Read the STANDARD

TKI Biology Assessment Resources

Download all these exemplars and commentary (PDF, 59KB)

For Excellence, the student needs to carry out a comprehensive practical investigation in a biological context, with direction.

This involves:

• justifying the choices made during an in-depth investigation by evaluating the validity of the method or reliability of the data
• explaining the conclusion in terms of applicable biological ideas.

The extract, investigating the effect of rennin enzyme on milk at different temperatures, shows that some choices made during the in-depth investigation are justified by evaluating the reliability of the data, i.e. by conducting three trials at each temperature and omitting an outlier to calculate an average (1).

The conclusion is explained in terms of some applicable biological ideas, e.g. the effect of temperature on enzymes and collision theory (2).

For a more secure Excellence, the student would need more detailed evidence to:

• justify the choices made during the investigation by evaluating the reliability (or validity) of the data, e.g. by describing how  more possible sources of error were considered
• explain applicable biological ideas,  e.g. by relating how and why enzymes become denatured at high temperatures.

For Merit, the student needs to carry out an in-depth practical investigation in a biological context, with direction. This involves:

• writing the purpose as a hypothesis
• developing a method with a valid range for the independent variable, describing the control of significant variables, the accurate measurement of the dependent variable (with units) and consideration of factors such as sampling bias and/or sources of error
• collecting, recording and processing data that enables a trend or pattern (or its absence) to be determined
• writing a valid conclusion based on interpretation of the processed data that links to the purpose.

This student aimed to investigate the effect of change in temperature on enzyme (catalase) action. The processed data in either the table (1) or graph (2) does enable a general trend to be determined.

The conclusion shows some understanding of applicable biological ideas, e.g. the effect of temperature on enzymes and collision theory (3).

To reach Excellence, the student would need to:

• include more specific information in the descriptive headings of either the table or graph, e.g. by identifying the enzyme and the substrate
• explain applicable biological ideas with regard to the effect of temperature on enzymes
• give more reasons why the choices made during the investigation (4) made the data more reliable (or valid)
• removing the outlier showing 20mm foam height at 50⁰C to lower the average at this temperature, and thereby show the expected downward trend after the optimum temperature was reached (5).

For Merit, the student needs to carry out an in-depth practical investigation in a biological context, with direction by:

• writing the purpose as a hypothesis
• developing a method with a valid range for the independent variable, describing the control of significant variables, the accurate measurement of the dependent variable (with units) and consideration of factors such as sampling bias, and/or sources of error
• collecting, recording and processing data that enables a trend or pattern (or its absence) to be determined
• writing a valid conclusion based on interpretation of the processed data that links to the purpose.

This student aimed to measure the effect of changing the amount of acid on the respiration of yeast. While the range of the independent variable is missing from the method (1) it is identified in the results (2). The collected and recorded data (2) is processed (3) to enable a general trend to be determined.

For a more secure Merit, the student would need to show more accuracy by:

• including more specific information in the descriptive headings of the table of averages, e.g. by identifying the investigation as anaerobic respiration in yeast
• showing the units measuring the volume of carbon dioxide correctly, i.e. ‘mL’ rather than ‘ML’.

For Achieved, the student needs to carry out a practical investigation in a biological context, with direction by:

• developing a method with sequential steps for collecting data. This includes identification of the range of the independent variable (at least three values) or sample, measurement of the dependent variable (or the collection of field data) with units.
• collecting, recording and processing primary data relevant to the purpose.  The raw data must be within a range of values feasible for the context.
• reaching a conclusion based on interpretation of the processed data.

The student investigated the effect of exercise on pulse and breathing rates. The method is developed with sequential steps to collect data and consider a possible sampling bias (1). The collected, recorded and processed data enables a general trend to be determined (2).

To reach Merit, the student would need to:

• write the purpose as a more explicit hypothesis, e.g. by investigating exercise in a specific gender, age group, and the recovery of either pulse or breathing rates
• consider more factors such as sampling bias and/or sources of error in the method
• include more specific information in the descriptive heading of the table (2), i.e. by briefly describing what the data is showing and what the units ‘bpm’ refer to.

For Achieved, the student needs to carry out a practical investigation in a biological context, with direction. This involves:

• developing a method with sequential steps for collecting data. This includes identification of the range of the independent variable (at least three values) or sample, measurement of the dependent variable (or the collection of field data) with units.
• collecting, recording and processing primary data relevant to the purpose.  The raw data must be within a range of values feasible for the context.
• reaching a conclusion based on interpretation of the processed data.

This student investigated the concentration of disinfectant to kill bacteria in a defined area. A method is developed that identifies the range of the independent variable, with some detail in sequential steps (1).

To reach Achieved more securely, the student would need more detailed information in the method, to:

• identify the disinfectant (1) (2) from a choice that was provided by the teacher
• elaborate on how the serial dilutions were made for the range of the independent variable chosen (2),  either from directions given by the teacher or by selecting values from a range of a named diluted disinfectant provided by the teacher
• show how the dependent variable (i.e. clear areas) were measured and recorded, with units (3).

For Achieved, the student needs to carry out a practical investigation in a biological context, with direction. This involves:

• developing a method with sequential steps for collecting data. This includes identification of the range of the independent variable (at least three values) or sample, measurement of the dependent variable (or the collection of field data) with units.
• collecting, recording and processing primary data relevant to the purpose.  The raw data must be within a range of values feasible for the context.
• reaching a conclusion based on interpretation of the processed data.

The student aimed to investigate the optimal temperature for catalysts to operate. The method developed identifies the range of the independent variable as two values (1) and the measurement of the dependent variable (2).

To reach Achieved, the student would need to show a collection method in sequential steps that includes:

• a range of the independent variable with at least three values
• the correct units measuring temperature
• the units measuring the dependent variable.