Biology Notes - Module 1 - Version 2-1

8/12/2019 Biology Notes - Module 1 - Version 2-1

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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

ompare the abiotic characteristics of a!uatic and terrestrialenvironments

An a!uatic environmentis one that consists in water.

The abiotic characteristics of an aquatic environment include:

o "iscosity 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. t is much more

difficult to travel through water than it is through air. This is why manyaquatic 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. #uoyancy is determined by the density of the

medium and determines the floating ability of an organism. $ater providessufficient buoyancy for many organisms, eg, the %ellyfish. f a %ellyfish 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 %ellyfish.

o #ressure This is the downward force that is applied on an organism by its

medium. n water, the pressure is dependant on the depth. &rganisms 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 suchharsh environments.

o Temperature "ariations 'sually in an aquatic environment there are

minimal temperature variations to that compared with terrestrial

environments. The temperature variations also depend on the si(e of thebody of water) a large body of water will experience much less temperature

variations than a smaller body of water. *lso, as depth increases thetemperature of the water decreases.

o Availability of gases in water the availability of gases depends on factors

such as temperature, depth and turbulence. +ot water holds much less

oxygen than cold water. The availability of gases also depends on the rate ofdiffusion which is much slower in water than it is in air. *lso, as the depth ofthe water decreases the availability of the gases decreases.

o Availability of $ater n aquatic environments water availability can be a

problem as osmosis occurs. &rganisms are suited to a particular type of water

either fresh water or salt water. f the organism is placed in the wrong typeof water they will die, thus wateravailability is an issue. n this scenario, the

salinityof the water is another factor.

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o Light penetration -ight is only able to penetrate about //m in oceans

and seas. Thus as the depth increases the light penetration decreases. -ightis essential for all aquatic plants, thus the plants need to have specific

adaptations that allow them to retrieve enough sunlight to survive. The lightpenetration is also dependant upon $ater clarity.

o E%posure to natural forces 0ifferent aquatic environments are exposed

to different natural forces such as tides, currents, waves etc. 1arineorganisms 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. -and organisms must therefore have adaptations to cope withsuch large temperature changes.

o Landscape position 2lope and aspect may affect temperature, water and

light availability as well as impact on soil quality. 3unoff and erosion may

also be prominent in particular landscapes.

o &ainfall and $ater availability $ater is not freely abundant in land. t

must be sourced from the soil or consumed. &rganisms must haveadaptations that allow them to survive using the amount of water available to

them

o 'alinity 0ifferent soils have different salinity levels and only particular

organisms thrive in certain salinity levels. 4lants must have adaptations that

enable them to cope with the different levels of salinity.

o p( )acidity*al+alinity 2oil p+ can vary. 0issolved salts play an

important role in determining the p+ of the soil and some plants need to have

a particular p+ to survive. 4lants need to have adaptations that allow them tocope with the p+ of the soil in their environment.

o Buoyancy *ir provides minimal buoyancy and therefore land organisms

need to have a skeletal and muscle structures that enable them to supportthem.

o E%posure to natural forces $ind, 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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o Availability of salts in the soil there must be specific salts for the plants.

4lants will only thrive if there are those specific salts available.

There are also other factors that affect distribution and abundance of both aquatic

and terrestrial organisms including:

o Availability of resources and Limiting factors * limiting factor is asingle resource that determines the maximum population of a specific species

in that area. n aquatic environments this could be factors such as foodresources. The amount of food available will determine the abundance of the

organism in that environment.o ompetition ompetition for resources from both the same species and

other species for specific resources can alter the abundance and distributionof that aquatic organism in that particular environment.

o #redation This is when one organism consumes another. f a species has

numerous predators in its environment, its abundance and distribution will

fluctuate.

o Ability to mate This refers to the organisms ability to reproduce efficiently.

f the organism reproduces extremely quickly its distribution and abundanceare likely to rise dramatically whereas if it was the opposite the distribution

and abundance will remain steady.

o hemical actors such as p+ of the soil

o ynamic actors 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

#hotosynthesisis the process by which plants take carbon dioxide and water and

with the use of sunlight convert it into glucose and oxygen.

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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 theair and provide energy for the organism. Thus, organisms respire in order to carry

out daily activities. The role of respiration is to used the stored energy within anorganism to carry out its daily functions. $ithout respiration, an ecosystem wouldn5t

function as none of the organisms would be able to use the energy they had storedwhich means they would die.

identify uses of energy by organisms

1a%ority of the energy in an ecosystem is lost as heat which is beneficial to most

organisms as the cells and en(ymes thrive under warm conditions.

&rganisms use energy for many purposes including:

o 2ynthesis of complex molecules such as proteins, lipids, carbohydrates and

nucleic acids.

o ?rowth involving the division, elongation and differentiation of cells

o 3epair and maintenance of damaged or old cells

o *ctive 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 &ther daily activities such as movement, making sound, producing heat andproducing light !called bioluminescence".

-dentify the general e!uation for aerobic cellular respiration and outline

this as a summary of chain of biochemical reactions

*erobic cellular respiration is respiration that occurs under the presence of oxygen.

3espiration involves a series of chemical reactions. t is a controlled process,occurring as a sequence of about 9/ different chemical reactions, each one cataly(ed

by a different en(yme. >nergy is released slowly in small amounts. The chemicalenergy 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

*T4.

*T4 is the energy store of the cell. $hen the energy is available , *04 !adenosine"

diphosphate" collects it. $hen the energy is needed, *T4 supplies it. n fact,respiration can be thought of as the process by which *T4 molecules are made in a

cell.

*04 = 4 = glucose = oxygen many reactions carbon dioxide = water = *T4

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6@*04 = 6@4 = ;+


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6. Each local a!uatic or terrestrial ecosystem is uni!ue

E%amine trends in population estimates for some plant and animal

species $ithin an ecosystem

Transects can be used to determine the distribution of an organism.

Transects / * 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. 4lants are usually the sub%ects of transects, but the distributionof extremely slow or nonmoving animals can still be calculated. There are two types

of transects plan sketch and profile sketch. * plan sketch is an aerial or surface

view of a representative area within an ecosystem. * profile sketch is a sideon viewof an area showing to scale the distribution of organisms along a line.

There are numerous ways of estimating populations through the use of samplingtechniques. These techniques are used if it is too difficult to count the exact number

of species or if only a round estimate is sufficient.

7uadrats / t is much easier to calculate the abundance or population of plantspecies because they the stay in the one place. Auadrats are squares !the si(e of

which depends on the organism the larger the organism the larger the quadrat"which are randomlyplaced in the area that is being studied. The number of

organisms within the quadrat is counted and this can be used to determine thepercentage cover of the organism within that area. For example, if the abundance of

grass was calculated to 987 of the total area. *nd it was known that approximately

/// blades of grass covered square metre and the total area was / meterssquared, the population of the grass could be estimated to be approximately 98//.

apture/Mar+/&ecapture This is a method which involves catching a certainnumber 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 samespecies 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 isvirtually impossible to count all individuals at one time.

The formula used to estimate the population goes as follows:

Bumber aptured C Bumber 3ecaptured

Bumber 1arked in the recapture

'ampling

Techni!ue

Advantages isadvantages

Transects 4rovides a quick, easy and inexpensive

method for measuring species occurrence. 1inimal 0isturbance to the environment

&nly suitable for plants or slow moving anim

2pecies occurring in low numbers may bemissed.

Auadrat >asy and inexpensive &nly suitable for plants or slow moving anim

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1inimal disturbance to the environment an also be used to determine distribution

apture1ark

3ecapture

2imple method that provides an estimateof abundance for animals in large

populations that are difficult to count.

&nly suitable for mobile animals Time consuming

an be disturbing to the environment

4utline factors that affect numbers in predator and prey populations in the

area studied

* relationship in which one organism eats another is called predatorDpreyrelationship, or predation. These types of relationships often have a ma%or impact on

the abundance of organisms. 4opulations of predator are dependant on thepopulation 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. &n the other hand, if the predator

population were to drop significantly then a huge increase in prey may be observed.

2uch obvious relationships are seldom observed under natural conditions because

many variables interact to influence the abundance of both predators and prey. nparticular, where predators have a variety of food sources, such simple patterns are

not observed.

* number of other factors could influence predatorDprey populations as well:

identify e%amples 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 theplants survival. Bot all plants have allelopathic tendencies. 2ince space is crucial to

the survival of plants, those that are able to produce effective allelochemicals areextremely advantaged. 2ince 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.

E%amples of allelopathy2

1 Eucalyptus leaf litter >ucalyptus trees5 foliage are able to produceeffective allelochemicals. $hen the leaves of the eucalyptus tree fall onto the

2i(e of ecosystem The larger the

ecosystem) the more resources

0iseases

*vailability of food for both the predator

and the prey.

1igration This could result in fluctuations in

both populations

3eproduction for both the predator and the

prey

ompetition for resources for both the

predator and the prey

+uman activity and intervention could havean effect on either or both of the populations.

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ground, they decompose. 0uring 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.6'orghum species )cereal grass release a chemical in the root exudates

that disrupts mitochondrial functions and inhibits photosynthesis.

'ymbiosis2 Term used for interactions in which two organisms live together in aclose relationship that is beneficial to at least one of them.

There are three types of symbiotic relationships:

1#arasitism This is where one species benefits where as the other is harmed. *

parasite obtains food and shelter from the host organism. They feed on the tissues orfluid of the host but do not usually kill it, as this would destroy the parasites food

supply. >ctoparasites are those that live outside the body of the host, whereasendoparasites live internally.

>xamples of 4arasitism:

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.FleasDticks may result in the dog becoming extremely ill and even death.

6 Mutualism this is where both the organisms in the relationship benefit.

>xamples of 1utualism

The relationship between the anemone and the clown fish !also knownas the anemone fish". The clown fish attracts prey to the anemone andas the prey approaches they are stung by the tentacles of the anemone.

This thus provided food for the anemone. The clown fish feeds on theremains 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. 3ote2the clown fishbecomes immune to anemone5s sting by brushing itself on the tentacles.

The Eant plant5 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 theplant. This allows the plant to absorb the waste nutrients.

8 ommensalism This is where one species benefits and the other is unaffected.

>xamples of ommensalism

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 feedfrom scraps from the shark5s food but appears not to benefit the shark.

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#arnacles and whales. #arnacles attach themselves to the surface of the

whale. They are able to be transported to diverse areas rich in food. Thewhale however is unaffected.

describe the role of decomposers in ecosystems

0ecomposers, or 2*43&4+T>2, are organisms that obtain energy by breaking downthe dead bodies of other organisms or their wastes !eg. faeces". 0ecomposers return

nutrients into the soil so that they can be reused. Their role is to recycle matterwithin an ecosystem. 0ecomposers include organisms such as fungi and bacteria.

0ecomposers are vital to the functioning of an ecosystem. They play a crucial role in

recycling materials. 2ince to amount of matter on >arth is finite, the materials indead bodies need to be released so that new organisms can use these materials for

growth, repair and maintenance. 0ecomposers are consumers and are mainlybacteria or fungi.

e%plain trophic interactions bet$een organisms in an ecosystem

using food chains, food $ebs and pyramids of biomass and energy

* trophic interactionis one where one organism is consumed by another.

A #roducer is also known as an autotroph

A consumeris also known as a heterotroph

ood hain s a single chain of feeding patterns. t shows a liner process in whichorganism is consequently consumed by another in increasing trophic order.

ood 9eb This is the combination and interaction of numerous food chains andshows the interactions and feeding patterns of numerous organisms. t is nonlinearand one organism can be in many different trophic levels depending on the

chainDweb. * food web and a food chain also show the flow of energy and matter inan ecosystem.

Biomass pyramid * biomass pyramid indicates the relative amount of matter inthe organisms of a community. The total amount of mass in a community is called its

biomass. n a self sustaining ecosystem, the biomass significantly decreases at each

trophic level. The normal pattern of a biomass pyramid has a huge percentage ofproducers, a limited percentage of herbivores and a small percentage of carnivores.

#iomass pyramids show the amount of matter at each trophic level. These whenused with food webs are best used to describe the energy and matter transfer

through a community.

Energy pyramid >nergy pyramids show the amount of energy at each trophiclevel in a community. The lower the organism on a food chain the more energy it has

available to it. >nergy pyramids indicate the relative amount of energy transferredfrom one trophic level to another. n a stable community, biomass and energy

pyramids decrease rapidly as the trophic level increases. #iomass and energypyramids can be used to predict and explain changes in a community.

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define the term adaptation and discuss the problems associated $ith

inferring characteristics of organisms as adaptations for living in a

particular habitat

Adaptationare inherited characteristics of organisms that increase the chance ofsurvival of the species. *daptations are also often described as characteristics of

organisms that are suited to the organisms5 habitats.

*daptations can either be structural, behavioral or physiological. 2tructuraladaptations 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". #ehavioral adaptation is the way an organism will act that

increases its chance of survival. !e.g. $hen you wear a %umper because it is cold

outside". * physiological adaptation is one that is related to the internal functioningof the organism !eg. * kangaroo will be able to produce two types of milk for it5s

%oeys which are of different ages".

t 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.- t 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

*nimal adaptations 2pider:

- @ legs !structural adaptation"- *bility to produce web !physiological adaptation"

- rawl away from any points of bright light !behavioral adaptation"

4lant adaptations &ld man #anksias:

- +uge Flower, thick bark, extremely fine intricate roots !structural"

- 2eeds falling to the ground after a fire !physiological"

3ote2*n ideal environment for a plant is usually the environment to which an

organism is adapted even when the environment might seem harsh to us.

:erophytesare plants that have adapted to dry environments by reducing the

surface area of their leaves in order to minimi(e water loss.

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identify and describe in detail adaptations of a plant and an animal

from the local ecosystem

Animal The +angaroo2

2tructural *daptations:

The tail is able to support the body when they are standing still. *lso 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 landand also to rest it5s main muscles at regular intervals.

The mother contains a pouch in which the %oey 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.

#ig ears that have large surface area so it loses heat more rapidly. This

structural adaptation allows for the kangaroos to quickly cool down.

#ehavioral *daptations:

Gangaroos 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.

Gangaroos sit in the shade during the day to avoid the heat absorption from

the sun

0ominant 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.

2iblings fight amongst each other to practice the fighting skills they need lateron in their lives.

The mothers hang around in groups to increase chances of detecting a

predator

1ales 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 findmates regularly.

Gangaroos run away if a predator is observed or if any unknown creature is

seen.

4hysiological *daptations:

Gangaroos 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.

1others produce two types of milk in order to feed %oeys of different ages.

0ilation of the blood vessels, bringing them close to the surface of the skin to

lose heat more rapidly !called vasodilation"

$hen the %oey is still suckling inside the mother5s pouch, the mother is unable

to release another embryo.

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#lant Mangroves

2tructural *daptations:

2ome mangroves species have aerial roots which are filled with spongy tissue

and small holes that provide structural support and transfer oxygen from theair to the roots trapped below the ground in lowoxygen soil.

The roots are also adapted to prevent the intake of a high amount of salt from

the water.

-eaves 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"

4hysiological *daptations:


huge amounts of salt in their leaves and then at a later point drop those

leaves into the soil. !*lso structural and behavioural"

1angrove seeds may be viviparous meaning they retain their seeds until they

have germinated. $hen they are dropped into the water from the parent tree,

the seed is able to remain dormant until it finds soil.

&ther 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.

#ehavioural *daptations:

1angroves can also restrict the opening of their stomata !pores in the leaves

which are responsible for regulating the exchange of gases and water duringphotosynthesis. This conserves fresh water within the leaves which is vital forsurvival in a saline environment.

1angroves are also able to reduce leaf exposure to the sun by turning the

leaves side on. This reduces excess water loss through evaporation.


huge amounts of salt in their leaves and then at a later point drop those

leaves into the soil. !*lso structural and behavioural".

describe and e%plain the short/term and long/term conse!uences onthe ecosystem of species competing for resources

$hen 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 limitedfactor in the environment. &rganisms may compete with members of their own

species or members of other species. ompetition between members of the samespecies is known as intraspecific competition. ompetition between members of

different species is called interspecific competition. 'sually interspecificcompetition is less intense than intraspecific.

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There are two types of competition:

3esource competition where the organisms utili(e a resource that is inshort supply

nterference competition where the organisms harm each other whileobtaining a resource, even if that is not in limited supply.

'hort/term conse!uences of competition2

f the competition is intraspecific then it will result in the reduction in

abundance of that organism.

f the competition is interspecific it will result in the reduction of abundancefor at least one of the organisms

*lso, if the competition is interspecific it will alter the distribution patterns of

the organism which can result in a chain of consequences especially if theorganism disappears from some areas where they are essential. This could

greatly alter the natural chain and cause problems.

Long/term conse!uences of competition2

f the competition is intraspecific it could result in some organisms in the

species starting to act in ways that are different to the normal. >g. Find adifferent source of food. This could eventually lead to the creation of a new

species that is unable to reproduce with their ancestral species.

f the competition is interspecific it could result in the extinction of onespecies from that area which could alter food chains especially if the extinct

organism was the only food supply of other organisms. t could lead to achain of terrible consequences. &n 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

+umans impact ecosystems in many ways. +uman activities can change the bioticand abiotic features of the environment. They alter the factors which determine the

abundance and distribution of species. They change the cycle of materials. Theyinterrupt the flow of matter and energy in ecosystems.

+umans have changed nearly half the world5s land surface and over half theaccessible fresh water is used by humans.

*boriginal *ustralians arrived many years ago and they had a drastic impact on the

local *ustralian environment. For example the use of controlled burning as huntingand land management technique influenced the abundance and distribution of native

plants with more fireresistant varieties surviving and becoming more prolific. *lsothe introduction of the dingo between ;/// and 6/// years ago was the next ma%or

change. The dingo appears to have no natural predators and therefore became themost dominant species.

Then >uropean settlers arrived. They started clearing the land for buildings and

agriculture. learing the land caused several disturbances such as removing habitatof many species. 1any organisms either migrated or became extinct. *lso clearing

the land caused soil erosion which resulted in the removal of topsoil !which had themost nutrients" which affected plant growth. *lso erosion caused siltation of rivers.

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*lso foreign species were introduced !either accidentally or intentionally". 1any ofthese species became feral and feral animals often have more favorable features for

survival than the native species and are better at competing for resources. Forexample the rabbit was introduced and this competes with the bilby for burrow space

and the rabbit always wins.

*lso the introduction of the prickly pear was disastrous as it caused widespreadhavoc across native ecosystems as well as agricultural systems.

The altering of waterways. #uilding dams not only floods areas that were once

terrestrial but also changes the flow patterns and temperatures in the river. Forexample HH7 of the water from the 2nowy river was diverted due to the introduction

of the 2nowy 1ountains +ydro>lectric 2cheme. hanging water ways can result inrising salt levels in certain areas. &ften the changes occur cause species to leave the

area or to become extinct.

Furthermore the introduction of monocultures impacted on the distribution andabundance of species. * monoculture restricts the number of species that can live in

that area.

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Biology Notes - Module 1 - Version 2-1