Graphs are a terrifically powerful way to visually communicate data. Biologists need to be able to present their own data in clear and appropriate ways and they need to be adept at deriving useful information from graphs produced by other researchers.
When shown information in a graphical format we need to be able to extract quantitative information.
When we have produced data we need to be able to select the most appropriate way to present this data so that it can be readily understood by others.
Linear relationships occur frequently in biology and it is valuable to be familiar with the equation describing such a relationship.
Intercepts are often points of particular interest in a graphical representation of data on a particular system such as a photosynthesising plant or a beating heart.
Graphs with time on the x axis are very common in biology and it is essential to be aware that in these cases the slope of a linear graph provides us with the rate of change of whatever variable is represented on the y axis.
Graphs with time on the x axis are very common in biology and even when the relationship shown is not linear it is possible to identify the instantaneous rate of change by finding the gradient of a tangent to the line.