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What is saltatory conduction?

· Myelin sheath is an insulating layer of fatty material, composed of Schwann cells wrapped tightly around the neurone.· Sodium and potassium ions cannot diffuse through this fatty layer.· In between the Sch...
NS
Answered by Natalia S. Biology tutor
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How does smoking affect gas exchange in the lungs?

Firstly, think of what you already know about the structure of the lungs and how that makes them so effective at their job. (Elasticity, large surface area for gas exchange, high gradient and short diffusion...
EE
Answered by Esther E. Biology tutor
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Explain how a rise in blood pressure results in a decrease in the rate of heartbeat.

Baroreceptors detect the rise in blood pressure in the aorta, they send impulses to the cardiovascular centre. Then, impulses are sent via parasympathetic nerves to the SAN. This triggers the release of ACh,...
KS
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Explain the role of anti-diuretic hormone in osmotic homeostasis.

Anti-diuretic hormone (ADH) is produced by the hypothalamus and stored in the posterior pituitary gland. When the hypothalamus identifies the bloods osmotic pressure as being outside the homeostatic range, t...
JB
Answered by Jonathan B. Biology tutor
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How are polynucleotide DNA strands held together? (3 marks)

The two antiparallel strands of DNA are held together by hydrogen bonds joining the bases of each complementary nucleotide; Adenine is held to Thymine by 2 hydrogen bonds, and Guanine to Cytosine by 3 hydrog...
SA
Answered by Srishti A. Biology tutor
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