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How can genetically identical twins look different?

There are two key pieces of terminology that it is important to understand with this question; genotype and phenotype . All sexual organisms inherit a mix of genes from their parents. This mix - the genetic ...
JH
Answered by Josh H. • Biology tutor
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Is normal expiration, at rest, a passive or active process in a healthy individual? And why?

Expiration is a passive process. It happens due to relaxation, not contraction, of the muscles of the chest. As well as the elastic recoil of the lungs. Both of these processes do not require energy and henc...
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Answered by Samuel J. • Biology tutor
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Describe the cardiac cycle (7 marks)

During diastole the atria and ventricles are relaxed. The atrioventricular valves are open and the semilunar valves are closed. Deoxygenated blood enters the right atrium from the venae cavae and oxygenated ...
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Answered by Tara S. • Biology tutor
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How do electrical impulses control contraction of the heart?

Electrical impulses from the SAN (sinoatrial node) spread across the atria walls to cause contraction. The impulses then pass to the ventricles via the AVN (atrioventricular node) after a short delay to allo...
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Answered by Jack A. • Biology tutor
3085 Views

Why is an action potential an all or nothing process?

An action potential is the signal neurons use to communicate with each other. It is caused by the rapid opening of sodium channels and influx of sodium ions. Because at rest the inside of the neuron is negat...
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Answered by Gemma G. • Biology tutor
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