Science - Combined - 0653 CIE

Size Of Specimens

Overview

A drawing of a cell might be the size of your hand, yet the real cell is far too small to see. How do biologists describe these sizes accurately? They use magnification: the number of times bigger the image is than the real object. One simple formula links the three quantities, and rearranging it lets you find any one from the other two.

In this lesson you will learn and use the magnification formula, work carefully with units in millimetres, and, at Extended level, convert between millimetres and micrometres so you can handle the tiny sizes of cells and organelles with confidence.

Objectives

  1. [Core] State and use the formula: magnification = image size / actual size
  2. [Core] Calculate magnification and size of biological specimens using millimetres as units
  3. [Supplement] Convert measurements between millimetres (mm) and micrometres (μm)

Lesson Note

Magnification questions appear on almost every paper because they test a real practical skill: measuring a drawing or photograph and working out the true size. The maths is easy once you are strict about units, and the marks are reliable. The same formula also lets you check that a quoted magnification is sensible.

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Lesson Evaluation

Congratulations on completing the lesson on Size Of Specimens. Now that youve explored the key concepts and ideas, its time to put your knowledge to the test. This section offers a variety of practice questions designed to reinforce your understanding and help you gauge your grasp of the material.

You will encounter a mix of question types, including multiple-choice questions, short answer questions, and essay questions. Each question is thoughtfully crafted to assess different aspects of your knowledge and critical thinking skills.

Use this evaluation section as an opportunity to reinforce your understanding of the topic and to identify any areas where you may need additional study. Don't be discouraged by any challenges you encounter; instead, view them as opportunities for growth and improvement.

  1. To calculate the magnification of a drawing, which division do you carry out? A. real size divided by drawing size B. drawing size divided by real size C. drawing size divided by eyepiece value D. real size divided by objective value Answer: B
  2. A drawing is 50 mm wide; the real object is 0.5 mm wide. The magnification is: A. x10 B. x25 C. x100 D. x500 Answer: C
  3. How many micrometres are there in 1 millimetre? A. 10 B. 100 C. 1000 D. 1000000 Answer: C
  4. An image is x200 and 40 mm wide. The actual size is: A. 0.2 mm B. 0.5 mm C. 5 mm D. 8000 mm Answer: A
  5. Magnification is measured in: A. millimetres B. micrometres C. no units D. centimetres Answer: C

Available on the Green Bridge App

Download the Green Bridge CBT app on your phone or computer to access full lesson notes, practice questions, and more.

Full lesson notes with diagrams
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Available on Android, Windows, macOS, and Linux

Available on the Green Bridge App

Download the Green Bridge CBT app on your phone or computer to access full lesson notes, practice questions, and more.

Full lesson notes with diagrams
AI-powered learning assistant
Study offline, anytime, anywhere
Available on Android, Windows, macOS, and Linux

Practice Mock Questions

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