OCR A Level Biology - Statistical Tests

Please enlarge the diagram to access this question.

• Chi squared (χ²)

• Spearman’s rank correlation coefficient

• Standard deviation

• t-test

A class compared the number of chloroplasts in the leaves taken from plants of the same species growing in two areas. One area had a high light intensity, the other had a low light intensity.
Which option is the correct procedure for statistical analysis of the data collected by the class?

• Calculate the mean number of chloroplasts per cell in the high and low light intensity areas and use a paired t-test.

• Calculate the mean number of chloroplasts per cell in the high and low light intensity areas and use an unpaired t-test.

• Calculate the median number of chloroplasts per cell in the high and low light intensity areas and calculate Spearman’s rank correlation coefficient.

• Calculate the median number of chloroplasts per cell in the high and low light intensity areas and use a chi-squared test.

The temperature coefficient (Q₁₀) for catalase is recorded in a data book as 1.15. A student carries out an experiment to test if this Q₁₀ value is correct and collects data with a high level of precision and accuracy. Which row shows the correct definition of both precision and accuracy for their data?

• A

• B

• C

• D

Answer explanation

Precise results are clustered together, while standard deviation gives an indication of how spread the data is around the mean and accuracy is a property of a single result.

Please enlarge the diagram to read this question.

• Chi-squared test

• Spearman’s rank correlation coefficient

• t -test – paired

• t -test – unpaired

Use the table to state the critical value for the following context.

"A student performs a Spearman's rank correlation coefficient as they walk further from the banks of a river. They sample 7 times in total".

Read the context, then choose the stats test and the critical value from the table.

"A student gathers data for the number of ice cream trucks spotted and the number of times that they sneeze in a day. They sample on 5 different occasions and want to do a statistical test on this data.".

Stats test: ​ (a)  

Critical value: ​ (b)  

Would you expect the data to be statistically significant? ​ (c)  

• spearman's rank correlation coefficient
• unpaired t test
• paired t test
• 0.900
• no
• yes
• 0.800
• 1.000
• 0.657
• 0.829

1. Adaptations can be categorised into three different types:

anatomical

behavioural

physiological.

The table lists four traits that kakapos have evolved.
Complete the table by naming the type of adaptation represented by each of the four kakapo traits.

Groups:

(a) Behavioural

,

(b) Anatomical

,

(c) Physiological

• Active at night to avoid predators

• Slow digestion to extract nutrients from a high-fibre, low-protein diet

• Strong beak and claws to climb trees

• Green feathers that camouflage with its surroundings

Please refer to the diagram for this question.

• variation in height between varieties is continuous and polygenic

• variation in height between varieties is discontinuous and controlled by one or two genes

• variation in height within varieties is continuous and controlled only by one or two genes

• variation in height within varieties is discontinuous and polygenic

The harlequin ladybird, Harmonia axyridis, has many different distinct forms, two of which can be seen below.
Which of the terms, A to D, best describes this type of variation?

• interspecific continuous

• interspecific discontinuous

• intraspecific continuous

• intraspecific discontinuous

Many crop plants are eaten by herbivorous ​ (a)   . Humans use ​ (b)   to reduce the consumption of crop plants by ​ (c)   . ​ (d)   might be less effective after being used for many years because the insects become ​ (e)   .

• resistant
• immune
• insects
• insecticides
• insecticide
• antibiotics
• antibiotic
• bacteria