What Is Alive? — Biology (Grade 7)

Define and explain What Is Alive? in your own words
Use key terms such as life processes accurately
Apply what you have learned to new examples and questions
Avoid the common mistakes learners make with this topic

Is a flame alive? It moves and grows, yet it cannot sense, reproduce or feed the way living things do. In this chapter you will learn the seven life processes shared by every living thing, explore the habitats around you, and discover how living things feed on one another.

This lesson focuses on What Is Alive?: learn the seven life processes (MRS GREN) that separate living things from things that were never alive.

Definition: What Is Alive?

Learn the seven life processes (MRS GREN) that separate living things from things that were never alive.

Key ideas

The seven life processes

Scientists remember the seven life processes with MRS GREN: Movement, Respiration, Sensitivity, Growth, Reproduction, Excretion and Nutrition. Every living thing carries out all seven. A car moves but does not grow or reproduce, so it is not alive; a mushroom grows, respires and reproduces, so it is.

Habitats and adaptation

A habitat is an organism's home. A pond, a woodland and a garden wall are all habitats. Living things suit their habitats: a frog's moist skin helps it live near water, while a cactus stores water to survive in a desert. When a habitat changes, the organisms living there must cope or move.

Key term — life processes: The seven activities all living things carry out: movement, respiration, sensitivity, growth, reproduction, excretion and nutrition.

Worked example: What Is Alive?

Why is a bicycle not alive?

It carries out none of the seven life processes: it does not grow, respire, sense, reproduce, excrete or take in nutrition on its own.

Answer: It carries out none of the seven life processes: it does not grow, respire, sense, reproduce, excrete or take in nutrition on its own.

Common mistakes

Calling anything that moves alive Wind, flames and cars move but carry out none of the other life processes. Movement alone does not make something alive.
Saying a dead leaf is alive The leaf was alive when it grew on the tree, but once it falls and dies it stops carrying out life processes, so it is once alive, not alive.

Practice

A fish and a fishing rod both come from the water. Which is alive and why?

One carries out life processes; the other never did.

The fish is alive because it carries out all seven life processes. The fishing rod was never alive and carries out none of them.

Name three of the seven life processes.

Think of MRS GREN.

Any three of: movement, respiration, sensitivity, growth, reproduction, excretion, nutrition.

Is a mushroom alive? Explain your answer.

Check it against the life processes.

Yes. A mushroom grows, respires to release energy, and reproduces by releasing spores, so it carries out the life processes.

Name a habitat near your home and one animal that lives there.

Think of gardens, ponds, parks or walls.

Example: a garden pond is a habitat for frogs, which need the water to keep their skin moist and to lay their eggs.

Quick check

What Is Alive? — quick check

Which of these best defines "life processes"?

The seven activities all living things carry out: movement, respiration, sensitivity, growth, reproduction, excretion and nutrition.

In the food chain grass → rabbit → fox, which is the producer and why?

The grass is the producer, because it makes its own food using energy from sunlight.

Key takeaways

What Is Alive?: learn the seven life processes (MRS GREN) that separate living things from things that were never alive.
The seven life processes: Scientists remember the seven life processes with MRS GREN: Movement, Respiration, Sensitivity, Growth, Reproduction, Excretion and Nutrition.
organism: A single living thing, such as a daisy, a sparrow or a person.
Watch out for: calling anything that moves alive

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