P4 Science Summary Notes
Created by Miss Clarissa Ng | www.clartutors.com
TOPIC 1Plant System
Parts of a Plant
Plants have different parts that work together to help the plant stay alive:
| Part | Main Function |
|---|---|
| Leaves | Trap light to make food by photosynthesis; exchange gases through stomata |
| Stem | Holds the plant upright; contains tubes that carry food, water, and mineral salts |
| Roots | Anchors the plant firmly to the ground; absorbs water and mineral salts from soil |
| Flowers | Reproductive part of the plant — produces seeds |
| Fruit | Protects and disperses seeds |
Parts of a Leaf
- Leaf Blade: Flat, broad portion containing chlorophyll and tiny openings called stomata.
- Stomata: Tiny openings mostly on the underside of a leaf. Allow exchange of gases (carbon dioxide and oxygen) between plant and surroundings.
- Leaf Stalk: Contains tubes that transport water from stem to leaf and food from leaf to stem.
- Leaf Veins: Distribute substances throughout the leaf; provide shape and support.
Functions of a Leaf
| Function | Details |
|---|---|
| Photosynthesis | Leaves trap light to make food. Uses carbon dioxide and water, in the presence of light and chlorophyll, releasing oxygen. |
| Gaseous Exchange | Through stomata — Respiration (all times): take in oxygen, give out carbon dioxide. Photosynthesis (when light present): take in carbon dioxide, give out oxygen. |
Stem
| Function | Details |
|---|---|
| Holds the plant upright | Elevates leaves to trap light. Some plants (e.g., morning glory) have weak stems that grow around supports. |
| Contains water-carrying tubes (xylem) | Carries water and mineral salts from roots to all parts of the plant. |
| Contains food-carrying tubes (phloem) | Carries food from leaves to all parts of the plant. |
Roots
| Function | Details |
|---|---|
| Anchors the plant firmly to the ground | Prevents the plant from falling over in wind. |
| Absorbs water and mineral salts from soil | Water needed for photosynthesis. Mineral salts required for health. |
TOPIC 2Human Body Systems
What is a System?
- A system is made of different parts that work together to perform a specific function.
- All living things are systems — their parts work together for the organism to survive and grow.
Respiratory System
Allows exchange of gases between the body and surroundings — takes in oxygen, removes carbon dioxide.
| Component | Function |
|---|---|
| Nose | Entry point for air; filters, warms, and moistens incoming air |
| Windpipe (Trachea) | Tube that carries air to the lungs |
| Lungs | Site of gas exchange — takes in oxygen, releases carbon dioxide |
Circulatory System
Carries substances to different parts of the body. Blood is pumped by the heart through blood vessels.
| Component | Function |
|---|---|
| Heart | Pumps blood around the body |
| Blood | Carries useful substances (digested food, oxygen, water) to different parts. Carries carbon dioxide and waste away. |
| Blood Vessels | Tubes through which blood travels to all parts of the body |
Skeletal System
- Bones support the body and give it shape.
- Protects important parts: brain, spinal cord, heart, and lungs.
Muscular System
- Works with the skeletal system to help body parts move.
- Muscles contract or relax for movement to occur.
Digestive System
Digestion breaks down food into simpler substances so it can be absorbed into the bloodstream for energy, growth, and repair.
| Organ | Function |
|---|---|
| Mouth | Teeth chew and grind food into smaller pieces, increasing the exposed surface area to digestive juices, allowing digestion to take place faster. |
| Gullet | Pushes food from mouth to stomach. |
| Stomach | Muscular bag that churns food with digestive juices. |
| Small Intestine | Digestion ends here. Digested food absorbed into bloodstream. |
| Large Intestine | Water absorbed from undigested food. |
Working Together
All body systems work together for the body to function:
| System | Role |
|---|---|
| Digestive System | Breaks down food into simpler substances. |
| Circulatory System | Carries digested food and oxygen to all parts of the body. |
| Respiratory System | Allows gaseous exchange to occur. |
| Muscular & Skeletal Systems | Work together to allow the body to move. |
TOPIC 3Matter
What is Matter?
Matter is anything that has mass and occupies space.
- Matter examples: marbles, water, air.
- Non-matter examples: light, music, shadows (these do not have mass or occupy space).
Mass
Mass = amount of matter in an object. Measured in kilograms (kg), grams (g) using beam balance, weighing scale, electronic balance.
Volume
Volume = amount of space an object occupies. Measured in cm³, ml, l using measuring cylinder, beaker, syringe.
States of Matter
| State | Shape | Volume | Compressibility |
|---|---|---|---|
| Solid | Definite shape | Definite volume | Cannot be compressed |
| Liquid | No definite shape | Definite volume | Cannot be compressed |
| Gas | No definite shape | No definite volume | Can be compressed |
Compressibility of Matter
- Solids and Liquids: Have a definite volume and cannot be compressed.
- Gases: Do not have a definite volume and can be compressed.
Gases Expand to Fill Their Container
Gases have no fixed volume and expand to fill whatever space is available.
Key concept: When air is pumped into a rigid container, the mass of air increases (air has mass), but the volume stays the same because the gas is compressed.
Displacement
Matter occupies space and displaces other matter.
- Stone in water: Water level rises — stone occupies space and displaces the water.
- Water between marbles: Water displaces the air in gaps between marbles.
- Sealed bottle: Air inside occupies space and cannot escape, preventing water from flowing freely in.
- Gap in opening: Air can escape, allowing water to flow freely into the bottle.
TOPIC 4Light & Shadows
Sources of Light
Objects that give off their own light — natural (Sun, fire) or man-made (lamps).
| Type | Examples |
|---|---|
| Natural sources | Sun, fire, stars, firefly, lightning |
| Man-made sources | Lamps, torches, lighted candle |
Moon and mirrors: Do not produce their own light; only reflect light from other sources. They can be seen when light reflects off them into our eyes.
Properties of Light
- Light travels in straight lines
- Light can be reflected
- Light can be blocked
Transmission of Light
| Type | Description | Example | Vision through it? |
|---|---|---|---|
| Transparent | Allows most light to pass through | Window pane, clear glass | Yes — clearly (clear vision) |
| Translucent | Allows some light to pass through | Frosted glass door | Partially (blurry vision) |
| Opaque | Allows no light to pass through | Mirror, wood, metal | Not at all (no vision) |
Shadows
Shadows form when light, travelling in straight lines, is blocked by a translucent or opaque object.
Conditions to Form a Shadow:
- A light source
- An object (opaque or translucent)
- A screen/surface for the shadow to fall on
Types of Shadows:
| Object Type | Shadow Formed |
|---|---|
| Opaque | Dark shadow |
| Translucent | Light shadow |
| Transparent | No shadow |
Size of Shadows:
- Object moves closer to light source → Bigger shadow
- Screen moves further from object → Bigger shadow
Shadows During the Day:
| Time of Day | Sun's Position | Shadow |
|---|---|---|
| Morning | Rises in the East | Long shadow pointing West |
| Noon | Overhead (directly above) | Shortest shadow (under object) |
| Evening | Sets in the West | Long shadow pointing East |
TOPIC 5Heat
Sources of Heat
- Heat is a form of energy. It can be felt but cannot be seen.
- Natural Sources: The Sun (main source), volcanoes, geysers.
- Man-Made Sources: Burning fuels such as firewood, charcoal, gas, electricity.
Temperature
Temperature is a measure of the degree of hotness of an object.
- Unit: degree Celsius (°C)
- Measured using: thermometer (clinical, laboratory)
Temperature vs. Heat Energy
| Heat Energy | Temperature | |
|---|---|---|
| Definition | The amount of energy an object has | A measure of the degree of hotness of an object |
| Measurable? | Cannot be measured directly | Can be measured (using thermometer) |
The amount of heat energy depends on its:
- Temperature — higher temperature = greater heat energy
- Mass or volume — greater mass/volume = greater heat energy
Property of Heat
Heat flows from regions of higher temperature to regions of lower temperature, until they reach the same temperature.
- When heat flows to an object → it has gained heat → temperature increases.
- When heat flows away from an object → it has lost heat → temperature decreases.
Effects of Heat: Change of State
| Process | Direction | Type |
|---|---|---|
| Solid → Liquid (Melting) | → | Heat gain |
| Liquid → Gas (Boiling) | → | Heat gain |
| Liquid → Solid (Freezing) | ← | Heat loss |
| Gas → Liquid (Condensation) | ← | Heat loss |
Expansion and Contraction
The gain or loss of heat can cause matter to expand or contract.
• Gain heat → expands (occupies more space)
• Lose heat → contracts (occupies less space)
• Mass will always stay the same!
• Gain heat → expands (occupies more space)
• Lose heat → contracts (occupies less space)
• Mass will always stay the same!
Conduction of Heat
- Good Conductors (Metals): Transfer heat quickly. Temperature changes fast.
- Poor Conductors (wood, rubber, air): Transfer heat slowly. Keep things hot/cold for a longer time.
Surface Area and Heat Transfer
As the surface area in contact increases, the rate of heat gain / heat loss increases.
Bigger contact area = faster heat transfer. Smaller contact area = slower heat transfer.
Bigger contact area = faster heat transfer. Smaller contact area = slower heat transfer.