B6, P6, C6 OCR Additional Science Full Revision Notes

For those doing the exam on Wednesday the 20th June, these notes pretty much cover everything! Hope they help as they took me ages!

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  • Created on: 17-06-12 23:03
Preview of B6, P6, C6 OCR Additional Science Full Revision Notes

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The CNS (see left) allows organisms to react to
their surroundings or stimuli and coordinate
their responses.
Animals respond to stimuli (change in
environment) in order to keep themselves in
favourable conditions.
The CNS is connected to the body via sensory
and motor neurons which make the peripheral
nervous system (the second major division of
the nervous system); this transmits messages
all over the body and also to and from the CNS.
Sensory Neurons carry nervous impulses FROM receptors TO the CNS
Motor Neurons carry nervous impulses FROM the CNS TO effectors.
Skin- touch, pressure, pain, temperature
Tongue ­ salty, sweet, bitter, sour, umami
Ear - sound, balance (position of head)
Retina - light
Nose ­ smell/chemicals in air, also helps with taste
When neurons are stimulated they transmit an impulse
In motor neurons, the cytoplasm forms a long fibre surrounded by cell membrane
called an axon.
Some axons are surrounded a fatty sheath, its job is to insulate the neuron from
neighbouring cells and speed up transmission of the impulse.
A synapse is a gap between two adjacent neurons (humans have between 100
and 500 trillion)
Receptor molecules only bind with specific chemicals.
1. The electrical signal or nerve impulse moves through the sensory neuron.
2. At the end of a sensory neuron chemicals or neurotransmitters are released into
the synapse and they then diffuse across the synapse.
3. When these chemicals reach a motor neuron they bind with receptor molecules on
the membrane of the motor neuron.
4. A nerve impulse is then initated in the motor neuron and the signal continues on its

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Simple reflexes produce rapid involuntary/automatic responses
These involve both sensory and motor neurons
Animals use these simple reflexes to help find food, shelter from predators, find a
mate or avoid injuries, they rely on reflex actions for the majority of their
However, the disadvantage of this type of behaviour is that animals have difficulty
responding to new situations
Reflex Arc
1. A receptor is stimulated by the stimulus (eg, drawing pin, fire)
2.…read more

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Every time a new experience happens, a different pathway between neurons is
stimulated, and as experiences are repeated, this is strengthened, with frequently
activated pathways being preserved and any pathways not used regularly being
deleted.…read more

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A wave consists of disturbances that transfer energy in the direction that the wave travels,
without transferring matter, there are two different types of waves (see below)
A longitudinal wave is when each particle moves backwards and fowards in the same plane
as the direction of wave movement. Each particle simply vibrates to and fro about it's normal
position. Sound is an example.…read more

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When two waves meet, their effects can add up, this is called interference.
Constructive Interference: When they arrive in step they reinforce each other,
adding up their amplitudes
Destructive Interference: When they arrive out of step they cancel each other
out as the peak of one can meet the trough of the other.…read more

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Analogue Signals
In AM, the amplitude of the carrier wave is changed by the input signal. In FM, the input
signal causes the frequency of the carrier wave to change. Both these signals vary in
exactly the same way as the information it is carrying and can have almost any value.
Digital Signals
Information, such as sound, can be transmitted digitally. This is when the signal is not
sent as a continually varying transmission but is first converted into a digital code.…read more

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Measured using a universal indicator
When dissolved in water, acidic compounds produce aqueous hydrogen ions.
When dissolved in water, alkali compounds produce hydroxide ions.…read more

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Hydrochloric Acid HCl Gas
Sodium Hydroxide NaOH -
Potassium KOH -
Magnesium Mg(OH)2 -
Calcium Hydroxide Ca(OH)2 -
When an acid and a base are mixed together in the correct amounts, they cancel
each other out.…read more

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Oxygen O2
Chemical Synthesis
Reactants react to produce products and the greater the reactants used, the
greater the product formed. You can calculate the percentage yield:
Percentage Yield = Actual yield/Theoretical yield x 100
This shows how much you produced compared to what you expected.
Stages to Chemical Synthesis
1. Choosing reaction/reactions that are needed to make the product
2. Risk assessment
3. Calculating quantities of reactants needed
4. Carry the reaction out using suitable apparatus/conditions
5. Separate product from reaction mixture
6.…read more

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Write down the equation
CaCO3 -> CaO + CO2
2. Work out the formula mass of each substance
40+12+(3x16) -> (40+16) + (12+(2x16))
3. Check total mass for both equals up
4. You can then write the ratio, ignoring carbon dioxide as the question does not
mention it
5. You can then use this to answer the question, which would be 28kg of Calcium
Oxide.…read more


Sanjeeda Jalil

This was really useful as I have an exam tomorrow.

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