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Part of the retina of a young rat was removed and kept in the dark for two hours. This allowed the pigment in the rod cells to recover from bleaching caused by exposure to light. Suggest what happens in the rod cells during this two hours of darkness.

Rhodopsin is the pigment found in rod cells, which consists of cis-retinal and the protein opsin. When the rod cells are kept in darkness, the opsin is uncoupled from the cell surface membrane of the rod cel...
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Answered by Panos L. • Biology tutor
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Explain how the sinoatrial node (SAN) ensures that oxygenated blood enters the aorta.

The sinoatrial node is a region found on the right atrium which acts as a pacemaker. Cells at the SAN can depolarise (become more positively charged with respect to the outside) and generate electrical activ...
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Answered by Panos L. • Biology tutor
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Prove that sin(x)+sin(y)=2sin((x+y)/2)cos((x-y)/2)

We know that 1. sin(a+b) = sin(a)cos(b)+sin(b)cos(a) and 2. sin(a-b) = sin(a)cos(b)-sin(b)cos(a) Add equations 1. and 2. sin(a+b)+sin(a-b) = 2sin(a)cos(b)+sin(b)cos(a)-sin(b)cos(a) = 2sin(a)cos(b) Let x=a+b ...
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Answered by Anna V. • Maths tutor
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What is the significance the paper lantern in 'A Streetcar Named Desire'?

Williams employs plastic theatre as a means of giving physical onstage presence to abstract concepts in order to better clarify for the audience their meaning and significance within 'A Streetcar Named Desir...
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The points A and B have coordinates (3, 4) and (7, 6) respectively. The straight line l passes through A and is perpendicular to AB. Find an equation for l, giving your answer in the form ax + by + c = 0, where a, b and c are integers.

For the line passing through A and B: m = (y2-y1)/(x2-x1) = (-6-4)/(7-3) = -5/2 For the perpendicular line: m = -1/(-5/2) = 2/5 y - y1 = m*(x - x1) >> y - 4 = (2/5)*(x - 3) >> 5y - 20 = 2x - 6 &g...
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Answered by Deji A. • Maths tutor
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