The shape of the lesson
By the end of the lesson, learners can
- New cells from old: Press Divide every cell and watch the order of events.
- Cells built for one function: Choose each cell in the simulator and watch it at work.
- Cell, tissue, organ, system: Pick the human, then step up through the five levels.
- New cells come only from the division of existing cells.
- Seven specialised cells: ciliated, root hair, palisade mesophyll, neurone, red blood cell, sperm and egg.
- Link a feature to a job: large surface area for absorption, chloroplasts for photosynthesis, no nucleus for more haemoglobin.
- Levels: cell, tissue (similar cells), organ (several tissues), organ system (several organs), organism.
One picture every idea returns to
New cells are produced by division of existing cells. Specialised cells have specific functions: ciliated cells move mucus in the trachea and bronchi, root hair cells absorb water and mineral ions, palisade mesophyll cells photosynthesise, neurones conduct electrical impulses, red blood cells transport oxygen, and sperm and egg cells (gametes) are for reproduction. Similar cells form a tissue, tissues form an organ, organs form an organ system, and organ systems together form an organism.
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, Shaped for one job.. New cells only come from the division of existing 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: New cells from old | Press Divide every cell and watch the order of events. Project tab 3 of the lab (Cells lab, new cells) and let a student drive it while the class predicts. | Whole class, then pairs |
| 13 to 21 min | Teach and check: Cells built for one function | Choose each cell in the simulator and watch it at work. Project tab 4 of the lab (Cells lab, specialised cells) and let a student drive it while the class predicts. | Pairs |
| 21 to 30 min | Teach and check: Cell, tissue, organ, system | Pick the human, then step up through the five levels. Project tab 5 of the lab (Cells lab, levels of organisation) and let a student drive it while the class predicts. | Corners |
| 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, 18 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 Cell, tissue, organ, system, 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.
Corners
Put one answer or viewpoint in each corner of the room. Students move to the corner they agree with, justify the choice to a partner there, then hear one voice from each corner before the reveal.
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 |
|---|---|
| Learn the function in the syllabus words. | A red blood cell's function is the transport of oxygen, not just carrying blood; a ciliated cell moves mucus, it does not trap dust itself (the mucus, made by other cells, does the trapping). |
| An organ contains several different tissues; a tissue is made of similar cells. | A leaf is an organ (epidermis, palisade and spongy mesophyll, xylem and phloem tissues), not a tissue. The heart is an organ, not an organ system: it is one part of the circulatory system. |
Specialised cells and levels of organisation: worksheet
6 questions, 18 marks. Written in the style of the papers; no past paper question is reproduced.
State the function of each of these specialised cells: (a) ciliated cell, (b) root hair cell, (c) palisade mesophyll cell, (d) neurone, (e) red blood cell, (f) egg cell.
State how new cells are produced.
A single cell divides into two, and then every new cell divides once every 20 minutes. Calculate how many cells there are after 2 hours, assuming none die.
Classify each of these as a cell, tissue, organ or organ system: (a) the stomach, (b) a sperm cell, (c) the digestive system, (d) a layer of palisade mesophyll cells.
Explain how the structure of a red blood cell is related to its function.
Explain the difference between a tissue and an organ, using the leaf as an example.
Answer key and marking notes
- (a) Movement of mucus in the trachea and bronchi.
- (b) Absorption (of water and mineral ions).
- (c) Photosynthesis.
- (d) Conduction of electrical impulses.
- (e) Transport of oxygen.
- (f) Reproduction: it is a female gamete.
By the division of existing cells.
- 2 hours = 120 minutes, so 120 ÷ 20 = 6 divisions.
- The number doubles each time: 26 = 64 cells.
- (a) Organ.
- (b) Cell.
- (c) Organ system.
- (d) Tissue.
- Its function is the transport of oxygen.
- It is full of haemoglobin, which carries oxygen, and has no nucleus, so there is more room for haemoglobin.
- Its biconcave shape gives a large surface area for oxygen to move in and out.
- A tissue is a group of cells with similar structures working together for a shared function, such as palisade mesophyll tissue.
- An organ is made of several different tissues working together; the leaf contains epidermis, palisade and spongy mesophyll, xylem and phloem, so it is an organ.
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 specialised cell is correctly matched with its function?
- Asperm cell: reproduction
- Bciliated cell: trapping dust
- Cred blood cell: killing pathogens
- Dneurone: transport of oxygen
The heart, the blood vessels and the blood work together to transport substances around the body. What level of organisation do they form together?
- Aan organ system
- Ban organ
- Ca tissue
- Dan organism
Which of these is a tissue?
- Aa layer of ciliated cells lining the trachea
- Bthe trachea
- Ca single neurone
- Dthe nervous system
Palisade mesophyll cells are packed near the upper surface of a leaf and contain many chloroplasts. How does this help the leaf?
- Athe cells absorb as much light as possible for photosynthesis
- Bthe cells release energy by respiration much faster
- Cthe cells absorb water and mineral ions from the air
- Dthe cells make the leaf strong enough to stay flat
The diagram shows a group of specialised cells. What is the function of these cells?
- Amoving mucus in the trachea and bronchi
- Babsorbing water and mineral ions from soil
- Cconducting electrical impulses
- Dtrapping dust and pathogens themselves
A culture starts with 3 bacterial cells. Every cell divides once every 25 minutes. Assuming no cells die, how many cells are there after 100 minutes?
- A48
- B16
- C12
- D24
Which list shows these plant structures in order from the smallest level of organisation to the largest?
- Aroot hair cell, xylem tissue, leaf, shoot system
- Bxylem tissue, root hair cell, leaf, shoot system
- Croot hair cell, leaf, xylem tissue, shoot system
- Droot hair cell, xylem tissue, shoot system, leaf
Mature red blood cells have no nucleus. Which statement about them is correct?
- Athey cannot divide, so new ones come from division of other cells
- Bthey cannot carry oxygen, because there is no nucleus to control it
- Cthey are bacterial cells, because they have no nucleus
- Dthey form by joining fragments of old red blood cells together
Quiz key
Sperm cells are male gametes, so their function is reproduction. Ciliated cells move mucus; the mucus, made by other cells, is what traps dust. Killing pathogens is done by white blood cells, not red blood cells. Neurones conduct electrical impulses; red blood cells transport oxygen.
A group of organs with related functions working together is an organ system, here the circulatory system. The heart on its own is an organ, but together with the vessels and blood it is a system. A tissue is a group of similar cells, which is a lower level. The organism is the whole human, made of many organ systems.
A layer of similar ciliated cells working together is a tissue. The trachea is made of several different tissues, so it is an organ. A single neurone is one cell. The nervous system is made of several organs, such as the brain and spinal cord, so it is an organ system.
The function of palisade mesophyll cells is photosynthesis. Chloroplasts contain chlorophyll, which absorbs light, and the upper surface receives the most light. Respiration happens in mitochondria, not chloroplasts. Water and mineral ions are absorbed from the soil by root hair cells. Strength comes mainly from cell walls and full vacuoles, not from chloroplasts.
The cells carry many cilia on one surface, so they are ciliated cells; the cilia beat to move mucus up the trachea and bronchi. Root hair cells absorb water and ions, but each has one long extension, not many fine cilia. Neurones conduct impulses and have long thin fibres. The mucus traps dust and pathogens; the cilia only sweep it along.
100 ÷ 25 = 4 divisions. Each division doubles the number: 3 → 6 → 12 → 24 → 48. 16 is 24, the answer for a single starting cell. 12 adds 3 cells each time (3 × 4) instead of doubling. 24 is the number after only three divisions.
A root hair cell is a cell, xylem is a tissue, a leaf is an organ made of several tissues, and the shoot system is an organ system. So the order is cell, tissue, organ, organ system. The second option puts a tissue before a cell. The third treats the leaf as smaller than a tissue. The last puts an organ above an organ system.
New cells are produced only by the division of existing cells, and a cell with no nucleus cannot divide, so red blood cells are replaced by the division of other cells in the bone marrow. Having no nucleus leaves more room for haemoglobin, so they carry oxygen well. They are not bacteria: they have no cell wall, plasmids or circular DNA. Cells never form by joining fragments together.
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.