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Explain how a nerve impulse causes the chambers of the heart to contract (6).

The heart's excitation is myogenic and therefore can be started without any transmission from the brain. The sino-atrial node is found behind the posterior wall of the left atrium and is where the action pot...
JS
Answered by Jeremy S. • Biology tutor
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How do catalysts speed up the rate of a reaction?

A catalyst increases the rate of the reaction because: They provide an alternative energy pathway that has a lower activation energy This means that more particles have the activation energy required for the...
VO
Answered by Vanessa O. • Chemistry tutor
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Study Figure 3 which shows a satellite image of an area of vegetation that has been affected by human activity. Describe and comment on the impact of the human activity shown. (7 marks)

The image is of what looks to be a quarry. In the left of the image there is a lake, possibly with waste materials from the quarry. There are roads leading away from the area on the right, presumably to carr...
CG
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“Everyone knows what good means” Discuss (meta ethics)

Meta-ethics is the branch of ethics that aims to determine the usefulness of ethical language. Cognitivists believe that ethical language is meaningful, thus implying that everyone should know what good is. ...
LS
5951 Views

Give two reasons why tropical storms eventually lose their energy

Friction from passing over the land makes them lose their energy Land at high altitudes and water have a cooling effect, causing a loss of energy
CG
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