Top answers

What are the differences between directional and stabilising selection? Give an example of each.

In directional (a.k.a. adaptive) selection, one extreme of a population has a selective advantage i.e. is fitter than other individuals of the population. This causes a directional shift towards this extreme...
BS
Answered by Ben S. • Biology tutor
5544 Views

Can you explain the oxygen dissociation curve.

What is the graph telling us?On the graph, we can see two axes. We have partial pressure of oxygen on the X axis and Hb saturation on the Y axis. Partial pressure is another way of saying how much oxygen the...
TK
Answered by Thomas K. • Biology tutor
4716 Views

What is the link between electrical activity of the heart and its contraction?

The electrical current is produced in the SA node (the primary pacemaker of the heart) and travels to the AV node via fibres in the walls of the atria. These impulses cause the muscular walls of the atria to...
SM
Answered by Stephen M. • Biology tutor
7057 Views

Can you explain the oxygen dissociation curve.

What is the graph telling us? On the graph, we can see two axes. We have partial pressure of oxygen on the X axis and Hb saturation on the Y axis. Partial pressure is another way of saying how much oxygen th...
TK
Answered by Thomas K. • Biology tutor
3062 Views

Name a non-reducing sugar and outline a test which can identify its presence. (6)

Sucrose (1)Rule out reducing sugars - heat in a water bath. Add Benedict's solution. Should remain blue. (1)Add dilute HCl to a new sample and heat in a water bath (1)Neutralise with NaHCO3 (1)Add Benedict's...
AR
Answered by Annie R. • Biology tutor
4083 Views