Cell Structure

What Cell Structure covers

Cell structure is the first section of Module 2 and the foundation the rest of the course builds on. It covers the three types of microscope and how a slide is prepared and stained, magnification and resolution and the calculations behind them, the organelles of a eukaryotic cell and the route a secreted protein takes, and how prokaryotic cells differ.

The 5 subtopics

Each one has its own page.

• Microscopy, slide preparation and stainingLight, transmission electron and scanning electron microscopes, preparing and mounting a slide, calibrating an eyepiece graticule against a stage micrometer, and differential staining.Open →
• Biological drawings, magnification and resolutionThe rules a biological drawing follows, the magnification equation and its rearrangements, and why an electron microscope resolves detail that a light microscope cannot.Open →
• Eukaryotic cell ultrastructureThe nucleus, endoplasmic reticulum, Golgi apparatus, mitochondria, lysosomes, chloroplasts, centrioles, cilia and flagella, and how each appears in an electron micrograph.Open →
• The secretory pathway and the cytoskeletonThe route a protein takes from ribosome to Golgi apparatus to the cell surface, and the cytoskeleton that gives a cell its strength, internal transport and movement.Open →
• Prokaryotic and eukaryotic cells comparedSize, ribosomes, cell wall composition, plasmids and the way DNA is held, together with the structures both cell types share.Open →

What you need to know

Answer each one before you reveal it.

Take Cell Structure further

The same content, four other ways.

Commonly confused

Pairs that lose marks when they are blurred together.

• Magnification vs Resolution

  Magnification: how many times larger an image appears. Resolution: ability to distinguish two close points as separate.

Questions from this topic

Each one with the model answer underneath.

1. 1

   How does a light microscope produce an image of a specimen?

   Model answer

   It uses visible light and glass lenses to magnify specimens, producing 2D images of cells and tissues with relatively low resolution.

2. 2

   What type of radiation does a transmission electron microscope use, and how does it interact with the specimen?

   Model answer

   A TEM uses a beam of electrons that is transmitted through a thin specimen to produce high-resolution 2D images of internal ultrastructure.

3. 3

   How does a scanning electron microscope generate an image?

   Model answer

   An SEM uses a beam of electrons scanned across the surface of a specimen to produce 3D images of surface structure.

4. 4

   Compare the resolution and magnification capabilities of light microscopes and electron microscopes.

   Model answer

   Light microscopes have lower resolution and magnification than electron microscopes.

5. 5

   What type of image does a TEM produce compared to an SEM?

   Model answer

   TEM produces 2D images showing internal structure, while SEM produces 3D images showing surface topography.

6. 6

   When preparing a microscope slide, what is the first step involving the specimen?

   Model answer

   Place a thin specimen on a glass slide.

What is inside Levo

Six ways to work the same material.

Cell Structure revision questions

What does Cell Structure cover in OCR A-Level Biology?

5 subtopics: microscopy, slide preparation and staining, biological drawings, magnification and resolution, eukaryotic cell ultrastructure, the secretory pathway and the cytoskeleton and prokaryotic and eukaryotic cells compared. Each one has its own page with questions and model answers.

How is Cell Structure organised?

By the OCR H420 specification, subtopic by subtopic, so it matches the order you are taught it in.