Topic 5 Relationship of Living Things With Its Environment

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X INTRODUCTION

What is the relationship between living things and their environment?

All living organisms on earth are part of one great, interdependent system. Theyinteract with and depend on one another and the environment in ecosystems toform the foundation of sustainable development. In this topic, you will learnabout how living things relate with each other and their surroundings.

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55 X

Relationship of Living Thingswith itsEnvironment

By the end of this topic, you should be able to:

1. Explain ecosystem and interaction between living organisms;

2. Describe energy flow between organisms;

3. Discuss various material cycles; and

4. Identify man-made disruption of the ecosystem and how it can besaved.

LEARNING OUTCOMES



X TOPIC 5 RELATIONSHIP OF LIVING THINGS WITH ITS ENVIRONMENT 106

ECOSYSTEM

Ecology involves studying the relationships between organisms and between

organisms and their environment. Ecosystem is the basic unit of study inecology. It describes a more or less self-contained part of the biosphere, like apond or an oakwood. ‰Self-contained‰ means that each ecosystem has its ownorganism with specific characteristics not usually found in other ecosystems.

There are a variety of ecosystems. An ecosystem has no particular size and can beas large as a desert or a lake or as small as a tree or a puddle.

Ecosystems are dynamic. All biotic communities are continually changing. Theychange in response to external factors such as changing climates as well as

internal factors caused by the organisms themselves. Let us go through thefeatures of an ecosystem as listed below:

(a) HabitatA habitat is the home of an organism. It is the place where an organismobtains its basic resources of life – food, shelter, living space, nesting,

breeding sites and protection.

(b) NicheThis refers to the role an animal plays in its ecosystem. This includes its

habitat, interactions with other organisms, the types of food it consumes,the range of temperatures it tolerates and the space it occupies. Therefore,an organismÊs niche is its ecological role, that is, its ability to fit into anecosystem.

According to its feeding role in a food chain, an organism can becategorised into producer, predator or parasite. Two species cannot sharethe same ecological niche but individuals belonging to the same speciesmay have different niches.

(c) SpeciesA group of organisms which are very alike, share similar characteristicswith the ecological niche and can mate together to produce healthyoffspring.

(d) PopulationA population is made up of organisms of the same species living andreproducing in a particular habitat. The individuals of a population rely onthe same resources and are influenced by similar environmental factors.

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TOPIC 5 RELATIONSHIP OF LIVING THINGS WITH ITS ENVIRONMENT W 107

(e) CommunityA community refers to different populations of plants and animals livingtogether in a habitat. Members of a community are interdependent and

interact with one another. A change in the population of one species willaffect the population and distribution of the other species within thecommunity. Communities are named after one of the dominant species ormajor physical characteristics of the area.

INTERACTION BETWEEN LIVINGORGANISMS

In an ecosystem, organisms interact with one another in various ways in order tosurvive. Take a look at Figure 5.1 showing the interaction between livingorganisms.

Figure 5.1: Interaction among living organisms

(a) Symbiosis Symbiosis is defined as a close interaction between different species whichlive together and interact with each other for an extended period. Insymbiotic relationships, one species always benefits, while the other speciesmay be unaffected, harmed or helped. The large organism is known as thehost.

5.2

Using your own creativity, draw a concept picture to show therelationship among a population, a community and an ecosystem.

ACTIVITY 5.1




There are three categories of symbiotic relationships, which are as follows:

ȱ(i) Commensalism

In this type of interaction, one partner benefits (commensal) while theother (host) derives neither benefit nor harm. An example of this is theclown fish which lives around the sea anemone (see Figure 5.2).

Figure 5.2: Clown fish and sea anemoneSource: http://www.inetteacher.com

(ii) Mutualism

Mutualism is a relationship between two species of organisms inwhich both benefit. For example, crocodile with clover birds. Thecrocodile allows the bird to enter its mouth and eat the food betweenthe crocodile's teeth. The bird benefits because it is able to eat. Thecrocodile also benefits as its teeth are cleaned (see Figure 5.3).

Figure 5.3: Crocodile and clover birdSource: http://www.inetteacher.com




(iii) ParasitismParasitism is a symbiotic relationship in which one organism benefitswhile the other is harmed. The intestinal worm, for example, takes the

nutrients from a human intestine, causing the human to be depletedof nutrients.

(b) SaprophytismSaprophytism is a type of interaction in which living organisms obtain foodfrom dead and decaying organic matter. Bacteria, for example, attack adead animal for food and in doing so, decompose the dead body.

(c) Prey-predatorPrey-predator interaction occurs when an organism, called the prey, is

hunted and eaten by a stronger and bigger organism, called the predator.An example of this would be a crocodile (predator) hunting for fish (prey)in a river. Eventually, prey species with the best defensive strategies willescape capture and survive.

(d) CompetitionCompetition is an interaction between organisms which live together in ahabitat and compete for the same resources that are in limited supply.

Plants compete for light, nutrient, water and space. Animals compete forfood, shelter and breeding mates.

Competition between individuals of the same species is called intraspecificcompetition. On the other hand, competition between individuals of different species is known as interspecific competition.

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1. Identify the relationship between the following pairs of organisms:

(i) A bobcat can run faster and has sharp claws to help it huntfor hares.

(ii) Ticks live on the body of dogs, feeding on their blood.

(iii) The oxpecker picks out blood-sucking insects from the skin of the ox.

2. How do parasites differ from predators?

3. Most parasites do not kill their hosts. Why?

ACTIVITY 5.2




ENERGY FLOW

In an ecosystem, organisms interact through food relationship.

(a) Food Chain The feeding relationship between organisms in an ecosystem forms a foodchain. Each organism involved is a link in the food chain.

It shows a sequence of organisms through which energy from the sun istransferred. A food chain usually starts with a producer from which energyis transferred through several levels of consumers. Each category of organism in a food chain is known as a trophic level (feeding level).

A food chain can be represented as follows (also refer to Figure 5.4):

Producer primary consumer secondary consumertertiary consumer quarternery consumer

Figure 5.4: A food chain

(b) Food Web

In a community, an organism usually feeds on several different types of food. Instead of one simple food chain there are many food chains, whichshare the same organism. Many food chains interact to form a food web.Food web helps to maintain a balanced environment by controlling thenumber of organisms at each level of the food chain.

A food web can be represented as shown in Figure 5.5.

5.3




Figure 5.5: A food web

(c) Pyramid of NumbersFood relationships between the organisms in a food chain can berepresented in the form of a pyramid of numbers.

A pyramid of numbers shows the numbers of organisms at each level. The base of the pyramid represents the producers. This level has the largestnumber of organisms.

Each level up from the base represents the primary, secondary and topconsumers respectively. The number of organisms at each level gets smalleras the size of the organisms gets bigger and as the level goes higher.

They are drawn up by counting the number of individuals in a certain area.These numbers are plotted like bar chart but horizontally (see Figure 5.6).Pyramid numbers do not take into account the size of the organisms at eachtrophic level.

Figure 5.6: A pyramid number

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The main source of energy in an ecosystem is the sunlight which isabsorbed by the producer (green plants) and changed into food or chemicalenergy.

Each time food is eaten, energy is transferred from the food to theorganism. When the primary consumer feeds on the producer, energy istransferred to the primary consumer. This energy transfer continues to thenext level. In the pyramid numbers, less energy flows from the base of thepyramid upwards. Energy is lost in the transfer of food from one trophiclevel to the next.

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MATERIAL CYCLES

When an organism uses energy for its activities, the energy is released to theenvironment and can be used again. Biogeochemical cycles involve materialswhich are essential to life like nitrogen, phosphorus and carbon. They are called

nutrient cycles. Materials are recycled within the ecosystem.

5.4

Using producers and consumers from a community near where you live,draw several interconnecting food chains that form a simple food web.

ACTIVITY 5.3




(a) Nitrogen cycle

ȱFigure 5.7: Nitrogen cycle

Source: www.bromarshall.blogspot.com

Figure 5.7 shows the process of nitrogen cycle. Nitrogen is needed becauseit produces protein, nucleic acid and other products that are essential for

living things. 79% of the atmospheric gaseous is dominated by nitrogen.Eventually, it cannot be used as it is chemically unreactive. Before plantsand animals absorb nitrogen, it must first be converted into ammonia,nitrites or nitrates. This conversion process is called nitrogen fixation.

Ammonium ions (NH4+) or ammonia (NH3) is converted from nitrogen gas

through ammonification process by nitrogen fixing bacteria. It is soonconverted into nitrites (NO2

-) and nitrates (NO3-) by nitrifying bacteria

through nitrification process. The nitrate ions produced will become plantprotein. As we consume vegetables, we will assimilate protein for our

bodies.

Dead animals and plants will be decomposed by bacteria and fungi whichwill break down the bodies. Again, ammonification process takes place.

The nitrogen cycle is completed by denitrifying bacteria, converting thenitrates into nitrites and finally back to the nitrogen gas. This denitrificationprocess leads to the loss of nitrogen compounds in the ecosystem to theatmosphere.




(b) Phosphorous Cycle

ȱFigure 5.8: Phosphorus cycle

Source: Pearson Education (2003)

Figure 5.8 illustrates the phosphoros cycle. Phosphorus cannot be found inthe air in a gaseous state. At normal temperature, it occurs in liquid stateand can be easily found in water, soil and rock. In the atmosphere,phosphorus can mainly be found as very small dust particles. Phosphorusmoves slowly from deposits on land and in sediments, to living organisms,and then much more slowly back into the soil and water sediment.

Phosphorus cycles through plants and animals much faster than it doesthrough rocks and sediments. When animals and plants die, phosphateswill return to the soil or water during decay. Finally, phosphorus will endup as rock precipitation again.

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(c) Carbon Cycle

Figure 5.9: Carbon cycleSource: Pearson Education (2003)

Carbon cycle is depicted in Figure 5.9. The burning of wood and fossil fuelsproduces carbon dioxide in the atmosphere. Same goes for the cellularrespiration of living things like detritivores and animals. Plants, algae andcyanobacteria absorb carbon dioxide from the atmosphere and use it. As theplants grow, they become the food source for primary consumers (mostlyherbivore). Higher-level consumers eat primary consumers, using thecarbon inside primary consumersÊ tissues for their own needs. When allliving things die, the carbon is returned to the soil during decomposition.




HOW HUMANS DISRUPT ECOSYSTEMS

Human activities often affect the whole ecosystem. With greater advancement inthe medical field, modern farming techniques and better infrastructure, theworldÊs population has grown to over six billion today. Many of the problemsrelated to the environment are the result of human activities and interferencewith the ecosystems.

Among the problems is that we are polluting the environment with wasteproducts. Any kind of waste can cause pollution. Manufacturing, agriculture,mining and transportation help improve the quality of life for humans. However,

these activities are also major sources of pollution. Can you identify wasteproducts that can cause pollution and how they pollute the land, water or air?

5.5

ACTIVITY 5.4

Apart from the other cycles we have gone through, there is also thewater cycle. Based on the picture below, search the Internet to namethe labelled processes (A, B, C and D).




Human activities disturb the balance in the ecosystem. Among them are thefollowing:

(a) Garbage DisposalOne of the most difficult problems facing humans today is the disposal of solid wastes. Garbage, refuse and litter are some of the terms used todescribe solid waste. The main human contribution to pollution is landfills.Approximately half of our trash is disposed in landfills. Only 2% of ourwaste is actually recycled. Many of the country's landfills have been closedfor one of or both these reasons:

(i) They were full; and

(ii) They were contaminating groundwater. The water that flows beneath

these deep holes is our drinking water. Once groundwater iscontaminated, it is extremely expensive and difficult, and sometimeseven impossible, to clean it up.

Excess packaging contributes to solid waste, and disposing of packagingand other solid waste is a serious problem. Some communities dispose of garbage in an open dump, where the garbage is left on the ground. Theseopen dumps are health hazards and a threat to the environment. Raincarries materials from the dump into water supplies. Since rats, insects,

bacteria and fungi are found in open dumps, such dumps are potentialsources of diseases.

(b) Factory Waste DisposalIndustrial firms find it convenient to discharge wastes into rivers andestuaries. Toxic waste from factories which flow into rivers and seas, maypoison and kill aquatic organisms.

A well-known case of industrial pollution is the tragedy of Minamata in Japan. A plastic factory started discharging waste into the bay in 1952. By1953, a thousand people in Minamata were seriously ill (see Figure 5.10).The cause of the disease was found to be mercury compounds.




Figure 5.10: Victim of the Minamata tragedySource: http://politicstheoryphotography.blogspot.com

ȱ(c) Use of Chemical Fertilisers and Pesticides

Chemical pesticides have caused a lot of environmental damage in the lasthundred years. On the other hand, without the pesticides many cropswould have failed and millions more people would have died of starvation.

Using chemical pesticides and herbicides to control pests and weeds inagriculture may cause air, land and water pollution. The fertilisers used toincrease crop yields can also cause problems in rivers, ponds and lakes. Theexcess fertilisers are washed away by rainwater. They enter rivers and seasand result in death of aquatic or marine plants and animals. When cropsreceive more fertiliser than they can use, the excess washes into lakes and

rivers stimulating the growth of plants and algae. When the plants die, bacterial decay of the dead material uses oxygen. The resulting shortage of dissolved oxygen will then kill fish in the lakes and rivers.

(d) Vehicles and Machine The earth's air contains pollutants or harmful material, which we may also

breathe. Some of these air pollutants may be odourless and colourless.Other air pollution may be so apparent that it surrounds us like smog orhaze.




The internal combustion engines that power cars, trucks and buses producecarbon monoxide, which is an odourless, highly poisonous gas. Thesevehicles also emit hydrocarbons and nitrogen oxides, which, under the

influence of sunlight, form low atmosphere ozone, a major irritant and airpollution. Lead, which is added to petrol, is also a threat. Excess lead levelsin the atmosphere can damage the brain and nervous system.

Power plants and factories that burn coal and oil will produce nitrogenoxides and sulphur dioxide. These gases when combined with atmosphericmoisture form nitric acid and sulphuric acid – which eventually becomeacid rain that has harmful effects on the environment.

The combustion of coal and oil in power stations and factories sends carbon

dioxide into the air. However, releasing too much carbon dioxide into theair can make the earthÊs atmosphere too warm causing global warming.Carbon dioxide and water vapour reduce the amount of heat radiated fromthe earthÊs surface into space, thus keeping it warm. This action is called thegreenhouse effect.

Carbon monoxide is dangerous because it combines much more readilywith haemoglobin than does oxygen. The body is therefore starved of oxygen.

(e) Sewage Disposal Wastewater needs to be managed in order to reduce its threat to publichealth, safety and the environment. Wastewater consist of industrial waste,human waste (or sewage) and runoff from rainwater. All of the wastewaterproduced by a city eventually ends up in a river, lake or ocean. On its way,this wastewater flows through a sewage treatment plant.

(f) Use of Chlorofluorocarbon (CFC)The ozone layer is a layer of the upper atmosphere about 16 to 48 km or 10to 30 miles above earthÊs surface. The ozone layer acts as a shield, shieldingus from the harmful effects of ultraviolet radiation from the sun. In 1985,researches discovered a „hole‰ in the sky over the Antarctic. The hole was aresult of ozone depletion in the atmosphere. Chlorofluorocarbon (CFC) is amajor cause of ozone loss. CFCs are remarkably stable compounds used assolvents in the electronics industry and as coolants in refrigerators and airconditioners. CFCs rise to the ozone layer. Once there, chlorofluorocarbonmolecules break down, releasing chlorine.

Chlorine reacts with the ozone molecule to form chlorine monoxide andoxygen. Each chlorine atom destroys hundreds and thousands of ozone




molecules. So, the constantly forming, splitting and reforming of the ozonelayer is interrupted by CFCs and leads to far-reaching effects. A prolongedincrease in the amount of ultraviolet radiation reaching the earthÊs surface

could increase the incidence of sunburn, eye disease and skin cancer as wellas accelerate skin ageing.

Husna measured the pH of soil samples taken at different distancesfrom the main road. The graph below shows the result.

Distancefrom

road(m)

pH

9

7

5

0.5 1.0 1.5 2.0 2.5

1. What can you infer from the graph above on the pH of the soil at

different distances from the main road? Give a possible reason for

your answer.

2. Predict the pH of the soil at 3m from the road.

ACTIVITY 5.5




SAVING OUR ENVIRONMENT

Poor disposal of wastes happens every single day. The damage it can cause to the

environment and humans can be very devastating. We need to find the rightways to save our environment.

(a) Use of TechnologyThere are many available air pollution control technologies and urbanplanning strategies available to reduce air pollution; however, theworldwide costs of addressing the issue are high. The most immediatemethod of improving air quality would be the use of bioethanol fuel,

biodiesel, solar energy and hybrid vehicle technologies.

For soil pollution, microbes can be used in soil cleanup. Cleanup orremediation is analysed by environmental scientists who utilise fieldmeasurement of soil chemicals and also apply computer models foranalysing the transport and fate of soil chemicals.

There are several principal strategies for remediation:

(i) Excavate soil and remove it to a disposal site away from readypathways for human or sensitive ecosystem contact. This techniquealso applies to dredging of bay mud containing toxins;

(ii) Aeration of soils at the contaminated site (with attendant risk of creating air pollution);

(iii) Bioremediation, involving microbial digestion of certain organicchemicals. Techniques used in bioremediation include land farming,

biostimulation and bioaugmentation soil biota with commerciallyavailable microflora;

(iv) Extraction of groundwater or soil vapour with an activeelectromechanical system, with subsequent stripping of thecontaminants from the extract; and

(v) Containment of the soil contaminants (such as by capping or pavingover in place).

(b) Enforcement of Laws and RegulationsEnforcement procedures must be clearly stipulated by relevant governmentauthorities in curbing pollution of the various kinds that we have discussedearlier in this topic. A coordinated effort initiated by the Department of Environment with the state and district environmental offices should be inplace to deal with these huge problems. Companies are too often engrossedin making profit to the extent of harming the environment.

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Some strategies that can be taken into consideration include:

(i) Establishing a threshold standard for air pollutants to protect humanhealth. This includes giving chemicals a carcinogenicity index.

Standards such as the Air Quality Index (AQI), Air Pollutant Index(API) and Ozone Standards must be informed to the public so thatthey appreciate the importance of a healthy environment;

(ii) The Clean Water Act must be enforced to control the passage of contaminant discharge and to support efforts in the direction of bestmanagement practices for a wide range of water discharges includingthermal pollution;

(iii) The Noise Control Act needs to establish mechanisms of settingemission standards for every source of noise including motor

vehicles, aircraft and major appliances. People should also notify thelocal government as to their responsibilities in land use planning toaddress noise mitigation. This noise regulation framework needs toencompass a broad database detailing the extent of noise healtheffects;

(iv) Imposing heavy fines on individuals or establishments which violatethe environmental acts and laws (Environmental Protection Act)including measures to close down factories that do not obey localgovernmentÊs rules and regulations; and

(v) The Kyoto Protocol is an amendment to the United NationsFramework Convention on Climate Change (UNFCCC), aninternational treaty on global warming. Countries which ratified thisprotocol commit to reduce their emissions of carbon dioxide and fiveother greenhouse gases, or engage in emissions trading if theymaintain or increase emissions of these gases.

(c) Environmental Impact of Assessment (EIA)Environmental Impact Assessment (EIA) is used to identify theenvironmental and social impacts of a project prior to decision-making. It

aims to predict environmental impacts at the early stage in project planningand design, find ways and means to reduce adverse impacts, shape projectsto suit the local environment and present the predictions and options todecision-makers.

By using EIA, both environmental and economic benefits can be achieved,such as reducing cost and time of project implementation and design, andavoiding treatment/clean-up costs and impacts of laws and regulations.




The United Nation Environmental Programme (UNEP) promotes theappropriate application of the EIA process to major projects, and supportspractitioners, clients and review agencies through the publication of

guidance documents. A recent review of the EIA process recommendedthat it should consider, and be used during, the entire project cycle fromplanning through operation to the projectÊs eventual closure. EIA shouldalso be closely integrated with the environmental management systems,which are now used by major companies worldwide.

The key elements of EIA are as follows:

(i) Scoping – Identify key issues and concerns of interested parties;

(ii) Screening – Decide whether an EIA is required based on information

collected;(iii) Identifying and evaluating project alternatives – List alternative sites

and techniques and the impacts of each;

(iv) Mitigating measures dealing with uncertainty – Review the proposedactions to prevent or minimise the potential adverse effects of theproject; and

(v) Issuing environmental statements – Report the findings of the EIA.

Reports of the form such as The Contaminated Land Exposure Assessment

should act as a prescriptive document to determine the potential need forremediation of lands currently contaminated or exposed to the effects of pollution. Assessment of risks to human health from contaminated landshould be made public and authorities should have adequate mechanism toenforce punitive measures from citizen committing crimes against theenvironment.

Ground water supply needs to be assessed from time to time to avoidpollutants seeping into the food chain. Drinking Water Quality Index could

be used as a measure to look at the pollutant level in water.

(d) Education and the Mass MediaGrowing evidence of local and global pollution and an increasinglyinformed public over time have given rise to environmentalism and theenvironmental movement, which generally seek to limit human impact onthe environment. Education plays a key role in informing the citizens of thenation of the need to preserve the environment. Governments around theglobe need to systematically introduce environmental education courses,either in the school curriculum or in teacher education programmes. Inaddition, most of the world religions emphasise the need to maintain a




healthy coexistence with the environment and this could be tapped intoenvironmental education programmes. Furthermore, existing schoolsubjects could integrate environmental issues in the curriculum to allow for

dissemination of information to the students who will eventually grow upinto responsible citizens of the nation. Only through informing citizensregarding environmental aspects can we emphasise on the importance of maintaining environmental stability.

The role of mass media is vital in curbing harm done to the environment.The mass media should highlight the grave harm done to nature and thetype of punishment meted out on the perpetrators. Newspapers, radio andtelevision communication are important tools available for thedissemination of information regarding environmental issues to the public.

The mass media must be given the freedom to exercise their rights topublish articles and footage on what is happening around the globe withrespect to controlling pollution. In short, the latest technology on massmedia can be used to help fight global warming and other related issues.

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• An ecosystem is a complete set of relationships among living things and itsenvironment. It includes animals, trees, microorganisms, soil, water andhuman beings.

• Everything that lives in an ecosystem is dependent on the other species and

elements that are also part of the ecological community.

• Plants obtain inorganic nutrients like nitrogen, carbon (in the form of carbondioxide) and phosphorus from the soil or water surrounding. These inorganicnutrients are passed from organism to organism as one organism isconsumed by another. Ultimately, all organisms die and decompose. At thisstage, the last of the energy is extracted (and lost as heat) and the inorganicnutrients are returned to the soil or water to be used again. The inorganicnutrients are recycled, the energy is not.

Name the mechanisms in relation to enforcement of laws and regulationsin Malaysia that you think can help overcome or reduce pollution.

ACTIVITY 5.6




• A healthy ecosystem is considered sustainable. This means that all theelements live in balance and are capable to survive. Thus, we must make surethat in doing our activities we take saving the environment into consideration

and try our best to avoid harming our precious ecosystem.

Chlorofluorocarbon (CFC)

Community

Cycles

Ecosystem

Environmental Impact Assessment (EIA)

Food chain

Food web

Habitat

Niche

Organisms

Population

Pyramid numbers

Species

Topic 5 Relationship of Living Things With Its Environment

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