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Why does an action potential not flow backwards in a neuron? How does it always reach the pre-synaptic knob?

When an action potential occurs, the neuron reaches the maximum voltage of +40mV. It then begins to repolarise, with potassium ions diffusing back in to the neuron, down the concentration gradient. This make...
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Answered by Erin M. • Biology tutor
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Describe the loading and unloading of oxygen by Haemoglobin in red blood vessels

Haemoglobin is a protein consisting of four haem groups contained in four polypeptide chains. The loading of oxygen consists of oxygen binding to iron in the haem group at areas of higher oxygen concentratio...
Answered by • Biology tutor
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When is the present subjunctive used?

The subjunctive is a mood rather than a tense and, unlike in English, is used frequently in the French language in both spoken and written forms. It is used: when expressing personal desire (e.g. je veux que...
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Answered by Olivia T. • French tutor
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Find the area under the curve y=xsin(x), between the limits x=-pi/2 and x=pi/2.

We are going to need to use integration for this problem as it involves finding an area under a curve. Also notice that y is a product of two functions of x ; x and sin(x). This means in this particular case...
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Answered by Oakley Y. • Maths tutor
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Give two features of DNA and explain how each one is important in the semi-conservative replication of DNA.

DNA has a number of important features that allow semi-conservative replication to take place. These include:1. DNA bases are held together by weak hydrogen bonds between bases that can be easily broken, all...
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Answered by Alex M. • Biology tutor
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