Cells
Convert before calculating
A cell is 50 μm long. Its drawing is 30 mm long. Calculate the magnification (enter the number after ×).
CAMBRIDGE 5090 + BIOLOGY APPLICATION
Think with your hands.
Calculate, plot, label and explain. Original practice inspired by the 2026–2028 syllabus skills, with feedback after you attempt.
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Movement into and out of cells
Osmosis: signed percentage change
A potato cylinder changes from 5.00 g to 4.40 g. Calculate its percentage change in mass, including the sign.
Handling data
Calculate a mean
Three repeat reaction times are 42 s, 45 s and 48 s. Calculate the mean reaction time.
Plant nutrition
Calculate a production rate
An aquatic plant produces 12.0 cm³ of gas in 5.0 minutes. Calculate the mean gas-production rate.
Enzymes
Identify the dependent variable
A student changes pH while holding temperature, enzyme concentration and substrate concentration constant. They measure the time for starch to disappear. Which is the dependent variable?
Evaluation
Separate bias from random variation
A balance reads +0.20 g when empty and is not zeroed. Which improvement directly addresses this error?
Ecology
Estimate a population
Five randomly placed 0.25 m² quadrats contain 6, 8, 5, 7 and 9 plants. Estimate the number in a uniform 100 m² area.
Investigation planning
Plan a fair osmosis investigation
Plan how you would investigate the effect of sucrose concentration on the percentage mass change of potato cylinders. Include measurement, controls, repeats and one safety precaution.
These are original teaching exercises, not official past-paper questions or examiner marking. Official Cambridge 5090 syllabus. Schematics simplify anatomy and are not clinical references. Activities here are virtual; practical investigations need appropriate supervision.