Topic 5.1: Practical and Data-Analysis Skills Questions

Which expression correctly gives the chi-squared statistic, where O is each observed count and E is each expected count?

A student compares the number of red-flowered and white-flowered plants from a cross against an expected 3 : 1 ratio. State which statistical test should be used to decide whether the observed numbers differ significantly from the expected ratio.

Plates of bacteria are kept at 15, 25 and 35 °C and the number of colonies is counted after two days. Which is the dependent variable?

Mean shoot lengths (cm) of four bean varieties after two weeks are: P 12, Q 9, R 21, S 15. What is the range of the data?

On a bar chart of mean results, each bar is capped with an error bar drawn at ± one standard deviation. State what these error bars represent.

In an investigation of how light intensity affects the rate of photosynthesis in pondweed, the temperature of the water is kept at 25 °C throughout. State one further variable, other than temperature, that must be kept constant in this investigation.

A correlation coefficient of r = 0.02 is found between shoe size and exam score in adults. What does this value indicate?

The wing lengths of 80 butterflies are grouped into length classes and plotted as a frequency histogram. Which feature of a frequency histogram identifies the MODAL class?

A forensic scientist has only a tiny trace of DNA from a crime scene and needs millions of copies before it can be analysed. Which technique should be used?

Four students each report the magnification of the same micrograph using the same correctly measured scale bar. Whose answer is written correctly?

State the name of the laboratory technique used to amplify (make many copies of) a small sample of DNA.

Draw a suitable graph of these data.

Calculate the mean.

State the name of the device fitted inside the eyepiece of a light microscope that is used to measure the size of a cell.

To calculate the percentage change in a measurement, by which value must the change be divided?

Which instrument is used to measure the rate of respiration of a small organism such as a germinating seed or a woodlouse?

On a kite diagram of seaweed abundance up a rocky shore, each species is drawn as a symmetrical band along the transect line. What does the WIDTH of a species' band at a given point show?

Six maize seedlings have leaf lengths (in mm) of 24, 28, 22, 30, 26 and 26. What is the mean leaf length?

A bar chart shows mean leaf area for plants grown in shade (24 cm²) and in full sun (40 cm²). State the difference in mean leaf area between the two conditions.

A table records the mean browning index of cut apple slices after 30 minutes for five antioxidant dip concentrations (arbitrary units): 0% dip = 8.4, 1% = 5.1, 2% = 3.0, 3% = 1.8, 4% = 1.9. State the dip concentration that gave the lowest browning index.