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F214 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
Respiration ­ the process whereby energy stored in complex organic molecules (carbohydrates, fats and proteins)
is used to make ATP, occurring in living cells.

All living…

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F214 Module 4: Respiration

(d) explain the importance of coenzymes in respiration, with reference to NAD and coenzyme A

The Stages of Respiration:
Glycolysis occurs in the cytoplasm which can take place in aerobic or anaerobic conditions. Glucose is broken
down to two molecules of pyruvate.
The link reaction occurs…

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F214 Module 4: Respiration
fatty acids or from some amino acids onto

Krebs cycle.
(e) state that glycolysis takes place in the cytoplasm
Glycolysis is a very ancient biochemical pathway, occurring in the cytoplasm of all living cells (prokaryotic and
eukaryotic) that respire. It is an anaerobic metabolic pathway.


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F214 Module 4: Respiration
8. The triose phosphate molecules are converted to pyruvate , which is actively transportedto the mitochondrial
matrix . In the process, another two molecules of ADP are phosphorylated to make twomolecules of ATP .

(g) state that, during aerobic respiration in animals, pyruvate is actively transported…

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F214 Module 4: Respiration
the next electron carrier. They are oxidoreductase enzymes as they are involved in oxidation
and reduction reactions.
3. Some of the electron carriers also have a coenzyme that pumps (using the energy released
from the passage of electrons) protons from the matrix to the intermembrane space…

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F214 Module 4: Respiration

1. The acetate is offloaded from coenzyme A and joins with oxaloacetate (4C), to form citrate (6C).
2. Citrate is decarboxylated and dehydrogenated forming a 5carbon compound . The pair of hydrogen atoms is
accepted by the coenzyme NAD (hydrogen acceptor), which becomes reduced NAD .…

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F214 Module 4: Respiration

1. NADH is reoxidised to form NAD+ and 2 hydrogen atoms, aided by the enzyme NADH dehydrogenase
which is attached to the first electron carrier. The hydrogen atoms split into protons and electrons.

2H 2H + 2e
2. The electrons are…

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F214 Module 4: Respiration
The electron transfer enzymes are embedded in
the inner membrane.

The pH of the intermembrane space was lower than There's a higher concentration of H+ ions in the
that of the matrix . intermembrane space meaning the H ions move
from the matrix, across the…

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F214 Module 4: Respiration

(v) define the term respiratory substrate
Respiratory Substrate ­ an organic substance that can be used for respiration.

The more protons , the more ATP produced as most ATP is formed from the flow of protons through channel
proteins during chemiosmosis . Therefore the more hydrogen…

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F214 Module 4: Respiration
How does a respirometer work?
1. In the boiling tube the volume of oxygen decreases due to respiration . The volume of carbon dioxide also
decreases as the soda lime absorbs it.
2. Overall, the volume of the boiling tube decrease , causing an air pressure…


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