystem because it produces the chemical
energy needed for all ecosystems to survive. The ultimate source of all energy on
Earth is the sun. Plants use chlorophyll to capture some of the suns energy in
photosynthesis. This is vital because this energy is then able to flow through the
ecosystem for survival. Thus the ecosystem depends on plants conducting
photosynthesis.
The overall role of photosynthesis is to provide energy for all other organisms in the
ecosystem. The plants conduct photosynthesis to store energy. The plant gets eaten
by an animal and part of the stored energy (about 10%) is passed on to the animal
and so on. In ecosystems there is no re-use of energy. It is either used by the living
thing or lost as heat. Because of this, a continual input of energy is required to keep
living systems functioning and that is the ultimate role of photosynthesis.
Respiration takes place in the mitochondria of all living cells and results in the
release of energy for organisms to use. Glucose if broken down in the presence of
oxygen to produce carbon dioxide and water and in doing so energy is released.
Energy in the form of ATP (adenosine tri-phosphate) is released as heat from this
process and is used for cell functions such as growth, repair and maintenance.
The role of respiration is to remove oxygen from the air, return carbon dioxide to the
air and provide energy for the organism. Thus, organisms respire in order to carry
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out daily activities. The role of respiration is to used the stored energy within an
organism to carry out its daily functions. Without respiration, an ecosystem wouldn’t
function as none of the organisms would be able to use the energy they had stored
which means they would die.
 identify uses of energy by organisms
Majority of the energy in an ecosystem is lost as heat which is beneficial to most
organisms as the cells and enzymes thrive under warm conditions.
Organisms use energy for many purposes including:

o
Synthesis of complex molecules such as proteins, lipids, carbohydrates and
nucleic acids.
o
Growth involving the division, elongation and differentiation of cells
o
Repair and maintenance of damaged or old cells
o
Active transport of materials across cell membranes
o
Functioning of special cells that need extra energy, such as nerves, muscles,
liver etc.
o
Transport of materials within organisms such as in the circulatory systems of
animals
o
Other daily activities such as movement, making sound, producing heat and
producing light (called bioluminescence).
Identify the general equation for aerobic cellular respiration and outline
this as a summary of chain of biochemical reactions
Aerobic cellular respiration is respiration that occurs under the presence of oxygen.
Respiration involves a series of chemical reactions. It is a controlled process,
occurring as a sequence of about 50 different chemical reactions, each one catalyzed
by a different enzyme. Energy is released slowly in small amounts. The chemical
energy is stored in the bonds of complex organic molecules and is released when
these bonds are broken. The energy is transferred to the energy carrier molecule
ATP.
ATP is the energy store of the cell. When the energy is available , ADP (adenosine)
di-phosphate) collects it. When the energy is needed, ATP supplies it. In fact,
respiration can be thought of as the process by which ATP molecules are made in a
cell.
ADP + P + glucose + oxygen many reactions carbon dioxide + water + ATP
38ADP + 38P + C6H12O6 + 6O2 Many reactions 6H2O + 6CO2 + 38ATP
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There are two stages of respiration:
Stage 1 - This occurs in the cytoplasm of the cell and results in the splitting of the 6carbon sugar molecules into 3-carbon molecules (called pyruvates), and two
molecules of ATP are gained by the cell. This is anaerobic respiration.
Stage 2 - this occurs in the mitochondrion of the cell and it involves the use of
oxygen. This results in the complete breakdown of the pyruvate into carbon dioxide
and water. This breakdown is done by enzymes. A total of 36 ATP molecules are
gained in this process. The energy is released gradually. This is aerobic respiration.
Overall, 38 molecules of ATP were released. Only 40% of the glucose is converted to
ATP. The rest is lost as heat.
There is also another type of respiration called ANAEROBIC CELLULAR
RESPIRATION. In this type of respiration there is not a sufficient amount of oxygen
present. Anaerobic cellular respiration does not produce the high levels of ATP has
aerobic respiration does because there is no oxygen to assist the release of ATP
when glucose is converted to carbon dioxide and water. Anaerobic cellular respiration
releases only 2 ATP molecules in total.
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2. Each local aquatic or terrestrial ecosystem is unique

Examine trends in population estimates for some plant and animal
species within an ecosystem
Transects can be used to determine the distribution of an organism.
Transects - A transect is a narrow strip that crosses the entire area being studied,
from one side to the other. Transects provide an accurate and easy method of
representing an area. Plants are usually the subjects of transects, but the
distribution of extremely slow or non-moving animals can still be calculated. There
are two types of transects - plan sketch and profile sketch. A plan sketch is an aerial
or surface view of a representative area within an ecosystem. A profile sketch is a
side-on view of an area showing to scale the distribution of organisms along a line.
There are numerous ways of estimating populations through the use of sampling
techniques. These techniques are used if it is too difficult to count the exact number
of species or if only a round estimate is sufficient.
Quadrats - It is much easier to calculate the abundance or population of plant
species because they the stay in the one place. Quadrats are squares (the size of
which depends on the organism - the larger the organism the larger the quadrat)
which are randomly placed in the area that is being studied. The number of
organisms within the quadrat is counted and this can be used to determine the
percentage cover of the organism within that area. For example, if the abundance of
grass was calculated to 54% of the total area. And it was known that approximately
1000 blades of grass covered 1 square metre and the total area was 10 meters
squared, the population of the grass could be estimated to be approximately 5400.
Capture-Mark-Recapture – This is a method which involves catching a certain
number of individuals of a particular species, marking or tagging them in some way.
They are then released into the wild and then at a later time a group of the same
species is caught and the number that were already tagged is recorded. This is then
repeated numerous times. This method is appropriate for mobile organism where it
is virtually impossible to count all individuals at one time.
The formula used to estimate the population goes as follows:
Number Captured X Number Recaptured
Number Marked in the recapture
Sampling
Technique
Transects
Quadrat
CaptureMarkRecapture
Advantages
Disadvantages
- Provides a quick, easy and inexpensive
method for measuring species occurrence.
- Minimal Disturbance to the environment
- Easy and inexpensive
- Minimal disturbance to the environment
- Can also be used to determine distribution
- Simple method that provides an estimate
of abundance for animals in large
populations that are difficult to count.
- Only suitable for plants or slow moving animals
- Species occurring in low numbers may be
missed.
- Only suitable for plants or slow moving animals.
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- Only suitable for mobile animals
- Time consuming
- Can be disturbing to the environment

Outline factors that affect numbers in predator and prey populations in the
area studied
A relationship in which one organism eats another is called predator/prey
relationship, or predation. These types of relationships often have a major impact on
the abundance of organisms. Populations of predator are dependant on the
population of the prey and vice versa.
For example, if the population of the prey were to drop significantly then the same
trend could be seen in the predator population. On the other hand, if the predator
population were to drop significantly then a huge increase in prey may be observed.
Such obvious relationships are seldom observed under natural conditions because
many variables interact to influence the abundance of both predators and prey. In
particular, where predators have a variety of food sources, such simple patterns are
not observed.
A number of other factors could influence predator/prey populations as well:

Size of ecosystem – The larger the
ecosystem; the more resources

Diseases

Availability of food – for both the predator
and the prey.

Migration – This could result in fluctuations in
both populations

Reproduction – for both the predator and the
prey

Competition for resources – for both the
predator and the prey

Human activity and intervention could have
an effect on either or both of the populations.

identify examples of allelopathy, parasitism, mutualism and commensalism
in an ecosystem and the role of organisms in each type of relationship
Allelopathy – This is the process by which plants are able to produce
allelochemicals (also called biomolecules) which they release into the environment.
These allelochemicals inhibit the growth of other plants in the area surrounding the
plant, thus reducing competition for the plant, which increases the chances for the
plants survival. Not all plants have allelopathic tendencies. Since space is crucial to
the survival of plants, those that are able to produce effective allelochemicals are
extremely advantaged. Since the fewer the plants around, the more water the plant
can absorb from the soil, and more soil for stability and more sunlight to absorb.
Examples of allelopathy:
1) Eucalyptus leaf litter – Eucalyptus trees’ foliage are able to produce
effective allelochemicals. When the leaves of the eucalyptus tree fall onto the
ground, they decompose. During the decomposition of the leaves, the allelochemicals
(in the form of acid) are released into the soil and these inhibit the growth of other
plants in that area.
2) Sorghum species (cereal grass) release a chemical in the root exudates
that disrupts mitochondrial functions and inhibits photosynthesis.
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Symbiosis: Term used for interactions in which two organisms live together in a
close relationship that is beneficial to at least one of them.
There are three types of symbiotic relationships:
1) Parasitism – This is where one species benefits where as the other is harmed. A
parasite obtains food and shelter from the host organism. They feed on the tissues
or fluid of the host but do not usually kill it, as this would destroy the parasites food
supply. Ectoparasites are those that live outside the body of the host, whereas
endoparasites live internally.
Examples of Parasitism:

Tapeworms live attached to the lining of the digestive system of their
host animal and absorb digested food without causing any serious harm,
however, the animal does become weaker and slightly sick.

Ticks and fleas feed off the blood of dogs. They are benefiting whereas
the dog is being harmed and it tries to scratch them to get rid of them.
Fleas/ticks may result in the dog becoming extremely ill and even death.
2) Mutualism – this is where both the organisms in the relationship benefit.
Examples of Mutualism

The relationship between the anemone and the clown fish (also known
as the anemone fish). The clown fish attracts prey to the anemone and
as the prey approaches they are stung by the tentacles of the anemone.
This thus provided food for the anemone. The clown fish feeds on the
remains of the prey and it receives protection from predators and also
food. The anemone is able to obtain its feed this way as well as be
cleaned by the clown fish. Thus it is mutualistic. Note: the clown fish
becomes immune to anemone’s sting by brushing itself on the tentacles.

The ‘ant plant’ has a mutualistic relationship with a species of ant. The
plant has a swollen bas in which the ants are able to build their colony.
The ants carry corpses and excreta to parts of the chambers within the
plant. This allows the plant to absorb the waste nutrients.
3) Commensalism – This is where one species benefits and the other is unaffected.
Examples of Commensalism

The relationship between the remora fish and the shark. The remora fish
attaches itself to the shark and thus is able to get a free ride and feed
from scraps from the shark’s food but appears not to benefit the shark.

Barnacles and whales. Barnacles attach themselves to the surface of the
whale. They are able to be transported to diverse areas rich in food. The
whale however is unaffected.
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
describe the role of decomposers in ecosystems
Decomposers, or SAPROPHYTES, are organisms that obtain energy by breaking down
the dead bodies of other organisms or their wastes (eg. faeces). Decomposers return
nutrients into the soil so that they can be re-used. Their role is to recycle matter
within an ecosystem. Decomposers include organisms such as fungi and bacteria.
Decomposers are vital to the functioning of an ecosystem. They play a crucial role in
recycling materials. Since to amount of matter on Earth is finite, the materials in
dead bodies need to be released so that new organisms can use these materials for
growth, repair and maintenance. Decomposers are consumers and are mainly
bacteria or fungi.

explain trophic interactions between organisms in an ecosystem
using food chains, food webs and pyramids of biomass and energy
A trophic interaction is one where one organism is consumed by another.
A Producer is also known as an autotroph
A consumer is also known as a heterotroph
Food Chain – Is a single chain of feeding patterns. It shows a liner process in which
organism is consequently consumed by another in increasing trophic order.
Food Web – This is the combination and interaction of numerous food chains and
shows the interactions and feeding patterns of numerous organisms. It is non-linear
and one organism can be in many different trophic levels depending on the
chain/web. A food web and a food chain also show the flow of energy and matter in
an ecosystem.
Biomass pyramid – A biomass pyramid indicates the relative amount of matter in
the organisms of a community. The total amount of mass in a community is called its
biomass. In a self sustaining ecosystem, the biomass significantly decreases at each
trophic level. The normal pattern of a biomass pyramid has a huge percentage of
producers, a limited percentage of herbivores and a small percentage of carnivores.
Biomass pyramids show the amount of matter at each trophic level. These when
used with food webs are best used to describe the energy and matter transfer
through a community.
Energy pyramid – Energy pyramids show the amount of energy at each trophic
level in a community. The lower the organism on a food chain the more energy it has
available to it. Energy pyramids indicate the relative amount of energy transferred
from one trophic level to another. In a stable community, biomass and energy
pyramids decrease rapidly as the trophic level increases. Biomass and energy
pyramids can be used to predict and explain changes in a community.
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
define the term adaptation and discuss the problems associated with
inferring characteristics of organisms as adaptations for living in a
particular habitat
Adaptation are inherited characteristics of organisms that increase the chance of
survival of the species. Adaptations are also often described as characteristics of
organisms that are suited to the organisms’ habitats.
Adaptations can either be structural, behavioral or physiological. Structural
adaptations are the physical characteristics (anatomy) of the organism to help it
survive (eg. For a spider, its eight legs is an adaptation because it allows for agile,
nimble movement). Behavioral adaptation is the way an organism will act that
increases its chance of survival. (e.g. When you wear a jumper because it is cold
outside). A physiological adaptation is one that is related to the internal functioning
of the organism (eg. A kangaroo will be able to produce two types of milk for it’s
joeys which are of different ages).
It is sometimes difficult to infer that the characteristic of an organism is an
adaptation to its particular habitat because:
-
-

The organism may be observed outside the habitat in which it evolved,
for example, in a suburban garden.
The characteristic may provide no particular advantage in a particular
habitat but has been inherited from ancestral organisms that inhabited
different habitats.
It may simply be difficult to be certain how a particular characteristic
helps a species to survive.
identify some adaptations of living things to factors in their environment
Animal adaptations – Spider:
-
8 legs (structural adaptation)
Ability to produce web (physiological adaptation)
Crawl away from any points of bright light (behavioral adaptation)
Plant adaptations – Old man Banksias:
-
Huge Flower, thick bark, extremely fine intricate roots (structural)
Seeds falling to the ground after a fire (physiological)
Note: An ideal environment for a plant is usually the environment to which an
organism is adapted even when the environment might seem harsh to us.
Xerophytes are plants that have adapted to dry environments by reducing the
surface area of their leaves in order to minimize water loss.
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 identify and describe in detail adaptations of a plant and an animal
from the local ecosystem
Animal – The kangaroo:
Structural Adaptations:



The tail is able to support the body when they are standing still. Also two hind
legs are extremely strong and are able to support the weight of the kangaroo.
This structural adaptation allows for the kangaroo to move quickly across land
and also to rest it’s main muscles at regular intervals.
The mother contains a pouch in which the joey is able to feed as well as have
protection. This structural adaptation allows for protection of young and also
gives a efficient method of feeding young.
Big ears that have large surface area so it loses heat more rapidly. This
structural adaptation allows for the kangaroos to quickly cool down.
Behavioral Adaptations:







Kangaroos lick their forearms to lose heat as the evaporation of saliva draws
heat from the surface. This behavioral adaptation allows for the kangaroo to
cool down quickly.
Kangaroos sit in the shade during the day to avoid the heat absorption from
the sun
Dominant males regularly check hormonal patterns of his females. This
behavioural adaptation allows for the males to reproduce efficiently and at the
right times, ensuring survival of the species.
Siblings fight amongst each other to practice the fighting skills they need later
on in their lives.
The mothers hang around in groups to increase chances of detecting a
predator
Males fight with one another in order to assume the top spot in the mob. This
behavioural adaptation ensures only the dominant characteristics will be
passed on to future generations as only the dominant males are able to find
mates regularly.
Kangaroos run away if a predator is observed or if any unknown creature is
seen.
Physiological Adaptations:




Kangaroos do not sweat, so they are able to avoid losing water on hot days
through sweating. This allows them to live in fairly arid conditions.
Mothers produce two types of milk in order to feed joeys of different ages.
Dilation of the blood vessels, bringing them close to the surface of the skin to
lose heat more rapidly (called vasodilation)
When the joey is still suckling inside the mother’s pouch, the mother is unable
to release another embryo.
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Plant – Mangroves
Structural Adaptations:



Some mangroves species have aerial roots which are filled with spongy tissue
and small holes that provide structural support and transfer oxygen from the
air to the roots trapped below the ground in low-oxygen soil.
The roots are also adapted to prevent the intake of a high amount of salt
from the water.
Leaves may possess glands that excrete salt, or they may will be able to store
huge amounts of salt in their leaves. (also behavioural and physiological)
Physiological Adaptations:



Leaves may possess glands that excrete salt, or they may will be able to store
huge amounts of salt in their leaves and then at a later point drop those
leaves into the soil. (Also structural and behavioural)
Mangrove seeds may be viviparous meaning they retain their seeds until they
have germinated. When they are dropped into the water from the parent tree,
the seed is able to remain dormant until it finds soil.
Other mangrove species may be able to produce seeds that are able to float,
this allows for the tide to assist in dispersal, and also avoids overcrowding.
Behavioural Adaptations:



Mangroves can also restrict the opening of their stomata (pores in the leaves
which are responsible for regulating the exchange of gases and water during
photosynthesis. This conserves fresh water within the leaves which is vital for
survival in a saline environment.
Mangroves are also able to reduce leaf exposure to the sun by turning the
leaves side on. This reduces excess water loss through evaporation.
Leaves may possess glands that excrete salt, or they may will be able to store
huge amounts of salt in their leaves and then at a later point drop those
leaves into the soil. (Also structural and behavioural).
 describe and explain the short-term and long-term consequences on
the ecosystem of species competing for resources
When in competition two organisms use one or more resources in common, such as
food, shelter and mates. The competition is so the organism can acquire a limited
factor in the environment. Organisms may compete with members of their own
species or members of other species. Competition between members of the same
species is known as intraspecific competition. Competition between members of
different species is called interspecific competition. Usually interspecific
competition is less intense than intraspecific.
There are two types of competition:
– Resource competition – where the organisms utilize a resource that is in
short supply
- Interference competition – where the organisms harm each other while
obtaining a resource, even if that is not in limited supply.
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Short-term consequences of competition:



If the competition is intraspecific then it will result in the reduction in
abundance of that organism.
If the competition is interspecific it will result in the reduction of abundance
for at least one of the organisms
Also, if the competition is interspecific it will alter the distribution patterns of
the organism which can result in a chain of consequences especially if the
organism disappears from some areas where they are essential. This could
greatly alter the natural chain and cause problems.
Long-term consequences of competition:


If the competition is intraspecific it could result in some organisms in the
species starting to act in ways that are different to the normal. Eg. Find a
different source of food. This could eventually lead to the creation of a new
species that is unable to reproduce with their ancestral species.
If the competition is interspecific it could result in the extinction of one
species from that area which could alter food chains especially if the extinct
organism was the only food supply of other organisms. It could lead to a
chain of terrible consequences. On the other hand, other species might
flourish due to this and this may improve the ecosystem.
 identify the impact of humans in the ecosystem studied
Humans impact ecosystems in many ways. Human activities can change the biotic
and abiotic features of the environment. They alter the factors which determine the
abundance and distribution of species. They change the cycle of materials. They
interrupt the flow of matter and energy in ecosystems.
Humans have changed nearly half the world’s land surface and over half the
accessible fresh water is used by humans.
Aboriginal Australians arrived many years ago and they had a drastic impact on the
local Australian environment. For example – the use of controlled burning as hunting
and land management technique influenced the abundance and distribution of native
plants with more fire-resistant varieties surviving and becoming more prolific. Also
the introduction of the dingo between 6000 and 3000 years ago was the next major
change. The dingo appears to have no natural predators and therefore became the
most dominant species.
Then European settlers arrived. They started clearing the land for buildings and
agriculture. Clearing the land caused several disturbances such as removing habitat
of many species. Many organisms either migrated or became extinct. Also clearing
the land caused soil erosion which resulted in the removal of topsoil (which had the
most nutrients) which affected plant growth. Also erosion caused siltation of rivers.
Also foreign species were introduced (either accidentally or intentionally). Many of
these species became feral and feral animals often have more favorable features for
survival than the native species and are better at competing for resources. For
example the rabbit was introduced and this competes with the bilby for burrow space
and the rabbit always wins.
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Also the introduction of the prickly pear was disastrous as it caused widespread
havoc across native ecosystems as well as agricultural systems.
The altering of waterways. Building dams not only floods areas that were once
terrestrial but also changes the flow patterns and temperatures in the river. For
example 99% of the water from the Snowy river was diverted due to the introduction
of the Snowy Mountains Hydro-Electric Scheme. Changing water ways can result in
rising salt levels in certain areas. Often the changes occur cause species to leave the
area or to become extinct.
Furthermore the introduction of monocultures impacted on the distribution and
abundance of species. A monoculture restricts the number of species that can live in
that area.
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