13/04/23

Science Revision for Science Revision for Junior CertificateJunior Certificate

Theresa Lowry-LehnenRGN, BSc (Hon’s) Specialist Clinical Practitioner (Nursing), Dip

Counselling, Dip Adv Psychotherapy, BSc (Hon’s) Clinical Science, PGCE (QTS) , H. Dip. Ed, MEd, Emotional Intelligence (Level 9) MHS

Accredited

13/04/23DiffusionDiffusionDiffusion is when something travels from an area of high concentration to an area of low concentration. For example, consider the scent from a hamburger…

The “scent particles” from this hamburger are in high

concentration here:

Eventually they will “diffuse” out into this

area of low concentration:

13/04/23DiffusionDiffusion

Cells use diffusion to swap the oxygen they need for the carbon dioxide they no longer want:

Other examples of where diffusion happens in humans:

Alveoli in the lungs Villi in the intestines

Oxygen diffuses in

Out goes waste CO2

13/04/23The digestive systemThe digestive systemThe whole point of digestion is to break down our food so that we can get the bits we need from it…

The main foods affected are CARBOHYDRATES – these are broken down into GLUCOSE

13/04/23EnzymesEnzymesEnzymes are chemicals produced by the body to help _______. When they react with food they break it down into ______ pieces which can then pass into the ______:

Carbohydrase (produced in the mouth, pancreas and small intestine) breaks _______ (a carbohydrate) down into glucose:

Protease (produced in the stomach, pancreas and small intestine) breaks _______ down into amino acids:

Lipase (produced in the pancreas and small intestine) breaks fats (_____) down into fatty acids and glycerol:

Words – blood, lipids, proteins, digestion, starch, smaller

Blo

od

stre

am

13/04/23A closer look at alveoli:A closer look at alveoli:

Trachea

Bronchi

Bronchioles

Alveoli

13/04/23Gas exchangeGas exchange

Alveoli are very good at exchanging gases because…

1) They have a LARGE surface area

2) They have a good blood supply

3) They are moist

13/04/23RespirationRespirationRespiration is the chemical reaction the cells in our bodies use to release ________. The equation:

Glucose + _____ Carbon dioxide + _____ + ENERGY

Glucose is provided by ______ and oxygen is provided when we __________. The energy we obtain from this reaction was originally contained inside the ________ molecules and is released when the bonds are ________.

The energy produced by respiration is used for building and repairing _____, movement, transporting materials across __________ and maintaining a constant ___________.Words – water, temperature, membrane,

broken, food, energy, oxygen, glucose, breathe, cells

13/04/23Anaerobic respirationAnaerobic respirationUnlike aerobic respiration, anaerobic respiration is when energy is provided WITHOUT needing _________:

This happens when the body can’t provide oxygen quick enough for __________ respiration to take place.

Anaerobic respiration produces energy much _______ than aerobic respiration but only produces 1/20th as much.

Lactic acid is also produced, and this can build up in muscles causing ______ and an oxygen ______.

This “debt” then needs to be “repaid” by deep breathing to ________ the lactic acid.

Words – debt, oxygen, fatigue, oxidise, aerobic, quicker

Glucose lactic acid + a bit of energy

13/04/23The four parts of bloodThe four parts of blood1. RED BLOOD CELLS – contain haemoglobin and carry ______ around the body. They have no _______ and a large surface area.2. PLATELETS – small bits of cells that lie around waiting for a cut to happen so that they can ____ (for a scab).

3. WHITE BLOOD CELLS – kill invading _______ by producing _________ or engulfing (“eating”) the microbe.

These three are all carried around by the PLASMA (a straw-coloured liquid). Plasma transports CO2 and ______ as well as taking away waste products to the ______.

Words – antibodies, clot, kidneys, oxygen, nucleus, glucose, microbes.

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Section 2Section 2

Maintenance of LifeMaintenance of Life

13/04/23PhotosynthesisPhotosynthesis

PHOTOSYNTHESIS is when a plant makes its own food.

Photosynthesis USES:

Carbon dioxide

Water

Energy (from the sun)

Photosynthesis PRODUCES:

Oxygen

Glucose

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Four things are needed for photosynthesis:

Travels up from the roots

WATER

CARBON DIOXIDEEnters the leaf through small holes on the underneath

SUNLIGHTGives the plant energy CHLOROPHY

LL The green stuff where the chemical reactions happen

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The word and chemical equations for photosynthesis:

Carbon dioxide + water glucose + oxygen

6CO2 + 6H20 C6H12O6 + 6O2

Sunlight

Chlorophyll

Sunlight

Chlorophyll

Glucose (sugar) can be used to make long chains of starch…

Glucose molecules

Starch molecule

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Three factors can affect Three factors can affect photosynthesis:photosynthesis:

1. Temperature – the best temperature is about 300C – anything above 400C will slow photosynthesis right down

2. CO2 – if there is more carbon dioxide photosynthesis will happen quicker

3. Light – if there is more light photosynthesis happens faster

13/04/23Drawing graphs of these Drawing graphs of these factorsfactors

1. Temperature

Photosynthesis is controlled by enzymes – these are destroyed at temperatures above 400C

2. Carbon dioxide

3. Light

Photosynthesis increases at first but is then limited by a lack of increase in temp or CO2

Photosynthesis increases at first but is then limited by a lack of increase in temp or light

13/04/23HomeostasisHomeostasisHomeostasis means “controlling internal conditions”:

Waste products that need to be removed + how

CO2

Urea

Internal conditions that need controlling + how

Temperature

Ion content

Water content

Produced by respiration, removed via lungs

Produced by liver breaking down amino acids, removed by kidneys and transferred to bladder

Increased by shivering, lost by sweating

Increased by eating, lost by sweating + urine

Increased by drinking, lost by sweating + urine

Some of these processes are controlled by HORMONES. Hormones are chemical messengers produced by glands and transported in

the blood.

13/04/23KidneysKidneys

Blood in

Blood out

Ureter (tube that takes urine down to bladder)

Kidneys are made up of two important tissues – BLOOD VESSELS and TUBULES.

Kidneys are responsible for controlling ion, urea and water content.

13/04/23KidneysKidneysKidneys work in 3 stages:

1. ULTRAFILTRATION - Lots of water and products of digestion are squeezed out of the blood and into tubules under pressure.

3. WASTE – excess water, excess ions and any urea are now removed through the ureter

2. SELECTIVE REABSORPTION – the blood takes back the things it wants (e.g. glucose and ions) even though this means going against a concentration gradient.

Blood vessel Tubule

13/04/23Controlling water contentControlling water contentThe amount of water reabsorbed into the blood vessels in the kidney is controlled by the hormone ADH:

13/04/23Controlling body Controlling body temperaturetemperature

Body temperature is controlled by the thermo-regulatory centre in the ________. It is kept at 370C as this is the best temperature for __________ to work in. If the body becomes too hot then blood vessels _________ and sweat glands release ________. If the body is too ______ then blood vessels constrict and muscles start to __________.

Words – sweat, enzymes, cold, dilate, shiver, brain

13/04/23

Section 3Section 3

MetalsMetals

13/04/23Section 4 - MetalsSection 4 - Metals

Metals Non-metals

Properties? Properties?

13/04/23Group 1 – The alkali metalsGroup 1 – The alkali metals

Li

Na

K

Rb

Cs

Fr

13/04/23Group 1 – The alkali metalsGroup 1 – The alkali metals

1) These metals all have to be stored under ____ because they react with _______

Some facts…

2) Reactivity increases as you go _______ the group. This is because the electrons are further away from the _______ every time a _____ is added, so they are given up more easily.3) They all react with water to form an alkali (hence their name) and __________, e.g:

Words – down, oil, shell, hydrogen, nucleus, water

Potassium + water potassium hydroxide + hydrogen

13/04/23The Transition MetalsThe Transition Metals

1) This section includes metals like gold, mercury, iron, copper

Some facts…

2) They are all ______ and solid (except _________)

3) They are ____ reactive than the alkali metals

Words – hard, coloured, mercury, less

4) They can form __________ compounds

13/04/23The Reactivity SeriesThe Reactivity Series

Potassium

Sodium

Calcium

Magnesium

Aluminium

Zinc

Iron

Tin

Lead

Copper

Silver

Gold

Platinum

13/04/23Displacement ReactionsDisplacement Reactions

A displacement reaction is where a more reactive metal will displace a less reactive metal from one of its compounds.

e.g.

Predict the following reactions:

1) Lead + copper chloride

2) Silver + copper chloride

3) Magnesium + iron oxide

4) Aluminium + copper sulphate

5) Zinc + lead nitrate

Potassium

Sodium

Calcium

Magnesium

Aluminium

Zinc

Iron

Tin

Lead

Copper

Silver

Gold

Platinum

13/04/23Extracting MetalsExtracting Metals

Some definitions:

A METAL ORE is a mineral or mixture of minerals from which it is “economically viable” to extract some metal.

Most ores contain METAL OXIDES (e.g. rust = iron oxide).

To “extract” a metal from a metal oxide we need to REDUCE the oxygen. This is called a REDUCTION reaction.

13/04/23How do we do it?How do we do it?Potassium

Sodium

Calcium

Magnesium

Aluminium

Carbon

Zinc

Iron

Tin

Lead

Copper

Silver

Gold

Platinum

Metals ABOVE CARBON, because of their high reactivity, are extracted by ELECTROLYSIS

Metals BELOW CARBON are extracted by heating them with carbon in a BLAST FURNACE

These LOW REACTIVITY metals blatantly won’t need to be extracted because they are SO unreactive you’ll find them on their own, not in a metal oxide

13/04/23Extracting metalsExtracting metals

1) What is an ore?

2) In what form are metals usually found in the Earth?

3) How do you get a metal out of a metal oxide?

4) What is this type of reaction called?

Type of metal Extraction process

Examples

High reactivity (i.e anything above

carbon)

Middle reactivity (i.e. anything below

carbon)

Low reactivity

13/04/23Acids and alkalisAcids and alkalis

Using a Universal Indicator we can detect what pH a solution is by observing the colour:

1 2 3 4 5 6 7 8 9 10 11 12 13 14

1 2 3 4 5 6 7 8 9 10 11 12 13 14

13/04/23Neutralisation reactionsNeutralisation reactions

Acid + Alkali Salt + Water

1) Sulphuric acid + potassium hydroxide

2) Nitric acid + calcium hydroxide

3) Hydrochloric acid + calcium hydroxide

4) Nitric acid + potassium hydroxide

5) Sulphuric acid + sodium hydroxide

Acids: Hydrochloric acid

Sulphuric acid

Nitric acid

Alkalis: Sodium hydroxide

Calcium hydroxide

Potassium hydroxide

E.g. hydrochloric acid + sodium hydroxide sodium chloride + water

13/04/23

Section 4Section 4

Earth MaterialsEarth Materials

13/04/23Hydrocarbons and crude Hydrocarbons and crude oiloil

Longer chains

mean…

1. Less ability to

flow

2. Less flammable

3. Less volatile

4. Higher boiling

point

Incre

asin

g le

ng

th

Crude oil is a mixture of HYDROCARBONS (compounds made up of carbon and hydrogen). Some examples:

Ethane

C C

HH

H

HH

H

Butane

C C

HH H

HH

H C C H

H

HH

13/04/23Fractional distillationFractional distillationCrude oil can be separated by fractional distillation. The oil is evaporated and the hydrocarbon chains of different lengths condense at different temperatures:

Fractions with low boiling

points condense at

the top

Fractions with high boiling

points condense at the bottom

13/04/23CrackingCrackingShorter chain hydrocarbons are in greater demand because they burn easier. They can be made from long chain hydrocarbons by “cracking”:

Butane

Ethane

Ethane

For example, this bond can be

“cracked” to give two of these:

13/04/23CrackingCracking

This is a THERMAL DECOMPOSITION reaction, with clay used as a catalyst

1) Carbon dioxide causes the _________ effect

2) Sulphur dioxide causes _____ _____

3) Plastics are not _____________

Cracking is used to produce plastics such as polymers and polyethanes. The waste products from this reaction include carbon dioxide, sulphur dioxide and water vapour. There are three main environmental problems here:

13/04/23AlkenesAlkenesAlkenes are different to alkanes; they contain DOUBLE COVALENT bonds. For example:

Ethane Ethene

Butane Butene

This double bond means that alkenes have the potential to join with other molecules – this make them REACTIVE. We can test for alkenes because they turn bromine water colourless.

ALK

AN

ES

ALK

EN

ES

13/04/23Carbon dioxide in the Carbon dioxide in the atmosphereatmosphereThe amount of CO2 in the atmosphere is affected by 3

things: 1) Geological activity moves carbonate rocks deep into the Earth and they release ______ _______ into the atmosphere during volcanic activity.

2) When fossil fuels are burned the carbon contained in them reacts with _____ to form CO2.

3) Increased CO2 in the atmosphere causes a reaction between it and _______. These reactions produce two things: INSOLUBLE CARBONATES (which are deposited as ______) and SOLUBLE HYDROGENCARBONATES (which ________ in the seawater). These reactions do not remove ALL of the new CO2 so the greenhouse effect is still getting _______!Words – oxygen, seawater, carbon dioxide, worse, dissolve,

sediment

13/04/23The CrustThe Crust

Sedimentary rocks settle in layers. The oldest rock is at the bottom.

Layers of sedimentary rock can be examined to discover how they were formed. They are often found folded or fractured:

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Section 5Section 5

EnergyEnergy

13/04/23RadiationRadiation

When you wear a black t-shirt on a hot, sunny day you would feel ______ than if you wore ____. This is because black _______ infrared radiation (i.e. heat) from the sun better than white does.

I’m very hot!I’m cool!

13/04/23Some examples of radiationSome examples of radiation

13/04/23Some examples of radiationSome examples of radiation

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Radiation is when heat moves around in electromagnetic _________ like light does. Any hot object will emit heat radiation – the hotter it is, the more radiation it emits. This type of radiation is called __________, and too much of it will cause _________. Dark, matt colours will absorb AND emit the _____ infra-red radiation, and light, shiny colours will ________ it.

The main difference with radiation is that conduction and convection could ONLY happen in solids, liquids or gases, whereas radiation will happen through an _____ _____. This is just as well, as otherwise we wouldn’t be able to get any heat from the ___.

RadiationRadiation

Words – sun, reflect, infra-red, waves, most, empty space, sunburn

Anything HOT emits HEAT RADIATION – the hotter it is, the more infra red radiation it emits

13/04/23House insulationHouse insulation

Draught excluders

Double glazing

Loft insulation

Cavity wall insulation

13/04/23House insulationHouse insulation

Type of insulation

Cost Annual amount saved

Loft insulation £400 £80

Double Glazing £2,000 £50

Cavity wall ins. £600 £60

Draught excluder

£40 £20

13/04/23The 9 types of energy and Energy The 9 types of energy and Energy transferstransfers

Kinetic (movement)

Sound

Light

Heat

Nuclear

Electrical

Chemical

Gravitational potential

Elastic potential

What are the energy changes of the following devices?

1) A TV

2) A car engine

3) A battery

4) An electric motor

5) A bow and arrow

6) A skier skiing down a hill

7) Solar panels

13/04/23EfficiencyEfficiency

Efficiency is a measure of how much USEFUL energy you get out of an object from the energy you put INTO it.

Efficiency = Useful energy given out by the device

Energy put into it

e.g. if 2000 joules of electrical energy are put into a kettle and 500 joules of heat energy are gained from it, its efficiency is 500/2000 x 100% = 25%

x100%

1) How efficient is a 3kW electric fire if it gives out 750W of heat?

2) How efficient is a TV that gives out 30J of wasted energy for every 50J of electrical energy? Where does this waste energy go?

13/04/23Some examples of Some examples of efficiency…efficiency…

1) 5000J of electrical energy are put into a motor. The motor converts this into 100J of movement energy. How efficient is it?

2) A laptop can convert 400J of electrical energy into 240J of light and sound. What is its efficiency? Where does the rest of the energy go?

3) A steam engine is 50% efficient. If it delivers 20,000J of movement energy how much chemical energy was put into it?

13/04/23Energy Transfer diagramsEnergy Transfer diagrams

Consider a light bulb. Let’s say that the bulb runs on 100 watts (100 joules per second) and transfers 20 joules per second into light and the rest into heat. Draw this as a diagram:

100 J/s electrical energy

“Input” energy “Output” energy

80 J/s heat energy (given to

the surroundings)

20 J/s light energy

13/04/23Example questionsExample questionsConsider a kettle:

1) Work out each energy value.

2) What is the kettle’s efficiency?

Sound energy

Wasted heat

Heat to water

2000 J/s electrical energy

Consider a computer:

150 J/s electrical energy

10 J/s wasted sound

20 J/s wasted heat

Useful light and sound

1) How much energy is converted into useful energy?

2) What is the computer’s efficiency?

13/04/23Non-renewable energy sourcesNon-renewable energy sources

Coal, oil, gas and nuclear

Advantages Disadvantages

Cheap fuel costs

Short start-up time

Good for “basic demand”

Fuel will run out

Costs a lot of money to

decommission a nuclear plant

Pollution – CO2 leads to global warming and SO2 leads to acid rain

Reliable

13/04/23Renewable energy sourcesRenewable energy sources

Wind, tidal, hydroelectric and solar

Advantages Disadvantages

Zero fuel costs

Hydroelectric is good for a

“sudden” demand

Don’t produce pollution

Tidal barrages destroy the habitats of wading birds and hydroelectric

schemes involve flooding farmland

Unreliable (except for

hydroelectric)

Expensive to build

Solar is good for remote locations (e.g. satellites)

13/04/23Renewable energy sourcesRenewable energy sources

Wind – free energy but very “dilute”, depends on weather, visual pollution

Tidal – as with wave power

Wave – free energy but can harm wildlife and cause visual pollution. As with wind, energy is “dilute”

Hydroelectric – Can provide instant energy but can destroy ecosystems

13/04/23

Section 6Section 6

ElectricityElectricity

13/04/23Basic ideas…Basic ideas…Electric current is when electrons start to flow around a circuit. We use an _________ to measure it and it is measured in ____.

Potential difference (also called _______) is how big the push on the electrons is. We use a ________ to measure it and it is measured in ______, a unit named after Volta.

Resistance is anything that resists an electric current. It is measured in _____.”

Words: volts, amps, ohms, voltage, ammeter, voltmeter

13/04/23

Georg Simon Ohm 1789-1854

ResistanceResistance

Resistance is anything that will RESIST a current. It is

measured in Ohms, a unit named after me.

The resistance of a component can be calculated using Ohm’s Law:

Resistance = Voltage (in V)

(in ) Current (in A)

V

RI

13/04/23An example question:An example question:

V

A

1) What is the resistance across this bulb?

2) Assuming all the bulbs are the same what is the total resistance in this circuit?

Voltmeter reads 10V

Ammeter reads 2A

13/04/23More examples…More examples…

12V

3A

3A

6V

4V

2A

1A

2V

What is the resistance of these bulbs?

13/04/23ResistanceResistance

Resistance is anything that opposes an electric current.Resistance (Ohms, ) = Potential Difference (volts, V)

Current (amps, A)

What is the resistance of the following:

1) A bulb with a voltage of 3V and a current of 1A.

2) A resistor with a voltage of 12V and a current of 3A

3) A diode with a voltage of 240V and a current of 40A

4) A thermistor with a current of 0.5A and a voltage of 10V

13/04/23Current-voltage graphsCurrent-voltage graphs

I

V

I

V

I

V

1. Resistor 3. Diode2. Bulb

Current increases in proportion to

voltage

When current through the bulb increases its temperature increases, thereby increasing its resistance

Behaves like a resistor, but only lets current flow in one direction

13/04/23Three simple components:Three simple components:

1) Diode – only lets current flow in one direction

2) Light dependant resistor – resistance DECREASES when light intensity INCREASES

3) Thermistor – resistance DECREASES when temperature INCREASES

13/04/23Examples of Examples of electromagnetselectromagnets

1. Speaker 2. Relay switch

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ElectromagnetElectromagnetic inductionic induction

The direction of the induced current is reversed if…

1) The magnet is moved in the opposite direction

2) The other pole is inserted first

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ElectromagnetElectromagnetic inductionic induction

The size of the induced current can be increased by:

1) Increasing the speed of movement

2) Increasing the magnet strength

3) Increasing the number of turns on the coil

13/04/23AC GeneratorAC Generator

Induced current can be increased in 4 ways:

1) Increasing the speed of movement

2) Increasing the magnetic field strength

3) Increasing the number of turns on the coil

4) Increasing the area of the coil

13/04/23

Section 7Section 7

Physics in ActionPhysics in Action

13/04/23Electronic systemsElectronic systems

Electronic systems are made up of 3 parts:

1) An INPUT SENSOR – these detect changes in the environment

Examples:

3) An OUTPUT DEVICE – these are controlled by the processor

Examples:

2) A PROCESSOR – these decide what action is needed

Examples:

13/04/23The RelayThe Relay

13/04/23RelaysRelaysCircuits such as those containing logic gates only take very ______ currents. These circuits may be needed to operate a device that takes a much _____ current, e.g. a _________. To do this the circuit would need a RELAY switch, a device made of an _______ that can operate a switch. A relay switch is activated by the small current and the switch part is placed in the circuit needing a large current:

Symbol for relay:

Words – motor, larger, electromagnet, small

M

13/04/23Logic gatesLogic gatesLogic gates are the basics behind any kind of processor. There are 3 that you need to know for GCSE:

NOT gate – “the output is NOT what the input is”

AND – “the output is on if A AND B are both on”

OR – “the output is on if A OR B are on”

Input Output

0 1

1 0

Input A Input B Output

0 0 0

0 1 0

1 0 0

1 1 1

Input A Input B Output

0 0 0

0 1 1

1 0 1

1 1 1

13/04/23Logic gate symbolsLogic gate symbols

NOT gate:

AND gate:

OR gate:

13/04/23Some problems to solveSome problems to solve

• The pump on a central heating system is switched on at room temperature if the system is switched on (with the slide switch). When the temperature rises the pump needs to be switched off.

• Design a circuit that will sound a buzzer if the temperature of a hot radiator falls during the day ONLY. Include a test switch to check the operation of the buzzer.

• Design a circuit for a gardener that will warn them of cold conditions at night. The alarm should be able to be switched off.

13/04/23Potential DividersPotential Dividers

0V

VIN

VOUT

0V

R1

R2

(R1 + R2)

VIN x(R2)VOUT

The Potential Divider equation:

13/04/23Some example questionsSome example questions

0V

12V

VOUT

0V

100

100

0V

1.5V

VOUT

0V

50

45

0V

50V

VOUT

0V

10

75

0V

3V

VOUT

0V

75

25

13/04/23Practical applicationsPractical applications

0V

Vin

VOUT

Here’s a potential divider that is used to control light-activated switches…

When the light intensity on the LDR decreases its resistance will ________. This causes VOUT to _______ so the processor and output will probably turn _____. The variable resistor can be adjusted to change the ________ of the whole device.

Words – decrease, sensitivity, increase, off

13/04/23The CapacitorThe Capacitor

A capacitor is a device that can store charge (it has a “capacity”). It is basically made of two plates:

…or…

Charge builds up on these plates and the voltage between them increases until it reaches the supply voltage.

13/04/23Charging and discharging a Charging and discharging a capacitorcapacitor

P.d. across capacitor

Time

P.d.

Time

P.d.

Time Time

Increase resistance or capacitance

Increase resistance or capacitance

13/04/23Electronic systemsElectronic systems

System Advantages Disadvantages

CCTV

Internet

Mobile Phones

13/04/23Converging and diverging Converging and diverging lenseslenses

CONVERGING (Convex)

Thickest at the centre

DIVERGING (Concave)

Thinnest at the centre

13/04/23Ray diagramsRay diagrams

The rays of light are refracted INWARDS and meet at the focus, F.

The image formed is REAL – in other words, it can be seen on a screen

The rays of light are refracted OUTWARDS.

A VIRTUAL image is formed – in other words, the image doesn’t actually exist

F

F

13/04/23Ray diagramsRay diagramsTo draw ray diagrams follow these two rules:

1) Draw a ray from the TOP of the object PARALLEL to the axis and then going through F:

2) Draw a ray from the TOP of the object going through the CENTRE of the lens (which will be undeviated)

F

This image is REAL, UPSIDE DOWN and SMALLER than the object

13/04/23