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Describe the sliding filament theory.

The sliding filament theory demonstrates how the muscles in our body contract. As a signal reaches the neuromuscular junction (motor end plate), neurotransmitters such as Acetylcholine will diffuse across th...
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Answered by Rithvik G. • Biology tutor
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What is the structure of a protein?

Structure of the protein is easier to understand if we start from the beginning and gradually build up our knowledge. Firstly, proteins are made of amino acids. Each amino acid is made of a central carbon at...
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Answered by Daria S. • Biology tutor
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Why do chemical impulses only go in one direction across a synapse?

Ca2+ channels are only in the membrane of the presynaptic neuron. ACh-containing vesicles are only within the presynaptic neuron. (ACh only produced within the presynaptic neuron, has choline and acetyl)APs ...
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Answered by Reiss C. • Biology tutor
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Describe how oxygen in the air reaches capillaries surrounding alveoli in the lungs. Details of breathing are not required. (AQA Biol. 2016)

Oxygen diffuses from the air where it is present at a higher concentration and pressure, to the lungs where it is at a lower concentration and pressure - we say it moves 'down' these gradients; high to low. ...
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Answered by David M. • Biology tutor
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Describe what is meant by the double circulation system of the heart.

The double circulatory system refers to the heart having two, connected, closed circuits. The first goes from the right ventricle of the heart to the lungs and back to heart via the left atrium. The second p...
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Answered by Ibrahim M. • Biology tutor
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