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Using a diagram, outline the path the blood takes through the human body, starting with the aorta and identifying the major vessels and chambers of the heart.

Aorta --> systemic circulation [branches in order: coronary artery (to supply the heart), carotid artery (to supply the head), hepatic artery (to supply the liver), mesenteric artery (to supply the gut), ...
SG
Answered by Sophie G. • Biology tutor
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Gas exchange happens in the alveoli of the lungs. What are three adaptations of the alveoli that allow for this?

Thin alveolar walls for O2 and CO2 to travel through - To travel across the membrane, gases have to be dissolved, so the alveolar walls are moist - Large surface area to volume ratio allows for maximum gas e...
SL
Answered by Sarah L. • Biology tutor
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Describe the process of natural selection

There is genetic diversity within the population. Random mutation can occur, forming new alleles of a gene. Though many mutations are harmful, in certain environments the new allele may benefit its possessor...
JJ
Answered by Jewel J. • Biology tutor
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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...
RH
Answered by Rachel H. • Biology tutor
26564 Views

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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