A2 Biology Communication, Homeostasis and Energy (OCR F214)

A comprehensive revision guide made using the OCR syllabus so that absoultely everything is covered. Quite detailed so not ideal if your after quick notes, but theyre more condensed than a text book. Some extra detial to help answer the "suggest why" questions we all know and hate. Hope these can come in useful :)

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Biology F214
Contents
Communication and Homeostasis ..................................................................................................... 1
Communication ............................................................................................................................. 1
Cell signalling ............................................................................................................................. 1
Homeostasis .............................................................................................................................. 1
Thermoregulation ...................................................................................................................... 2
Nerves ........................................................................................................................................... 5
Sensory receptors ...................................................................................................................... 5
Sensory and motor neurones ..................................................................................................... 5
Resting potential........................................................................................................................ 6
Action potential ......................................................................................................................... 6
Cholinergic synapse ................................................................................................................. 10
Hormones.................................................................................................................................... 12
Adrenaline ............................................................................................................................... 12
Pancreas .................................................................................................................................. 13
Glucoregulation ....................................................................................................................... 14
Diabetes Mellitus ..................................................................................................................... 16
Controlling heart rate .............................................................................................................. 17
Excretion ......................................................................................................................................... 18
Importance of removing wastes................................................................................................... 19
CO2 .......................................................................................................................................... 19
Nitrogenous compounds.......................................................................................................... 19
Liver ............................................................................................................................................ 19
Structure ................................................................................................................................. 19
Formation of urea .................................................................................................................... 21
Detoxification .......................................................................................................................... 22
Kidney ......................................................................................................................................... 23
Structure ................................................................................................................................. 23
Function .................................................................................................................................. 25
Osmoregulation ....................................................................................................................... 28
Kidney failure........................................................................................................................... 29
1
©Ross Edwards 2013

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Biology F214 10/05/2013 10:59
Testing urine samples .............................................................................................................. 31
Photosynthesis ................................................................................................................................ 32
Chloroplasts ................................................................................................................................ 32
Photosynthetic pigments ......................................................................................................... 33
Light-dependant stage ................................................................................................................. 34
Photolysis ................................................................................................................................ 34
Photophosphorylation ............................................................................................................. 35
Light-independent stage .............................................................................................................. 36
Limiting factors ............................................................................................................................ 38
Carbon dioxide concentration .................................................................................................. 38
Light intensity .......................................................................................................................... 38
Temperature ........................................................................................................................... 39
Investigating limiting factors .................................................................................................... 39
Respiration ...................................................................................................................................... 41
ATP .............................................................................................................................................. 41
Coenzymes .................................................................................................................................. 43
NAD ......................................................................................................................................... 43
Coenzyme A............................................................................................................................. 43
Overview ..................................................................................................................................... 43
Mitochondria ........................................................................................................................... 43
Glycolysis..................................................................................................................................... 44
Glycolysis summary ................................................................................................................. 46
Link Reaction ...............................................................................................................................…read more

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Biology F214 10/05/2013 10:59
Carbohydrates ......................................................................................................................... 53
Protein .................................................................................................................................... 53
Lipids .......................................................................................................................................…read more

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Biology F214 10/05/2013 10:59
Communication and Homeostasis
Communication
Multicellular organisms require communication systems between cells, tissues and organs
Communication systems respond to changes in internal and external environments
External:
o Changes in external environment can place stress on an organism (e.g.…read more

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Biology F214 10/05/2013 10:59
The initial change in the internal environment is called a stimulus, and is detected by receptor
cells
o These sensory receptors are internal, constantly monitoring a specific condition (e.g.…read more

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Biology F214 10/05/2013 10:59
Less surface area exposed so less heat absorbed
o Increase breathing movements
More water evaporates from breath, drawing away latent heat
When they are too cold:
o Expose body to sun
Absorb heat from the sun
o Orientate body to sun
More surface area exposed so more heat absorbed
o Alter body shape (e.g.…read more

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Biology F214 10/05/2013 10:59
o When it is too hot, rate of metabolism in hepatocytes (liver cells) is reduced, decreasing
exergonic reactions
o When it is too cold, rate of metabolism in hepatocytes is increased, increasing exergonic
reactions
Shivering
o When it is too cold, muscles spontaneously contract, requiring more respiration
producing more heat
Limb orientation
o When it is too hot, spread limbs out to increase surface area heat can be lost from
o When it is too cold, curl into a ball to…read more

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Biology F214 10/05/2013 10:59
Nerves
Sensory receptors
Sensory receptors detect a stimulus
They convert the energy of the stimulus into electrical energy
This electrical energy is sent down sensory neurones as a nerve impulse
Sensory receptors are called energy transducers because they convert one form of energy to
another
The types of energy which can be converted by sensory receptors are
o Light intensity (light energy) ­ sight
o Volatile chemicals (chemical energy) - smell
o Soluble chemicals (chemical energy) ­ taste
o Pressure (kinetic…read more

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Biology F214 10/05/2013 10:59
Motor neurones have their cell body within the CNS (no Dendron) and a long axon
(CNSeffector)
Both types have many dendrites which connect with other neurones
Resting potential
Neurones contain gated sodium and potassium ion channels
o These are channel proteins that allow only either sodium or potassium through
o They are gated so that their passage through the channel can be controlled
o When the gates are open, the cell surface membranes permeability to the particular ion
is increased
Neurones…read more

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Biology F214 10/05/2013 10:59
The sodium/potassium ion pumps remain active to maintain the resting potential
Some gated potassium ion channels are open, so some potassium ions diffuse back out of the
neurone
When there is a stimulus, the receptor cells (in the generator region), the gated sodium ion
channels open due to the change in energy which the specific receptor cells detect
Sodium ions diffuse into the cell through these channels
The membrane depolarises to become less negative with respect to the outside
It reaches…read more

Comments

Swallowtail

These notes are brilliantly presented with good annotated diagrams covering the topics included in the OCR F214 module. This includes communication, homeostasis, nerves, hormones, respiration and photosynthesis. Use them as your notes or to create revision cards of the key facts. 

Alex`

where can I get this

mariam

Hi 

the link doesnt seem to be working, could you please fix it. Very much appreciated!

holly

no link?

Momo.

Can someone please re upload this? Don't want to miss out!

Bethany Sawyer

Please re-upload this, it says page not found and I am in urgent need of it

yalini97

Hi thank you so much for these notes! they were very detailed and it was so helpful. I do CIE not OCR but still your notes were so understandable with the common topics. Thank you so much again!

YusufTheMan

SUPER DUPER

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