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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 mut...

VP
Answered by Vlad P. Biology tutor
21627 Views

Solve the simultaneous equations: (1) 4x + y = 7 and (2) x - 3y = 5

Start by multiplying equation (2) by 4 so both equations contain 4 lots of x: 4x - 12y = 20 Then take away equation 1 from equation 2 to eliminate x -13y = 13 divide by 13 and then reverse the negative si...

BK
Answered by Ben K. Maths tutor
4031 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 + 3...

KM
Answered by Knox M. Maths tutor
12508 Views

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=(2x2+5)

however we still need to find du/dx an...

AH
Answered by Abby H. Maths tutor
6159 Views

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 sli...

LR
Answered by Lauren R. Biology tutor
55908 Views

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