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a) Compare the differences between an artery and a vein. b) List and explain 2 features that allow capillaries to exchange substances efficiently.

a) Veins have a larger lumen and a thinner wall as they carry blood at a lower pressure than the blood in arteries. Due to this low pressure, veins have valves to assist with the continuous movement of blood...
ZG
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a) What is the function of the atrioventricular valves? b) When the ventricles are contracting, are the arterioventricular valves open or closed? c) Explain why the muscle walls of the atria are thinner than the walls of the ventricles.

a) To prevent backflow of blood from the ventricles into the atria.b) Closedc) The atria only have to pump blood into the ventricles, where as the ventricles have to pump blood at a high pressure all the way...
CO
Answered by Catherine O. • Biology tutor
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In a study, researchers had to use different participants in each condition and this could have affected the results. Outline one way in which the researchers could have addressed this issue. 4 marks.

The researchers could have used a matched pairs design in order to create 'experimental twins'. The researchers would first have to identify a variable which may affect the dependent variable - the one being...
NG
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Please describe how temperature, concentration and the use of a catalyst affects rate of reaction.

For a reaction to be successful two atoms need to collide with a sufficient amount of energy (activation energy). Raising the temperature increases the amount of kinetic energy that the atoms have, which mea...
GS
Answered by Georgie S. • Chemistry tutor
3443 Views

What is the best way to prepare for my history interview at Oxford/Cambridge?

The key thing to remember about interviewing at either Oxford or Cambridge is that you deserve to be there! Tutors seriously consider each individual application, so they will only invite you to interview if...
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