The Study of Life
Life Processes
What makes something alive?
The Seven Life Processes
All living organisms carry out seven essential processes. We use the mnemonic MRS GREN to remember them:
Movement
Changing position or moving body parts. Even plants move (e.g., tracking the Sun).
Respiration
Releasing energy from food. Happens in every cell, all the time.
Sensitivity
Detecting and responding to changes in the environment.
Growth
Increasing in size and complexity. Making new cells.
Reproduction
Producing offspring to continue the species.
Excretion
Removing waste products from the body.
Nutrition
Obtaining and processing food for energy and growth. Plants make their own food through photosynthesis; animals eat other organisms.
Key Point
Something is considered alive only if it carries out all seven life processes. A car might move and use fuel (nutrition), but it doesn't grow, reproduce, or excrete - so it's not alive!
Cells & Organisation
The building blocks of life
Interactive Cell Diagram
Click on any part of the cell to learn about it
Quick Comparison
Only in plant cells: Cell wall, chloroplasts, large permanent vacuole
In both cells: Cell membrane, cytoplasm, nucleus, mitochondria
Levels of Organisation
Living organisms are organised in a hierarchy, from smallest to largest:
Cell
Basic unit
Tissue
Similar cells
Organ
Tissues working
System
Organs together
Organism
Whole being
Example: The Heart
Muscle cells → Muscle tissue → Heart (organ) → Circulatory system → You (organism)
Plants
Structure and function of roots, stems, and leaves
External Structure of Flowering Plants
Roots
- • Anchor plant in soil
- • Absorb water and minerals
- • Root hairs increase surface area
- • Often spread wide or grow deep
Stems
- • Support leaves and flowers
- • Transport water up (xylem)
- • Transport sugars down (phloem)
- • Hold leaves in sunlight
Leaves
- • Site of photosynthesis
- • Broad and flat for light absorption
- • Thin for gas exchange
- • Stomata for CO₂ entry
Plant Adaptations
Plants are adapted to survive in their habitats. Here are some examples:
Desert Plants (Cacti)
Thick, waxy stems store water; spines reduce water loss; deep roots find water.
Water Plants (Lilies)
Large floating leaves capture light; air spaces help them float; flexible stems.
Musculo-Skeletal System
Bones, muscles, and movement
Functions of the Skeleton
Support
Provides a framework that holds your body up and gives it shape.
Protection
Skull protects brain; ribs protect heart and lungs; spine protects spinal cord.
Movement
Muscles pull on bones to create movement at joints.
Making Blood Cells
Red and white blood cells are made in the bone marrow.
Antagonistic Muscles
Muscles work in pairs called antagonistic pairs. When one contracts, the other relaxes. This allows movement in both directions.
The Arm Example: Biceps and Triceps
Bending the Arm (Flexion)
- • Biceps contracts (shortens)
- • Triceps relaxes (lengthens)
- • Arm bends at elbow
Straightening the Arm (Extension)
- • Triceps contracts (shortens)
- • Biceps relaxes (lengthens)
- • Arm straightens
Ecosystems
Food chains, webs, and adaptation
Build a Food Chain
Drag the organisms into the correct order to build a food chain. Remember: energy flows from producer to consumer!
Producers
Make their own food through photosynthesis. Always plants or algae. Start of every food chain.
Consumers
Eat other organisms. Primary consumers eat producers; secondary eat primary; tertiary eat secondary.
Predators
Hunt and eat other animals. The animal being hunted is called prey.
Decomposers
Break down dead organisms and waste. Bacteria and fungi are decomposers.
Practice Questions
Test your understanding
Life Processes
Name the seven life processes. Use the mnemonic MRS GREN to help you remember.
Answer:
The seven life processes are:
- Movement - changing position
- Respiration - releasing energy from food
- Sensitivity - detecting and responding to changes
- Growth - increasing in size
- Reproduction - producing offspring
- Excretion - removing waste
- Nutrition - obtaining and using food
Cell Structure
Name three structures found in plant cells but NOT in animal cells. Explain the function of each.
Answer:
Made of cellulose, provides rigid support and protection. Keeps the plant cell's fixed shape.
Contain chlorophyll and are the site of photosynthesis. They make food for the plant using light energy.
Large, central structure filled with cell sap. Keeps the cell firm (turgid) and stores water and dissolved substances.
Food Chains [4 marks]
A food chain is: grass → rabbit → fox → eagle
a) What is the producer in this food chain? [1 mark]
b) What type of consumer is the rabbit? [1 mark]
c) What type of consumer is the eagle? [1 mark]
d) What do the arrows represent? [1 mark]
Mark Scheme:
a) Grass [1 mark] - The producer is always a plant that makes its own food through photosynthesis.
b) Primary consumer [1 mark] - The rabbit eats the producer (plant), making it the first consumer in the chain.
c) Tertiary consumer [1 mark] - The eagle is the third consumer in the chain (after rabbit and fox).
d) Energy flow / transfer of energy [1 mark] - Arrows show the direction energy moves from one organism to the next when it is eaten.
Exam tip: Always draw arrows pointing TOWARDS the organism that is eating, not away from it!
Antagonistic Muscles [3 marks]
Explain how the biceps and triceps work together to bend and straighten the arm.
Answer:
The biceps and triceps form an antagonistic pair - they work in opposite directions:
To bend the arm:
- The biceps contracts (becomes shorter and thicker)
- The triceps relaxes (becomes longer and thinner)
- This pulls the forearm up, bending the elbow
To straighten the arm:
- The triceps contracts
- The biceps relaxes
- This pulls the forearm down, straightening the elbow
Key term: Antagonistic muscles work in pairs - when one contracts, the other relaxes. This allows movement in both directions.
Ready for More?
Continue your science journey with Year 7 Chemistry or Physics.