Animal and plant cells: cytoplasm

The idea

Cytoplasm is the jelly-like substance that fills the cell and surrounds the organelles. It is mainly water with dissolved substances, and it is where many of the cell's chemical reactions take place. In animal and plant cells the cytoplasm contains the nucleus, mitochondria, ribosomes and other structures, holding them in position. In prokaryotic cells such as bacteria, the cytoplasm also holds the genetic material because there is no nucleus. A helpful method is to imagine the cytoplasm as the fluid in which the cell's machinery floats and works.

What earns the marks

• Describes cytoplasm as a jelly-like or fluid substance that fills the cell and surrounds the organelles.
• States that many chemical reactions of the cell take place in the cytoplasm.
• Explains that the cytoplasm holds organelles such as the nucleus, mitochondria and ribosomes in place.
• Recognises that in prokaryotic cells the genetic material is found in the cytoplasm because there is no nucleus.
• Identifies the cytoplasm on a labelled diagram or microscope image of an animal or plant cell.

Common mistakes and how to put them right

• Confusing cytoplasm with the cell membrane.

  Put it right: The membrane is the outer barrier while the cytoplasm is the contents inside it.

• Saying the cytoplasm is only water.

  Put it right: It is a mixture of water, dissolved substances and enzymes that allow reactions to occur.

• Claiming all chemical reactions happen in the cytoplasm.

  Put it right: Some reactions occur in organelles such as mitochondria and chloroplasts.

Exam tips

• Write 'site of chemical reactions' as well as 'jelly-like substance' so your answer covers both structure and function.
• When comparing plant and animal cells, remember cytoplasm is present in both, so do not list it as a difference.
• Use the cytoplasm to explain why substances can move around the cell, linking it to diffusion of dissolved molecules.