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Biology
A Level

Explain the role of the diaphragm when breathing in and out

The diaphragm is a large muscle located at the base of the lungs. It is naturally dome shaped when relaxed. 

When we need to inhale, the diaphragm will contract and flatten out. This increases the ...

SK
Answered by Salko K. Biology tutor
5436 Views

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 th...

JH
Answered by Josh H. Biology tutor
8312 Views

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 h...

SJ
Answered by Samuel J. Biology tutor
9456 Views

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 oxygenat...

TS
Answered by Tara S. Biology tutor
16460 Views

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 a...

JA
Answered by Jack A. Biology tutor
2506 Views

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