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Explain how a nerve impulse passes along a non-myelinated neuron.

Generation of a Resting Potential ▪ The sodium-potassium pump (Na + /K + pump) maintains the electrochemical gradient of the resting potential (-70 mV) ▪ It is a membrane protein that uses active transport t...
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Explain the relationship between the structure and function of arteries, capillaries and veins.

Arteries have a thick outer layer of longitudinal collagen and elastic fibers to avoid leaks and bulges. They have a thick wall, which is essential to withstand the high pressures. They also have thick layer...
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Outline the control of the heartbeat in terms of myogenic muscle contraction, the role of the pacemaker, nerves, the medulla of the brain and epinephrine (adrenaline).

The heart muscle can contract by itself , without the stimulation of a nerve. This is called myogenic muscle contraction. The region that initiates each contraction is found in the wall of the right atrium a...
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Explain two examples of evolution in response to environmental change; one must be antibiotic resistance in bacteria.

Antibiotic resistance in bacteria is a common problem. It results from the transfer of a gene that gives resistance to a specific antibiotic usually by means of a plasmid to a bacterium. Some bacteria will t...
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Outline the consequences of a global temperature rise on arctic ecosystems.

· Changes in arctic conditions (arctic ice cap may disappear, permafrost will melt during the summer) · As the ice melts, sea levels will rise and flood low lying areas of land. · Expansion of temperate spec...
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