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How are B cells activated?

A phagocyte will engulf the pathogen by endocytosis. The vesicle containing the pathogen will fuse with the lysosome where it is degraded by hydrolytic enzymes. Short peptides of the pathogen will be display...
EB
Answered by Eleanor B. • Biology tutor
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Derive an expression to show that for satellites in a circular orbit T² ∝ r ³ where T is the period of orbit and r is the radius of the orbit.

For an object to stay in a steady orbit; F=mv 2 /r where: F is the force on the object towards the centre of the orbit, m is the mass of the object, v is the radial velocity of the object, and r is the radiu...
JM
Answered by James M. • Physics tutor
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Solve 5x + 10 = 2x(5x + 10)

First multiply out the right hand side to get5x + 10 = 10x^2 + 20xThen rearrange so everything equals zero, forming a quadratic equation10x^2 + 15x - 10 = 0 To make things easier, you can simplify the equati...
AM
Answered by Amy M. • Maths tutor
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Discuss the possible effects that mutation can have on the structure and function of a protein (3 marks)

Mutation can result in changes to a proteins primary, secondary and tertiary structure . Deletion mutations and mutations resulting in a new stop codon can result in the shortening of a protein. Proteins can...
EM
Answered by Emma M. • Biology tutor
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Explain a reflex arc

A reflex arc is the nerve pathway which follows a reflex action. First a stimulus, like a pin prick, is detected by receptors in the skin. A sensory neurone then sends electrical impulses to a relay neurone,...
CS
Answered by Clara S. • Biology tutor
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