Characteristics of Living Organisms: IGCSE Biology Notes

You can recite MRS GREN in your sleep. But IGCSE examiners rarely ask you to just list it. They ask you to define, describe, and apply it, and that is where marks quietly disappear.

This is the opening topic of the Cambridge IGCSE Biology 0610 syllabus. Master it early and the payoff builds across the whole course. By the end, you will name, define, and apply all seven characteristics of living organisms like an examiner does.

What are the characteristics of living organisms?

Living organisms are things that carry out seven life processes. These processes separate them from non-living matter like rocks or water. The seven are movement, respiration, sensitivity, growth, reproduction, excretion, and nutrition. A true organism shows every one, not just a few.

Here are the seven characteristics of living organisms, the 7 life processes Cambridge biology students must know:

1. Movement
2. Respiration
3. Sensitivity
4. Growth
5. Reproduction
6. Excretion
7. Nutrition

Cambridge sets this as the very first subtopic of your IGCSE Biology course. It shows up on both Paper 1 and Paper 2, so early mastery pays off. Miss one process, and the object is not classed as living.

What does MRS GREN stand for?

MRS GREN stands for Movement, Respiration, Sensitivity, Growth, Reproduction, Excretion, and Nutrition. Each letter points to one life process. It is the memory aid most IGCSE students use for fast revision.

The table below maps every letter of MRS GREN to its life process. Keep it handy as your core set of MRS GREN revision notes for the final week before an exam.

Letter	Life process
M	Movement, changing position or body parts
R	Respiration, releasing energy from food
S	Sensitivity, detecting and reacting to changes
G	Growth, a permanent increase in size
R	Reproduction, making new organisms
E	Excretion, removing toxic waste products
N	Nutrition, taking in food or nutrients

Read the letters top to bottom to rebuild the full acronym. Some students learn it as MRS NERG, which lists the same seven processes in a different order.

How is each life process defined with an example?

Each characteristic needs a precise one-line definition plus a named example to earn full marks. A vague answer loses marks even when the idea is right. The reference table below gives you both.

This reference table pairs each of the seven characteristics with a short definition and a named example. Use it as your base for defining living organisms IGCSE answers, then expand each point in your revision.

Characteristic	Definition	Example
Movement	Action causing a change in position	A cheetah running to hunt
Respiration	Reactions that release energy from food	Glucose broken down in cells
Sensitivity	Detecting and reacting to a stimulus	Shoots growing toward light
Growth	Permanent increase in size and mass	A seedling getting taller
Reproduction	Making new organisms of the kind	A rabbit having young
Excretion	Removing toxic waste from the body	Humans passing urea in urine
Nutrition	Taking in food for energy and growth	Plants making food by photosynthesis

Define means give the precise meaning. Describe means add observable detail, like what respiration produces. A Cambridge IGCSE Biology tutor can help you turn each definition into a full-mark answer.

According to Cambridge Assessment International Education, the body that sets the 0610 syllabus, students must know and use these characteristics as defined life processes. Learning the exact wording protects your marks.

How do you tell living from non-living things?

Apply all seven characteristics as a checklist. If even one is truly missing, the object is not alive. It may instead be non-living, or it may be dead or dormant.

A car moves and a robot responds to signals. Neither respires, grows, or reproduces, so both stay non-living. A dead leaf once showed all seven processes but no longer does.

A dry seed looks lifeless but is only dormant. It can still respire slowly and will grow once conditions are right. Examiners reward this careful checklist thinking, so name the missing process every time.

Why are viruses hard to classify as living?

Viruses sit on the border between living and non-living. They can reproduce, but only inside a host cell. On their own they show no respiration, no nutrition, and no independent metabolism.

A common exam question asks you to suggest why viruses are hard to classify. The safe answer names what they do and do not do. Viruses reproduce inside hosts but fail most other life processes.

So, are viruses living? Most biologists say no, because they cannot carry out all seven processes by themselves.

How are these characteristics tested in IGCSE exams?

The same characteristic earns different marks depending on the command word. State or list wants a quick name. Define wants the precise meaning. Describe wants observable detail, and explain wants the reason why.

Here is how to match the four main command words to the depth of answer each one expects in the characteristics of living organisms IGCSE questions:

• State or list: name the process only.
• Define: give the exact meaning.
• Describe: add what you would observe.
• Explain: give the reason behind it.

Always pair a characteristic with a named example. That single habit secures method marks across Paper 1 and Paper 2. Mark schemes reward precise wording, so match the verb the question uses.

Working through IGCSE past-paper questions is the fastest way to learn how examiners phrase these commands.

Key Takeaways and Next Step

Seven characteristics, remembered as MRS GREN, define every living organism. All seven must be present. Know each definition with a named example, apply the checklist to tricky cases like viruses, and always answer to the command word.

Now test your recall. Try a topic-1 past-paper set on these characteristics, then move on to the next subtopic, Classification and Dichotomous Keys. You can also explore more IGCSE Biology topics to keep the momentum going. Revise, test, then advance.