The shape of the lesson
By the end of the lesson, learners can
- Animal and plant cells compared: Pick the animal cell in the simulator, turn it, and click each part to read what it does.
- Bacteria: no nucleus: Switch the simulator to the bacterial cell.
- Spotting structures in diagrams and photographs: Exam questions show a drawing or a photomicrograph (a photograph taken through a microscope) and ask you to name or label the parts.
- All three cell types: cell membrane, cytoplasm and ribosomes.
- Plant cells add: cellulose cell wall, chloroplasts and a large permanent vacuole.
- Bacteria: no nucleus; circular DNA and plasmids instead; a cell wall that is not cellulose.
- Function words: controls entry and exit (membrane), protein synthesis (ribosomes), aerobic respiration (mitochondria).
One picture every idea returns to
Animal and plant cells both have a cell membrane, cytoplasm, a nucleus, mitochondria and ribosomes. Plant cells also have a cellulose cell wall, a large permanent vacuole and, in parts exposed to light, chloroplasts. A bacterial cell has a cell wall, cell membrane, cytoplasm and ribosomes, but no nucleus: its genetic material is a loop of circular DNA, and it may also carry small rings of DNA called plasmids.
Forty-five minutes, phase by phase
| Time | Phase | What happens in the room | Grouping |
|---|---|---|---|
| 0 to 5 min | Hook: predict | Open with the question in the title, Same building blocks, different extras.. Every living thing is made of cells. Put the figure on the board: it is the one picture every idea in the lesson returns to. | Whole class, then pairs |
| 5 to 13 min | Teach and check: Animal and plant cells compared | Pick the animal cell in the simulator, turn it, and click each part to read what it does. Project tab 1 of the lab (Cells lab, cells in 3D) and let a student drive it while the class predicts. | Whole class, then pairs |
| 13 to 21 min | Teach and check: Bacteria: no nucleus | Switch the simulator to the bacterial cell. | Pairs |
| 21 to 30 min | Teach and check: Spotting structures in diagrams and photographs | Exam questions show a drawing or a photomicrograph (a photograph taken through a microscope) and ask you to name or label the parts. Project tab 2 of the lab (Cells lab, test yourself) and let a student drive it while the class predicts. | Jigsaw |
| 30 to 36 min | Check | The four Stage 1 questions from the student lesson, answered on mini whiteboards or by show of fingers. Re-teach the one most get wrong. | Individual, then whole class |
| 36 to 43 min | Plenary | The exam-style questions from Stage 2, one at a time: thirty seconds alone, then a random call. The feedback lines in the key give the examiner's wording. | Individual, random call |
| 43 to 45 min | Exit and homework | Set the worksheet below (6 questions, 17 marks). Learners self-assess against the objectives before they leave. | Individual |
Protect the parts that carry the learning
The sequence carries about fifty minutes of material, so the lab is driven by one student while the class predicts rather than explored freely. Times are a guide.
Protected: the check at 30 minutes. It is the only individual read on whether the key idea landed, and it is not cut.
Cut first if the build overruns: the last check in Spotting structures in diagrams and photographs, never the check or the plenary.
In a 60 minute block: run worksheet questions 1 to 3 in class as a Rally Coach set and model both the hardest worked example and its check live.
Jigsaw
Split the content into expert pieces. Expert groups master one piece each, then regroup so every home team has one expert per piece, and each expert teaches their piece to the team.
The full structure, with its variations and the other twelve, is on the cooperative-learning page.
What to head off, and how
| Trap learners fall into | Teaching move that pre-empts it |
|---|---|
| Plant cells have mitochondria as well as chloroplasts. | Chloroplasts do not replace mitochondria: plant cells respire all the time, day and night, so a palisade cell contains both. Not every plant cell has chloroplasts either: root cells and onion bulb cells are not exposed to light and have none. |
| A label line must touch the structure you name. | A line ending in the vacuole but labelled cytoplasm, or ending on the thick outer line of a plant cell but labelled cell membrane, scores no mark. |
Animal, plant and bacterial cells: worksheet
6 questions, 17 marks. Written in the style of the papers; no past paper question is reproduced.
State three structures found in a palisade mesophyll cell that are not found in a cheek cell.
State the function of (a) the cell membrane, (b) the nucleus, (c) the ribosomes, (d) the chloroplasts.
Describe three ways in which the structure of a bacterial cell is different from the structure of an animal cell.
A student looks at cells from the root of a bean plant under a light microscope. She sees a cell wall and a large vacuole but no chloroplasts. She concludes that the cells are not plant cells. Explain why her conclusion is wrong.
A diagram of a leaf cell shows a thick outer layer, a large clear central space, a round darkly stained body pressed against one side and many small green oval bodies. Name the structures described.
A palisade mesophyll cell contains both chloroplasts and mitochondria. Explain why it needs both.
Answer key and marking notes
- Cell wall (made of cellulose).
- Chloroplasts.
- Large permanent vacuole (containing cell sap).
- (a) Controls which substances enter and leave the cell.
- (b) Contains the genetic material (chromosomes / DNA) that controls the activities of the cell.
- (c) Protein synthesis: proteins are made there.
- (d) Contain chlorophyll, which absorbs light energy for photosynthesis.
- A bacterial cell has a cell wall; an animal cell does not.
- A bacterial cell has no nucleus; its DNA is a single circular loop free in the cytoplasm.
- A bacterial cell may contain plasmids (small rings of DNA); it has no mitochondria.
- The cell wall and the large (permanent) vacuole show that they are plant cells.
- Chloroplasts are only found in plant cells in parts exposed to light; roots are underground, so their cells have none.
- Thick outer layer: cell wall.
- Large clear central space: (permanent) vacuole; round darkly stained body: nucleus.
- Small green oval bodies: chloroplasts.
- Chloroplasts absorb light energy for photosynthesis, to make food.
- Mitochondria are where aerobic respiration releases energy; all living cells respire all the time, including in the dark.
8 multiple-choice questions on this lesson
From the topic question bank. Assign them in the app for a marked score in your gradebook, or run the topic as a class game.
Which structure is found in both a plant cell and a bacterial cell, but not in an animal cell?
- Aa cell wall
- Ba nucleus
- Ca plasmid
- Da mitochondrion
What does the large permanent vacuole of a plant cell contain?
- Acell sap, a solution of sugars and salts
- Bchlorophyll, which absorbs light energy
- Cplasmids, small rings of DNA
- Dthe chromosomes that control the cell
The table shows which structures four cells, W, X, Y and Z, contain. Which cell could have been taken from the root of a plant?
- AY
- BZ
- CX
- DW
A student looks at an unknown cell with a light microscope. Which feature would show that it is a plant cell and not an animal cell?
- Aa cellulose cell wall outside the cell membrane
- Ba nucleus surrounded by cytoplasm
- Ca small vacuole in the cytoplasm
- Dmitochondria scattered in the cytoplasm
What are plasmids?
- Asmall rings of DNA found in some bacterial cells
- Btiny structures where bacteria make proteins
- Cthe main loop of circular DNA in a bacterium
- Dpores in the cell wall of a bacterium
A single-celled organism has a cell wall, a nucleus, mitochondria and chloroplasts. Which conclusion is correct?
- Ait is not a bacterium, because it has a nucleus
- Bit is a bacterium, because it has a cell wall
- Cit is an animal cell, because it has mitochondria
- Dit is not a plant cell, because plants lack mitochondria
The diagram shows a bacterial cell. Which label points to the structure that controls which substances enter and leave the cell?
- AB
- BA
- CC
- DD
Muscle cells contain many more mitochondria than cheek cells. Which is the best explanation?
- Amuscle cells need more energy released by aerobic respiration
- Bmuscle cells make more protein, and mitochondria make proteins
- Cmuscle cells need more oxygen, which mitochondria produce
- Dmuscle cells divide more often, and mitochondria control division
Quiz key
Plant cells have a cellulose cell wall and bacteria have a cell wall too (not made of cellulose), but animal cells have only a cell membrane. A nucleus is found in plant and animal cells but not in bacteria. Plasmids are found only in bacteria. Mitochondria are in plant and animal cells but not in bacteria.
The vacuole is full of cell sap, a solution of sugars and salts in water; when it is full it presses outwards and keeps the cell firm. Chlorophyll is inside the chloroplasts, not the vacuole. Plasmids are found in bacteria, not plant cells. The chromosomes are inside the nucleus.
Y has a cell wall, a nucleus and mitochondria but no chloroplasts: a plant cell that is not exposed to light, such as a root cell. Z has a cell wall but no nucleus and no mitochondria, so it is a bacterium. X has no cell wall, so it is an animal cell. W has chloroplasts, so it comes from a part of the plant in the light, such as a leaf.
Only plant cells have a cellulose cell wall. Both plant and animal cells have a nucleus surrounded by cytoplasm, and both have mitochondria. Animal cells can have small, temporary vacuoles; it is the large permanent vacuole that is a plant feature, so a small vacuole does not decide it.
Plasmids are small circles of DNA, separate from the main chromosome, found in many bacteria. Proteins are made on ribosomes, not plasmids. The main genetic material is one large loop of circular DNA; plasmids are extra, smaller rings. They are not part of the cell wall.
Bacteria have no nucleus, so an organism with a nucleus cannot be a bacterium (its other features match a plant-like cell). A cell wall does not prove it is a bacterium, because plant cells have one too. Mitochondria are found in plant cells as well as animal cells, and an animal cell would not have a cell wall or chloroplasts. Plant cells do contain mitochondria, because they respire all the time.
B is the thin cell membrane just inside the wall; it controls what enters and leaves. A is the thick cell wall, which is fully permeable and gives strength and shape. C is the loop of circular DNA, which carries the genes. D is a plasmid, a small extra ring of DNA.
Mitochondria are where most of the reactions of aerobic respiration release energy, and contracting muscles use a great deal of energy. Proteins are made on ribosomes, not mitochondria. Mitochondria use oxygen in respiration; they do not produce it. Cell division is controlled by the nucleus, not by mitochondria.
What to project
The student lesson embeds these tabs. Open them full screen on the projector; every slider has a drag handle on the stage.
Slides for this lesson
A projectable deck for every pack is on the way. Until then, present the student lesson full screen: its sections, figure and lab tabs follow the same order as the plan above.