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Use the example of antibiotic resistant bacteria to explain directional selection.

DNA mutations happen randomly during division by mitosis. Some of these mutations code for antibiotic resistance. When a bacterial colony is exposed to antibiotics most bacteria without the resistance mutati...
VP
Answered by Vlad P. • Biology tutor
22779 Views

How do I integrate x/(x^2 + 3) ?

To solve this you need to integrate by substitution. You can spot this because the differential of the bottom of the fraction is a multiple of the top part, showing this quickly; if u = x 2 + 3 (the bottom p...
KM
Answered by Knox M. • Maths tutor
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integrate by parts the equation dy/dx = (3x-4)(2x^2+5).

The equation we use to integrate by parts is y = uv - ∫ v(du/dx) dx + c so we separate dy/dx into u=(3x-4) and dv/dx=(2x 2 +5) however we still need to find du/dx and v, by differentiating u (bring the power...
AH
Answered by Abby H. • Maths tutor
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How does water travel up the stem of a plant from the roots to the leaves, wouldn't gravity prevent this?

Water molecules are polar. This means that one end of the molecule is slightly negatively charged (the oxygen atom) and one end of the molecule is slightly positively charges (the hydrogen atoms). The slight...
LR
Answered by Lauren R. • Biology tutor
57911 Views

What are the characteristics for perfect competition firms and when do they make profit?

The chracteristics of perfect competition are: many firms, freedom of entry and exit, all firms produce identical or homogenous products, all firms are price takers(have no influence over the price) and have...
DC
Answered by Diana C. • Economics tutor
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