P5 Science Revision Summary
Created by Miss Clarissa Ng | www.clartutors.com
CH 1Reproduction & Heredity
Why Reproduce?
- Living things reproduce to ensure the continuity of their own kind.
- During reproduction, parents pass on their characteristics to offspring.
Heredity in Humans
- We inherit characteristics from both parents.
- Hereditary information is stored in the nucleus of cells.
- Inherited traits: eye colour, hair type, blood group, height.
- Unique traits: fingerprints and iris patterns are unique to each individual.
Heredity in Plants
- A young plant grows from a seed and inherits characteristics from its parent plant.
- A plant always bears flowers, fruit, and seeds of the same kind.
- Example: A rose plant produces only roses; a mango tree produces only mangoes.
Key Takeaways
| Concept | Fact |
|---|---|
| Reproduction ensures | Continuity of their own kind |
| Inheritance comes from | Both parents |
| Hereditary info stored in | Nucleus of cells |
| Fingerprints & iris patterns | Unique to each individual |
CH 2Reproduction in Plants
Parts of a Flower
| Part | Type | Function |
|---|---|---|
| Anther | Male | Contains pollen grains |
| Filament | Male | Supports the anther |
| Stigma | Female | Receives pollen grains during pollination |
| Style | Female | Tube that connects the stigma to the ovary |
| Ovary | Female | Contains ovules; protects seeds until fruit is ripe |
| Ovule | Female | Contains an egg cell |
Pollination → Fertilisation → Seed Formation
| Stage | What Happens |
|---|---|
| Pollination | Pollen grain lands on the stigma of a flower (same or different plant) |
| Fertilisation | Pollen tube grows down; male cell fuses with egg cell in ovule |
| Ovary → Fruit | Ovary enlarges and develops into a fruit |
| Ovule → Seed | Ovule develops into a seed |
- Pollination is the transfer of pollen grains from the anther to the stigma of a flower.
Seed Dispersal Methods
- Seeds need to grow far from parent plants to prevent overcrowding and reduce competition for resources such as sunlight, water, space and mineral salts.
| Method | Adaptations | Examples |
|---|---|---|
| Wind | Light, small; wing-like structures or fine hairs | Shorea, Dandelion |
| Water | Waterproof coverings or fibrous husks that trap air to float | Coconut, Pong pong |
| Animals (eating) | Colourful, fragrant, sweet, fleshy, juicy fruits | Mango, Kiwi |
| Animals (sticking) | Sticky or have tiny hooks to attach to fur | Mimosa, Love grass |
| Splitting / Explosive | Fruits split open when ripe and dried up | Balsam, African tulip |
Germination
- A seed needs water, air and warmth to germinate.
- The root emerges first, then the shoot grows upward.
- Seedling gets food from the seed leaves until true leaves develop for photosynthesis.
Key Takeaways
| Concept | Fact |
|---|---|
| Pollination | Pollen lands on stigma |
| Fertilisation | Male + female cells fuse in ovule |
| Ovary develops into | Fruit |
| Ovule develops into | Seed |
| Germination needs | Water, air, warmth |
CH 3Reproduction in Humans
Male Reproductive System
- Testis — produces sperm.
- Penis — delivers sperm into the female body.
Female Reproductive System
- Ovary — produces eggs.
- Fallopian tube — site of fertilisation.
- Womb (uterus) — where the fertilised egg develops into a foetus.
- Vagina — where sperm is deposited; birth canal.
From Fertilisation to Birth
- Fertilisation is the process where the sperm and the egg fuse, producing a fertilised egg.
- Although females usually release one egg from either ovary each time, males release a large number of sperm each time to increase the chances of a sperm reaching the egg for fertilisation to occur.
| Stage | Description |
|---|---|
| Fertilisation | Sperm fuses with egg in the fallopian tube — only ONE sperm can enter an egg |
| Implantation | Fertilised egg attaches to the wall of the womb |
| Gestation | Baby develops for about 9 months (40 weeks) |
Similarities: Humans vs Flowering Plants
- Both reproduce by fusing male and female reproductive cells.
- Fertilisation involves the fusion of a sperm cell with an egg cell.
Key Takeaways
| Concept | Fact |
|---|---|
| Fertilisation occurs in | Fallopian tube |
| Baby develops in | Womb (uterus) |
| Gestation period | About 9 months / 40 weeks |
| Only one sperm enters | An egg at a time |
CH 4Cycles in Water
Three States of Water
| State | Shape & Volume | Temperature Range |
|---|---|---|
| Solid (ice) | Definite shape, definite volume | 0°C and below |
| Liquid (water) | No definite shape, definite volume | Between 0°C and 100°C |
| Gas (vapour/steam) | No definite shape, no definite volume | 100°C and above |
- Clouds, mist, dew and fog are all water in the liquid state.
Changes of State
- Melting: Solid → Liquid (at 0°C, temperature stays constant during melting).
- Freezing: Liquid → Solid (at 0°C, temperature stays constant during freezing).
- Evaporation: Liquid → Gas (occurs at any temperature; faster with higher temperature/surface area/wind speed).
- Condensation: Gas → Liquid.
- Key words for condensation: (Water gains heat to evaporate into water vapour) Warmer water vapour from the ___ comes into contact with and loses heat to the cooler inner/outer surface of ___, condensing to form water droplets.
Factors Affecting Rate of Condensation
- The greater the temperature difference between the water vapour and the surface for condensation, the greater the rate of condensation of water vapour to form more water droplets.
Factors Affecting Rate of Evaporation
- Wind speed ↑ → evaporation rate increases.
- Exposed surface area ↑ → evaporation rate increases.
- Temperature ↑ → evaporation rate increases.
Evaporative Cooling
- Water gains heat from the surrounding air to evaporate into water vapour.
- The surrounding air loses heat and cools down.
Key Takeaways
| Concept | Fact |
|---|---|
| Melting point of ice | 0°C (temp stays constant during melting) |
| Freezing point of water | 0°C (temp stays constant during freezing) |
| Boiling point of water | 100°C |
| Evaporation occurs at | Any temperature |
| Condensation needs | Cold surface for vapour to cool on |
CH 5The Water Cycle
Processes in the Water Cycle
- Evaporation: Sun heats water from oceans, rivers, lakes → becomes water vapour.
- Condensation: Water vapour cools and forms tiny droplets → clouds.
- Precipitation: Droplets become too heavy → fall as rain or snow.
- Collection: Rainwater collects in rivers, lakes, oceans; some seeps into ground (groundwater).
Importance of the Water Cycle
- Ensures a continuous supply of fresh water.
Water Conservation (3Rs)
| Action | Example |
|---|---|
| Reduce | Use a watering can instead of spraying water from a hose to water plants. |
| Reuse | Use water for washing clothes to flush the toilet. |
| Recycle | Treat and process wastewater collected from households. |
Key Takeaways
| Concept | Fact |
|---|---|
| Water cycle ensures | Continuous supply of fresh water |
| Sun provides energy for | Evaporation in the water cycle |
| Precipitation includes | Rain, snow, hail |
CH 6Plant Transport System
Two Types of Tubes
| Tube Type | What It Carries | Direction |
|---|---|---|
| Food-carrying tubes (phloem) | Sugars made in leaves | Leaves → all parts of the plant |
| Water-carrying tubes (xylem) | Water and dissolved minerals from soil | Roots → upward to leaves |
Removing the food-carrying tubes
- After a few days, Leaf X remained healthy.
- The food-carrying tubes were removed but not the water-carrying tubes.
- Water absorbed by the roots could be transported to Leaf X through the water-carrying tubes.
- Hence, Leaf X could make food through photosynthesis, causing it to remain healthy.
- After a few days, the part above the cut became swollen.
- Without the food-carrying tubes, food made by the leaves through photosynthesis could not be transported to the roots and accumulated above the cut, causing the part above the cut to become swollen.
- After a few weeks, the plant died.
- The cut removed the food-carrying tubes of the plant.
- The food made by the leaves through photosynthesis could not be transported below the cut to the roots, causing them to die from the lack of food.
- When the roots died, water could not be absorbed by the roots, causing the plant to die from the lack of water.
Removing the water-carrying tubes
- After a few days, Leaf X died.
- Without the water-carrying tubes, water absorbed by the roots could not be transported to the leaves above the cut.
- Without water, Leaf X could not make food through photosynthesis, causing it to die from the lack of water and food.
- After a few days, Leaf Y remained healthy.
- Water absorbed by the roots could be transported to Leaf Y through the water-carrying tubes.
- Leaf Y could make food through photosynthesis, causing it to remain healthy.
Stomata
- Tiny openings on leaves that allow excess water to evaporate (transpiration) and gas exchange.
- Day: Stomata are OPEN — photosynthesis occurs; oxygen released, CO₂ taken in.
- Night: Stomata are CLOSED — only respiration occurs; CO₂ released, O₂ taken in.
Key Takeaways
| Concept | Fact |
|---|---|
| Phloem carries | Sugars from leaves to all parts |
| Xylem carries | Water + minerals upward from roots |
| Stomata open at | Day (for photosynthesis) |
| Transpiration is | Evaporation of water through stomata |
CH 7Respiratory System
Parts of the Human Respiratory System
- Nose → Windpipe → Lungs (air sacs)
- Air sacs increase exposed surface area of the lungs, allowing gaseous exchange to take place faster.
Gaseous Exchange in Lungs
| Gas | Direction |
|---|---|
| Oxygen | Air sacs → Bloodstream (enters blood) |
| Carbon dioxide | Bloodstream → Air sacs (leaves blood, exhaled out of the body through nose) |
Breathing Rate and Exercise
- When we exercised, our Body required more Energy.
- Thus, we Breathed faster to take in more Oxygen to undergo a greater rate of Respiration to release more Energy.
- This also allows carbon Dioxide given out during respiration to be removed faster.
Fish Respiration (Gills)
- Fish take in water through the mouth; it passes over gills and exits through gill openings.
- Dissolved oxygen enters blood; carbon dioxide leaves into the water.
- Gill filaments increase surface area (like air sacs in lungs).
Gills vs Lungs Comparison
| Gills | Lungs | |
|---|---|---|
| Similarities | Both allow gaseous exchange to occur | |
| Difference | Take dissolved O₂ from water | Take O₂ from air |
Key Takeaways
| Concept | Fact |
|---|---|
| Breathing vs Respiration | Breathing = taking in air; Respiration = using O₂ to release energy from food |
| Air sacs function | Increase surface area for gaseous exchange (O₂ in, CO₂ out) |
| Gill filaments | Increase surface area for gaseous exchange in water (like air sacs do in lungs). |
| Exercise increases | Breathing rate and volume of air taken in |
CH 8Circulatory System
Three Components
- Heart — pumps blood to all parts of the body.
- Blood vessels — carry blood.
- Blood — carries digested food, oxygen, water and waste materials like carbon dioxide.
Functions of Blood
| Component | Function |
|---|---|
| Red blood cells | Transport oxygen from lungs to body; CO₂ back to lungs |
Heart rate and exercise
- When we exercise, our Body needs more Energy.
- Thus, our heart Pumps faster to transport more oxygen and digested food in the blood to other parts of our body faster, to undergo a greater rate of respiration to release more energy.
- This also allows carbon Dioxide given out during respiration to be removed faster.
Human vs Fish Circulatory System
| Humans (Double) | Fish (Single) | |
|---|---|---|
| Blood passes through heart | Twice per complete circuit | Once per complete circuit |
| Path | Heart → Lungs → Heart → Body → Heart | Heart → Gills → Body → Heart |
Circulatory System + Other Systems
- Digested food and water from the digestive system enter the bloodstream.
- Oxygen from the respiratory system enters the blood in lungs.
- The circulatory system transports these to all body parts.
Key Takeaways
| Concept | Fact |
|---|---|
| Heart pumps | Blood to all parts of the body |
| Human system is | Double circulatory (blood passes heart twice) |
| Fish system is | Single circulatory (blood passes heart once) |
CH 9Electricity
Components of an Electric Circuit
| Component | Function |
|---|---|
| Battery | Energy source — has positive (+) and negative (−) terminals |
| Wire | Connects components; made of copper with plastic insulation |
| Light Bulb | Produces light when current flows through the filament |
| Switch | Controls flow: ON = closed circuit, OFF = open circuit |
Closed Circuits
- A closed circuit is formed when all the electrical components are connected without any gaps.
- Electric current flows through and lights up the bulb.
Open Circuits
- An open circuit is formed when there is a gap between the electrical components in an electric circuit.
- No electric current flows through and the light bulb does not light up.
Conductors vs Insulators
| Type | Description | Examples |
|---|---|---|
| Conductor | Allows electric current to flow through it | Metal (iron, copper), graphite, salt water |
| Insulator | Does NOT allow electric current to flow | Plastic, rubber, wood, glass, pure water |
Circuit A — Iron Rod (Conductor)
- The iron rod is a conductor of electricity and a closed circuit is formed.
- Hence, electric current flowed through the bulb, causing the bulb to light up.
Circuit B — Glass Rod (Insulator)
- The glass rod is a non-conductor of electricity and an open circuit is formed.
- Hence, no electric current flowed through the bulb, causing the bulb not to light up.
Key Takeaways
| Concept | Fact |
|---|---|
| Closed circuit means | Current flows, bulb lights up |
| Open circuit means | No current flows, bulb does not light |
| Conductors allow | Electric current to pass through |
CH 10Series & Parallel Circuits
Effect of Changing Batteries (in Series)
- More batteries in series → brighter bulb.
- Too many batteries → filament overheats and melts → bulb becomes fused.
Effect of Changing Bulbs (in Series)
- More bulbs in series → each bulb becomes dimmer.
- Brightness is shared equally among all bulbs.
Effect of Changing Bulbs (in Parallel)
- More bulbs in parallel → each bulb stays the same brightness.
- Each bulb gets the full voltage from the battery.
🧲 Electromagnets
- What makes an electromagnet stronger?
- More batteries in series → more current → stronger magnet.
- More coils of wire around the rod → stronger magnet.
How electromagnets work (Electric Bell):
- Attract — When the switch is pressed, a closed circuit is formed. Electric current flows through the circuit, causing the electromagnets to be magnetised. The electromagnets then attract the iron strip, causing the hammer to hit the gong and make a sound.
- Electric current stops flowing — When the iron strip is pulled away, the metal contact loses touch with the screw. An open circuit is formed and electric current stops flowing through the electromagnets.
- Lose their magnetism — The electromagnets lose their magnetism and stop attracting the iron strip. The spring pulls the iron strip back, reconnecting the metal contact with the screw to close the circuit again. This cycle repeats continuously.
Conservation of Electricity
- Electricity is produced from fossil fuels (coal, natural gas) — these are non-renewable.
- Ways to conserve: switch off lights when not in use, use energy-efficient appliances, use natural light.
Using Electricity Safely
- Overloading: Too many devices on one outlet → wires overheat → fire risk.
- Damaged wires: Exposed metal can cause electric shock — replace immediately.
- Wet hands: Never touch switches or plugs with wet hands (water conducts electricity).
Key Takeaways
| Concept | Fact |
|---|---|
| More batteries in series → | Bulb brighter (but risk of fusing) |
| More bulbs in series → | Each bulb dimmer |
| Add bulb in parallel → | Original bulb brightness unchanged |
| Fossil fuels are | Non-renewable — must conserve electricity |
| Stronger electromagnet | More current + more coils of wire |