F214 OCR A2 Biology Module 4 Respiration

This is a very detailed document on Respiration answering every part of the specification. It is along the same lines as all of the other F214 and F215 documents I have put up on here...there is now one for every module in the A2 specification. 

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  • Created on: 21-06-11 20:29
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F214 Communication, Homeostasis and Energy
Module 4 Respiration
4.4.1 Respiration
a. Outline why plants, animals and microorganisms need to respire, with reference to
active transport and metabolic reactions
All living organisms need energy so as to undergo their biological processes, of
which all of the reactions are known altogether as metabolism.
Metabolic reactions
o Those that build large molecules are anabolic.
o Those that break large molecules into smaller ones are catabolic.
o Active transport
It is when ions and molecules are moved across a membrane
against the concentration gradient. A lot of an organisms energy
is used for this.
o Secretion
When large molecules in some cells are removed via exocytosis.
o Endocytosis
The movement of large molecules into the cell.
o Synthesis of large molecules from smaller ones.
o Replication of DNA and synthesis of organelles.
o Movement e.g. cilia
o Activation of chemicals.
b. Describe the structure of ATP
Adenosine= Ribose + Adenine
Adenosine Monophosphate= Phosphate + Ribose + Adenine
Adenosine Diphosphate= Phosphate + Phosphate + Ribose + Adenine

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Adenosine Triphosphate= Phosphate + Phosphate + Phosphate + Ribose + Adenine
c. State that ATP provides the immediate source for biological processes
ATP is a universal energy currency because it is in every living organism in cells,
and energy can be created by losing a phosphate group and can be added to the
molecule by adding a phosphate.
Each phosphate released releases 30.6Kj of energy.
A phosphate is released by hydrolysis of ATP.
d.…read more

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Another ATP molecule is hydrolysed to release another 30.6Kj of
o This released phosphate group joins to the fructose 6-phosphate.
o This activates the hexose sugar so it is now fructose 1,6-bisphosphate.
o It now becomes a phosphorylated sugar known as hexose
o Two molecules have been used for each molecule of glucose
Splitting of hexose bisphosphate
o Each molecule is split into two molecules of triose phosphate which is a
three carbon sugar.…read more

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Here there are the enzymes needed for the reactions.
o There are molecules of NAD for the hydrogen molecules to attach to.
o There is oxaloacetate which accepts acetate from the link reaction.
o There is mitochondrial DNA which codes for some of the proteins and
mitochondrial enzymes that may be needed.
o There are mitochondrial ribosomes for the assemblage of proteins.
Outer membrane
o It contains proteins some of which will form channels or carriers to allow
the passage of molecules.…read more

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Krebs cycle
o Acetate is removed from the coenzyme a and joins with oxyaloacetate to
form citrate.
o Citrate is decarboxylated (removing one carbon dioxide molecule) and
dehydrogenated (removing a pair of hydrogen atoms) to form a five
carbon compound.
o The pair of hydrogen atoms are accepted by NAD which makes Reduced
o The 5 carbon compound is decarboxylated and dehydrogenated to form
a 4 carbon compound and another molecule of Reduced NAD is made.…read more

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The electrons flow down the electron transport chain releasing energy
which is used by the coenzymes associated with some of the electron
o The energy pumps the protons across the intermembrane space.
o So a proton gradient, a pH gradient and a electrochemical gradient build
o Potential energy builds up in the intermembrane space.
o The hydrogen ions cannot diffuse through the lipid inner membrane but it
can diffuse through channels in it. The channels are associated with ATP
synthase.…read more

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Some protons may leak across the mitochondrial membrane so reducing
the number of protons to generate the proton motive force.
o Some ATP produced is used to actively transport pyruvate into the
o Some ATP is used to bring hydrogen from reduced NAD made in
glycolysis into the cytoplasm of the mitochondria.
t. Explain why anaerobic respiration produces a much lower yield of ATP than aerobic
There is no final electron acceptor in oxidative phosphorylation if there is no
oxygen.…read more

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Explain the difference in relative energy values of carbohydrate, lipid and protein
respiratory substrates
Carbohydrate Lipid Protein
Energy value=15.8 Energy Energy
kJg-1 value=39.4kJg-1 value=17.0kJg-1
Theoretically the Each fatty acid is When an organism
respiration of 1 mol combined with CoA undergoes fasting,
of glucose should be which needs energy starvation or
nearly 94 but it is from the hydrolysis prolonged exercise
more like 30 mol of ATP to AMP. protein from
ATP. muscles can be
The fatty acid-CoA respired.…read more



there are some errors in your notes regarding the light dependant and light independant reactions

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