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How to answer an exam question such as "how might action potential transmission be affected by multiple sclerosis, a nervous system disease characterised by damage to neuronal myelin sheaths"

5 marking points to hit:Transmission of action potential will be slower in neurons with damaged myelin sheaths (1) because myelin is an electrical insulator (2) so increases the speed of action potential con...
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Answered by Rebecca A. • Biology tutor
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How does sexual selection lead to the evolution of elaborate male traits?

Observing animal species with exaggerated ornaments and weapons that do not seem of importance in the animal’s struggle for survival, Darwin created the concept of sexual selection to account for the evoluti...
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Answered by Zdravko Z. • Biology tutor
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How are epigenetics involved in regulating gene expression?

Epigenetic control of gene expression involves mechanisms that do not alter the sequence of DNA itself. External factors acting upon cells translate their signals via cascades to the nucleus, where they act ...
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Answered by Harry H. • Biology tutor
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What's the difference between the 'lock and key' and 'induced fit' models for enzymes?

The lock and key hypothesis suggests that the enzyme has a fixed shape/structure and the substrate has to fit into this exactly for catalysis to occur. The induced fit hypothesis is different in that it sugg...
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Answered by Harriet W. • Biology tutor
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Describe and explain how an action potential is generated

This is a common question, that takes a little while to get your head around. Once you've understood the process, it can be simplified down to a cycle of 3 steps for memory: depolarisation , repolarisation a...
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Answered by Diluxshan S. • Biology tutor
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