AQA AS Level Biology Paper 1, June 2024: Question 5

11 marks · Medium difficulty · Practical Techniques & Data Analysis

Describe methods to measure plant heights and calculate a reliable mean, construct a histogram table, calculate the index of diversity using provided bee species data, and explain the difference in bee species richness between wild flower and wheat fields.

Practise this question

Question

A four-part exam question about plant heights, data tables for histograms, bee biodiversity index calculation, and species richness comparison. Part 05.1 asks to describe how to measure plant heights and obtain a reliable mean (5 marks). Part 05.2 asks to use Figure 6 (an empty 6-row, 2-column results table) to design a table for a histogram of plant heights between 60 cm and 120 cm (2 marks). Part 05.3 provides Table 4 containing trapped bee species and numbers, along with the index of diversity formula d = N(N-1) / sum(n(n-1)), to calculate the index of diversity (2 marks). Part 05.4 asks to suggest and explain one reason why bee species richness is greater in wild flower fields than wheat fields (2 marks).
Question text

05.1 Malva sylvestris is a plant species.

A student wanted to determine the mean height of M. sylvestris plants growing in a

field.

Describe how the student should obtain measurements of the plants and then process

these measurements to obtain a reliable mean height of plants growing in that field.

[5 marks]

05.2 The student wanted to present the results for the distribution of plant heights in a

histogram.

Figure 6 shows the outline of a results table.

Use Figure 6 to design a suitable results table the student should use for a histogram

of plant height measurements ranging between 60 cm and 120 cm.

[2 marks]

Figure 6

05.3 A student investigated biodiversity in a community of bee species in a field of

wild flowers.

The student trapped and identified the bee species in the field over 6 months.

Table 4 shows some of the student’s results.

Table 4

Total number of trapped bees after 6

Bee species

months

Cuckoo bee 250

Domestic honeybee 800

Clover bee 200

The index of diversity in a community of organisms is determined using the formula

*15* where N = total number of organisms of all species

and n = total number of organisms of each species.

Use the formula and information in Table 4 to calculate the index of diversity in this

community of bee species.

[2 marks]

Answer17

05.4 In a different investigation, the student found that:

• the species richness of plants in a field of wild flowers is greater than the species

richness of plants in a field of wheat

*16* • the species richness of bees in a field of wild flowers is greater than the species

richness of bees in a field of wheat.

Suggest one reason why the species richness of bees in a field of wild flowers is

greater than the species richness of bees in a field of wheat.

Explain your answer.

[2 marks]

Mark scheme

Show the mark scheme The mark scheme provides detailed marking points for each part of question 05. Part 05.1 awards up to 5 marks for methods involving random sampling (grids/coordinates), consistent measuring technique, large sample size, and calculating a mean. Part 05.2 awards 2 marks for proper table column headings (plant height/frequency) and non-overlapping class intervals from 60 to 120. Part 05.3 awards 2 marks for the correct index of diversity answer of 2.11 (or 2.1), with partial credit for correct numerator or denominator totals. Part 05.4 awards 2 marks for linking greater plant species diversity/variety in wild flower fields to more food sources, habitats, or protection for bees.

1. Use a grid 1. Accept use tape

measures for ‘use a

OR

grid’

Divide area into squares/sections/plots;

2. Method of obtaining random 2. Accept

coordinates/numbers; calculator/computer/

random numbers

3. Use same method of measurement (of the plants table/generator for

each time); method

4. Repeat a large number of times

3. Accept descriptions

OR of measurements eg

Measure a large number of plants; from soil/ground to

highest leaf or to top

5. (Find the) sum of heights and divide by number of plant or to (shoot)

5 max

of plants; tip or to highest

05.1 (5 x

part/bit

6. Calculate a running mean until number becomes AO1)

(fairly) constant; 4. Accept ≥ 10 for

large number

4. Accept

many/multiple but

ignore several

5. Accept total for sum

5. Accept

measurements for

heights or plants

5. Accept a word

equation eg

Height total __

Number of plants

Question Marking Guidance Mark Comments

1. Plant height and /cm in first column and 1. Accept M. sylvestris

Frequency (density), in second column; for plant

1. Accept length for

height

2. Non-overlapping class intervals between 60 and

120; 1. Accept mm or m for

cm

eg

1. Accept number for

60 ≤ × < 70 11

frequency

OR

2. Accept unequal

60 – 69, 70 – 79 etc class widths if

OR frequency density

used in heading

60 – 69.9, 70 – 79.9 etc

2. Accept correct

OR 2

figures in either

05.2 (2 x

59.5 – 69.0, 69.5 – 79 etc column

AO2)

2. Figures given must

match units in

heading, eg 600 if

heading shows / mm

or 0.6 if heading

shows /m

2. Accept fewer or

more than 6 rows of

data if data covers a

range between 60 and

2. Ignore any

numbers in the

frequency column

Correct answer of 2.11 = 2 marks;; For 2 marks, accept

2.1(0623946) or any

Incorrect answer that shows correct total in 2

correct rounding eg

05.3 numerator 1561250 = 1 mark (2 x

2.1 or 2.106 etc

OR AO1)

Correct total in denominator 741250 = 1 mark;

(In relation to wild flower fields) Accept the converse

in the context of

1. More plant species

wheat fields

OR

1. Accept more

12 Larger (index of bio)diversity;

plant types/variety of plants

1. Accept greater

2. (So) more variety of food/nectar/pollen species richness of

OR plants

2 2. Ignore more/better

05.4 (So) more (types of) habitat/niche (2 x

food but accept more

OR AO2) food sources

(So) more/better protection from predators; 2. Ignore more shelter

2. Ignore more homes

2. Accept ‘types of’ for

‘variety of’

2. Accept ‘fewer

predators’ for ‘more

protection’

How to answer it

Ecology Fieldwork & Biodiversity Study Guide

AQA AS Level Biology

What this question tests

This exam sequence assesses core practical competencies in ecological sampling, data organisation for graphical presentation, quantitative calculation of biodiversity using Simpson's Index, and applying ecological concepts like species richness, habitats, and trophic food sources.

Question 05.1: Sampling Plant Populations

Describe how to obtain and process reliable plant height measurements (5 marks)

✅ Correct Answer / Mark Scheme Points

  • Use a grid / divide the area into squares, sections, or plots.
  • Obtain random coordinates or numbers (e.g., using a random number generator).
  • Use a consistent method of measurement for every plant (e.g., ground level to highest leaf/tip).
  • Repeat a large number of times (or measure a large number of plants, usually 10 or more).
  • Calculate a mean by finding the sum of heights divided by the total number of plants.
  • Alternative: Calculate a running mean until the value becomes fairly constant.

🧠 Exam Technique

This is a standard 5-mark extended response question on practical methodology. To secure full marks, you must include a sampling strategy (grid + random coordinates), consistency in how measurements are taken, a large enough sample size, and a clear mathematical processing step (mean calculation).

❌ Common Errors

Students often lose marks by suggesting biased sampling methods (such as walking in a straight line or choosing "representative" plants instead of random sampling). Another frequent error is failing to mention repeat measurements or a running mean.

Question 05.2: Designing a Results Table for Histograms

Design a results table for a histogram showing plant heights from 60 cm to 120 cm (2 marks)

✅ Correct Answer / Mark Scheme Points

  • Column 1 heading: Plant height (or equivalent, with appropriate units like cm, mm, or m).
  • Column 2 heading: Frequency (or density/number of plants).
  • Class intervals: Non-overlapping consecutive intervals spanning 60 to 120 cm (e.g., 60 - 69 , 70 - 79 , or inequality notation like 60 ≤ x < 70 ).

💡 Key Knowledge

Histograms display continuous data grouped into class intervals. Unlike bar charts, the bars touch because data on the x-axis is continuous. Class intervals must be non-overlapping to prevent data ambiguity.

Question 05.3: Calculating Biodiversity Index

Calculate the index of diversity for the bee community (2 marks)

📐 Step-by-Step Calculation

Formula: d = N(N - 1) / Σn(n - 1)

  1. Find total organisms ( N ): 250 (Cuckoo) + 800 (Honeybee) + 200 (Clover bee) = 1250
  2. Calculate numerator ( N(N - 1) ): 1250 × 1249 = 1,561,250
  3. Calculate n(n - 1) for each species:
    • • Cuckoo bee: 250 × 249 = 62,250
    • • Honeybee: 800 × 799 = 639,200
    • • Clover bee: 200 × 199 = 39,800
  4. Calculate denominator ( Σn(n - 1) ): 62,250 + 639,200 + 39,800 = 741,250
  5. Final division: 1,561,250 / 741,250 = 2.11 (or 2.1)
Award 2 marks for correct answer (2.11). 1 mark awarded if either the numerator or denominator is correct on its own.

❌ Common Calculation Traps

Arithmetical errors when squaring large numbers or forgetting to subtract 1 before multiplying ( n - 1 ) are the most common reasons students drop marks here. Always show working out to secure error-carried-forward (ECF) marks!

Question 05.4: Explaining Differences in Species Richness

Suggest why species richness of bees is greater in wild flower fields than wheat fields (2 marks)

✅ Correct Answer / Mark Scheme Points

  • Point 1: Greater plant species richness / higher plant biodiversity in wild flower fields.
  • Point 2: Provides a greater variety of food sources (nectar, pollen) or a wider range of habitats / niches / protection from predators.

🧠 Exam Technique

Make sure to link biological cause and effect clearly. Point 1 establishes the ecological baseline (more plant species), and Point 2 explains why this supports more bee species (food availability and varied niches).

Topics

Biology · Practical skills · 3.4 Genetic information, variation and relationships between organisms · Experimental design · Data analysis

Question and mark scheme from the AQA AS Level Biology examination, Paper 1, June 2024. QuestionVault is an independent revision resource; questions remain the copyright of the awarding body.