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How does speciation occur?

A barrier separates the original population into two groups. Due to the different environmental conditions (selection pressures) either side of the barrier, different alleles are selected that better adapt t...
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Answered by Hasna B. • Biology tutor
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How do you conjugate verbs in the preterite tense for AR verbs in spanish?

To form the preterite tense of AR verbs such as cocinar you have to take off the -AR- so you are left with the stem - COCIN- and add the specific endings:yo (me) - é, tu (you) - aste, el/ella (he/she) - ó, n...
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Answered by Cicely F. • Spanish tutor
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Can you teach me how to rationalise the denominator of an algebraic expression?

You may be asked to rationalise the denominator of an algebraic expression if it contains a surd in the denominator - such as a 1/2 . They can get slightly more complex than this though! What it is asking fo...
Answered by • Maths tutor
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Solve the differential equations dx/dt=2x+y+1 and dy/dt=4x-y+1 given that when t=0 x=20 and y=60. (A2 Further pure)

These questions are really mean but if given in the exam give ALOT of marks and whilst scary at first follow a very general pattern. First I would take either equation and re-arrange for the lone variable. T...
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Describe how a change in temperature affects enzyme activity.

Enzymes are substrate specific proteins which act as biological catalysts and as temperature increases, we see an increase in enzyme activity. This occurs because an increase in temperature causes molecules ...
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Answered by Freya H. • Biology tutor
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