The eight characteristics — MRS H NERG
All living organisms share EIGHT characteristics (Edexcel lists eight, not seven): Movement, Respiration, Sensitivity, Homeostasis, Nutrition, Excretion, Reproduction, and Growth and development — mnemonic MRS H NERG (also written Mrs Gren). All eight must be present for something to count as living. Viruses are NOT classed as living organisms: they cannot respire, excrete, grow or feed independently, and reproduce only inside a host cell.
Three high-risk two-element definitions
Respiration = the chemical release of energy from glucose in cells (NOT breathing, which is the mechanical movement of air). Excretion = removal of the waste products of metabolism, e.g. from respiration and urea from amino-acid breakdown (NOT faeces, which is egested). Homeostasis = maintaining a constant INTERNAL environment, e.g. body temperature, blood glucose and water content. Each definition needs BOTH elements for the mark.
Apply all eight to any organism
Every living thing shows all eight. Plants show them all — movement by tropisms (a shoot bends to light), respiration in cells, growth at meristems, reproduction by seeds and runners, excretion. Fungi are living too: they respire, excrete, grow, reproduce by spores and feed by absorption. Viruses are the non-example — no independent respiration, excretion, homeostasis, movement or growth; they replicate only in a host cell.
Drawn from real examiner reports.
Respiration is not breathing
'Respiration' in everyday English means breathing, but the two differ. Respiration is the CHEMICAL release of energy from glucose in cells; breathing is the mechanical movement of air in and out of the lungs. Writing 'respiration is breathing' describes gas exchange, not respiration — it scores zero, and a correct answer need not mention oxygen.
Excretion ≠ egestion
Excretion removes the waste products of METABOLISM — substances made inside cells, e.g. from respiration and urea from breaking down excess amino acids. Egestion removes UNDIGESTED food (faeces) at the anus; it was never absorbed into cells, so it is not a metabolic waste. Writing 'excretion is getting rid of faeces' conflates the two and scores zero.
Homeostasis vs sensitivity
Sensitivity is DETECTING and responding to a change (an external stimulus) — e.g. sensing that it is cold. Homeostasis is MAINTAINING a constant INTERNAL environment — e.g. shivering and vasoconstriction to hold body temperature steady. So feeling cold is sensitivity; correcting the internal temperature is homeostasis. Do not swap the two terms.
Movement is not only locomotion
Movement is a characteristic of ALL living things, including plants, so 'plants cannot move' is wrong. Movement means the organism OR ITS PARTS can move: shoots grow towards light (phototropism), roots respond to gravity, stomata open and close. It need not be locomotion — do not drop movement just because an organism is rooted.
Growth is more than getting bigger
'Increases in size' alone does not earn the growth mark. Growth is a PERMANENT increase in size and DRY MASS through cell division and enlargement. Dry mass matters because water content fluctuates — a plant swelling with water has not grown, since the water can leave again and no organic material was made. Always include 'permanent' and 'dry mass'.
Eight, not six — do not drop homeostasis
List questions award one mark per correct characteristic, so a short list loses marks. The most commonly missed is HOMEOSTASIS — students write 'temperature control' but not the term — and sometimes sensitivity or excretion. Edexcel expects EIGHT; run through MRS H NERG to check you have them all before choosing the number the question asks for.
Match the command word
'State/name' wants the term only. 'Describe what is meant by...' wants the term plus its two-element definition. 'Explain/apply' wants the definition PLUS an explicit link to the organism named. Answer to the verb — a bare name where a definition is asked drops marks.
Use MRS H NERG as a checklist
For 'state four characteristics', run through MRS H NERG and pick the number asked, using the exact biological terms. Vague descriptions score zero, 'breathing' is never accepted for respiration, and 'faeces' is never accepted for excretion.
Link each characteristic to the organism
For 'explain how organism X shows characteristic Y', name and define it, then tie it to a feature of that organism (e.g. 'sensitivity: the shoot grows towards light'). In evaluate questions like 'are viruses living?', give BOTH sides — a one-sided answer caps the mark.
Spec reference: 4BI1 Section 1 sub-topic (a), statement 1.1.
All living organisms share eight characteristics. A useful mnemonic is MRS H NERG:
| Letter | Characteristic | Mark-scheme-precise definition |
|---|---|---|
| M | Movement | The organism or its parts can move in response to stimuli (not limited to locomotion) |
| R | Respiration | The chemical release of energy from glucose in living cells |
| S | Sensitivity | The ability to detect changes in the environment (stimuli) and respond to them |
| H | Homeostasis | The maintenance of a constant internal environment |
| N | Nutrition | Taking in materials needed for energy, growth and repair |
| E | Excretion | Removal of the waste products of metabolism from the body |
| R | Reproduction | Producing offspring (sexual or asexual) to continue the species |
| G | Growth and development | A permanent increase in size and dry mass; increase in cell number and complexity |
Critical definitions (two-element form required for full marks):
Define homeostasis.
State four characteristics shared by all living organisms. (4 marks)
