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NS Term 1 2013 Teacher’s Guide R. Swanie

Natural Science

Gr 8: Term 1

2013: Teacher’s Guide

School: ________________________________

Teacher: _______________________________

Ensure that learners do ALL the work in the book

You need not mark all the exercises yourself, but can ask the learners to do PEER

assessment. When they mark the work, they do it with a PENCIL, or a different

coloured pen than RED.

Ensure that learners do the CORRECTIONS

Stick to the time frame, as far as possible

All answers are indicated in RED on this document.

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Week 1

Let’s see what you remember from last year:

Name any three sources of energy:

Sun, coal, water, wind, fossil fuels (like oil)

How is energy transferred when a light bulb is switched on?

The electrical energy moves through the connecting wires and the filament of the

globe back to the cells again.

How is energy transferred when an electric fan is switched on?

Electricity is transmitted from the plug to the fan, and it turns the fan. Scientific Experiment: Every time an experiment is done, the following steps must be followed:

1. What is my question? (This will be the investigative question which must be well

defined, measurable and controllable. Remember: a question with a “yes” or “no” as

an answer is not a good investigative question)

2. What is my prediction? (This is what you think will happen)

3. What is my hypothesis? (It is a possible explanation for a

problem using what you know and what you observe. The

format of a hypothesis is always: IF independent variable…

THEN dependant variable. For example, if I heat (independent

variable) water, then the sugar will dissolve (dependant

variable) easier).

4. What will I change, measure, keep the same? (When

investigating something, you must change certain factors, some of them will be kept

constant and observation is what you are measuring. These factors are called

VARIABLES. There are dependant variables which you measure. The independent

variable is the one that is changed by you. The constant variables are the ones that

must stay the same for the duration of the investigation. The variable that must

be measured is the dependant variable. Most investigations also make use of a

control. During the control the limiting factor is removed.)

5. What equipment will I need? (This is also known as the apparatus. You can name

them, or describe the method and/or make a diagram of the apparatus and the

setup.)

6. How will I record my data? (Will you describe the results in words, or make a

drawing or use a table? Different methods will suit different investigations.)

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7. How will I present my results to others? (You can use diagrams or tables or

graphs, any way in which others will be able to read your results in an easy,

accessible way.)

8. What does my data tell me? (Is there a general trend in the result? What is

your conclusion?)

9. Status of the Hypothesis: Is it accepted (correct according to the results of the

experiment) or rejected (not according to the results of the experiment)?

10. What can I do next? (Is there a follow-up on this experiment? If you

have to do it over, what will you change?)

Assignment 1: Study the following scenario and answer the following questions

regarding the information:

The Johnson family has decided to try to save electricity (and money at

the same time). They were told that they could replace their regular light

bulbs with special fluorescent bulbs that use less energy. They wonder if it

is really worth doing.

1.1 What is the investigative question?

Can fluorescent light bulbs save energy?

1.2 Write a testable hypothesis in the "If..., then" form. Be sure it is in this form and

a complete sentence and not a question.

If the regular light bulbs are replaced by fluorescent light bulbs, it will save

electricity.

1.3 Describe in 3 – 6 sentences any experiment Peter could do to test his hypothesis.

o If you use pay-as-you-go electricity, use the current regular light bulbs and

monitor the usage over a period of 24 hours. Write down the reading.

o Replace the regular light bulbs with fluorescent bulbs and monitor the usage

over a period of 24 hours. (Ensure that the same lights are switched on as

during the previous day). Write down the reading.

o Compare the readings.

o (Any other valid experiment will do)

1.4 What would the independent variable be?

Type of light bulb used

1.5 What would the dependent variable be?

Amount of electricity and money saved

1.6 What would the control variables be?

Use the regular light bulbs.

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1.7 What would you prediction be?

Fluorescent light bulbs will use less electricity.

1.8 How will you record your results?

Draw a table to compare the results of the regular light bulbs and the fluorescent

light bulbs.

1.9 If one filament light bulb uses 2kW per hour and a fluorescent bulb 0.5kW per

hour, estimate the amount of energy saved per year if you use the light bulb for 5

hours per day.

1,5 kWh difference x 5 x 365 = 2700 kWh (if estimated). If calculated, the

answer is 2737,5 kWh.

Week 2

Is there any difference between type of energy and energy sources? The answer is YES.

Energy sources help us, through the different ways, to get energy to generate power.

Different types of energy means different forms of energy like kinetic energy, chemical

energy, potential energy etc. If energy is stored, we refer to is as potential energy, but

when the energy is making an object move, we refer to it as kinetic energy. Your body is a

great example of this: food contains chemical energy and your body stores it until you

release this energy when your body starts to move or play. The chemical energy form

potential energy until it is converted into kinetic energy.

All forms of energy are stored in different ways, in the energy sources that we use every

day.

There are three main categories of energy sources: non renewable sources (the fossil

fuels), renewable sources and nuclear sources.

Non renewable sources of energy: This kind of energy cannot be replaced once it has

been used. Examples of these are coal, petroleum,

natural gas, crude oil and nitrogen. These are all fossil

fuels.

Renewable sources of energy: This kind of energy can be replaced daily, if not faster.

This is friendly to the environment. Examples are solar

energy, wind power, hydroelectricity, biomass energy,

geothermal energy, oceanic energy, biofuels.

http://www.energykids.eu/type-of-energy

http://www.energykids.eu/renewable-energy-sources

http://www.energykids.eu/conventional-uranium

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Where do fossil fuels come from? When fossils are formed, the process is called

“fossilization.” This is how fossilization takes place: 1. An organism dies. 2. The organism must quickly be covered by sediment (layers of soil). 3. The soft parts of the dead organism decompose. 4. The hard parts of the organism absorb the minerals in the muddy water. 5. The hard parts become harder (petrified). The petrified parts form the fossil. 6. Fossils are therefore the hard remains of dead organisms.

The following is a diagram of how fossilization takes place (in learner’s book): How does solar energy work? The diagram on the right is a representation of how solar energy works. Can you write down this process in words?

Solar power is produced by collecting sunlight and converting it into electricity.

This is done by using solar panels, which are large flat panels made up of many individual solar cells.

These cells transmit electrical current to a charge controller which will control the electrical charges generated by the solar panels

A battery system saves the electricity and allow electricity for DC (direct current) power.

If AC (alternate current) is used, it is changed from CD in an inverter. The diagram on the right and at the bottom show how wind energy works. Can you write this process down in words?

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(If you have access to internet in the class, look at http://www1.eere.energy.gov/wind/wind_animation.html to show an animation)

The energy in the wind turns two or three

propeller-like blades around a rotor.

The rotor is connected to the main shaft, which

spins a generator to create electricity.

Wind turbines are mounted on a tower to

capture the most energy. At 100 feet (30 meters) or more above ground, they can

take advantage of faster and less turbulent wind.

Kinetic energy from the moving air is

converted into electrical energy. The diagram on the right shows how hydroelectricity is generated. Can you write this process down in words?

(If you have access to the internet in class, use the following link for an animation:

http://ga.water.usgs.gov/edu/hyhowworks.html)

A dam is built a dam on a large river that has a large drop in elevation.

The dam stores lots of water behind it in the reservoir.

Near the bottom of the dam wall there is the water intake. Gravity causes it to fall

through the penstock inside the dam.

At the end of the penstock there is a

turbine propeller, which is turned by the

moving water.

The shaft from the turbine goes up into

the generator, which produces the

power.

Power lines are connected to the

generator that carries electricity to

your home and mine.

The water continues past the propeller

through the tailrace into the river past

the dam.

A hydraulic turbine converts the energy

of flowing water into mechanical energy.

A hydroelectric generator converts this mechanical energy into electricity.

http://www1.eere.energy.gov/wind/wind_animation.html

http://ga.water.usgs.gov/edu/hyhowworks.html

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Look at the picture at the top and this is how electricity is formed from coal. See if you can follow the process from the diagram:

1. Coal power stations are built near coal mines for easy transport of the raw material.

2. The coal is transported to the power station by means of the conveyor belts from the coal mines.

3. The coal is grind into a fine powder, because this will increase the reaction area when generating electricity.

4. The fine coal powder is blown into boiler burners. These burners heat the water and water becomes steam.

5. The smoke from the boiler burners is blow into the air (via the “stack”). This can cause air pollution, acid rain and smog, which is harmful for the environment.

6. The steam is blown under high pressure onto the vanes of the turbines. The vanes turn.

7. The steam condensates in big condensating towers where steam changes into water liquid and is circulated to be used again when it is changed by the boiler burners into steam.

8. The turbines are connected to huge generators. 9. A generator consists of a coil with a magnetic field around it. When the turbines

turn the generator, it generates electricity. 10. The electricity is transported to a transformer where the voltage is increased by

the transformer. 11. The high voltage electricity is transported by huge power lines throughout the

country. 12. This high voltage electricity cannot be used in our homes and must be stepped

down in another transformer to 220V, which can be used in our homes.

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The following diagram shows how sunlight energy can be used by plants. Write down the process in your own words:

The sunlight shines on green leaves

The green pigment, chlorophyll, converts the solar energy into chemical potential energy.

This energy causes the formation of carbohydrates from water and carbon dioxide.

The food energy is stored

Oxygen is released. Solar energy is

converted into chemical energy.

Do you know the following kinds of fuel? It is used daily. Describe it in short: Fossil fuels (give examples and where to use it):

Crude oil which is used to manufacture petrol, diesel and other petroleum products. This can be used as fuels for engines. It is a liquid that comes from fossilized plant material and it mined from deep within the earth.

Uranium (where it comes from and what it is used for):

Uranium is a silvery white metal. It is harder than most elements. It is malleable and slightly magnetic and a poor conductor of electricity. It has a very high density. It can start a nuclear chain reaction, and it therefore used to generate nuclear power.

Wood (where it comes from and what it is used for): The dry remains of plants. If lighted, it can cause huge fires. It is used at home to cook food, for heating, to boil water.

Not all sources of energy have the same degree of effectiveness. When energy is generated from certain sources of energy, pollution may be caused. Some sources are very expensive and others cheaper. Use the following list of different kinds of sources of energy and tick the appropriate box:

Energy source Renewable or non renewable

Cost Availability Cleanliness

Low High Easy Difficult Causes

pollution

Not causing

pollution

Solar energy Renewable Hydro electricity Renewable Wind energy Renewable Coal power Non-renewable Natural gas Non-renewable Wood Non-renewable Uranium Non-renewable

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Week 3

Explain the following terms:

Electricity: The movement of electrons through a circuit (the word

electricity comes from the word electrons)

Development: growth, change, change in direction, new things that were

made to make life easier

Poverty: Lack of money, maybe because of unemployment. People do not

have the monetary resources to buy what they need.

Energy supply: Energy that is used by a specific action to start or to maintain

or to supply another action with energy

Electrification: The movement of electrons which is transported in wires to

various places where it is needed

Electrical energy: Energy that is formed by the movement of electrons in wires

from one place to another.

Why is electricity needed for development in SA?

Factories need electricity to have functioning machines where objects that can be

sold, is manufactured. The more factories build, more people can word there and will

eradicate poverty.

Electrical equipment is used to build structures which will increase the tourism in

SA, therefore decreasing poverty.

More tourists will increase the monetary potential of SA and will contribute to the

national budget.

Light is essential to see what we are doing, the same goes for electricity to power

radios, laptops, etc.

Any other good reason, which is fully explained.

How did electricity improve the lives of people in rural areas of SA?

Many learners don’t have to study by candle light

More computers can be used in rural schools

More clinics can be built in rural areas and more people can have access to health

services

Communication between people increased with the laying of more power lines

Think of examples in your own area – good reasons which are fully explained.

What is the main source of electrical energy that is used in SA?

Coal

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Week 4

Explain the following terms regarding electricity:

Electricity supply: The distribution of electricity to many places /

households / factories / etc

Generator: A device used to make electricity from water or wind

or sunlight or coal or fuel etc

Turbine: A device with vanes / rotors which turns when wind or

water moves through it

Burning gas: Eg methane gas. A gas that produces flames when

ignited

Burning coal: When coal (fossilized plant material) is set alight so

that it produces flames

Falling water: Water that moves from a higher place to a lower place,

naturally

Nuclear reactions: When a substance like uranium is heated and producing

chain of reactions emitting lots of energy

Global environment: The worldwide environment

Local environment: The environment where you life

Pollutants: All particles that are released into the air or into water

or soil, therefore harming plants and animals.

Non-pollutants: Particles that are released into the air or into water or

Into soil without causing any harm to plants and animals.

Sometimes more than one way of generating electricity is used to supply energy to a region

or country. Explain why, for example, coal and nuclear energy must be used together to

generate electricity in SA.

SA has a big population and all must be supplied with electricity.

SA mainly uses coal to generate electricity.

Because of the pressure that is put on the national electricity supply grid, the coal

power stations do not produce enough electricity to supply in the demands of the

growing population

Other sources of electricity supply can be added to aid the coal power stations

This will relieve the pressure on the national electricity supply grid. So: you did not know that SA has its own nuclear power station? Koeberg is in the Western Cape, about 30 km north of Cape Town. This is the only nuclear power station in SA. This power station contains two uranium pressurized water reactors. It supplies electricity to the national electricity grid so that over-capacity can be redistributed to the rest of the country when need be. This power plant was build because of the huge demands of power supply in the Western Cape. To build new coal power stations in this

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region, it required 300m tall chimneys to comply with the clean air legislation. Koeberg is cooled by the cold water from the Atlantic ocean. Waste from the power station is transported in steel and concrete containers to a rural disposal site, about 600 km away from the power plant. The building of this power plant started in 1976 and electricity was supplied to the national grid in 1985. Look at the following diagram and follow the whole process of the generation of nuclear

energy:

This is how it works:

1. The Fuel

The fuel used in nuclear generation is primarily uranium 235. It is manufactured as small

round fuel pellets. A single pellet is less than an inch long, but produces the energy

equivalent to a ton of coal. The pellets are placed end-to-end into fuel rods that are 4m

long. Over 200 of these rods are grouped into what is known as a fuel assembly.

2. Reactor

The process of producing electricity begins when uranium atoms are split (i.e., fission) by

particles known as neutrons. Uranium 235 has a unique quality that causes it to break

apart when it collides with a neutron. Once an atom of uranium 235 is split, neutrons from

the uranium atom are free to collide with other uranium 235 atoms. A chain reaction

begins, producing heat. This reaction is controlled in several ways, including by control

rods which absorb neutrons. Control rods are inserted among the fuel assembly rods that

hold the uranium pellets. When they are in place, they absorb the atomic particles that

would normally initiate the chain reaction. When they are withdrawn from the fuel

assembly, fission is allowed to occur.

3. Pressurizer

The heat produced in the reactor is transferred to the first of three water systems: the

primary coolant. The primary coolant is heated to over 315°C. In a pressurized water

reactor, a pressurizer keeps the water under pressure to prevent it from boiling.

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4. Steam Generator

The hot, pressurized water passes through thousands of tubes in nearby steam

generators. These tubes are surrounded by another water system called the secondary

coolant. The heat from the primary coolant is transferred to the secondary coolant, which

then turns into steam. The primary and secondary systems are closed systems. This

means that the water flowing through the reactor remains separate and does not mix with

the water from the other system or the lake.

5. Turbine

The steam is piped from the containment building into the turbine building to push the

giant blades of a turbine. The turbine is connected to an electric generator by a rotating

shaft. As the turbine blades begin to spin, a magnet inside the generator also turns to

produce electricity.

6. Condenser Coolant

After turning the turbines, the steam is cooled by passing it over tubes carrying a third

water system, called the condenser coolant or lake water. The steam is cooled so it

condenses back into water and is returned to the steam generator to be used again and

again.

7. Lake or Cooling Towers

At some nuclear stations, lake water flows through thousands of condenser tubes to

condense steam back to water. It is then discharged down a long canal (for cooling) and

eventually enters the main part of the lake.

At other plants, the condenser cooling water is circulated through cooling towers to

remove the extra heat it has gained. The water is pumped to the top of the cooling towers

and is allowed to pour down through the structure. At the same time, a set of fans at the

top of each tower pulls air up through the condenser water. This lowers the temperature

of the water. After it is cooled, the condenser water flows back into the turbine building

to begin its work of condensing steam again.

Study the following table showing the cost of generating electricity per kWh in cents from

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2008 until 2010. A kWh is a kilo watt hour. In other words: 1 000 W of power delivered

in one hour. Answer the questions that follow. Average Power Plant Operating Expenses for Major U.S. Investor-Owned Electric Utilities, 1999 through 2010

(cents per Kilowatt-hour)

Plant Type 2010 2009 2008

Operation

Nuclear 10.50 10 9.89

Fossil Steam 4.04 4.23 3.72

Hydroelectric 5.33 4.88 5.78

Gas Turbine and Small Scale 2.79 3.05 3.77

Maintenance

Nuclear 6.80 6.34 6.2

Fossil Steam 3.99 3.96 3.59



Fuel used

Nuclear 6.68 5.35 5.29

Fossil Steam 27.73 32.3 28.43

Hydroelectric -- -- --


Total

Nuclear 23.98 21.69 21.37

Fossil Steam 35.76 40.48 35.75


Gas Turbine and Small Scale 48.74 57.55 70.72 Note: Some calculations may not be 100% correct due to the rounding of numbers.

1. Which energy source was the cheapest in

2010?

Hydroelectricity

2. Which energy source was the most expensive

in 2010?

Gas Turbine and Small Scale

3. Which energy source required the most

maintenance in 2010?

Nuclear

4. Which energy source used the most fuel in

2010?

Gas turbine and small scale

5. Which energy source was the lowest regarding

the operational costs in 2008?

Fossil Steam

6. Which energy source is the cheapest over the

three years?

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Hydroelectricity

7. Use the information in this table, and draw a bar graph to show the total cost of

generation of energy in 2010.

Mark allocation: Title with two variables

Name of x-axis Name of y-axis Unit of y-axis Correct kind of graph (bar graph) All bars correct / 2 -3 bars correct / 1 bar correct THIS IS THE WAY IN WHICH ALL GRAPHS MUST BE MARKED Study the following table showing the environmental implications of the use of different energy sources and answer the questions that follow.

0

10

20

30

40

50

60

Nuclear Fossil Steam Hydroelectric Gas Turbine and Small Scale

Co

st in

cen

ts p

er k

Wh

Different energy sources

Total cost of generation of electricity in 2010

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Type of energy

How does it affect health & environment? Does it release greenhouse gases?

Is it renewable?

Coal Major contributor to smog, acid rain. Emits mercury, lead and arsenic. Mountain top removal in mining. Asthma & pulmonary diseases from airborne particles.

Yes. Carbon dioxide, carbon monoxide, nitrous oxide, sulfur oxides, airborne particles.

No

Hydro electricity

Affects wild life, natural water systems. Huge dams can cause earthquakes, displace people, can be catastrophic if they fail.

Not during generation. Yes

Natural gas Can produce less carbon dioxide than coal. Hydro-fracking may pollute water, trigger earthquakes

Yes. Carbon dioxide, nitrous oxides, carbon monoxide, sulfur oxide, airborne particles.

No

Nuclear Spent fuel storage is unresolved. On average nuclear emissions and accidents less deadly, less cancer-causing than coal or gas, but meltdown can lead to land loss, cancer.

Not during generation. No

Oil Gas flaring during drilling emits extra carbon dioxide. Significant airborne particles, carcinogens, oil spills, foreign wars.

Yes. Carbon dioxide, nitrous oxides, carbon monoxide, sulfur oxides, airborne particles.

No

Solar Turbines require water which can be contentious if desert location. Requires as lot of land.


Wind Requires a lot of land. Kills some bats, birds, through new designs are slower & less deadly. Does not require water for generation.


1. Look up the meaning of the following terms:

1.1 carcinogens Chemicals that are harmful to plants and animals and which may cause cancer or cancerous growths

1.2 hydro-fracking High pressure liquids are used to make fractures (cracks) in rocks in order to get to the petroleum or gas underneath the rocks.

1.3 airborne particles Any small parts that are released into the atmosphere and now forms part of the layer of gases around the earth

1.4 acid rain The combination of sulfur dioxide and water or nitrogen oxide and water to form precipitation that is acidic and can cause harm to plants and animals.

1.5 renewable sources Any kind of source that can be replaced after usage, or not be used up during the process, e.g. the use of wind for generation of electricity.

1.6 non-renewable sources Any kind of source that cannot be replaced after usages or can be used up during the process, e.g. coal and natural gas.

2. Give the names of the energy sources which do not contribute to global warming. Solar energy / Wind energy / Nuclear energy / hydro electrical energy

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3. Give the names of the energy sources which are renewable. Solar energy / wind energy / hydro electrical energy

4. Which one of the above mentioned energy sources can emit radioactive waste? Nuclear energy

5. How can the emitting of radioactive waste be minimized? Stabilize the waste into a form which will not react or degrade within a long period of time Seal the radioactive waste in a steel container and store it underneath the ground Treat the radioactive waste with ions or mix it with a cement-like substance to form a solid which is harmless The radioactive wastes can be dry casked by sealing it in a container and storing it above the ground Some of the radioactive material can be recycled after being treated with certain chemicals Radioactive wastes can be placed in a rocket and shot into space. This is very expensive.

6. Which of the mentioned energy sources will cause acid rain? Coal energy

7. Why is acid rain detrimental to the environment? Can cause the death of plants and animals Changes the pH (degree of acidity) in the rain water Can change the chemistry of soil and therefore that plants will not be able to grow where they were supposed to, or can cause a change in biodiversity Acid rain can damage buildings, especially those made up of concrete and sand stone.

Week 5

Explain the following concepts:

Adaptation: A change in the physical appearance of organisms to help them

to survive in its environment.

Biodiversity: The total living organisms found on the earth, which include

plants, animals, fungi, viruses and bacteria.

Ecosystem: An ecosystem is a community of living organisms (plants,

animals and microbes) in conjunction with the nonliving

components of their environment (things like air, water and

mineral soil), interacting as a system

Environment: The physical and biological factors along with their chemical

interactions that affect an organism

Food chain: A simple linear connection of organisms starting from a

producer to primary, secondary and tertiary organisms that

eats no other species and ends with a decomposer.

Food pyramid: A simple connection of organisms starting from a producer to

primary, secondary and tertiary organisms that eats no other

species in and ends with a decomposer. This is written down in

the form of a triangle. Habitat: The natural environment where organisms can live and interact

with other organisms.

Interdependence: The dependence of organisms on each other to ensure the survival thereof.

http://en.wikipedia.org/wiki/Community_(ecology)

http://en.wikipedia.org/wiki/Abiotic_component


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Invertebrate: Organisms without a backbone, usually with exoskeletons or hydrostatic skeletons. Eg slugs, insects, prawns

Vertebrate: Organisms with a backbone, usually with endoskeletons. Eg fish, amphibians, reptiles, birds, mammals.

Species: Organisms of the same kind, living in the same place, at the same time and they can interbreed.

Classification of organisms Everything in your life needs to be classified. Look in the kitchen cupboard: all plates are together. The pots and the pans are placed in the same shelf. There usually is a divider in a drawer where knives, forks and spoons are organized separately. The same in science: we need to organize different structures in such a way that it will make sense. Classification is therefore an organized way in which organisms with the same characteristics are grouped together. The first scientist, who used a classification system, was Swedish botanist, Carl Linnaeus, and he started with it about 300 years ago. We are still following his example when classifying organisms. Can you remember the classification on biological level? It works like this:

Cell: the smallest unit of life. Eg: nerve cell, skin cell. Tissue: like cells together performing the same function. Eg: nervous tissue, blood

tissue Organ: like tissue together performing the same function. Eg: liver, skin, nose. System: like organs together performing the same function. Eg: digestive system,

circulatory system. Organisms: systems enclosed by one layer where a number of functions are

performed. Eg: animals, plants. There is a wide variety of organisms on earth. When discussing the variety, we refer to diversity. When we refer to the total number of different organisms on the earth, we refer to is a biodiversity. Vertebrates are all animals with a backbone. These organisms usually have an endoskeleton (hard bones or cartilage in the inside of an organism). Invertebrates do not have a backbone. These organisms usually have a hydrostatic skeleton (a skeleton supported by water or fluid) or an exoskeleton (hard covering on the outside of an organism). Vertebrates can be classified into 5 classes according to its characteristics. Here are the five classes of vertebrates with characteristics of each. Fish: These can be with a bony or a cartilage skeleton. It has fins, scales and gills. Cold blooded. It lives in water. They lay soft-shelled eggs. Amphibians: All the frogs, with four appendages. Cold blooded. They spend part of their lives in water

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and part of their lives on land. They lay soft shelled eggs. Reptiles: Organisms like snakes, lizards and crocodiles. Some have appendages, others not. They are cold blooded. They have lungs and a dry skin. They lay eggs, but some of the representatives of this class’ young hatch in eggs inside the body of the female. Birds: Wings with feathers, legs with scales. They are warm blooded. They have lungs. They lay hard-shelled eggs. Mammals: Hair, wool or fur on the body. Four appendages. They are warm blooded. They give birth to live organisms and produce milk to feed them. What if you were given a handful of organisms and someone wants you to classify it? How will you go about? Scientists use a dichotomous key to find out which organism belongs to which group (classification) or to find out the name of the organism (identification). A dichotomous key uses two characteristics at a time to classify or identify an organism. You will remember that the prefix di- means two. Therefore two characteristics are used that describe certain characteristics. The statements are mutually exclusive for the key to work efficiently. For example, 'it is either red or it isn't'. By choosing the correct characteristic, you can eventually reach the correct name of the organism. An exercise: A Dichotomous Key using smiley faces.

Choose one of the characteristics at each number, and see if you can reach the name of

the smiley face. Write down the name of the face underneath it. The list of the smiley

faces are on the next page.

Dichotomous Keys Using Smiley Faces

Instructions: Use the key below to identify the species name of each of the smileys below.

1. Smiling, happy face Smilus traditionalis

Not happy, frowning or other go to 7

2. Mouth curved down, frowning Smilus saddus Mouth is a small circle Smilus suprisus

3. Has a pirate eye patch Smilus piratus

Does not have eye patch go to 9

4. One eye is much larger than the other eye Smilus mutatus

One eye is winking Smilus winkus

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5. Teeth visible go to 2

Teeth not visible go to 4

6. Has a wide, toothy smile Smilus toothyus

Is not smiling go to 3

7. Visibly crying Smilus dramaticus

Frowning Smilus upsettus

8. Eyes are symmetrical go to 5

Eyes not symmetrical go to 8

9. Eyes shaped like hearts Smilus valentinus

Eyes are shaped as ovals go to 6

Smilus dramaticus

Smilus upsettus

Smilus saddus

Smilus winkus

Smilus mutatus

Smilus piratus

Smilus valentines

Smilus surprisus

Smilus toothyus

Smilus traditionalis

(Remember that this was only a fun-exercise!)

Another few questions:

10. The names of the smilies give you another bit of information about their taxonomy.

Each of these smileys belongs to the same genus. What is their genus? Smilus (Remember that the name of a genus and species must always be underlined, or, when in print, in italics)

11. Suppose you discovered the new smiley pictured to the right.

What name would you give it? Smilus spacus (Maybe a smiley that comes from space? Any answer applicable)

Here is your animal dichotomous key. See if you can find the names of the

animals at the bottom of this worksheet.

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1. Do you have a backbone? Yes - wait for number 3

No - you are an insect - wait for number 2

2. Do you change (metamorphosis) from a caterpillar to your adult form? Yes - you are

a butterfly!

No - you are a grasshopper!

3. Do you have gills and scales? Yes - you are a fish!

No - wait for number 4

4. Do you lay eggs? Yes - wait for number 5


5. Do you have feathers? Yes - you are a bird!


6. Do you lay eggs in the water? Yes - wait for number 7


7. Do you live on land but come back to the water to lay your eggs. Yes - wait for

number 9

No - you are a pickerel frog!

8. Do you have a protective shell? Yes - you are a turtle!

No - you are a snake!

9. Do you have lots of warty bumps and no tail? Yes - you are a toad!

No - you are a newt

10. Are you a carnivore (eat meat)? Yes - you are a fox

No, wait for 11

11. Are you an omnivore? Yes - you are a raccoon!

No - you are a herbivore - wait for number 12

12. Are you a rodent? Yes - you are a squirrel!

No - you are a moose!

Butterfly Pickerel frog

Turtle

Newt

Bird

Snake

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Grasshopper

Squirrel

Moose

Fish Raccoon

Fox

Insect Toad

Week 6 Explain the following terms:

Biodiversity: The total living organisms found on the earth, which include


Carrying capacity of ecosystems: The number of organisms that can be

successfully sustained on a piece of land.

Environment: The physical and biological factors along with their chemical

interactions that affect an organism

Alien species: Any living species that are not naturally found in a certain area

and which originated from a different region

Over-consumption: The over-use of natural resources in such a way that the

natural resources are depleted.

Sustainability: The use of natural resources in such a way that it is not

depleted

Endangered species: Species of any kind of organism that are on the verge of

extinction

Extinct species: All the living organisms of a specific species have died out and

there are none of them left on earth.

Abiotic factors: All non-living factors that may influence living organisms, e.g.

water, air, gases.

Biotic factors: All living organisms. Certain characteristics must be present

like gaseous exchange, movement, reproduction, excretion etc.

http://howtodrawanimals.net/wp-content/uploads/2010/08/moose.jpg

22


Here are the names and pictures of a few extinct species:

Dodo

Quagga

Tyrannosaurus Rex

Tasmanian Tiger

Whoolly Mammoth

When organisms are extinct, no more of that species are alive anymore. You cannot find

any organism of that kind on earth.

The following are examples of a few endangered animals:

23


Cape Vulture

Rhino

Cheetah

Blue Crane

Riverine

Rabbit

When species are endangered, there are very little of them left on earth. It must

therefore be protected. To try to increase the numbers of these organisms (which may

be plants or animals), there are laws against the unlawful catching or removal (poaching) of

these organisms.

Sometimes the amount of organisms may decrease because of a lack of food, water,

shelter and reproductive mates. When there is not enough food for animals, they die out.

http://blog.getaway.co.za/wildlife/5-endangered-local-animals/attachment/cheetah-2/

http://blog.getaway.co.za/wildlife/5-endangered-local-animals/attachment/blue-crane/

http://blog.getaway.co.za/wildlife/5-endangered-local-animals/attachment/riverine-rabbit/

24


It is therefore necessary that the carrying capacity of a region or farm or plot is known.

The carrying capacity can be defined as follows: The number of organisms that can be

successfully sustained on a piece of land.

The advertisement to the right is found on

http://www.youtube.com/watch?v=tIaM8dkns2E which states that the rhino population

will be extinct in 2022 if the poaching thereof keeps going on. Study the following

statistics and answer the questions that following:

Amount of rhino poached over the past three years.

Place in SA Year

2010 2011 2012

Kruger National Park 146 252 272

Marakele National Park 0 6 3

Gauteng 15 9 1

Limpopo 52 74 49

Mpumalanga 17 31 20

North West Province 57 21 46

Eastern Cape 4 11 7

Free State 3 4 0

KZN 38 34 55

Western Cape 0 6 2

Northern Cape 1 0 0

To the teacher: explain to learners that rhino horn is used as an aphrodisiac, ornaments

and to some as medicine. YOU can first read the article on

http://www.pbs.org/wnet/nature/episodes/rhinoceros/rhino-horn-use-fact-vs-

fiction/1178/

1. Which province(s) experienced a decrease in the amount of rhino poaching?

Gauteng, Northern Cape

2. Which province(s) experienced an increase in the amount of rhino poaching?

Kruger National Park

3. Find the total of rhinos poached in 2010, 2011 and 2012. Show all calculations.

2010: 333

2011: 448

2012: 455

4. According to the advertisement, the rhino will be extinct in 2022. Do you agree

with this statement? Use calculations from the statistics given in the table on the

previous page to explain.

http://www.youtube.com/watch?v=tIaM8dkns2E

http://www.pbs.org/wnet/nature/episodes/rhinoceros/rhino-horn-use-fact-vs-fiction/1178/

http://www.pbs.org/wnet/nature/episodes/rhinoceros/rhino-horn-use-fact-vs-fiction/1178/

http://www.nikela.org/wp-content/uploads/2012/01/Infographic-countdown-to-rhino-extinction-2022-645x.jpg

25


If statistics stay the same, and the average can be used: 412 per year from 2010.

Therefore: 412 x 12 years (2010 – 2022) = 4944 OR

If the increments over three years are used (448 – 333 = 115 and 455 – 448 = 7,

average over 3 years is 122/3 = 61), and 61 is added to each year’s total from 2013,

the answer is 8305.

NO – unless poaching increases rapidly. (Not in 2022, but maybe later). Any

conclusion that can be reached using the data provided)

5. What can be done to restore the numbers of this animal? (To prevent extinction).

Some researches wants to lift the ban on rhino horn, and believe that poaching will

then decrease

Special breeding programs for rhino

Use GPS to track rhinos

Implement faster and more severe fines for rhino poaching

Guard the rhino’s night and day

Other: must be practical solutions

Interesting article on http://www.news24.com/SciTech/News/Schoolgirls-win-

science-prize-20120724

Most of the species that we find in South Africa, are indigenous. Indigenous means that

the specific plant or animal started to develop naturally in that specific region without

human intervention. When other species, coming from other regions or countries, are

introduced to a region it does not come from originally, we regard this as alien species.

Here is a list and examples of alien plant species in SA:

Name of species Picture Where it comes from originally

Port Jackson Willow

Western part of Australia

http://www.news24.com/SciTech/News/Schoolgirls-win-science-prize-20120724

http://www.news24.com/SciTech/News/Schoolgirls-win-science-prize-20120724

26


Lucerne Dodder Tropical regions

(The plant has no chlorophyll

and lives parasitically on green

plants)

Water Hyacinth

Tropical and subtropical South

America (an aquatic plant)

Cluster Pine Tree France, Spain and Corsica (used

mainly for paper and furniture)

White Poplar Tree

Northern Hemisphere

Weeping Willow

Northern Hemisphere

http://en.wikipedia.org/wiki/File:Salix_alba_Morton.jpg

27


A full list of alien plant species in SA can be found on http://www.sana.co.za/Alien-

Invasive-Plants/. A full list of alien animal species in SA can be found on

http://www.koedoe.co.za/index.php/koedoe/article/view/1032/1290.

Alien plant species usually are fast growers and it takes up the water and minerals from

the soil that was supposed to be used by indigenous plants.

How can you contribute to eliminating alien plant species?

Remove alien species from your garden

Prevent more alien species to invade the environment

Restore soil so that indigenous species are replanted

Read more on http://www.cbd.int/invasive/done.shtml

When there is human activity, plant usually suffers from that. Discuss three ways in

which human activity can decrease the plant biodiversity in your area. The development of human settlement can decrease biodiversity When forests are chopped down for fire wood, furniture, building material and

paper When more factories are needed and plants need to be removed to make place for

it Global warming may cause the death of plants and animals

Week 7

Explain the following terms:

Ecosystems: An ecosystem is a community of living organisms (plants,

animals and microbes) in conjunction with the nonliving

components of their environment (things like air, water and

mineral soil), interacting as a system Food web: A number of interlinked food chains where animals can feed on

more than one organism Competition: When two or more organisms fight for the same resource, be

it food, water, shelter or reproductive mates Population: A group of different kinds of organisms (species) living in the

same place, at the same time and cannot interbreed Biodiversity: The total living organisms found on the earth, which include


Sustainable development: The use of natural resources in such a way that it is not

depleted Carnivore: Organisms that eat only meat, e.g. lions Herbivore: Organisms that eat only plant material, e.g. kudu Omnivore: Organisms that eat plant- and animal material, e.g. humans Producer: All organisms that have chlorophyll and can photosynthesize,

manufacturing its own food

http://www.sana.co.za/Alien-Invasive-Plants/

http://www.sana.co.za/Alien-Invasive-Plants/

http://www.koedoe.co.za/index.php/koedoe/article/view/1032/1290

http://www.cbd.int/invasive/done.shtml

http://en.wikipedia.org/wiki/Community_(ecology)



28


Consumer: All organisms that cannot manufacture its own food and which lacks the green pigment, chlorophyll.

Here follows a list of living organisms. Complete the table by adding the different feeding habits of these organisms (in other words: carnivore, herbivore, omnivore, producer) Name of organism Feeding habit Goat Herbivore Jackal Carnivore (and predator) Wild Cat Carnivore Snake Carnivore (and predator) Owl Carnivore (and predator) Green Plant Producer Lion Carnivore (and predator) Rabbit Herbivore Mouse Herbivore Eagle (Kite on the diagram) Carnivore (and predator) Now use all the organisms in the list above and make up your own food web.

29


What are we doing to the earth? We use lots of energy in the form of electricity, usually

generated by the burning of coal. This causes air pollution, and we are depleting the

natural energy sources of the earth. We throw around paper and tin and rubbish, and we

call it “job creation”. If this was really “job creation”, why are there still people without

jobs? We cause global warming with all the chemicals we use and decrease the plant- and

animal biodiversity. Study the following passage and answer the questions regarding the

effect of pollution on the earth’s temperature and the decrease of the size of species.

Massive Extinctions from Human Activity

Despite knowing about biodiversity’s importance for a long time, human activity has been

causing massive extinctions. According to scientists, the current extinction rate is 1000

times higher than that of the years 1900 – 1999, and is expected to increase 10 000 times

from 2000 until 2100. A major report from the Millennium Ecosystem Assessment which

was released on March 2005, means that the is currently an irreversible loss in the

biodiversity, with 10 – 30% decrease in the mammal, birds and amphibian species, all

because of human actions. The World Wide Fund (WWF) added that earth is unable to

keep up in the struggle to regenerate from the demands we place on it. The following

organisms are mostly in thread of extinction:

1 out of 8 birds

1 out of 4 mammals

1 out of 4 pine trees

1 out of 3 amphibians

6 out of 7 marine turtles (turtles living in sea water)

75% of agricultural crops

75% of the world’s fisheries

70% of the world’s known species are at risk if the global temperatures rise by

more than 3,5°C

One third of the coral reefs

350 million humans (of water is not replaced with clean water)

1. Which group(s) of organisms (excluding humans) are the nearest to extinction?

Marine turtles

2. Give a reason for the agricultural crops that are under threat.

Most of the soil is used for human settlement or factories.

Plants are negatively influenced by global warming and acid rain

3. Why would the marine turtles face such a high risk of extinction?

They lay their eggs on the beach. Some people dig out the eggs to be used as a

source of food.

Although it is illegal to hunt most turtle species, they are also poached and

regarded as a delicatessen.

The shells of the animals are used for decorative purposes and are hunted for it.

http://www.globalissues.org/article/170/why-is-biodiversity-important-who-cares

http://www.ens-newswire.com/ens/aug1999/1999-08-02-06.asp

http://www.ens-newswire.com/ens/aug1999/1999-08-02-06.asp

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4. What is wrong with the water which may cause the extinction of humans?

Water can be contaminated by mines and factories, which makes it dangerous for

human consumption

Water is not saved and just flows away. Many humans are wasting water that can

be recycled

Many wars can be fought in order to obtain enough water.

5. What can you do to decrease global warming?

Use less electricity. Coal is the main source of energy in SA, but causes massive

pollution and the release of sulfur dioxide and nitrogen dioxide into the air.

(Learners can give ways in which they can save electricity) If you live in a region where there is a high biodiversity, or where there are organisms (plants and animals) which are not seen often, how would you use this to your advantage to earn an income? Start with ecotourism: The whole community can take part. The following are guidelines:

Become a tour leader to take visitors around Another member of the community can be involved in selling tickets Someone can be the driver of the bus / form of transport Someone can be employed as mechanic A person can be responsible for running the tuck shop or curio shop A member must get a cleaning team together Think of more opportunities. ______________________________

Do you know the meaning of the term “sustainability”? Sustainability is the responsible managing of our natural resources. To be sustainable, we can do the following:

We need to use less of our non-renewable resources. We need to keep our environment clean and not litter. We also must decrease the amount of greenhouse gases that are released when

fuel is burnt. We must use less harmful chemicals. We must use less electricity and water. We must protect all indigenous organisms on earth. Can you add a few more? ______________________________________________________________ ______________________________________________________________ ______________________________________________________________ _______________________________________________________

*&*&*&*&*&*&*&*

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