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What is an enzyme and explain its mechanism of action

An enzyme is a protein that is used as a catalyst in a reaction within an organism. This is used in such a way that it lowers the energy requirement for a specific reaction to occur and this could either be ...
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Answered by Michael B. • Biology tutor
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Describe the ionic basis of an action potential, and how this is reflected on the cell's membrane potential (6 marks)

At rest (steady state) there is a greater concentration of Na+ ions and a smaller concentration of K+ ions on the outside compared to the inside of the cell, and the membrane potential is about -70mV. Upon d...
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What causes the heart to contract?

This type of question requires careful explanation and therefore would need to be broken down into chunks. One of the reasons for this is that it may be completely new concepts for students. My answer to a s...
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Answered by Saajan R. • Biology tutor
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Explain the nervous pathway reflex when touching something hot (5 marks)

The stimulus/heat is detected by receptors in the hand It sends an impulse via sensory neurones to the spinal cord/CNSChemicals are transmitted via the synapses and diffuses across the gap The impulses trave...
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Answered by Lia H. • Biology tutor
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What is left sided heart failure (mark 1), which organ can it lead to fluid buildup in (mark 2) and why (mark 3)

The left atrium receives oxygenated blood from the lungs via the pulmonary vein (the only vein to pump oxygenated blood) and ejects via the left ventricle to the aorta.Left sided heart failure means that the...
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Answered by James P. • Biology tutor
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