A-Level Edexcel Biology Ratios and Percentages

Review A-Level Edexcel Biology ratios, fractions and percentages through biomass, disease data, surface-area-to-volume ratios and biological comparisons.

Exam points

calculate percentage change, decrease or difference from graph and table values
express biological comparisons as ratios such as SA:V, trophic energy or ion concentration
use fractions or percentages to find biomass, cell counts, deaths or energy conversion

[Maximum number: 1]

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.

$Figure for Question A.0.3—Ratios, fractions and percentages question 1 — Edexcel A-Level Biology AS$

A cell in tissue B of the vascular bundle has a cross-sectional area of $6.13 \times 10^{-11} \mathrm{~m}^{2}$ .

Calculate how many times larger the cross-sectional area of cell F is than this cell in tissue B.

Give your answer to three significant figures.

Answer

division of area of F by area given of E
(1)

ecf from 1aiii

eg

$1.194 \div 0.0613=19.5$ times

(1)

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