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What are the non-specific defence systems of the body against pathogens?

There are four main non-specific defence systems, all of which are immediate and the same for all pathogens (hence 'non-specific).1) skin: it acts as a primary defence mechanism as the dry, dead cells on the...
SH
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People who have McArdie's disease produce less ATP than healthy people. As a result, they are not able to maintain strong muscle contraction during exercise. Use your knowledge of the sliding filament theory to suggest why (AQA BIOL5)

Idea ATP is needed for:1. Attachment / cross bridges between actin and myosin;2. Power stroke / movement of myosin heads in rowing action / pulling of actin towards the centre of the sarcomere;3. Detachment ...
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Answered by Salma O. • Biology tutor
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Discuss the basis and variable outcomes of gene mutations

Mutations may be inherited or may arise sponataneously, resulting in distinct differences between individuals. Thus, given that genetic material is the single determinant of phenotypical characteristics, gen...
YM
Answered by Yousef M. • Biology tutor
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What exactly causes the sounds heard by a stethoscope

There are 2 sounds heard by a stethoscope, the so called 'lub dub'. The lub being the closing of the atrioventricular valves (i.e. the valves between the atria and the ventricles). This is caused by an incre...
JL
Answered by John L. • Biology tutor
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Explain why cell surface membranes are also called 'phospholipid bilayers'?

A cell surface membrane is made up of a type of molecules called phospholipids , so what is a phospholipid bilayer ? The first step would be to break down the term. ‘ Phospho ’ means that the molecule(s) mus...
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Answered by Jamie C. • Biology tutor
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