year 8 ko - colonel frank seely academy
TRANSCRIPT
YEAR 8 KO
Breathing &
Respiration
Keywords
Breathing The inflation and deflation of the lungs by the contraction of the diaphragm and intercostal
muscles.
Lung volume Measure of the amount of air breathed in or out.
Respiration Reaction which release energy from glucose.
Gas exchange Process involving gases moving in and out of our blood.
Aerobic respiration Breaking down glucose with oxygen to release energy and producing carbon dioxide and water.
Anaerobic
respiration
Releasing energy from the breakdown of glucose without oxygen, producing lactic acid (in
animals).
Fermentation Yeast anaerobically respiring to produce ethanol and carbon dioxide.
Structure of the Lungs
Trachea - Carries air from the mouth and nose to the lungs.
Bronchi - Two tubes which carry air to the lungs.
Bronchioles - Small tubes in the lung.
Alveoli - Small air sacs found at the end of each bronchiole.
Diaphragm - A sheet of muscle found underneath the lungs.
Respiration
Aerobic respiration in animals:
Glucose + oxygen → carbon dioxide + water
C6H12O6 + 6O2 → 6CO2 + 6H2O
Anaerobic respiration in animals:
Glucose → lactic acid
C6H12O6 → 2C3H6O3
A poisonous waste product called lactic acid is produced, which can be
removed by reacting it with oxygen:
Lactic acid + oxygen → carbon dioxide + water
Anaerobic respiration in yeast (fermentation):
Glucose → Ethanol and carbon dioxide
Gas Exchange
Gas exchange takes place in the
alveoli, the tiny air sacs at the end of
the bronchioles.
1. Oxygen molecules diffuse from the
alveolus into the blood in the
capillary, moving from higher to lower
concentration.
2. Carbon dioxide molecules diffuse
from the blood in the capillary into
the alveolus, moving from higher to
lower concentration.
Root structure showing root hair cell
Keyword Definition
Photosynthesis The chemical reaction by which plants make glucose using
light, carbon dioxide and water
Xylem Tissue that carries water from the roots to the leaves
Phloem Tissue that carries dissolved sugars around the plant
Transpiration The loss of water vapour through pores in the leaf
Transpiration stream Movement of water through roots and xylem to the leaves
Reactants Chemicals required for a chemical reaction
Product Chemicals produced in a chemical reaction
Part of Plant Adaptations
Roots Root hair cells to increase surface area for
absorption of water
Stem Tube like xylem to carry water
Tube like phloem to carry dissolved sugars
Leaf - Epidermis/cuticle Reduces water loss and prevents the entry of
pathogens
Leaf - Palisade mesophyll Regular shaped cells with large numbers of
chloroplasts to increase the rate of photosynthesis
Leaf - Spongy mesophyll Provides air gaps to allow gas exchange (oxygen
out, carbon dioxide in)
Leaf - Guard cells Allow pores (stoma) to be opened and closed to
control water loss
Factors affecting the rate of
photosynthesis:
Light intensity
Colour of light
Carbon dioxide concentration
Availability of water
Temperature
Number and size of leaves
How do plants use glucose?
Respiration
Production of large molecules:
● Starch
● Proteins
● Oils and fats
Roles of roots
● Stability of plant
● Absorb water
● Absorb minerals
Cross section of a leaf:
Water + carbon dioxide → oxygen + glucoselight
chlorophyll
Year 8
Photosynthesis
SoundKeywords
Vibration A back and forth repeating motion.
Vacuum A space with no particles of matter in it.
Oscilloscope Device for viewing patterns of sound
waves that have been turned into
electrical current.
Absorption When energy is transferred from sound to
a material.
Echo Reflection of sound waves from a surface
back to the listener.
Wave Characteristics
Wavelength
The distance from a point on one wave to the same
point on the next wave.
Measured in metres and has the symbol λ (Greek letter
lambda).
A shorter wavelength = higher frequency.
Frequency
The number of waves passing a point every second
and is measured in hertz (Hz).
A higher frequency means a high pitch.
Amplitude
The height of the wave from the centre line to a peak
or trough.
Measured in metres.
The more energy a wave has the bigger the amplitude
and the louder the sound.
Waves
Waves can travel in two ways:
1. Longitudinal waves travel in straight lines - where the
direction of vibration is the same as that of the wave.
2. Transverse waves move at right angles to the
direction of the wave.
Sound waves are longitudinal waves. They involve particles
and have areas of compression and rarefaction.
The Ear & Hearing
1. Your outer ear channels sound waves into your ear.
2. The sound waves travel along the auditory canal.
3. The ear-drum vibrates when a sound hits it.
4. The vibrating ear-drum makes the little bones in your ear
vibrate.
5. The vibrations pass along the auditory nerve your brain.
6. Your brain sorts the messages and you hear the sound.
Hearing loss could be caused by:
Wax blocking the ear
Loud noises tearing eardrum
Ear infection
Small bones in the ear can get stuck together
Loud noises can damage the cochlea
Light
Keywords
Normal line A line drawn at right angles to the surface where the ray hits. Angles are
measured from this line.
Absorption Light is transferred to a material and is not reflected or transmitted.
Transmitted Light that passes through an object is transmitted.
Scattering When light bounces off an object in all directions.
Transparent An object that allows light through without scattering.
Translucent An object that allows light through with scattering.
Opaque An object that allows no light through.
Reflection
When light is reflected it
bounces off of something.
We use ray diagrams to
draw reflections.
To help us with our ray
diagram, we can draw a
line 90o to the reflective
material.
This line is called the normal.
Angle of incidence = angle of reflection.
Calculating wave speed
Speed = wavelength x frequency
(m/s/) (m) (Hz)
Symbol equation: v = f x λ
Equation rearranged:
Wavelength = Speed/frequency
Frequency = Speed/wavelength
Refraction
Waves are refracted when they change speed.
When waves slow down they bend towards the normal line. This happens when light travels
from air to glass.
When waves speeds up they bend away from the normal line. This happens when light
travels from glass to air.
The angle of refraction is less than the angle of incidence.
InheritanceKeywords
Inherited
characteristics
Features that are passed from parents to offspring.
Allele The form of a gene (e.g. an allele for the hair colour gene might be blonde, or
brown etc).
Dominant The allele that will show up. (Written as a CAPITAL letter eg B for brown)
Recessive The allele that does not show up if there’s a dominant allele too. (Written as a
lowercase letter eg b for blonde)
Genotype Genetic makeup of an individual for a particular characteristic eg Dd
Phenotype Physical appearance eg dimples or no dimples, black fur or brown fur.
Genetics
Our genetic information is stored inside the nucleus of all cells.
DNA consists of two long strands wound together in a double helix structure.
In our cells, long DNA strands form structures called chromosomes.
A gene is a specific section of a chromosome (eg. the gene for eye colour).
Humans get 23 chromosomes from their Father (sperm) and 23 chromosomes from
their Mother (egg), which combine to make an embryo with 23 pairs of chromosomes.Variation
Variation is the differences in characteristics
between individual organisms.
There are 2 types of variation:
1. Genetic Variation: Genes control the
development of characteristics. Eg, eye colour.
2. Environmental Variation: Characteristics may
be changed by the environment. Eg,
personality.
Genetic Modification
Genetic modification is the modification of
an organism's characteristics by
manipulating its genetic material.
Examples:
- Modifying bacteria to produce insulin for
human use.
- Modifying rice to contain more vitamin A to
reduce deficiencies in developing countries.
- Modifying vegetables to have a longer
shelf life.
Evolution
Keywords
Adaptations Features that help an organism survive in a particular environment.
Natural selection Species change over time in response to environmental changes and competition.
Extinct When no more individuals of a species remain.
Biodiversity The variety of living things.
Competition When organisms struggle against each other to get the same resource.
Evolution Theory that the organisms living today descended from species that existed in the
past.
Natural selection
1. Each species naturally shows variation.
2. There is intraspecific competition for resources (food, water, land, mates, etc).
3. The individuals who are better adapted to the environment are better competitors.
4. These individuals are more likely to survive and reproduce.
5. The advantageous genes are passed onto their offspring, which makes them better
competitors too.
6. Poor competitors die out.
Fossils
1. Death: Having died, the organism slowly sinks to the sea floor. After a few weeks, the flesh
decays, leaving only the hard bones or shells behind.
2. Deposition: The shell or bones gradually become covered with layers of silt and sand, which
provide a shield, protecting it from damage. After a few hundred years the shell or bones are several
feet beneath the surface.
3. Mineralisation: Thousands of years pass. In the wet environment the shell or bones are exposed
to, minerals pass through and react with them.
4. A fossil is formed: After millions of years, the original shell or bone is completely replaced by the
minerals and what remains is a rock-like copy of the original shell. The fossil has the same shape as
the original object, but is actually rock.
Adaptations for hot climates Adaptations for cold climates
Little fur
Little fat
Large surface area to volume ratio
Thick fur
Lots of fat/blubber
Small surface area to volume ratio
Darwin’s theory of evolution
Darwin noticed slight differences between similar species and proposed the theory of
evolution:
“All species of living things alive today have evolved from the first simple life forms that
first developed three billion years ago.”
Evidence: fossil record, selective breeding of animals and plants, observations of
species, DNA analysis
SpeedKeywords
Speed How much distance is covered in how much time.
Average speed The overall distance travelled divided by overall time for a journey.
Relative motion Different observers judge speeds differently if they are in motion too, so an
object’s speed is relative to the observer’s speed.
Acceleration How quickly speed increases or decreases.
Distance-time graphs
A distance-time graph shows how an object moves in a given period of time.
We can find out:
- How far the object travelled from its starting point.
- How long it took to make the journey.
- If the speed was constant or if the speed changed.
- When the object was stationary.
If the graph CURVES UPWARDS, this means the object is accelerating.
If the graph line is STRAIGHT, the object is going at a CONSTANT speed.
If the slope is LESS STEEP, this shows the object is travelling at a slower constant
speed.
If the graph line is HORIZONTAL, the object is stationary.
Calculating speed
Speed = Distance
Time
The unit for speed depends on the units for distance and time given in the question. For example, if
distance is in km and time is in seconds, then the unit for speed is km per second.
Worked example:
A boy takes 2 hours to travel from his home to grandparents, a distance of 10 km. Calculate his
average speed in km/h.
Speed = Distance = 10 km = 5 km/h
Time 2 h
Calculating relative motion
1. For objects moving in the SAME direction:
Calculate the difference between the fastest and slowest speeds.
(i.e. Fastest speed – slowest speed)
2. For objects moving in the OPPOSITE direction:
Add the two speeds together
Pressure
Keywords
Fluid A substance with no fixed shape, a gas or a liquid.
Pressure The ratio of force to surface area, in N/m2 and how it causes stresses in
solids.
Upthrust The upward force that a liquid or gas exerts on a body floating in it.
Atmospheric
pressure
The pressure caused by the weight of the air above a surface.
Area The area of a shape is a measure of the two dimensional space that it covers.
A shape’s area can be measured in square centimeters, square metres or
square kilometres
Hydraulic systems
Hydraulic systems use the principle that pressure is transmitted throughout a liquid.
They are used to transfer movement from one part of a machine to another without linking the
parts mechanically.
All hydraulic systems use two pistons linked via a pipe carrying a special oil called hydraulic fluid.
The piston where the force is applied is called the master piston, and the piston where the force
is transferred is called the slave piston.
Calculating pressure
Pressure (Pa) = Force (N)
Area (m2)
If the force is in N and the area is in m2, the unit for pressure is Pa.
However, if the force is in N and the area is in cm2, the unit for pressure is N/cm2.
Worked example:
An elephant that weighs 40,000N stands on one leg during a circus performance. The
area on the bottom of the elephant’s foot is 0.4m².
Pressure = Force = 40,000 N = 100,000 Pa
Area 0.4 cm2
Floating and sinking
An object will float if weight is equal to the upthrust.
How to work out if an object will sink or float:
1. Measure the mass of an object.
2: Work out the weight (weight = mass x gravitational field strength (10))
3. Submerge the object in water and work out how much water was displaced. (water level
in the cylinder after - water level before)
4. Work out the mass of displaced water. Water has a mass of 0.001kg per 1cm3. So your
answer will be:
Mass of water displaced (step 3) x 0.001 = ______
5. Work out the weight of water displaced (answer to step 4 x 10).
6. The weight of the displaced water is equal to the upthrust, You can now compare the
weight of the object and the upthrust to judge whether it will float or sink.
The Periodic Table
Keywords
Periodic table Shows all the elements arranged in rows and columns.
Groups Columns of the periodic table that group elements with similar properties
together.
Periods Rows of the periodic table that arranges atoms by their proton number.
Element A substance made up of one type of atom.
Compound A substance that consists of two or more elements chemically bonded
together.
Conservation of
mass
The rearrangement of atoms during chemical reactions results in the overall
mass being unchanged.
The arrangement of the periodic table
All of the different elements are arranged in a chart called the periodic table.
The columns are called groups, and the rows are called periods.
Elements to the left of the staircase line are metals and the elements to the right of this
line are non-metals.
Group 1 metals are called the alkali metals.
Group 7 elements are called the halogens.
Group 0 elements are called the noble gases.
The elements in between group 2 and 3 are called the transition elements.
Naming compounds
When atoms combine, their names often change slightly.
Rules to help you name compounds:
1. Use prefixes - mono, di, tri.
For example, SO is sulphur monoxide. SO2 is sulphur dioxide. SO3 is
sulphur trioxide.
2. When a metal and non-metal combine, change the non-metal to
‘ide’.
For example: NaCl is sodium chloride. MgO is magnesium oxide.
3. When 3 or more different elements combine and one is oxygen,
change the end to ‘ate’.
For example, CuSO4 is copper sulphate. CaCO3 is calcium carbonate.
KNO3 is potassium nitrate.
The structure of the atom
Subatomic particle Relative charge Relative mass
Proton +1 1
Neutron 0 1
Electron -1 Almost 0
Metals and Non-Metals
Keywords
Metals Shiny, good conductors of electricity and heat, malleable and
ductile, and usually solid at room temperature.
Non-metals Dull, poor conductors of electricity and heat, brittle and usually
solid or gaseous at room temperature.
Malleable Can be hammered or pressed into shape without breaking or
cracking.
Brittle Easily broken or shattered.
Conductor A material that transmits heat or electricity.
Rust The corrosion of iron.
Metal + Water
Metal + water → Metal hydroxide + hydrogen
Example:
Lithium + water → Lithium hydroxide + hydrogen
2Li + 2H2O → 2LiOH + H2
Rusting
Rusting is a term used to describe the corrosion, or wearing down, of the metal iron
Iron + oxygen → Iron oxide
4Fe + 3O2 → 2Fe2O3
Oxygen and water are necessary for rusting to occur.
Common Salts
Hydrochloric acid (HCl) → chlorides (-Cl)
Sulphuric acid (H2SO4) → sulphates (-SO4)
Nitric acid (HNO3) → nitrates (-NO3)
Metal + Acid
Metal + acid → Metal salt + hydrogen
Example:
Magnesium + hydrochloric acid → Magnesium chloride + hydrogen
Mg + 2HCl → MgCl2 + H2
Metal + Oxygen
Metal + oxygen → Metal oxide
Example:
Copper + oxygen → Copper oxide
2Cu + O2 → 2CuO
Metal Carbonate + Acid
Metal carbonate + acid → Metal salt + water + carbon dioxide
Example:
Zinc carbonate + sulphuric acid → Zinc sulphate + water + carbon dioxide
ZnCO3 + H2SO4 → ZnSO4 + H2O + CO2
Y8 - Earth’s Resources
Keywords
Natural
resources
Materials from the Earth which act as raw materials for making a
variety of products.
Mineral Naturally occurring metal or metal compound.
Ore Naturally occurring rock containing sufficient minerals for extraction.
Extraction Separation of a metal from a metal compound.
Recycling Processing a material so that it can be used again.
Electrolysis Using electricity to split up a compound into its elements.
Displacement Reactions
Some metals are more reactive than others. This is displayed in the reactivity series (on the left
hand side).
A displacement reaction is where a more reactive metal takes the place of a less reactive metal in a
compound.
Example:
Copper + silver nitrate → copper nitrate + silver
Copper is more reactive than silver, so the copper has ‘stolen’ the nitrate from the silver - therefore
silver has been displaced.
Extracting Metals
Metals can be extracted from their ores using different methods, depending on their reactivity.
1. Very unreactive metals (the metals less reactive than hydrogen) occur native and do not need extracting.
1. Metals between carbon and hydrogen on the reactivity series can be extracting with a displacement reaction using
carbon. For example: Lead oxide + carbon → Lead + carbon dioxide. Carbon is more reactive than copper, so lead
is displaced.
1. Metals that are more reactive than carbon can be extracted using electrolysis.
Y8 - Climate
Keywords
Global warming The gradual increase in surface temperature of the Earth.
Fossil fuels Remains of dead organisms that are burned as fuels, releasing carbon
dioxide.
Carbon sink Areas of vegetation, the ocean or the soil, which absorb and store carbon.
Greenhouse effect When energy from the sun is transferred to the thermal energy store of
gases in Earth’s atmosphere.
Processes involved in the carbon cycle
1. Photosynthesis:
Green plants and algae remove CO2 from the atmosphere.
Carbon dioxide + water → glucose + oxygen
6CO2 + 6H20 → C6H12O6 + 6O2
2. Respiration:
Respiration causes carbon to be returned to the environment.
Glucose + oxygen → carbon dioxide + water
C6H12O6 + 6O2→ 6CO2 + 6H2O
3. Combustion:
When we burn fossil fuels the carbon within them combines with oxygen to produce
CO2. In this way carbon is returned to the environment.
4. Decay:
The dead organisms are eaten by decomposers and the carbon is returned to the
atmosphere as carbon dioxide.
Gases in our atmosphere
Nitrogen makes up most of our atmosphere.
Currently carbon dioxide levels are about 0.04%.
Methane and carbon dioxide are greenhouse gases.
The greenhouse effect
1. Heat from the Sun enters the earth’s atmosphere and warms the surface of the planet.
2. The earth’s surface becomes warm and radiates heat back out.
3. Some of this heat is absorbed by greenhouse gases. These gases then radiate the heat back towards earth.
4. The earth becomes warmer as a result.
Keywords
Enzyme A biological catalyst
Substrate Molecule(s) acted on by an enzyme
Active Site The site on enzymes where the substrate binds
Denature Change the shape of the active site
Carbohydrates The body’s main source of energy. 2 types: simple (sugars) and complex
(starch).
Lipids Fats and oils. A source of energy.
Protein Nutrient your body uses to build new tissue for growth and repair.
Stomach Where food is mixed with acidic juices and churned
Small intestine Where digestion is completed and nutrients are absorbed by the blood.
Large intestine Where water is absorbed and faeces are formed.
Molecule for
testing
Food test Positive result Negative result
Protein Biuret solution Purple Stays blue
Lipids Sudan III stain Red oil layer at
the top
No layers form
Starch Iodine Blue / black Stays orange
Simple sugars
(glucose)
Benedict’s solution &
heat
Red Stays blue
Enzymes
Enzymes break long food molecules into smaller particles ready for absorption. Without enzymes, the long food molecules
would never be able to pass through the intestine.
Enzymes are a specific shape - complementary to their substrate (the molecule they are breaking down). The enzyme has
an ‘active site’ where it binds onto the substrate.
Digestion
WorkKeywords
Work The transfer of energy when a force moves an object, in joules.
Lever A type of machine which is a rigid bar that pivots about a point.
Input force The force you apply to a machine.
Output force The force that is applied to the object moved by the machine.
Displacement The distance an object moves from its original position.
Deformation When an elastic object is stretched or squashed, which requires work.
Moments
A turning force is called a moment.
We can work out the moment by using this formula:
M = F x r
M = Moment (Nm)
F = Force (N)
r = Perpendicular distance (m)
Worked example: This seesaw is balanced. Calculate force
A
Anticlockwise moment = 50 x 1 = 50Nm
For the seesaw to balance, the anticlockwise and clockwise
moments must be equal.
Force A = 50 / 0.5 = 100N
Mechanical Work
Energy can be transferred from store to store
by forces moving.
When this happens we say that mechanical
work is done.
We can work out how much work has been
done by using this formula:
W = Fs
W = Work done (J) - This is also the amount of
energy transferred.
F = Forces applied (N)
S = Displacement of force (m) - This is the
distance the force has moved.
Remember: Weight (N) = mass (kg) x
gravitational field strength.
1m
50N
50cm
A
Levers
Levers are simple machines that allow us to multiply the force applied.
The longer the lever, the greater the moment created for the same
amount of force applied.
A lever can be used to lift heavy objects.
The weight of the object is called the load.
The force the person applies is called the effort.
The point about which the lever turn is called the pivot or the fulcrum.
Heating & CoolingKeywords
Thermal conductor Material that allows heat to move quickly through it.
Thermal insulator Material that only allows heat to travel slowly through it.
Temperature A measure of the motion and energy of the particles.
Thermal energy The quantity of energy stored in a substance due to the vibration of its particles.
Conduction Transfer of thermal energy by the vibration of particles.
Convection Transfer of thermal energy when particles in a heated fluid rise.
Radiation Transfer of thermal energy as a wave.
Radiation
Thermal energy is transferred by infrared (thermal) radiation.
It travels in waves just like light. Therefore it does not require particles.
All objects emit and absorb radiation to some extent.
The hotter the object, the more radiation it emits.
Also, the darker the object, the more radiation is absorbs and emits.
Conduction
This method of energy transfer occurs in
solids.
All solids are made of particles in a rigid
structure.
As you heat up a solid these particles gain
kinetic energy and vibrate more.
This means more particles bump into each
other, causing the energy to pass through the
solid.
Convection
This method of energy transfer occurs in fluids
(liquids and gases).
When the particles are heated they gain kinetic
energy and move faster.
This means they crash into each other more often
and with greater force.
This makes the fluid expand and become less
dense.
The hot fluid is displaced (pushed out of the way)
by more dense cold fluid.
Reducing energy loss
An insulator is a material that does not transfer heat well.
Insulators in homes slow down the transfer of heat from the warmer internal
rooms the cooler outside.
The way insulators work is by preventing conduction, convection and
radiation.
Examples of insulation in houses:
Loft insulation
Cavity wall insulation
Aluminium foil behind a radiator
Double glazing
Chemical Energy
Keywords
Catalysts Substances that speed up chemical
reactions but are unchanged at the end.
Exothermic
reaction
One in which energy is given out, usually as
heat or light.
Endothermic
reaction
One in which energy is taken in, usually as
heat.
Chemical bond Force that holds atoms together in
molecules.
Activation energy The energy required to start a chemical
reaction (break bonds).
Catalysts
Catalysts never produce more product – they just produce the
same amount more quickly.
Catalysts work by providing an alternative pathway for the
reaction with a lower activation energy.
Energy in chemical reactions
In order for a reaction to occur, bonds in the reactant molecules must be broken, atoms then rearrange, and bonds are
remade to form the products.
In order for reactant bonds to be broken, thermal energy must be supplied. This is called the activation energy. Breaking
bonds therefore requires energy (endothermic).
When bonds are made, thermal energy is released (exothermic).
Exothermic reactions Endothermic reactions
Exothermic reactions release energy as heat during a
reaction.
This can be seen as a rise in temperature as the reaction
thermal energy to its surroundings.
This means that the energy of the products will be lower
than the energy of the reactants.
Endothermic reactions absorb thermal energy during a
reaction.
This can be seen as a drop in temperature as the
reaction absorbs thermal energy from its surroundings.
This means the energy of the products will be higher than
the energy of the reactants.
reaction (time)
en
erg
y
(kJ)
Ea with
catalyst
Ea
without
catalyst
Magnetic field around a bar magnetKeyword Definition
magnet an object that creates a magnetic field around itself
ferromagnetic material a material that experiences a magnetic force when
placed in a magnetic field.
magnetic force a non-contact force that acts of a magnetic material
or a magnet placed in a magnetic field
magnetic field the space around a magnet or a current-carrying
wire
magnetic field line line in a magnetic field along which a magnetic
compass points - also called a line of force
solenoid a long coil of wire that produces a magnetic
field in and around the coil when there is a
current in the coil
electromagnet an insulated wire wrapped round an iron bar
that becomes magnetic when there is a
current in the wire
pole position on a magnet where the magnetic
field is strongest
Increasing the strength of an electromagnet
Improvement Reason it works
Increase the number of coils Increases the length of the magnetic field
producing wire
Increase the current Makes each mm of wire produce a bigger
magnetic field
Parts of an electromagnet
Solenoid Carries the current
Core Focuses the magnetic field
Current Creates the magnetic field
Magnetic materials
Iron
Cobalt
Nickel
Year 8
Magnetism
Field lines - things to remember
● They never cross
● The arrows point from the north pole to the
south pole
● The points where they touch the magnet
are the poles
● Where they are closer together the
magnetic field is stronger
Electromagnet construction