Lewis Tran PEAK SCIENCE

A Local Ecosystem PRELIMINARY COURSE SYLLABUS DOT POINTS

A Local Ecosystem 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 Abiotic Factor Differences Similarities

Environment Aquatic Environment Terrestrial Environment

Availability of Water Rarely a problem in

aquatic environments

Varies according to rainfall; generally not

freely abundant

Organisms must work to keep the balance of water

Buoyancy Water offers support to both animals and plants

Plants and animals receive little to no

support from the air

Water and air both offer some buoyancy

Temperature Very little temperature

variation; gradual changes in temperature

Large spikes in temperature can occur

Temperature never stays the same; always

changing

Availability of gases (Oxygen and Carbon

Dioxide)

Gas availability in water is very low; oxygen

concentration varies with depth

Oxygen and carbon dioxide are freely available in the air

Gases are available in varying amounts

Pressure Pressure in water

increases with depth

Air pressure decreases with height; often

fluctuates

Organisms must adapt to changes in pressure

Viscosity Water has high viscosity

and movement is impeded

Air has low viscosity and organisms can move

freely

Organisms must adapt for easier movement

Light availability

Only 45% of light reaches the water at a depth of

1m; 1% at 100m Cloudiness or turbidity an

issue (degree at which water loses transparency

due to suspended particles)

Light is abundant Clouds affect the

availability of light

Salinity and ion availability

Ions are found dissolved in water; freely available

Ions found dissolved in soil

Salinity and ion availability depends on

type of water/soil

Choose equipment or resources and undertake a field study of a local terrestrial or aquatic ecosystem to identify data sources

Temperature: The Thermometer Temperature is a measure of how hot or cold the environment is. It is measured in degrees Celsius (C)

To measure the temperature of the air, hold the thermometer into the air without touching the bulb, then record

your result.

To measure the temperature of the water, put the thermometer bulb into the water, then record your result.

To measure the temperature of the soil, push the bulb into the soil until it completely disappears, then record

your result.

Air pressure: The Barometer Air pressure is a measure of how much force the air exudes above us. It is measure in hectopascals (hPa).

To measure air pressure, look at the reading on your barometer, then record your results.

Standard atmosphere (atm) is defined as 1013.25 hectopascals. This is a unit of measure, also.

Humidity: The Dry and Wet Bulb Thermometer Humidity is a measure of how much moisture there is in the air. It is measure as a percentage (% humidity)

To measure humidity, find the numerical difference between the dry bulb and the wet bulb. Then consult your

humidity chart and compare the difference to the dry bulb. Record your results.

Wind Speed: The Anemometer Wind speed is a measure of how fast wind is travelling. It is measure in kilometres per hour (km/h).

To measure wind speed, hold the anemometer in the direction of the wind, then record your results.

Light Intensity: The Lux Meter Light intensity is a measure of the amount of light in an area. It is measured in lux.

To measure light intensity, direct the mirror towards sunlight in the area you are standing. Record the light

intensity over equal time intervals and calculate the mean. Record your results.

pH: The pH Probe pH is a measure of how acidic or basic a substance is. Otherwise, it is the hydrogen ion concentration of a

substance. A pH of under 7 is considered acidic. A pH of over 7 is considered basic. A pH of 7 is neutral.

To measure pH, put the pH probe into the substance and record the result.

pH: Universal Indicator To measure pH of water, add universal indicator to the water and compare it to a colour chart. Record your

results.

To measure the pH of soil, take sample soil and sprinkle a layer of barium sulphate. Add universal indicator and

mix the combination. Check the pH from a colour chart and record your result.

Chloride Ions: Silver Nitrate To test for the presence of chloride ions in water, add a dilute solution of silver nitrate to the water. The water

will turn cloudy if there are chloride ions present.

Carbonate Ions: Hydrochloric Acid To test for carbonate ions in water, add a dilute solution of hydrochloric acid to the water. If the solution bubbles

and releases carbon dioxide, the water contains carbonate ions.

Sulphite Ions: Barium Chloride To test for sulphite ions in water, add barium chloride to the water. If a precipitate forms, there are sulphite ions

present.

Identify the factors determining the distribution and abundance of a species in each environment The distribution of a species describes where it is round. The abundance of a species is the amount of organisms

from that species living throughout the ecosystem.

Organisms need resources to survive. This will affect their abundance and distribution. There are many factors

which will affect the amount of resources in an ecosystem:

Abiotic factors

o Light, rainfall, temperature, altitude, depth, water currents, waves, salinity, ph, space availability,

shelter, gas availability, etc.

Biotic factors

o Food, number of partners, number of competitors, number of predators, disease spread, etc.

To measure distribution, we use transects. Transects are cross sections of an ecosystem which tell us where

certain organisms are located.

To measure abundance, we use various sampling techniques to estimate the population of an ecosystem. The two

main sampling techniques used are the quadrat sampling technique and the capture/recapture technique.

Describe the roles of photosynthesis and respiration in ecosystems Photosynthesis is a process where green plants and some bacteria generate energy from sunlight using

chloroplasts, a structure or organelle which contains chlorophyll.

The raw materials of this reaction are carbon dioxide and water. These materials are taken from the surrounding

environment where they are reacted. Oxygen is the by-product of this reaction and it is released into the air.

Photosynthesis

Carbon dioxide + water glucose + oxygen

6CO2 + 6H2O C6H12O6 + 6O2

Photosynthesis allows an ecosystem to harness light energy from the sun. Plants make food for themselves and

for other animals. Hence, plants are producers and animals are consumers.

Photosynthesis also allows carbon dioxide produced by animals to be removed into the atmosphere and oxygen

to be released back.

Aerobic cellular respiration is the process in which glucose molecules are broken down in the presence of oxygen

and energy is released. This energy is used for growth, repair and reproduction. Respiration removes oxygen from

the air and return carbon dioxide into the atmosphere to be used by plants.

Aerobic Cellular Respiration

Glucose + oxygen carbon dioxide + water + ENERGY

C6H12O6 + 6O2 6CO2 + 6H2O + ENERGY

Cellular respiration may sometimes occur without oxygen. This is known as anaerobic cellular respiration. This

form of respiration is very inefficient.

Anaerobic Cellular Respiration

Glucose Ethanol + Carbon Dioxide + ENERGY For plants

Glucose Lactic Acid + ENERGY For animals

Identify uses of energy by organisms In plants, glucose from photosynthesis is stored as starch, proteins or lipid in the plant body. When animals eat

plants, these energy stores are also consumed and combine with the animals energy stores. During cellular

respiration, these energy stores are used up and the energy released can be then used for growth reproduction,

maintain body temperature, repair of damaged cells, movement, etc.

Identify the general equation for aerobic cellular respiration and outline this as a summary of a chain of biochemical reactions

Aerobic Cellular Respiration

Glucose + oxygen carbon dioxide + water + ENERGY (ATP)

C6H12O6 + 6O2 6CO2 + 6H2O + ENERGY (ATP)

Cellular respiration is the breakdown of glucose into carbon dioxide and water in the presence of oxygen in the

cytoplasm and mitochondria of a cell. Energy from this process is used to make ATP, adenosine triphosphate, an

energy carrier. Energy is stored in the phosphate bonds of ATP. When these bonds are broken, energy is released.

Cellular respiration occurs in three steps:

1. Glycolysis

[Glyco glucose | lysis breaking down]

In glycolysis, one molecule of glucose breaks down into two molecules of pyruvate. This takes place in the

cytoplasm of the cell.

2. Krebs Cycle

[Also known as the citric acid cycle]

In the Krebs Cycle, pyruvate is converted into carbon dioxide using a series of chemical reactions in the

matrix of the mitochondria.

3. Terminal Oxidation

[Also known as electron transport]

In terminal oxidation, water and ATP molecules are produced in the inner membrane of the

mitochondria. Energy released during glycolysis is stored in the phosphate bond of the ATP molecules.

For every glucose molecule, 38 molecules of ATP is produced.

Process and analyse information obtained from a variety of sampling studies to justify the use of different sampling techniques to make population estimates when total counts cannot be performed An abundance is the number of organisms of the same species living in a given area. Counting an abundance,

especially for large areas, is very difficult and very time consuming. As a result, an abundance is usually estimated

using sampling techniques.

Quadrat Square Method This sampling technique is used for sessile organisms (i.e. plants). A square is placed on the ground and the

organism being analysed is counted. This is done many times over random spots in the given area.

Given the size of the square, the average of the number of organisms found within the square and the size of the

given area, the population estimate in given by this formula:

=( )( )

( )

Capture/Recapture Method This sampling technique is used for animals. We use a different sampling technique for animals because animal

move around, and therefore cannot be counted using quadrats.

To measure abundance using this technique, a certain number of organisms in the given area are captured and

tagged. They are then rereleased. After a period of time, another set of organisms from the area are recaptured.

From this sample, the number of already tagged organisms are counted.

Given the sample size of the first capture, the sample size of the second capture and the number of tagged

animals from the second capture, the population estimate in given by this formula:

= ( )( )

( )

Each aquatic or terrestrial ecosystem is unique

Examine trends in population estimates for some plant and animal species within an ecosystem Population is ever-changing because of change in biotic and abiotic factors.

If a population living in a given area remains the same over a period of time, it is said to be stable and in balance.

If a population suddenly increases, it is called a population explosion. Many things can contribute to a population

explosion. An increase in food availability, resources and certain human activities can cause a population

explosion.

If a population suddenly decreases, it is called a population decline. Factors such as disease, predation

competition and human activities can contribute to a population decline. If a population declines enough, it can

result in an extinction of that organism.

Outline factors that affect numbers in predator and prey populations in the area studied Factors that affect the numbers in predator and prey population include:

Food availability

Salinity of water

Water availability

Shelter availability

Etc.

Identify examples of allelopathy, parasitism, mutualism and commensalism in an ecosystem and the role of organisms in each type of relationship

Allelopathy Allelopathy is a relationship between organisms where one party kills off or

inhibits the growth of the other party. Some organisms release

allelochemicals, which are chemicals which inhibits the growth of organisms.

An example of this is the Casuarina, a plant with thin, stick like leaves. As

these leaves drop to the ground in large masses, it blankets the area surrounding it. This prevents any plants from

growing there and slowly kills off any developing plants as it cuts off their light supply.

Parasitism Parasitism is a relationship between organisms where one party benefits at

the expense of the other. The party that benefits is known as the parasite.

The party that is harmed in the relationship is known as the host.

An example of this is the mosquito. The mosquito is an insect which drinks

the blood of mammals. This way, the mosquito is benefitted whilst the

mammal suffers. The mosquito also acts as a vector for the Plasmodium sp. Parasite, a microorganism which

causes malaria.

Mutualism Mutualism is a relationship between organisms where both parties benefit.

In other words, the two parties help each other survive.

An example of this is fungi and algae, collectively known as a lichen. The

fungi provide the algae with protection and in return, the algae produce

energy for the fungi via photosynthesis.

Commensalism

Commensalism is a relationship between organisms where one party

benefits, but the other party is largely unaffected. The party benefitting from

the relationship is known as the commensal.

An example of this is whales and barnacles. Barnacles attach themselves to

the whales skin. As the whale moves, the barnacles can retrieve the

nutrients from the water. The barnacles are light, however, and the whale is indifferent to their presence.

Describe the role of decomposers in ecosystems Decomposers consist of bacteria and fungi. Their job in an ecosystem is to break down dead matter and recycle

the nutrients back into the ecosystem, as well as gathering energy from the dead tissue.

Explain trophic interactions between organisms in an ecosystem using food chains, food webs and pyramids of energy

Gather information from first-hand and secondary sources to construct food chains and food webs to illustrate the relationships between member species in an ecosystem

Food Chains A food chain is a linear diagram which shows the flow of energy from one

organism to another. Therefore, they show feeding relationships

between organisms.

At the beginning of a food chain is always an autotroph.

o Autotrophs are organisms that make food for

themselves using light energy from the sun or other

alternative energy source. Therefore, they do not need

to feed on other organisms like heterotrophs do.

o The trophic level of autotrophs are primary producers

for this reason.

Every organism that follows an autotroph in a food chain is a

heterotroph, or consumer.

o Animals that eat plants are either herbivores or

omnivores

The trophic level of plant eating animals is

primary consumers

o Every animal after that eats meat and are therefore

carnivores or omnivores

The trophic levels of consumers are ordered and named thusly:

Secondary consumer, Tertiary consumer, Quaternary consumer, etc

Food Webs A food web is a combination of multiple food

chains to show the complex interactions of the

whole ecosystem and not just one feeding

chain. Like the food chain, food webs show the

flow of energy and feeding patterns from one

organism to another.

Pyramid of Energy A pyramid of energy is a diagrammatic

representation of the number of energy

units available at a specific trophic level.

Producers are placed at the wider, bottom

end of the pyramid. This is because the

plants make up for the largest amount of

energy in any given ecosystem, since they

make their own energy from the sun.

As you go up the pyramid, the amount of

energy goes down until you get to the apex

of the pyramid where energy conversion is

least efficient.

In this example, energy efficiency is 10%.

The 90% that is not transferred into the next trophic level is converted into heat, movement or any other activity.

Energy levels always go down as you progress higher in an ecosystem.

Pyramid of Biomass A pyramid of biomass shows how much mass or

material there is at each trophic level.

In the example to the right, this pyramid of biomass tells

us that for every 1000kg worth of grass in an ecosystem,

there is 100kg worth of herbivores (in this case, deer

and rabbits), 10kg worth of primary carnivore and 1kg

of top carnivore.

The biomass efficiency in this pyramid is 10%. This

means that 90% of biomass is converted into waste on

its way up the food chain.

In an ecosystem, the biomass level always goes down as

you go higher up in trophic level.

Define the term adaptation and discuss the problems associated with inferring characteristics of organisms as adaptations for living in a particular habitat

Identify some adaptations of living things to factors in their environment An adaptation is any feature that an organism develops to help it survive in its environment. There are three

types of adaptations:

Structural Adaptation A structural adaptation is a physical characteristic of an organisms body

that helps it survive and reproduce.

An example of such an adaptation is the bilby and the red kangaroo. Their

ears are large and are filled with capillaries. As blood runs through these

capillaries, it reaches the air and cools due to the transfer of heat. This

enables the red kangaroo and bilby to cool down on hot days.

Another example of a structural adaptation is the cactus. Cacti have spine

like leaves. Having leaves like this reduces surface area and sun exposure.

As a result, they lose less water and absorb less sunlight, allowing them to

survive in the desert.

Behavioural Adaptation A behavioural adaptation is a change in the way an organism acts in order

to survive.

An example of a behavioural adaptation is the kangaroo rat and other

desert animals. Desert animals are often nocturnal, meaning they are

active at night and dormant during the day. This means that they have less

exposure to the scorching sun and stay cool within their burrows during

the day.

Physiological Adaptation A physiological adaptation is a change in the way an organisms body works

and functions that helps it to survive.

An example of a physiological adaptation is the Koala and its digestive system.

The Koalas digestive system is very long and coiled up. This is because the

Koalas diet, mainly consisting of eucalyptus leaves, is wholly plant material.

Plant material is hard to digest because of the tough cellulose surrounding

each cell. By exposing the plant material to digestion for a longer period of

time, it can be broken down into energy to be used by the Koala.

Describe and explain the short-term and long-term consequences on the ecosystem of species competing for resources When two or more organisms use the same resources (food, water, shelter, etc.), it can result in competition

among organisms. Competition can be divided into two categories:

Intraspecific competition

[Intra inside | specific species]

This means that organisms are fighting others of the same species for food, water or mating partners.

Interspecific competition

[Inter among | specific species]

This means that organisms of different organisms are fighting for food, water and shelter.

Competition can also be divided into two categories based on resource availability:

Resource competition

Resource competition is when organisms fight for a resource that is in short supply.

Interference competition

Interference competition is when organisms use aggression to inhibit another organisms foraging,

feeding or reproduction.

Competition will always have an impact of population numbers of organisms within the area. Some species,

however, are better competitors than others, meaning that the other species may suffer and have their

population die out.

Short Term Effects Competition will cause a decrease in numbers of one species in the short term and an increase of numbers in the

other

Long Term Effects If one species is a much better competitor and successfully competes against the other species, the other species

may end up dying out and being eliminated from the ecosystem.

Identify the impact of humans in the ecosystem studied Human activities can have many negative impacts on the local environment. There are three main types of

ecosystems which humans impact in their activities:

Urban ecosystems

Rural ecosystems

Natural ecosystems

Some example of these impacts are:

Agricultural Land clearing and habitat destruction for farming clear away the shelters with are home to many

organisms

Burning crops after harvest release pollution into the air and soil

Use of pesticides pollutes the soil and water

Nitrates and phosphates used in farming leach into the waterways, causing an excess in nutrients in the

water

o This leads to eutrophication, where large algal blooms sprout from the excess nutrients leading

to the depletion of oxygen from the water and the deaths of any organisms living underneath

the bloom

Irrigation of the land brings salt closer to the surface, killing any organisms that live there and making

water unsuitable for further irrigation and drinking

The introduction of many species has led to the extinction of many native species

Urban Poor waste management can lead to water and land degradation

Excessive sewage leads to eutrophication in nearby water bodies

Housing development and infrastructure development can lead to soil erosion

Higher levels of carbon dioxide, carbon monoxide and sulphur dioxide contribute to the greenhouse

effect and global warming

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