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How is air breathed in to the lungs so that oxygen reaches the gas exchange surfaces?

The diaphragm contacts and moves down. The intercostal muscles between the ribs contract. This causes the ribcage and the sternum to move up and out. The thorax increases in width from back to front. This re...
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Answered by Medi S. • Biology tutor
4123 Views

Describe and explain how air enters the lungs during inspiration

The diaphragm contracts and flattens out, increasing the volume of the thorax and decreasing the pressure in there. This causes a pressure gradient between the thorax and the outside air, so air flows into t...
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Answered by Adithya K. • Biology tutor
3135 Views

How do enzyme controlled reactions work?

Firstly, an enzyme is a specific protein with a unique shape. The main aim of an enzyme is to CATALYSE a reaction. This means, the reaction is sped up, but the concentrations of reactants or products are unc...
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Answered by Vedia S. • Biology tutor
12616 Views

How is a nerve impulse transmitted across a synapse?

A synapse is gap between two neurones. When a nerve impulses travels along the axon reaches the end of the pre-synaptic neurone, the release of chemical messengers (called neurotransmitters) is triggered. Th...
MD
Answered by Marina D. • Biology tutor
13759 Views

What is the difference between allopatric and sympatric speciation?

Allopatric speciation occurs when two species are living in separate environments and therefore there is no gene flow between the populations. This will then cause the populations to differentiate (change) b...
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Answered by Olivia L. • Biology tutor
80131 Views