<h2 class="para"><b class="emphasis">Presenting Data Graphically: </b><b class="emphasis">Line Graphs</b></h2>
<h3 class="para"><b class="emphasis">Line graphs are used when:</b></h3>
<div class="list">
<ul class="bullet">
<li class="item">The relationship between the dependent and independent variables is continuous.</li>
<li class="item">Both dependent and independent variables are measured in numbers.</li>
</ul>
<p><img alt="A line graph showing the y-axis, the x-axis, and the origin." class="alignnone size-full wp-image-181074" height="483" src="https://data.ulearngo.com/assets/398860f5-ba9c-4632-a00a-cfde9d248158" title="A line graph showing the y-axis, the x-axis, and the origin." width="513"/></p>
</div>
<h3 class="para"><b class="emphasis">Features of line graphs:</b></h3>
<div class="list">
<ul class="bullet">
<li class="item">An appropriate scale is used for each axis so that the plotted points use most of the axis/space (work out the range of the data and the highest and lowest points).</li>
<li class="item">The scale must remain the SAME along the entire axis and use easy intervals such as 10's, 20's, 50's, and not intervals such as 7's, 14's, etc, which make it difficult to read information off the graph.</li>
<li class="item">Each axis must be labelled with what is shown on the axis and must include the appropriate units in brackets, e.g. Temperature (°C), Time (days), Height (cm).</li>
<li class="item">Each point has an x and y co-ordinate and is plotted with a symbol which is big enough to see, e.g. a cross or circle.</li>
<li class="item">The points are then joined.</li>
<li class="item">With a ruler if the points lie in a straight line (see Figure 3) or you can draw a line of best fit where the number of points are distributed fairly evenly on each side of the line.</li>
<li class="item">Freehand when the points appear to be following a curve (see Figure 4).</li>
<li class="item">DO NOT start the line at the origin unless there is a data point for 0. If there is no reading for 0, then start the line at the first plotted point.</li>
<li class="item">The graph must have a clear, descriptive title which outlines the relationship between the dependent and independent variable.</li>
<li class="item">If there is more than one set of data drawn on a graph, a different symbol must be used for each set and a key or legend must define the symbols.</li>
</ul>
<div class="wp-caption alignnone" id="attachment_181077" style="width: 419px"><img alt="An example of a height vs time line graph" class="size-full wp-image-181077" height="422" src="https://data.ulearngo.com/assets/75a2b4f2-093d-44fc-9da5-01d3c7373bea" width="419"/><p class="wp-caption-text">Graph showing change in plant height over 10 days</p></div>
</div>
<div class="ns-tutorial">
<div class="ns-school-defn2">
<h3 class="note-header"><span class="cnx_label">Note:</span></h3>
<p class="para">Table headings are always written ABOVE the table. Graph headings are always written BELOW the graph.</p>
</div>
</div>
<h2 class="para"><b class="emphasis">Bar Graphs</b></h2>
<h3 class="para"><b class="emphasis">Bar graphs are used when:</b></h3>
<div class="list">
<ul class="bullet">
<li class="item">The independent variable is discontinuous (i.e. The variables on the x-axis are each associated with something different)</li>
<li class="item">Independent variables are not numerical. For example, when examining the protein content of various <a data-lesson="ingestion" data-subject="biology" data-tutorial="digestive-system" href="https://app.ulearngo.com/biology/digestive-system/ingestion">food</a> types, the order of the food types along the horizontal axis is irrelevant.</li>
</ul>
</div>
<h3 class="para"><b class="emphasis">Bar graphs have the following features:</b></h3>
<div class="list">
<ul class="bullet">
<li class="item">The data are plotted as columns or bars that do not touch each other as each deals with a different characteristic.</li>
<li class="item">The bars must be the same width and be the same distance apart from each other.</li>
<li class="item">A bar graph can be displayed vertically or horizontally.</li>
<li class="item">A bar graph must have a clear, descriptive title, which is written beneath the graph.</li>
</ul>
<div class="wp-caption alignnone" id="attachment_181078" style="width: 530px"><img alt="Bar graph showing how many learners use each type of transport" class="size-full wp-image-181078" height="328" src="https://data.ulearngo.com/assets/ea2c7c83-86e6-47a7-83d1-f5feef106712" width="530"/><p class="wp-caption-text">Bar graph showing how many learners use each type of transport</p></div>
<h2 class="para"><b class="emphasis">Histograms</b></h2>
<p class="para">Histograms are used when the independent variable (x-axis) represents information which is continuous, such as numerical ranges, i.e. 0-9, 10-19, 20-29, etc.</p>
<p class="para">Histograms have the following features:</p>
<div class="list">
<ul class="bullet">
<li class="item">Unlike a bar graph, in a histogram the data are plotted as columns or bars that touch each other as they are related to each other in some way.</li>
<li class="item">The numerical categories <em class="emphasis">must not </em>overlap, for example, 0-10, 10-20, 20-30, etc. The ranges must be exclusive so that there is no doubt as to where to put a reading, for example, 0-9, 10-19, 20-29, etc.</li>
<li class="item">The bars can be vertically or horizontally drawn.</li>
<li class="item">A histogram must have a descriptive heading with is written below the graph.</li>
<li class="item">And, the axes must be labelled.</li>
</ul>
</div>
</div>
<div> </div>
<div>
<div class="wp-caption alignnone" id="attachment_181079" style="width: 630px"><img alt="A histogram showing the number of learners in an SS 2 Biology class with a particular percentage test score." class="size-full wp-image-181079" height="450" src="https://data.ulearngo.com/assets/4519726d-10d0-4ffd-8295-bf1a72b2aed3" width="630"/><p class="wp-caption-text">A histogram showing the number of learners in an SS 2 Biology class with a particular percentage test score.</p></div>
</div>

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Drawing Graphs in Biology

Biology studies life and living organisms. Biology can be divided into different sections that cover the morphology, physiology, anatomy, behavior, and so on of living organisms.

Biology

Learn the fundamentals of biology, including the characteristics of living things, scientific method, important principles and tools such as drawing graphs, tables, and biological drawings, and safety procedures in a lab environment.


Drawing Graphs in Biology

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