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Biology

A Level

What are enzyme inhibitors?

Enzyme inhibitors function to slow down the rate of an enzyme catalysed reaction by interfering with the enzyme in some form. There are two main types of inhibitors:

Answered by Yasmin A. • Biology tutor

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What are the roles of the sinoatrial node (SAN) and the atrio-ventricular node (AVN)?

The heart muscle is myogenic and initiates a heartbeat through an electrical conduction system; both the sinoatrial node and atrio-ventricular node are essential in this mechanism.

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Answered by Shelby P. • Biology tutor

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What events occur during the cardiac cycle?

Within the heart the atria contract creating a high pressure and squeezing blood into the ventricles. The semi lunar valves are closed so pressure within the ventricles builds up.Pressure within the ve...

Answered by James H. • Biology tutor

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Describe how negative feedback is used to control blood glucose concentration (6 marks)

Throughout your answer to this question make sure that you are cramming as much key language into it as possible! Phrases like 'islets of Langerhans', 'beta/alpha cells', and 'transporter proteins' will a...

Answered by Matt H. • Biology tutor

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How does a deletion of a base in the DNA base sequence lead to a mutated protein?

It is important to note that bases on the DNA (and mRNA) are read in separate sets of 3s along a DNA/(mRNA) stand (this is called a triplet code in DNA, or the codon in mRNA). So, if a base is deleted,...

Answered by Febi S. • Biology tutor

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