Cells, structures and scale

Learning objectives

• Identify cell membrane, cytoplasm and nucleus.
• Compare typical plant and animal cells.
• Use a scale or magnification correctly.

The big idea

Cells are small systems with a membrane controlling exchange and cytoplasm where many reactions occur. Most plant and animal cells contain a nucleus, while specialised cells may lose or modify structures.

Plant cells usually have a cellulose wall and may contain chloroplasts and a large permanent vacuole. A microscope image is magnified, so its displayed size is not its actual size; drawings show selected structures rather than every molecule.

Equations and relationships

Investigate and explain

Using the worked example as supplied data, predict the effect of changing one condition. Draw a labelled model, record your reasoning and identify a variable that would need controlling. No human, animal or microbial experiment is required.

No exact PhET model is claimed for this topic. Use diagrams and supplied-data reasoning instead.

Open the interactive investigation

Check your understanding