The shape of the lesson
By the end of the lesson, learners can
- Seven characteristics, every one of them: Pick the dog in the simulator and test each characteristic in turn, then do the same for the plant.
- It looks alive, but it is not: Now switch the simulator to the car, the fire and the salt crystal.
- Plants show all seven too: Students often say plants do not move or excrete.
- MRS GREN: movement, respiration, sensitivity, growth, reproduction, excretion, nutrition.
- Respiration is chemical reactions in cells that release energy; it is not breathing.
- Growth is a permanent increase in size and dry mass.
- Alive means all seven, carried out by the organism's own cells.
One picture every idea returns to
Every living organism shows all seven characteristics of life, often remembered as MRS GREN: movement, respiration, sensitivity, growth, reproduction, excretion and nutrition. Each has a precise definition. Respiration happens in cells and releases energy; growth is a permanent increase in size and dry mass; excretion removes the waste products of metabolism. Non-living things may seem to show one or two, but never all seven, and never by the processes that happen in cells.
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, Seven tests, and a living thing passes all of them.. Movement, respiration, sensitivity, growth, reproduction, excretion and nutrition. 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: Seven characteristics, every one of them | Pick the dog in the simulator and test each characteristic in turn, then do the same for the plant. Project tab 1 of the lab (Classification lab, alive or not?) and let a student drive it while the class predicts. | Whole class, then pairs |
| 13 to 21 min | Teach and check: It looks alive, but it is not | Now switch the simulator to the car, the fire and the salt crystal. | Pairs |
| 21 to 30 min | Teach and check: Plants show all seven too | Students often say plants do not move or excrete. | Connect-Extend-Challenge |
| 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, 15 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 Plants show all seven too, 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.
Connect-Extend-Challenge
After the new idea, each student writes three lines: how it connects to what they knew, how it extends their thinking, and what still challenges them. Pairs compare, then the challenges become the plenary.
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 |
|---|---|
| Respiration is not breathing. | Breathing moves air in and out of the lungs; respiration is the chemical reactions in cells that release energy. A plant has no lungs, but every one of its living cells respires all the time. |
| Growth means a permanent increase in size and dry mass. | A seed that swells by absorbing water gets bigger, but it has not grown, because water is not part of dry mass and can be lost again. Always write both parts of the definition. |
Characteristics of living organisms: worksheet
6 questions, 15 marks. Written in the style of the papers; no past paper question is reproduced.
Define (a) sensitivity, (b) nutrition and (c) reproduction, as characteristics of living organisms.
A student writes: “Plants do not respire, because they have no lungs.” Explain why the student is wrong.
A dry pea seed is soaked in water for a day and becomes much larger. Explain whether this is growth.
A robot vacuum cleaner moves around a room, detects walls and turns away, and is charged with electricity each night. Use three characteristics of living organisms to explain why it is not alive.
Name two substances that are excreted by a mammal and state where each one leaves the body.
A rose bush stays rooted in one place. Describe how it shows (a) movement, (b) excretion and (c) nutrition.
Answer key and marking notes
- (a) The ability to detect and respond to changes in the internal or external environment.
- (b) The taking in of materials for energy, growth and development.
- (c) The processes that make more of the same kind of organism.
- Respiration is the chemical reactions in cells that break down nutrient molecules and release energy; it is not breathing.
- Every living plant cell respires all the time, so plants respire even though they have no lungs.
- Growth is a permanent increase in size and dry mass.
- The extra size is water, which is not dry mass and can be lost again, so this is not growth.
- Respiration: it releases energy from a battery, not by chemical reactions in cells breaking down nutrient molecules.
- Growth: it never increases permanently in size and dry mass.
- Reproduction: it cannot make more of the same kind of robot. (Also accept: no excretion of waste products of metabolism.)
- Carbon dioxide, from respiration, leaves through the lungs in breathed-out air.
- Urea leaves through the kidneys in urine.
- (a) Parts of the plant change position: flowers open and close, and leaves turn towards the light.
- (b) It removes waste products of metabolism, such as oxygen from photosynthesis, through its leaves.
- (c) It takes in carbon dioxide and water for photosynthesis, and mineral ions from the soil, for energy, growth and development.
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 characteristic of living organisms is described as “the ability to detect and respond to changes in the internal or external environment”?
- Asensitivity
- Bmovement
- Cexcretion
- Dnutrition
When an insect touches the hairs inside a Venus flytrap leaf, the two halves of the leaf close quickly. Which two characteristics of living organisms does the closing of the leaf show?
- Asensitivity and movement
- Bgrowth and nutrition
- Cexcretion and reproduction
- Drespiration and growth
Which of these is an example of excretion by a green plant?
- Aoxygen made in photosynthesis leaving through the leaves
- Bwater being absorbed from the soil by the roots
- Cseeds being released from the fruit when it splits
- Dsugar being carried from the leaves to the roots
Which of these is NOT an example of excretion in a human?
- Aremoving undigested fibre from the gut in faeces
- Bremoving carbon dioxide from the body in breathed-out air
- Cremoving urea from the body in urine
- Dremoving excess water and salts from the body in urine
Which statement about respiration in a green plant is correct?
- AIt happens in all the living cells of the plant, both day and night
- BIt happens only at night, when the plant cannot photosynthesise
- CIt does not happen, because the plant has no lungs to breathe with
- DIt happens only in the leaves, where the plant takes in oxygen
The graph shows the mean dry mass of one bean seedling after the seeds were soaked in water. Calculate the percentage increase in dry mass from its lowest value to day 10.
- A100%
- B60%
- C50%
- D40%
When bean seeds germinate, their dry mass falls for the first few days and then rises. Which statement explains the fall in dry mass?
- AStored food is broken down in respiration before the leaves can photosynthesise
- BThe seedlings lose water by evaporation as they begin to grow
- CThe seedlings excrete urea while their roots are forming
- DDry mass always falls when a seed swells up by absorbing water
Germinating peas were placed in one sealed flask and boiled (dead) peas in another. After a day, the flask of germinating peas was 3 °C warmer and contained more carbon dioxide; the boiled peas showed no change. What do these results show?
- AThe living peas respire, releasing energy as heat and producing carbon dioxide
- BThe living peas photosynthesise, which produces both heat and carbon dioxide
- CThe boiled peas respire faster, so they use up all their carbon dioxide
- DThe living peas grow, and growth is what makes the flask warmer
Quiz key
Detecting and responding to changes is sensitivity. Movement is the change of position that may follow a response, but it is defined as an action causing a change of position or place. Excretion is removing waste products of metabolism, and nutrition is taking in materials for energy, growth and development.
The leaf detects the touch (sensitivity) and part of the plant changes position (movement). Closing the leaf is not a permanent increase in size and dry mass, so it is not growth; it makes no new organisms (reproduction) and removes no waste (excretion). Respiration supplies the energy, but the closing itself is not respiration.
Oxygen is a waste product of photosynthesis, a metabolic reaction, and it leaves through the leaves, so this is excretion. Absorbing water is taking in materials (nutrition), releasing seeds is part of reproduction, and moving sugar to the roots keeps it inside the plant, so nothing is removed.
Undigested fibre never entered the body's cells and was not made by metabolism, so getting rid of it is egestion, not excretion. Carbon dioxide (from respiration) and urea (from breaking down amino acids) are waste products of metabolism, and excess water and salts are substances in excess of requirements, so all three are excretion.
Respiration is the chemical reactions in cells that release energy, so every living cell, including root cells, respires all the time. It does not stop in daylight, it is not breathing (so lungs are not needed), and it is not limited to the leaves.
The lowest dry mass is 0.40 g on day 4, and on day 10 it is 0.80 g. Increase = 0.80 − 0.40 = 0.40 g, and (0.40 ÷ 0.40) × 100 = 100%. 60% uses the day 0 value (0.50 g) instead of the lowest value, 50% divides by the final mass instead of the starting mass, and 40% is the increase in grams written as a percentage.
Until its leaves photosynthesise, the seedling releases energy by respiring its stored food, and the carbon dioxide produced is lost, so dry mass falls. Losing water cannot change dry mass, because water is not part of dry mass. Plants do not excrete urea. Absorbing water increases fresh mass, not dry mass, and does not itself reduce dry mass.
Respiration in living cells releases energy (some as heat) and produces carbon dioxide; dead peas cannot respire, so nothing changes. Photosynthesis takes in carbon dioxide rather than producing it. Boiled peas are dead, so they do not respire at all. Growth needs energy from respiration, but growth itself is not the source of the heat or the carbon dioxide.
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.