Cell structures and organisation
Connect each cell structure with its role and distinguish membranes from walls.
What you will learn
- Identify the main structures in animal and plant cells.
- Explain selective movement across a membrane.
A cell is an organised system
The nucleus contains genetic material that influences cell activity. The cytoplasm is where many chemical reactions occur. The cell membrane separates the cell from its surroundings and controls the exchange of substances. Plant cells also have a cellulose wall, and many have chloroplasts and a large permanent vacuole.
A cell wall supports a plant cell; it is not a substitute for the membrane. Both structures are present in a typical plant cell.
Selectivity matters
The membrane allows some substances to cross more readily than others. This supports a different internal environment from the surroundings. Cells with related functions form tissues; different tissues combine in organs, and organs work together in organ systems.
Worked example
A question describes the boundary that controls what enters and leaves an animal cell. Identify it and explain your choice.
Show the worked solution
- An animal cell has no cellulose cell wall.
- The nucleus is internal and stores genetic information.
- The selectively permeable boundary is the cell membrane.
Answer Cell membrane
Common mistakes
- Do not confuse the cell wall's support role with membrane transport.
- Not every plant cell has chloroplasts, such as many root cells.
What can you explain now?
Which structure contains most of the genetic material in a typical animal cell?
Compare with the explanation
The nucleus
The nucleus contains the chromosomes; it is distinct from the cell membrane.
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