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Describe and explain how the lungs are adapted to allow rapid exchange of oxygen between the air in the alveoli and blood in the capillaries around them. (5 marks)

The lungs have million of alveoli which increases the surface area , therefore increasing the rate of diffusion of oxygen into the lungs. The alveoli are very thin walled , which reduces the diffusion pathwa...
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Answered by Aysha Z. • Biology tutor
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Describe the pressure and volume changes in the lungs during inspiration

During inspiration, the intercostal muscles contract, moving the sternum up and out. This increases the thoracic volume, hence decreasing the pressure. The pressure gradient set up causes air inflow from out...
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Answered by Dhaval N. • Biology tutor
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Outline the circulation of blood and the physical changes of the heart during the cardiac cycle.

The cardiac cycle is split into 2 main phases: systole where the heart contracts and ejects blood out from the heart and diastole where the heart relaxes and fills with blood. The right side of the heart pum...
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Answered by Aishah M. • Biology tutor
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Using a genetic diagram, identify the genotypes of the F2 generation of pea pods if a homozygous green pod and a homozygous yellow pod were crossed initially. The yellow pod contained recessive alleles (g).

A homozygous green pod will have a GG genotype while a homozygous yellow pod will have gg. Each parent has two alleles but only one is passed to an individual offspring via the gametes. In this case, the pos...
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Answered by Jessica N. • Biology tutor
4904 Views

Explain the process of oxidative phosphorylation and the electron transport chain in the production of ATP in respiration.

Oxidative phosphorylation and the electron transport chain (ETC) are both aerobic processes that require oxygen. These processes occur in the mitochondria of cells across the inner mitochondrial membrane. El...
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Answered by Keval P. • Biology tutor
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