AQA Biology Unit 5 notes (BIOL5)

So these notes are like my other ones. Ive made them mostly based on the book so everything you need to know is in there. They're more condensed than the book but i dont think there is any vital information missing. I hope they're useful good luck :)

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  • Created by: bssjonny
  • Created on: 10-06-12 20:31
Preview of AQA Biology Unit 5 notes (BIOL5)

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Unit 5 Biology notes

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Section 9.1 ­ Sensory Reception
Section 9.2 ­ Nervous Control
Section 9.3 ­ Control of heart rate
Section 9.4 ­ Role of receptors
Section 10.1 ­ Coordination
Section 10.2 ­ Neurons
Section 10.3 ­ The nerve impulse
Section 10.5 ­ The speed of a nerve impulse
Section 10.6/10.7 ­ Structure and function of the synapse / Transmission across a synapse
Section 11.1 ­ Structure of skeletal muscle
Section 11.2 contraction of skeletal muscle
Section 12.1 ­ Principle of homeostasis
Section 12.2 Thermoregulation
Section 12.…read more

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Section 9.1 ­ Sensory Reception
A stimulus is a detectable change in the internal or external environment of an
organism that produces a response.
The ability to respond to a stimulus increases an organism's chances of survival.
Receptors transfer the energy of a stimulus into a form that can be processed by the
organism and leads to a response.
The response is carried out by "effectors" which can include cells, tissues, organs
and systems.…read more

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Section 9.2 ­ Nervous Control
Nervous organisation
The nervous system can be thought of as having two main divisions:
1.) The central nervous system (CNS) ­ brain and spinal cord
2.…read more

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Coordinator (intermediate neuron)
6.) Synapse
7.) Motor neuron
8.) Effecter
9.) Response
Importance of the reflex arc
Involuntary ­ does not require the decision making power of the brains
Brain can override the response if necessary
Protects the body from harmful stimuli
Effective from birth ­ does not need to be learnt
Short pathway ­ fewer synapses
Synapses ­ slow
Neurons ­ fast
Section 9.…read more

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This section then increases the number of impulses sent to the S.A node via the sympathetic
nervous system
This results in an increase in heart rate which then causes blood pH to return to normal.
Control by pressure receptors
Pressure receptors occur in the wall of the carotid arteries and the aorta
When blood pressure is too high ­ impulses are sent to the medulla oblongata which then
sends impulses to the S.…read more

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Different receptors respond to a different intensity of a stimulus
Light receptors of the eye are found in the retina (the inner most layer)
The light receptors in the eye can are of two types, rod and cone cells. Both receptors
convert light energy into a nervous impulse and are therefore acting as transducers
Rod cells
Cannot distinguish between different wavelengths
Many rod cells are connected to the same neuron and so can function at low light intensities.…read more

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Section 10.1 ­ Coordination
Body systems cannot work in isolation and must therefore be integrated in a coordinated
Principles of coordination
In mammals, there are two main forms of coordination:
1.) The nervous system ­ Uses nerve cells that can pass electrical impulses along
their length. The result is the secretion of chemicals by the target cells called
neurotransmitters. The response is quick, yet short lived and only acts on a
localised region of the body.
2.…read more

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Effect may be permanent/long lasting/ Effect is temporary and reversible
Plant growth factors
Plants respond to external stimuli by means of plant growth factors (plant hormones)
Plant growth factors:
Exert their influence by affecting growth
Are not produced by a particular organ, but are instead produced by all cells
affect the tissues that actually produce them, rather than other tissues in a different
area of the plant.…read more

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Section 10.2 ­ Neurons
Specialised cells adapted to rapidly carry electrochemical changes (nerve impulses) from
part of the body to another
Neuron structure
Cell body
Large amounts of rough
endoplasmic reticulum to produce
Extensions of the cell body
subdivided into dendrites
Carry nervous impulses to the cell
A single long fibre that carries nerve impulses away from the cell body
Schwann cell
Surrounds the axon
Protection/electrical insulation/phagocytosis. Can remove cell debris and are
associated with nerve regeneration.…read more



absolute legend

Yusra Ahmed

when co2  concentration is high, the ph is lowered  and when co2 concentration is low ph increases .....there is a confusion of this in the notes in the control heart rate section. 

matthew adelekan

thanks pal

matthew adelekan

these notes are not goiod enough

matthew adelekan


Lucy Chapman

thank, helps a lot!

Grace Hillsmith

Great notes, but you've spelt neurones as neurons all the way through and being the grammar Nazi I am, I had to correct every single one.


Very good notes. 

sasha fortell

link doesnt work?

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