Teacher sheet · Ages 10–11 · about 45–50 minutes
Inside a cell: plant and animal cells
Lesson page: echoesof.science/school/cells/ages-10-11/ · Pupil worksheet: echoesof.science/school/cells/ages-10-11/print/
Learning aims
- State the three ideas of cell theory.
- Name the main parts of plant and animal cells and their jobs.
- Know that bacteria are single cells without a nucleus.
- Prepare a slide and use a microscope; change one variable in a fair test.
Lesson plan
| Time | Activity |
|---|---|
| 5 min | Starter: Hooke's cork drawing. What do you think the boxes are? |
| 10 min | Read the text; build a plant/animal comparison table on the board. |
| 20 min | Onion-skin slides in pairs. |
| 5 min | Game: Plant, animal or both? |
| 5 min | Quiz; worksheet for homework. |
Materials for the experiment
- Half an onion (cut by an adult)
- Microscope slides and coverslips
- A school light microscope
- Tweezers
- A dropper
- Water and a few drops of blue food colouring
- Paper towels
Safety: Only an adult uses the knife. Slides and coverslips are glass: handle them by the edges and tell an adult about any breakage. Never use direct sunlight as the microscope's light source. Food colouring stains: wear an apron.
Common misconceptions
| Pupils may think… | Actually… |
|---|---|
| Plant cells have no mitochondria because they photosynthesise. | Plant cells have mitochondria and respire all the time; chloroplasts are extra. |
| The cell wall and cell membrane are the same thing. | Plant cells have both: the membrane lies just inside the wall and controls what moves in and out. |
| All cells look the same. | Cells have different shapes and sizes for different jobs; the body has about 200 cell types. |
Worksheet answers
- All living things are made of cells; the cell is the basic unit of life; new cells come from existing cells.
- Brick- or box-shaped cells with a clear outline (the cell wall) and a small round dark spot (the nucleus).
- Cell wall: gives strength and shape. Chloroplasts: photosynthesis. (Also accept the large central vacuole: fluid-filled, helps control the cell's water.)
- So that only one thing changed; then any difference in what we saw must be caused by the colouring.
Quiz answers
- What does cell theory say about new cells? They come only from existing cells. Cell theory: new cells arise from existing cells.[1]
- About how wide is a human red blood cell? 8 micrometres. About 8 µm, so around 250 fit across a pinhead.[1]
- Which part controls what goes in and out of a cell? The cell membrane. The membrane controls what moves in and out.[3]
- Which part releases energy from food? Mitochondria. Mitochondria carry out respiration.[3]
- Which part is found in plant cells but not in animal cells? Cell wall. Plant cells have a cellulose cell wall; animal cells do not.[3]
- How is a bacterial cell different? It has no nucleus. Bacteria are prokaryotes: their DNA is not inside a nucleus.[2]
Going further
Compare onion skin with a thin piece of a green leaf, such as pondweed. What can you see in the leaf cells that the onion cells do not have?
Sources used in this lesson
- [1] Biology 2e, 4.1 Studying Cells (OpenStax, Rice University): reliability High
- [2] Biology 2e, 4.2 Prokaryotic Cells (OpenStax, Rice University): reliability High
- [3] Biology 2e, 4.3 Eukaryotic Cells (OpenStax, Rice University): reliability High
Full list with links and a note on each source's reliability: echoesof.science/school/cells/sources/
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