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Chemistry, Physics, Year 10 science, Organelles in plant cells which…
Chemistry
Principles of chemistry
atomic structure
mass number
is a weighted average mass
we can retain the
relative atomic mass
from this number with the following calculation
((m1p1) + (m2p2))/ 100
m = mass of isotope
p = percentage of abundance
number of protons+number of neutrons
atomic number
number of protons
also number of electrons
isotopes
atoms of the same element which have equal atomic numbers but differing mass numbers (numbers of neutrons)
proton
positively charged
found in nucleus
relative mass is 1
relative charge is +1
neutron
found in nucleus of atom
relative mass is 1
relative charge is 0
electron
negatively charged
found in outer shells
relative mass is 1/1840
relative charge is -1
electron configuration
organised in the outer shells
are placed in the order of 2,8 and 8 in the closest 3 shells
any number of electrons can be placed in the 4th shell
States of matter
Solid
High electrostatic attraction between particles
Arranged in uniform rows
Have the same shape and volume
Liquid
Lower electrostatic attraction between particles than solid
Organised in a relatively ordered fashion
Volume rays the same, even if the container changes
Shape of liquid will change if container shape changes
Gas
Lowest electrostatic attraction between particles
Organised in a random order
Do not have a fixed shape
Can be compressed
Elements, compounds and mixtures
Elements
A pure substance listed in the periodic table, with only one type of atom
Has a fixed mp and bp
Compounds
Two or more elements chemically bonded together
Mixtures
An impure substance made from different elements or compounds mixed together, which are not chemically bonded
May melt or boil over a range of temps
Experimental techniques fro the separation of mixtures
Simple distillation
Fractional distillation
Crystallisation
Filtration
The mixture is poured through filter paper which surrounds the entry of a different beaker. The solute stays on the filter paper, whereas the solvent will flow into the beaker.
Paper chromatography
Chromatogram provides info about the composition of the solvent
How to calculate the Rf values to identify components in the mixture
Distance travelled by substance / distance travelled by solvent
The periodic table
How elements are arranged
In order of atomic number
In groups (vertical rows)
in periods (horizontal rows)
How to deduce the electric configuration of an element
Observe the atomic number, which is the number of electrons
Electrons in the outer shells are organised into the sequence of 2,8,8
Identifying an element as a metal or non-metal
Starting at Boron, and working down the periodic table in right angles until reaching the division between astatine and potassium
All the elements to the left side of the line are metals, and all on the left are non-metals
Elements in the same group have the same chemical properties, as a result of their similar electronic configurations
Noble gases do not readily react because they have a full outer shell and are therefore stable
Physical chemistry
rates of reaction
fast examples
transmission of nerve impulses
fireworks exploding
lighting of a match
slow examples
rock weathering
setting of cement
rusting
how to find the rate of reaction
how quickly reactants change to products
how quickly products are formed
collision theory
the idea that for a chemical reaction to take place, successful collisions have to happen between particles
for the necessary collision to occur, particles must overcome the energy barrier for the reaction, a.k.a the
activation energy
factors affecting the rate of reaction
increased/decreased concentration
linked practical with increased concentration in:
solvent - hydrochloric acid
solute - calcium carbonate chips
see blue practicals workbook for explanation
decrease in volume -> increased pressure
increased/decreased surface area
increased/decreased temperature
added catalyst - a substance which speeds up chemical reactions
Inorganic chemistry
reactivity series
Potassium
Sodium
Calcium
Magnesium
Zinc
iron
tin
copper
lead
silver
gods
Passive Smoking Can Make Zombies In To Crazy Lazy Sex Gods
investigate reactions between dilute hydrochloric and sulfuric acids and metals
magnesium, zinc and iron
Click here for both acids
Physics
maths in physics
standard form
a way of writing down numbers easily and quickly, to a power of 10
e.g 4000
is 4 x 10 ^3
e.g 0.0004
is 4 x 10^-4
ratios
numbers either side of a colon that compare quantities
percentages
a number that is expressed as a fraction of 100
fractions
a principal part of a whole
reciprocal
is 1 divided by the number
always give decimalised answers
sig figs
the limit placed on answers to ensure simplicity
3 sig figs
4.555
4550
2 sig figs
0.025
450
rearranging equations
quantities
Tera
T
10^12
giga
G
10^9
mega
M
10^6
deci
d
10^-1
centi
c
10^-2
milli
m
10^-3
micro
µ
10^-6
nano
n
10^-9
pico
p
10^-12
acrostic
Terrible Giants Menace Deer Centenaries Mingling Mildly Near Piccolos
Tera, Giga, Mega, deci, centi, milli, micro, nano, pico
planning an investigation
variables
independent
the variable that the experimenter changes (x axis)
dependent
the variables that change as a result of the independent variables' changes
control
variables that stay the same to make it a fair test
make hypotheses
identify safety precautions
draw a results table and a graph
draw a conclusion
looking at and describing the relationship
write a summary
spread of data
minus smallest reading from the largest
errors
systematic error
when the outlier is continuous
random error
when an error affects the entire spread and causes outliers
precise
when all answers are in roughly the same place, and have been measured to an extreme increment, such as to five decimal places
accurate
results close to the true value
graphs
top tip - never draw graphs with scales which are multiples of 3, 7, 11 or 13
components of a perfect graph
sensible scale
labelled axis with units
clearly plotted data points
accurate line of best fit
axis are over half a page in each direction
data should fill majority of page
gradient = Δy/Δx
forces and motion
average speed
acceleration
deceleration
the speed of an object decreases
negative acceleration
the speed of an object increases
a = Δ v (m/s) / t (s)
calculated with the equation: acceleration = change in velocity / time
measured in m/s
calculated with the equation: speed = distance / time
s (m/s) = d (m) / t (s)
speed time graphs
positive gradient = acceleration
0 gradient = constant speed
negative gradient = deceleration
the area underneath a speed time graph is the
distance
final velocity
v^2 = u^2 + 2as
suvat equation
s - displacement
u - initial velocity
v - final velocity
a - acceleration
t - '+'
graphs
distance time graphs
see here for examples
the gradient of distance time graphs is the
speed
gradient = Δ y/Δ x
speed = distance (y axis) / time (x axis)
displacement time graphs
vectors and scalars
vectors
quantity with magnitude and direction
example - acceleration, weight, moment
scalars
quantity with magnitude (size)
examples - distance, speed, time, mass
force
force = mass (kg) * acceleration (m/s^2)
f = ma
electricity
resistance
R = V/I
Resistance = Voltage / current
a measure of how much a component decreases the current
measured in 'Ωs'
voltage/potential difference
measured in volts
symbol is 'V'
current
measured in Amps
symbol is 'I'
Year 9 Science
Biology
The nature and variety of living organisms
Characteristics of living organisms
All:
Require nutrition
Respire
Excrete their waste
Respond to surroundings
Move
Control internal conditions
Reproduce
Grow and develop
Require
Control (internal conditions)
Grow
Excrete
Respond
Move
Reproduce
Respire
Variety of living organisms
Plants
Multicellular
Cells contain cellulose cell walls
Cells contain chloroplasts, perform photosynthesis
Store carbs as starch/sucrose
Example : flowering plant, such as maize
Animals
Multicellular
Cells do not contain chloroplasts, do not perform photosynthesis
Have no cell walls
Usually have nervous coordination and ability of movement
Store carbs as glycogen
Example : human
Fungi
Unable to perform photosynthesis
Body organised into mycelium structure made from hyphae, which contain nuclei
Feed by an extra cellular secretion of digestive enzymes onto food material -> absorption of organic material
Known as saprotrophic nutrition
Some are unicellular
Have walls made of chitin
Store carbs as glycogen
Example : yeast
Bacteria
Microscopic
Unicellular
Cell components
Cell wall
Cell membrane
Cytoplasm
Plasmids
No nucleus, but have a circular chromosome of DNA
Some photosynthesise, but most are saprophytic
Example ; Pneumococcus
Viruses
Pathogenic
Can infect every type of living organism
Not living organisms
Are parasitic : can only reproduce inside of other organisms
Small particles, smaller than bacteria
Wide variety of shapes and sizes
No cellular structure
Have a protein coat and contain one type of
nucleic acid
DNA
Or RNA
Example : tobacco mosaic virus
Protocticts
Microscopic
Unicellular
Some have animal cell features
Some have plant cell features
Some are pathogenic (cause disease)
Pathogens
Disease causing organism
Fungi
Bacteria
Protocticts
Viruses
Structure and function in living organisms
Level of organisation (largest to smallest)
Organisms
Organ systems
Organs
Tissues
Cells
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Cell structures
Nucleus
Contains genetic material, which controls the cell’s activities
Cytoplasm
A jelly like material
Contains dissolved nutrients
Where many chemical reactions happen
The work floor
Vacuole
Filled with cell sap to keep cell turgid
Look like bubbles
Cell wall
Made from cellulose
Strengthens and supports the plant.
The structure of the factory
Cell membrane
Permeable to some substances but not others
Controls the movement of substances in and out of the cell
Not solid, is a flexible and porous container
The security guard of the factory
Mitochondria
Contain the enzymes for respiration
Where most energy is released in respiration.
Round, bean-like shapes.
Ribosomes
Where protein synthesis occurs
Tiny
Chloroplasts
Contains a green pigment called chlorophyll, which absorbs light energy needed for photosynthesis
Contains enzymes needed for photosynthesis
Biological molecules
Chemicals present in :
Carbohydrates
Carbon
Hydrogen
Oxygen
Lipids/fats
Carbon
Hydrogen
Oxygen
Proteins
Nitrogen
Carbon
Hydrogen
Oxygen
Structures
Carbohydrates
Starch (in plants) and glycogen (animals) are made up of
simple sugars
Glucose ( a monosaccharide)
Proteins
Components are primarily amino acids
Lipids
Made up of 3 fatty acid chains and 1 glycerol molecule
Fats - solid at room temp
Oils - liquid at room temp
Chemical tests
Benedict’s solution/agent
Glucose (sugars)
Red - positive
Blue - negative
Place into sample solution and heat at 60 degrees in water for 5 mins
Ethanol and water
Lipids
Clear solution - negative
Cloudy emulsion in water - positive
Mix 2cm^3 of ethanol with food sample and add to an equal volume of cold water
Iodine
Starch
Blue black - positive
Brick red - negative
At drops of iodine to food sample
Biuret solution
Proteins
Light blue - negative
Purple - positive
Add drops of biuret solution to food sample
Enzymes
Role - to act as biological catalysts which speed up the rate of useful chemical/metabolic reactions in living things
Specification
Enzymes are very specific as they have a certain active site that the substrate will react in
Substrate - a molecule that is changed in a reaction
Affected by pH - just understanding
Have an optimum pH (level of acidity)
If the pH is too high or too low, it affects the bonds holding the enzymes together
This changes the active site and denatures the enzyme
Affected by temperature - practical and understanding
Have an optimum temperature
If the temperature is increased too much, the bonds in the substrate break and change the active site, decreasing the rate of reaction exponentially
Practical
Change
Temperature of water bath
Organism
Source of catalase - e.g. potato
Repeat
Measure 1
Amount of oxygen produced per minute (dependent variable)
Measure 2
Temperature of water bath (independent variable)
Same 1
Mass of catalase source. (Potato)
Same 2
Amount of hydrogen peroxide solution
A water bath with a constant temp is set up
a measuring cylinder is placed in a tub full of water
a tube with a bung on one end is placed into the water tub and underneath the measuring cylinder
a measured amount of hydrogen peroxide is placed into a boiling tube and put in the water bath at 10 degrees
then place a measured mass of potato into the boiling tube and replace the bung quickly
measure the amount of oxygen produced in the measuring cylinder, and repeat three times to get an average
repeat process with 20, 30 and 40 degrees
At too low temperatures they are
inactive
Movement of substances in and out of cells
Diffusion
The net movement of particles from an area of high concentration to an area of low concentration
Osmosis
The net movement of wate particles across a partially permeable membrane from a area of high water concentration to an area of low water concentration
Active transport
Factors which affects the rate of movement of substance in and out of cells
Practical - investigate diffusion and osmosis using living and non-living organisms
Year 10 science
Physics
Forces and motion
Newton’s laws
1st
An object will remain at rest or in constant motion unless acted on by an external force
2nd
Every action has an equal and opposite reaction
F = m x a
Hooke’s law
Extension is directly proportional to force
Movement and position
Distance time graphs
Speed
Gradient
Relationship between average speed, distance moved and time taken
Speed (m/s) = d (m) / t (s)
Relationship between acceleration, change in velocity and time taken
Acceleration = change in velocity / time taken
Velocity time graphs
Distance travelled
Area under the line
Acceleration
Gradient
Relationship between final speed, initial speed, acceleration and distance moved
V^2 = u^2 + 2as
Forces
Forces between bodies
Changes in speed
Shape
Or direction
Identify different types of forces
Gravitational
Electrostatic
Elastic
Weight
Vector and scalar quantities
Vector - has magnitude and direction
E.g force
Scalar - has magnitude
E.g distance
Friction
A force that opposes motion
Relationship between unbalanced forces
Force = mass x acceleration
Relationship between weight mass and gravitational field strength
Weight = mass x g
Stopping distance
= thinking dist. + braking dist.
Factors effecting braking distance
Road conditions
Tyre conditions
Weather conditions
Mass of car
Factors effecting thinking distance - reaction time
Drugs
Alcohol
Tiredness
Distraction
Electricity
Units
Ampere (A)
Coulomb (C)
Joule (J)
Ohm (Ω)
Second (s)
Volt (V)
Watt (W)
Mains electricity
Alternating current (ac)
Energy supplied by the mains
A current which changes direction at regular intervals. Ie the curve alternates between positive and negative voltages
Direct current (dc)
Electricity supplied by a cell or battery
Only flows in one direction, with either constant negative or positive voltage
Relationship between power, current and voltage
P = I x V
Relationship between energy transferred, current, voltage and time
E = I x V x t
Power - the number of joules transferred per second
Energy and voltage in circuits
Propriety of series or parallel circuits
Properties of parallel circuits
The voltage across two components connected in parallel is the same
How current varies
How LDRs work
As light increases, resistance decreases
Low light intensity = increased change in resistance
High light intensity = decreased change in resistance
How thermistors work
As temperature increases resistance decreases
Non linear change
Low temps = increased change in resistance
High temps = decreased change in resistance
Relationship between voltage, current and resistance
V = I x R
Current - the rate of flow of charge
Relationship between charge, current and time
Q = I x t
Volatge - the energy transferred per unit charge passed
The volt is a joule per coulomb
Relationship between energy transferred, charge and voltage
E = Q x V
Properties of a series circuit
Current is equal everywhere
Voltage is shared between components
Why current is conserved at a junction in a circuit
When a circuit splits, the current is divided into the number of separate routes available. When the wires rejoin together, the current is still the same
Waves
Properties
Longitudinal
Oscillations are
paralell
to the direction of energy transfer
Transverse
Oscillations are
perpendicular
to the directions of energy transfer
Definitions
Amplitude
The maximum displacement of a wave from rest
Wavefront
The imaginary surface which is drawn to represent the vibrating part of the wave
Frequency
The number of waves passing a specific point per second
Wavelength
Distance converted by a full cycle of a wave
Period of wave
The time taken for a full cycle of a wave -measured from peak to peak/trough to trough
Waves transfer energy and info without transferring matter.
Relationship between the speed, frequency and wavelength of a wave
wave speed = frequency × wavelength
v = f × λ
Relationship between frequency and time period (equation given)
F = 1 ÷ time period
The Doppler effect
The apparent shift in frequency according to the observer due to the change in wavelength
When the source is closer to the observer, the wavelength decreases, and the pitch is higher compared to....
An observer far away from the source, who hears the sound produced at a lower pitch
All waves can be
reflected
and
refracted
Units
Degree - °
Hertz - Hz
Metre - m
Metre/second - m/s
Second - s
The EM spectrum
Full list - longest wavelength and lowest frequency -> shortest wavelength and highest frequency
Radio waves
Communication and broadcasting
No danger
Microwaves
Cooking, satellite transmissions
Internal heating of body tissue
Infra red
Heaters, night vision equipment
No danger
Visible light
Optical fibres, photography
No danger
Ultraviolet
Fluorescent lamps
Damage to skin cells
X rays
Observing the internal structure of objects and materials
Gamma rays
Sterilisation - food and medical equipment
Cancer, mutation
Preventative measures - rays are very directional and focused when used in machinery
Light and sound
Light
Transverse
The law of reflection
Angle of incidence = angle of reflection
Practical - investigating the refraction of light
Semi circular block
Rectangular block
Shine a light ray at an angle into the block. Some is reflected, but most is refracted
Draw around the block and trace the incident and emergent rays with a ruler. The two rays can be joined up inside the drawn rectangular block
As light has passed from a less too more dense medium (air to glass) on the first boundary, it has slowed down. As it passes from glass to air, the ligh wave speeds up and bends
away
from the normal
Triangular prism
Sound
Longitudinal
can be reflected and refracted
refractive index
n = Sin(i)/Sin(r)
i = angle of incidence
r = angle of refraction
has no units
practical
a ray of light is shined through a block, marked and drawn with a ruler. the glass block is drawn around and the light ray are joined up inside the drawn rectangle. the normal lines are drawn, perpendicular to the boundary and the angles are measured. the refractive index of glass will always be 1.5
is inversely proportional to the critical angle
n = 1/Sin(c)
TIR
Total Internal Reflection
when the angle of reraction is exactly 90 degrees,, the angle of incidence becomes the critical angle, measure from indside the medium
Click here
uses
fibre optic cables
endoscope
decorations
Energy resources and transfers
units
kilogram (kg)
joule (J)
metre (m)
metre/second (m/s)
newton (N)
second (s)
watt (W)
energy transfers
describing
energy stores
chemical
kinetic
gravitational
elastic
thermal
thermal energy transfer can take any of these forms
conduction
heat energy can be conducted through materials, travelling from the cold to the hot end
metals are often good conductors, whereas non metals are not, and named as insulators
convection
convection is used in ovens and radiators, found in an everyday home
only occurs in fluids (liquids and gases)
1 more item...
radiation
a type of electromagnetic radiation (see EM spectrum) which involves waves but no particles
dull surfaces are good absorbers and emitters of infrared radiation, whereas shiny surfaces are poor absorbers and emitters
practicals
conduction
1 more item...
radiation
4 more items...
convection
1 more item...
magnetic
electrostatic
nuclear
energy transfers
mechanically
electrically
heating
radiation (light and sound)
Example of a Sankey diagram :
the principle of the conservation of energy
energy can never be created or destroyed, only transferred from one form to another
efficiency = useful energy output / total energy input
ways of reducing unwanted energy transfer
Double glazed windows
Cavity wall insulation
Cavity wall
work and power
Relationship between work done, force and distance moved
W = F * d
Work done is equal to energy transferred
Relationship between GPE, mass, gravitational field strength and height
GPE = m x g x h
Relationship between kinetic energy, mass and speed
KE = 1/2 m * V^2
The link betweem GPE, KE and work in the the conservation of energy
As energy can never be created or destroyed, GPE will always invert to KE when an object is falling
In the absence of air resistance, GPE is transferred to KE
The relationship between power, and rate of work and energy transfer
Power = rate if energy transfer
Power = rate of doing work
Relationship between power, work done and time taken
Power = work done /time
Solids, liquids and gases
Units
Degrees Celsius ( °C)
Kelvin (K)
Temperature
Joule (J)
Energy
Kilogram )kg)
Mass
Kilogram/metre^3 (kg/m^3)
Density
Metre (m)
Distance
Metre ^2(m^2)
Area
Metre/second (m/s)
Velocity
Newton (N)
Force
Pascal (Pa)
Pressure
Density and pressure
Relationship between density, mass and volume
Density = mass/volume
Practical - investigating density using direct measurements of mass and volume
Relationship between force, pressure and area
P = F/a
Pressure in fluids
At any point acts in all directions equally
Equation for pressure difference
P = height (h) x density (p)x gravitational field strength (g)
Ideal gas molecules
Molecules in a gas
Have random motion
Exert a force and hence pressure on the walls of the container
Absolute zero
Is -273 °C
When temperature is decreased, pressure decreases. When the pressure becomes as low as possible, the temperature is -273 °C, also known as 0K
Conversion
Celsius -> Kelvin : +273
Kelvin -> Celsius ; -273
Why an increase in temperature results in an increase in average speed of gas molecules
Charles’ law
‘At a fixed pressure, the volume of a gas is proportional to the temperature of the gas
When gases in containers are heated, their molecules increase in average speed
The kelvin temperature of a gas is proportional to the average kinetic energy of the molecules inside the gas
The relationship between, in fixed amounts of gas:
Pressure and volume at constant temperature
Boyle’s law
Decreasing the volume of a gas increases the pressure of the gas
P1V1 = P2V2
Pressure and Kelvin temperature at constant volume
When gas is trapped inside a container which has a fixed volume, and the gas is heated, the particles will gain kinetic energy and move faster
This increased speed causes the number of exertions of force on the walls of the container, increasing the pressure
P1/T1 = P2/T2
Chemistry
Principles of chemistry
Chemical formulae, equations and calculations
Ionic bonding
Covalent bonding
Inorganic chemistry
Group 1 - alkali metals
Lithium
Sodium
Potassium
Reactions with water to prove trend in reactivity
Lithium - fizzes on the surface
Sodium - melts into ball on the surface and fizzes rapidly
Potassium - melts into a ball, fizzes around on the surface and ignites with a purple flame
Reactivity increases with number of period (down the column)
React with oxygen to form basic metal oxides
Physical properties
Soft - extent increases with reactivity
Good conductors (heat/electricity)
Shiny
Low density
Low mp/bp
Gases in the atmosphere
Approx abundance of four main gases in dry air
21% oxygen
Oxygen
Calculating the percentage of oxygen in air (practical)
Two plungers with labelled increments are placed firmly on either side of a hard glass tube containing pure copper
The copper is heated
One syringe is filled with air, and the plungers are used to push the air back and forth through the tube until the copper has turned black, the colour of copper oxide.
Syringes are left to cool, and the volume of gas in the syringes is measured
78% nitrogen
Just under 1% argon
1% > carbon dioxide
Carbon dioxide
Is a greenhouse gas
Increasing amounts will lead to climate change.
Formation from thermal decomposition
A green copper carbonate solution is heated
A colour change is observed form green to black - the colour of copper oxide
The carbon dioxide formed as a gas can be tested using the placement of limewater in a solution , which will turn cloudy if CO2 is present
Group 7 - halogens
Chlorine
Yellow/green gas
Bromine
Brown liquid
Iodine
Dark grey solid
Purple gas
Displacement reactions which prove the trend in reactivity
Potassium chloride
Chlorine
No reaction
Bromine
No reaction
Iodine
No reaction
Potassium bromide
Chlorine
Displacement reaction : bromine + potassium chloride
Turns yellow (colour of chlorine gas)
Bromine
No reaction
Iodine
No reaction
Potassium iodide
Chlorine
Displacement reaction : iodine + potassium chloride
Turns brown
Bromine
Displacement reaction : iodine + potassium bromide
Turns brown
Iodine
No reaction
As the period number increases, reactivity decreases
Properties
All very reactive non-metals
Make dense, coloured poisonous gases
React with metals to make white salts
All have seven electrons in outermost shell
Organic chemistry
Introduction
Hydrocarbon - a compound which is composed of
only
carbon and hydrogen atoms.
Formulae
Empirical
The simplest whole number ratio of atoms of each element in a compound.
Eg CH2 (2 in subscript)
General
An algebraic formula which describes any member of a compound family
Eg CnH2n -> for all
alkenes
Structural
Shows the arrangement of atoms carbon by carbon, with the attach hydrogens and functional groups
Eg CH2CH2 (numbers in subscript)
Molecular
The
actual
number of atoms of each element in a molecule
Eg C2H4 (numbers in subscript)
Displayed
Shows how the atoms are arranged, and the state of the bonds between them
homologous series, functional group and isomerism
Isomers
Have the same molecular formula but the atoms are arranged differently.
Functional group
An atom/group of atoms which determines the chemical properties of an organic compound.
Crude oil
A mixture of hydrocarbons
Organic compounds consisting only of hydrogen and carbon atoms
Fractions
Refinery gases, naphtha, kerosene, diesel and bitumen
Rich Girls Never Kiss Dirty Boys
Uses for the fractions
refinery gases - domestic heating and cooking
gasoline - used as a fuel in cars
Kerosene - used as a fuel in aircraft
Diesel oil - used as a fuel in some cars, and larger vehicles
fuel oil - used as a fuel in some power stations and large ships
bitumen - used for surfacing roads and roofs
Alkanes
General formula
Cn + H2n + 2
Ns are in subscript
Eg ethane
C2H6
2 carbon atoms = C2
H(2*2) + 2 = H6
Alkanes are classified as saturated hydrocarbons. Why?
Because they contain only hydrogen and carbon atoms
Because the carbon atoms are joined together by single bonds
Structural formulae
Methane
CH4
Ethane
C2H6
Propane
C3H8
Butane
C4H10
Pentane
C5H12
click here for diagrams
My Elephant Prefers Buttered Peanuts
are the simplest type of organic chemical
Alkenes
Alkenes are unsaturated hydrocarbons
They consist of only hydrogen and carbon atoms
They have
double bonds
between their carbon atoms
General formula
CnH2n
Eg ethane
C2H4
2 carbon atoms
Structural formula
Ethene
Propene
Butane
Pentene
click here for diagrams
The functional group of alkenes is C=C
Alkenes react with bromine to form dibromoalkanes
Ethene + bromine -> dibromoethane
CH2 = CH2 + Br2 -> CH2BrCH2Br
Synthetic polymers
An
addition polymer
is made by joining up many small molecules called ‘
monomers
’
See chemistry book for how to draw a
repeat polymer
. Include:
Poly ethene
carrier bags
Poly propene
crates, ropes
Poly chloroethene
cling film
Poly tetrafluorethene
polyphenylethene, aka polystyrene
food packaging
Problems with synthetic polymers
Unable to completely biodegrade
When required disposing of, they must be incinerated. This incineration produces toxic gases in the process of combustion.
Practice deducing monomers from poly,ears and vice versa
calculations
formula mass
the total of the atomic masses of the elements which it contains
percentage mass
where formula mass is used
e.g what percentage of nitric acid, HN03, is nitrogen?
total formula mass = 1 + 14 + (16*3)
total formula mass = 63
formula mass of nitrogen = 14
14/63 * 100 = percentage mass of nitrogen in nitric acid
the mole
as atoms are too small to count, they must be weighed
1 mole is the amount of substance that contains the same amount of particles as there are in atoms in 12g of carbon
Biology
Ecology and the environment
Feeding relationships
Why only 10% of energy is transferred from one trophic level to the next.
The other 90% is used in metabolic reactants in the organism which has consumed the energy.
The transfer of substances and energy along a food chain
Trophic levels
Concepts
Food chains
Arrows go in the direction of energy transfer
Food webs
Pyramids
Of number
Of biomass
Of energy transfer
Structure and functions in living organisms
Respiration
Aerobic
Respiration with oxygen
E.g oxygen + glucose -> carbon dioxide and water
Faster than anaerobic
C6H12O6 + 6O2 -> 6CO2 + 6H2O
Anaerobic
Respiration without oxygen
Glucose -> lactic acid (animals)
Glucose -> ethanol + carbon dioxide (plants)
Slower than aerobic
A chemical reaction which provides energy for cells in the form of ATP
Practical (carbon dioxide)
Change
Ability of organism to respire
E.g germinated beans and dried beans
Organism
Beans
Repeat x3 times
Measure 2
Colour of indicator in test tube with dried beans (orange)
Measure 1
Colour of indicator in test tube with germinated beans (change - yellow)
Same 1
Amount of time left (1hr)
Same 2
Temperature
Hydrogen carbonate indicator is used to show the production of carbon dioxide in respiration
Practical (temperature)
Change
Ability of organisms to respire
Eg dried and germinated beans
Organism
Beans
Repeat x3 times
Measure 1
The temperature of the control flask (dried beans) daily for a week
Measure 2
The temperature of the test flask (germinating beans) daily for a week
Same 1
Mass of beans
Same 2
Type of beans
Other info
Each set of beans is put in a vacuum flask, making sure there’s some air inside to respire, insert a thermometer and seal the flask with cotton wool
Gas exchange
structures of...
thorax
the ribs and upper backbone, and the organs found in the chest
ribs
a cage-like bone structure which protects the heart and lungs (thoracic organs)
intercostal muscles
sets of muscles between the ribs which lower and raise the ribcage
diaphragm
a large sheet of muscle which separates the lungs from the abdominal cavity
trachea
the pipe which connects the larynx to the lungs
bronchi
the two major air tubes in the lungs
bronchioles
the small branching tubules into which the bronchi divide
alveoli
tiny air sacs in the lungs, where gas is exchanged during breathing
pleural membranes
thin, moist membranes surrounding the lungs, keeping them airtight
the role of the diaphragm and intercostal muscles in ventilation/breathing
breathing in
internal intercostal muscles relax, external contract
rib cage is pulled upwards and outwards
lung volume increases and the air pressure decreases
the diaphragm contracts
air is pushed into the lungs
breathing out
internal intercostal muscles contract, external relax
the diaphragm relaxes
rib cage is pushed downwards
air is pushed out of the lungs
lung volume decreases and air pressure increases
how alveoli are adapted for their function
thin walls (only one cell thick)
surrounded by a large number of blood vessels, so as to transfer oxygen into said vessels quickly
moist walls
large surface area to volume ratio
biological consequences of smoking
smoke irritates the bronchus causing
bronchitis
cigarette smoke contains harmful chemicals which damage the cilia, cells which waft trapped pathogens inside sticky mucus
mucus builds up and causes the smoker to cough more often
cigarette smoke damages the walls of the alveoli, and cause them to merge together, decreasing the surface area and affecting the efficiency of the alveoli during gas exchange
carbon monoxide, a chemical inside cigarettes, combines with the haemoglobin in red blood cells. this reduces the amount of oxygen haemoglobin can transport inside the bloodstream, as there is too much carbon monoxide.
this produces strain on the circulatory system, and puts the smoker at higher risk of
coronary heart disease
and
strokes
tobacco smoke contains carcinogens, which cause cancer, such as tar. when smoking, you inhale these carcinogens, and tar coats your lungs, putting you at higher risk of lung, mouth, throat and oesophagus cancer
practical - effect of exercise on respiration
Change
amount of exercise (time)
Organism
human
Repeat x3 times
Same 1
age of human
Same 2
sex of human
Measure 1
number of breaths per minute before exercise
Measure 2
number of breaths per minute after exercise
additional info
sit still for five minutes and count breaths
do four minutes of exercise and then count breaths per minute
ask two people to do the explained test below three times
practical - investigate the release of carbon dioxide
Change
position of tube with mouthpiece inside test tubes
Organism
human
Repeat x3 times
Measure 1
colour of boiling tube without limewater
Measure 2
colour of boiling tube with limewater
Same 1
status before each breath (level of exercise)
Same 2
amount of limewater
two boiling tubes are filled with an equal amount of limewater. bungs with two holes in the top are fitted into the boiling tubes. place a mouthpiece as shown on the right into the test tubes and breath out through the mouthpiece
Transport
why simple unicellular organisms can rely on diffusion for movement of substances in and out of cell
unicellular organisms often have a large surface area to volume ratio
the needs of transport systems in multicellular organisms
multicellular organisms have a small area to volume ratio, and therefore require specialised exchange surfaces and transport systems
role of phloem
to transport sugars, such as sucrose and amino acids, from where they're made in the leaf to other parts in the plant
known as translocation
role of xylem
to transport water and mineral salts from the roots to the shoots in a plant
known as transpiration
composition of blood
platelets
white blood cells
plasma
the liquid part of the blood
carries almost everything in the blood
platelets, red and white blood cells
digested food products
carbon dioxide from body cells to lungs
urea from liver to kidney
hormones
heat energy
is a pale yellow liquid
red blood cells
transport oxygen from the lungs to everywhere in the body
plasma
Role
Carries large amounts of required substances for metabolic reactions
Platelets, red and white blood cells
Carbon dioxide from body cells to lungs
Digested food products
Urea from liver to kidneys
Hormones
Heat energy
The liquid part of the blood without the blood cells
how red blood cells are adapted to their function
Absence of a nucleus
Allows more space for haemoglobin which carries oxygen
Biconcave shape
To give a large surface area for absorbing and releasing oxygen
Presence of haemoglobin
What gives blood its colour
Contains high levels of iron
Reacts with oxygen to form oxyhemoglobin in the lungs
How the immune system responds to disease
Phagocytes ingest pathogens
Detect foreign substances by engulfing them
Are non-specific : attack anything that is unfamiliar
Lymphocytes produce antibodies
Every pathogen has unique surface molecules called antigens
When certain white blood cells - lymphocytes - came across foreign antigens, proteins called antibodies are produced
Antibodies lock onto the pathogen and label them for destruction by other white blood cells. Antibodies are specific to antigen, so they won’t lock onto any other pathogen
Antibodies are produced rapidly and flow throughout the body to label similar pathogenic cells
Memory cells are produced in reaction to a foreign antigen. These help to produce antibody producing cells rapidly if the same pathogen is detected.
Coordination and response
Homeostasis
How organisms respond to their environment.
The CNS (Central Nervous System) is made up of neurones. These neurones are attached to cells which perform different actions inside the CNS
Receptors
Groups of cells in he sense organs which detect stimuli
Effectors
Muscles or glands which receive electrical impulses and bring about a response
Different types of neurones
Motor
Where the electrical impulse travels when transferred from the CNS to the effector
Sensory
Where the electrical impulse travels from the receptors to the CNS (Brain and spinal cord)
Relay
The tiny neurones inside the CNS which connect the sensory to the motor neurones
Plants
Respond to stimuli
Trophic responses
Geotrophic
Positive -Growth in the direction of gravity
E.g plant roots
Negative - growth away from the direction of gravity
E.g plant shoots
Phototropism
Positive - Growth towards a source of light
E.g plant shoots
Negative - growth away from a source of light
E.g plant roots
Stimulus - a change in the environment
Nervous and endocrine system
Differences
Speed
Time period
Target area
Form of message
Nervous - electrical impulse
Endocrine - chemicals
Hormones
Adrenaline
Comes from the adrenal glands, above th kidneys
Readies the body for ‘fight or flight’ response
Insulin
Comes from the pancreas
Helps control the blood sugar level
Testosterone
Comes from testes
The main male sex hormone
Progesterone
Comes from the ovaries
Supports pregnancy
Oestrogen
Also comes from the ovaries
The main female sex hormone
The CNS
Brain
Spinal cord
Linked to sense organs by nerves
Synapses
The connection between two neurones
When the electrical impulse reaches the synapse, the diffusion of neurotransmitters is activated, carrying the electrical impulse across the gap and starting it at the next neurone
The eye
Accommodation
Focusing on distant objects
Ciliary muscles relax
Suspensory ligaments pull tight
Lens becomes thinnner
Less light is refracted
Focusing on near objects
Suspensory ligaments become loose
Lens widens
More light is refracted
Ciliary muscles contract
Parts of the eye
Conjunctiva
Lubricates and protects the outer surface of the eye
Conjunctivitis - the absence of aa conjunctiva, resulting in dry eyes and pain when blinking
Retina
The location in the eye with the highest concentration of
light receptors
Rods - sensitive in dim light, cant sense colour
Cones - sense colour
Iris
Controls the diameter of the
pupil
Suspensory ligaments
Connects ciliary muscles to the lens
Ciliary muscles
Muscles connected to the lens by suspensory ligaments
Optic nerve
Carries impulses from the receptors to the brain
Sclera
Tough outer layer which protects the eye
Cornea
Refracts light into the eye
Is transparent and has no blood vessels with oxygen supply
Lens
Focuses light onto the retina
Pupil
The large black hole where light enters the eye after being refracted by the cornea
Organelles in plant cells which aren’t in animal cells
