Biology- The Variety Of Life

AS level biology, revision index cards for the topics (AQA)

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  • Created by: joti
  • Created on: 01-05-12 08:30


Four polypeptide chains in a globular shape, Each is apart of a Haem (Fe2+), which can acrry one O2 molecule #

Must be able to readily assosciate/dissociate O2 at gas exchange/respiring tissues

Organisms that live in low O2 environments will have haemoglobin with a high affinity - hard to release O2

Organisms that live in high O2 environments will have a low affinity of O2- releases it easily

Both are caused by the shape in the molecule- they vary slightly between the two

O2 associates at the lungs and dissociates at respiring tissues

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Oxygen dissociation curves

Graph is to the left->the greater the affinity

Graph is to the right->the lower the affinity

Where CO2 is highly present, the affinity is lowered-> O2 released at tissues, and vice versa (Bohr effect)

^ rate of transpiration-> ^ CO2 produced @ tissues-> lower pH (due to low levels of CO2) -> ^ the shape change of haemoglobin-> ^ O2 is unloaded-> more O2 available for respiration

Factors= Size (v-s.a), Environment, Activity (birds/fish are demanding-> energy)  

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Plant cell structure

Leaf palisade cell--> long, thin (to absorb sunlight), large vacuoles  

Chloroplasts--> Envelope (double membrane), Grana (stacked up thylakoids), Thylakoids (contain chlorophyll, joint with others with tubes and where 1st stage of photosynthesis takes place), Stroma (fluid filled matrix, 2nd stage of photosynthesis)

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