Edexcel A-Level Biology Geometry Skills

Practise Edexcel A-Level Biology geometry skills through surface area, volume, cross-sectional area, radius-diameter conversion and SA:V ratios.

[Maximum number: 2]

A student used a microscope to study the tissues in a plant stem and the cell of an animal.

The photograph shows a vascular bundle in a transverse section of the plant stem, as seen using a light microscope.

Figure for Question A.4 Geometry and trigonometry question 1 — Edexcel A-Level Biology AS

This photograph shows a high-power view of some of the cells in tissue C in the vascular bundle.

Each of the smallest units on the eyepiece graticule shown in the photograph is $3 \times 10^{-6} \mathrm{~m}$ .

Assume that the cell labelled F in the photograph is circular.
Calculate the cross-sectional area of cell F .

Answer

An answer that includes the following steps:

- measurement of cell \{diameter / radius\} in epg units and conversion to m (1)

- calculation of area using $\pi \mathrm{r}^{2}(1)$

ACCEPT 14 to 14.5 as alternatives to 13.

e.g.

$\{13 / 6.5\} \times 3 \times 10^{-6}=39 \times 10^{-6}=3.9 \times 10^{-5}$

OR $19.5 \times 10^{-6}=1.95 \times 10^{-5}$ $\pi \times\left(\left(1.95 \times 10^{-5}\right)^{2}\right)=1.195 \times 10^{-9}$

OR $3.14 \times 3.8025 \times 10^{-10}=1.194 \times 10^{-9}$

ACCEPT 1.195, 1.19, 1.2

If include units must match answer, but units not needed

(2)

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Edexcel A-Level Biology Geometry Skills

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A.4 Geometry and trigonometry question 1