A teacher made a model of an animal cell for a class.
The real animal cell is 20 μm20\ \mu\text{m}20 μm wide. The model of the cell is 40 cm wide.
Calculate how many times larger the model is than the real cell.
A mitochondrion in the real cell is 2 μm2\ \mu\text{m}2 μm long. The model mitochondrion is made to the same scale.
Calculate the length of the model mitochondrion. Give your answer in cm\text{cm}cm.
Give one reason why scientists use models of cells.
48 exam-style questions on Edexcel GCSE Biology 1.2 Number, size and scale, covering 1.2.1 Number, size and scale with estimations and 1.2.2 Quantitative units in relation to cells. Each one has a worked solution and a mark scheme showing where the marks go.