CSEC BIOLOGY · LAB PREPARATION · SECTION TEST

Lab Skills Test: Practical Skills and the SBA

Fifteen multiple-choice items and three structured questions on safety, measurement, drawing, reports and graphs, planning and design, and analysing results.

Practical Skills and the SBA15 MCQ30 structured marks≈ 45 min

← Biology explainer library CSEC Biology course

Before you start

How to take this test

Take it after you have worked through the lessons below — it checks the whole section, not one lesson.
Work under exam conditions: about 45 minutes, no notes. Every question here is new; none is repeated from the lessons.
Part 1: answer every multiple-choice item, then check. Items you get wrong tell you which lesson to revisit.
Part 2: write full answers, then reveal each mark scheme and self-mark strictly.
Your test score (multiple choice 50% + structured 50%) counts towards your section and paper readiness.

Lessons covered: L1 Lab Safety and Apparatus, L2 The Microscope and Biological Drawing, L3 Lab Reports, Tables and Graphs, L4 Planning and Designing an Investigation, L5 Analysis and Interpretation of Results, L6 Compulsory Practical 1: Ecological Study, L7 Compulsory Practical 2: Diffusion and Osmosis, L8 Compulsory Practical 3: Photosynthesis and Respiration, L9 Compulsory Practical 4: Food Tests, L10 Compulsory Practical 5: Germination, L11 Compulsory Practical 6: Nutrition and Disease (Enzymes), L12 Compulsory Practical 7: Genetics and Variation, L13 Practicals: Transpiration and Invertebrate Behaviour

Part 1 · Multiple choice

Multiple choice

15 items covering the whole section. Choose the best answer for each, then check.

L1 · Safety

1. What is the safest way to heat ethanol when removing chlorophyll from a leaf?

(A) In a test tube placed in a hot water bath, with the Bunsen turned off (B) Directly over a blue Bunsen flame (C) Over a yellow (safety) flame (D) In an open beaker over a tripod and gauze

Answer: A. Ethanol is highly flammable, so it must never be near a naked flame.

L1 · MM

2. The volume of a liquid in a measuring cylinder should be read

(A) from above, at the top of the meniscus (B) at eye level, from the bottom of the meniscus (C) at eye level, from the top of the meniscus (D) from below, at the bottom of the meniscus

Answer: B. Eye level avoids parallax error; read the bottom of the meniscus for water.

L2 · MM

3. A microscope has a ×10 eyepiece and a ×40 objective. The total magnification is

(A) ×50 (B) ×4 (C) ×400 (D) ×30

Answer: C. Eyepiece × objective = 10 × 40.

L2 · Drawing

4. A drawing of an insect is 60 mm long. The actual insect is 20 mm long. The magnification of the drawing is

(A) ×40 (B) ×0.3 (C) ×1200 (D) ×3

Answer: D. Drawing ÷ actual = 60 ÷ 20.

L2 · Drawing

5. Which of the following BREAKS the rules for biological drawing?

(A) Using ruled label lines (B) Writing labels horizontally (C) Including the magnification in the title (D) Shading the darker parts of the specimen

Answer: D. Biological drawings use clean outlines only — never shading.

L3 · ORR

6. In a results table, the units should be written

(A) after every number (B) in the column headings only (C) in a separate row at the bottom (D) only in the title

Answer: B. Units go in the headings, e.g. “Length / cm”.

L3 · ORR

7. Which type of graph should be used to show the number of each species of plant found in a quadrat?

(A) Bar chart (B) Line graph (C) Histogram (D) Scatter graph

Answer: A. Species are categories (discontinuous), so a bar chart with separate bars is used.

L4 · PD

8. The variable that the investigator deliberately changes is the

(A) responding variable (B) manipulated variable (C) controlled variable (D) control

Answer: B. The manipulated (independent) variable is changed on purpose.

L4 · PD

9. In a Planning and Design proposal, the method should be written in the

(A) past tense (B) present tense as commands (C) future tense (D) first person past tense

Answer: C. P&D is a plan for an experiment not yet done.

L5 · AI

10. The mass of a potato cylinder fell from 4.0 g to 3.0 g. The percentage change in mass is

(A) −33% (B) −25% (C) −1% (D) +25%

Answer: B. (3.0 − 4.0) ÷ 4.0 × 100 = −25%.

L5 · AI

11. “Only one potato cylinder was used at each concentration.” This is BEST described as

(A) a source of error in measurement (B) a controlled variable (C) a conclusion (D) a limitation of the experiment

Answer: D. A weakness in the design is a limitation; errors are inaccuracies in measuring.

L8 · SBA topic 3

12. A plant is destarched before testing a leaf for starch in order to

(A) remove chlorophyll from the leaf (B) make the leaf soft (C) make sure any starch found was made during the experiment (D) stop the plant from respiring

Answer: C. Destarching removes old starch, so the result reflects only the experiment.

L9 · SBA topic 4

13. In the test for a non-reducing sugar, after boiling with dilute hydrochloric acid the solution must be

(A) cooled and tested with iodine (B) mixed with ethanol (C) neutralised with sodium hydrogencarbonate before adding Benedict’s (D) tested with biuret reagent

Answer: C. Benedict’s solution does not work in acid conditions.

L11 · SBA topic 6

14. In an experiment on catalase in potato, a suitable control is

(A) boiled potato in hydrogen peroxide (B) a larger piece of raw potato (C) raw potato in water (D) raw potato at a higher temperature

Answer: A. Boiling denatures the enzyme, showing the reaction is due to catalase.

L13 · Practical

15. When measuring water loss by weighing a potted plant, the pot and soil are sealed in a plastic bag in order to

(A) prevent water evaporating from the soil (B) keep the plant warm (C) stop the plant from photosynthesising (D) increase the humidity around the leaves

Answer: A. Then the mass lost is due to transpiration from the plant.

Part 2 · Structured questions

Structured questions

3 Paper 2 style questions (30 marks). Write your answers first, then reveal the mark scheme and tick the points you earned.

L4 · Original · Planning and Design

Question 1 [10 marks]

A student observes that bread left in the kitchen becomes mouldy faster than bread kept in the refrigerator.

(a) Write a suitable hypothesis. [2]

MARK SCHEME — (a) (max 2)

Testable statement linking temperature and mould growth [1] e.g. “Bread kept at a higher temperature will develop mould faster.” [1]

(b) Write an aim that matches the hypothesis. [1]

MARK SCHEME — (b) (max 1)

e.g. “To investigate the effect of temperature on the rate of mould growth on bread.” [1]

(c) Identify the manipulated variable, the responding variable and TWO controlled variables. [4]

MARK SCHEME — (c) (max 4)

Manipulated: temperature [1] Responding: time for mould to appear / area covered by mould [1] Controlled: same type/brand of bread [1] Controlled: same size of slice / same moisture / same bag type / same exposure to air [1]

(d) State the expected results if the hypothesis is supported. [1]

MARK SCHEME — (d) (max 1)

Bread at the higher temperature shows mould sooner / more mould [1]

(e) State ONE safety precaution and ONE way to make the results more reliable. [2]

MARK SCHEME — (e) (max 2)

Keep bags sealed; do not open or inhale mould spores; dispose of safely [1] Use several slices at each temperature and find the mean [1]

L3 · Original · ORR and Drawing

Question 2 [10 marks]

A student measured the length of potato strips (initially 5.0 cm) after one hour in salt solutions: 0.0 mol dm⁻³ → 5.3 cm; 0.4 mol dm⁻³ → 4.9 cm; 0.8 mol dm⁻³ → 4.6 cm.

(a) Describe FOUR features of a suitable results table for these data. [4]

MARK SCHEME — (a) (max 4)

Title [1] First column: concentration of salt solution with unit (mol dm⁻³) [1] Columns for initial length, final length, change in length with units in headings (cm) [1] Ruled lines / values to the same number of decimal places [1]

(b) State the type of graph to draw and which variable goes on the x-axis. [2]

MARK SCHEME — (b) (max 2)

Line graph [1] Salt concentration on the x-axis [1]

(c) A student’s drawing of a leaf is 150 mm long; the real leaf is 50 mm. Calculate the magnification, showing your working. [2]

MARK SCHEME — (c) (max 2)

Magnification = drawing length ÷ actual length = 150 ÷ 50 [1] = ×3 [1]

(d) State TWO rules for biological drawing the student must follow. [2]

MARK SCHEME — (d) (max 2)

Clean, continuous lines / no shading [1] Ruled label lines with no arrowheads that do not cross [1] Labels horizontal [1] Large drawing; title with name, view and magnification [1]

L5 · Original · Analysis and Interpretation

Question 3 [10 marks]

Potato pieces were added to hydrogen peroxide at different pH values; foam height was measured after 2 minutes. At pH 7 the four repeats were 31, 33, 50 and 32 mm. The mean foam heights at the other pH values were: pH 3 — 5 mm; pH 5 — 18 mm; pH 9 — 20 mm; pH 11 — 6 mm.

(a) Identify the anomalous result at pH 7 and calculate the mean foam height, showing your working. [3]

MARK SCHEME — (a) (max 3)

Anomalous: 50 mm [1] (31 + 33 + 32) ÷ 3 [1] = 32 mm [1]

(b) Describe the trend in the results. [2]

MARK SCHEME — (b) (max 2)

Foam height increases from pH 3 to a maximum at pH 7 [1] Then decreases to pH 11 (quotes figures) [1]

(c) Explain the results. [2]

MARK SCHEME — (c) (max 2)

Catalase has an optimum pH around 7 [1] At other pH values the active site changes shape, so fewer substrate molecules fit / less oxygen produced [1]

(d) State ONE source of error and ONE limitation of this experiment. [2]

MARK SCHEME — (d) (max 2)

Error: foam height hard to read / pieces not exactly equal in size [1] Limitation: few pH values tested / only one type of tissue [1]

(e) Write a conclusion. [1]

MARK SCHEME — (e) (max 1)

Catalase in potato works best at about pH 7 (activity lower in acid and alkaline conditions) [1]

Your result

Test score

0%
SCORE

Not started

Multiple choice (50%)0%

Structured (50%)0%

← Back to the library All lessons & readiness

CSEC BIOLOGY · SECTION TEST · EDUTECH STEM ACADEMY · Original questions written for EduTech STEM Academy, aligned to the CXC CSEC Biology Syllabus (CXC 20/G/SYLL 13, amended 2017).

© 2026 EduTech STEM Academy. All rights reserved. The lessons, videos, practice questions and other materials on this site are for the personal study of authorised users only. They may not be copied, downloaded, recorded, shared or resold without written permission from EduTech STEM Academy (edutechstemacademy@gmail.com).