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Describe an action potential.

A stimulus excites a neuron by causing the opening of sodium channels. This causes an influx of sodium which causes the opening of other voltage-gated sodium channels. This causes the membrane to depolarise ...
MK
Answered by Maciek K. • Biology tutor
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Emphysema is a disease of the lungs. Explain why people suffering from this condition may feel weak and short of breath.(6 marks)

Emphysema is an obstructive lung disease(1), where alveoli collapse due to break down of elastin in their walls(2). This means that the lungs cannot recoil(3), making expiration difficult. There is less surf...
SI
Answered by Sara I. • Biology tutor
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Succinate is converted to fumarate by the enzyme dehydrogenase. This reaction can be inhibited by adding malonate. a) What are enzymes and what are their function? Use this information to explain how malonate acts as an inhibitor.

a) What are enzymes and what are their function? Use this information to explain how malonate acts as an inhibitor. What are enzymes? Enzymes are proteins that act as catalysts in living cells. Catalysts inc...
LS
Answered by Laura S. • Biology tutor
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Suggest and explain why the combined actions of exopeptidases and endopeptidases are more efficient than exopeptidases on their own.

Endopeptidases hydrolyse internal (peptide bonds) OR exopeptididases remove amino acids/hydrolyse (bonds) at the ends therefore there are more ends/increase in surfacae area for expopeptidases to work on.
FT
Answered by Flora T. • Biology tutor
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Endopeptidases and exopeptidases are involved in the hydrolysis of proteins. Name the other type of enzyme required for the complete hydrolysis of proteins to amino acids.

The other type of enzyme required is a dipeptidase.
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Answered by Flora T. • Biology tutor
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