Edexcel IAL Biology 3.7 Microscopy magnification, resolution and staining

Measure the image consistently, convert mm, micrometres and nanometres before substituting and justify stain or coverslip choices through visibility and specimen quality.

Exam points

Calculate magnification or actual size after converting every measurement to one unit.
Define resolution as separating two close points and distinguish it from magnification.
Explain how staining and slide preparation improve contrast and image quality.

[Maximum number: 1]

Abaca plants are found in the Philippines.
The photograph shows a mat made from abaca plant fibres.

Figure for Question 3.7—Microscopy magnification, resolution and staining question 1 — Edexcel A-Level Biology AS

Plant fibres include xylem vessels.

The photograph shows some xylem vessels, as seen using a light microscope.

A stain was added to the xylem before viewing using a microscope.
Give a reason why it is usual to stain specimens in microscopy.

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3.7—Microscopy magnification, resolution and staining question 1