Plant organ system: extract and interpret information from graphs, charts and tables.

The idea

Interpreting data means reading values from graphs, charts and tables and explaining what they show about a biological process. In the plant organ system topic, you might read a graph of transpiration rate against temperature or a table of stomatal density on upper and lower leaf surfaces. To extract information, locate the correct row or column, read across or down carefully, and quote values with units. To interpret, describe the trend, compare sets of data, and link the pattern to scientific ideas such as evaporation, diffusion or water loss. For example, a graph showing transpiration rising as temperature increases can be explained by faster evaporation and diffusion of water vapour. Assessed through structured questions requiring values, trends and explanations.

What earns the marks

• Read values accurately from the correct axis, row or column, including the unit.
• Describe the overall trend, for example as temperature increases the rate of transpiration increases.
• Compare data sets, such as stating that stomatal density is greater on the lower leaf surface than the upper surface.
• Use data from the graph, chart or table as evidence to support a conclusion.
• Link the pattern to a scientific explanation, such as evaporation or diffusion of water vapour.
• Identify anomalous results or points that do not fit the overall trend.

Common mistakes and how to put them right

• Reading the wrong axis or scale, for example using the x-axis value when the question asks for the y-axis value.

  Put it right: Trace carefully from the point to the correct axis and check the scale.

• Quoting a number without a unit or with the wrong unit.

  Put it right: Include the unit shown on the axis or in the table heading.

• Describing a trend without explaining it scientifically.

  Put it right: Add a cause, such as increased kinetic energy leading to faster evaporation.

Exam tips

• Underline the command word so you know whether to describe, compare or explain.
• Quote specific figures from the data to support each point you make.
• When comparing, use comparative language such as higher, lower, faster or slower rather than just listing values.