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Explain the roles of ATP and calcium ions in muscle contraction. (4 marks)

The hydrolysis of ATP provides the energy necessary to break the cross-bridges formed between actin and myosin heads. The hydrolysis of ATP is also used to provide the energy for the power stroke, which is w...
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Answered by Rachel H. • Biology tutor
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What is ATP and why do we need it?

ATP is short for adenosine triphosphate, and it can be thought of as the energy 'currency' in our cells. It has a similar structure to that of an RNA nucleotide, as it is comprised of a nitrogenous base (ade...
TD
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I feel like I understand the concept, why I am I still not getting full marks on the question?

Understanding concepts in exams is only part of the battle. To improve your marks you need to improve your exam technique! For example: Have you correctly interpreted what the question is asking of you? Is y...
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Answered by Tom R. • Biology tutor
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Explain pieces of evidence that support the theory that mitochondria evolved from bacteria?

Mitochondria are one of the three eukaryotic organelles that have a double membrane (along with chloroplasts and the nucleus), two of which are believed to have evolved from bacteria (mitochondria from Prote...
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Answered by Angus L. • Biology tutor
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What factors affect the rate of conduction of an action potential (AP) down a neurone?

MYELINATION A lipid myelin sheath is wrapped around the axon of the neurone in SEGMENTS. Only the parts of the axon exposed contain Na/K channels that will participate in the conduction of the AP. These segm...
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Answered by Fahad A. • Biology tutor
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