P6 Science Topical Notes (Latest MOE PSLE Syllabus)

Primary 6 Science culminates inquiry skills through two core themes: Energy and Interactions. In Energy, students explore conversions between forms like chemical to electrical or light, alongside photosynthesis as plants convert light energy for growth. In Interactions, they investigate frictional force (effects and reduction), gravitational force (on falling objects), elastic spring force, plus interactions within the environment like man-animal relationships. These topics refine analysis and real-world application for PSLE success.

Last updated 20 January 2026

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1. Chapter 1: Photosynthesis [Energy]

2. Chapter 2: Materials [Diversity]

3. P6 Science Tuition with UpLabs

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Chapter 1: Photosynthesis [Energy]

Photosynthesis

It is the process which plants take in carbon dioxide and water to produce sugar and oxygen, in the presence of light.

Factors needed for photosynthesis to occur:

• Light

• Carbon dioxide

• Water

Plants produce the following during photosynthesis:

• Sugar

• Oxygen

The leaves of a plant has chlorophyll which helps to trap sunlight from the Sun / light from a light source. Water is absorbed by the roots and transported to the leaves. Carbon dioxide enters the leaves through the stomata during gaseous exchange.

For water plants, we can increase the amount of carbon dioxide by adding baking soda in the water. We can increase the amount of light received by the plant by moving it closer to the light source.

Excess sugar is stored as starch. Photosynthesis does not produce starch. Starch is stored in different parts of the plant such as storage roots, storage stems and fruits.

Test for presence of starch (Iodine solution)

When starch is present, solution will turn blue-black/ dark blue.

When starch is absent, solution will remain yellowish-brown.

Respiration

All living things undergo respiration in order to release energy stored in food in order to carry out all of their activities.

Respiration in humans require:

• oxygen

• water

• digested food

Produces:

• energy

• carbon dioxide(g)

• water vapour(g)

Carbon dioxide blown into limewater will turn it chalky or cloudy.

Regardless of the way different groups of living things obtain food, they still need energy to carry out life processes such as growing and reproducing.

Groups	How they obtain food	How they release energy
Plants	Photosynthesis	Respiration
Animals	Consume other living things
Fungi and Bacteria	Decomposition

For plants, the sugar produced through photosynthesis can be broken down through respiration to release energy.

During the day / there is light	At night / there is no light
Photosynthesis Respiration	Respiration

That is why even for plants, respiration occurs all the time. In the presence of light, the rate of photosynthesis is higher than the rate of respiration.

The Sun is our main or primary source of energy on Earth. Plants trap sunlight to make sugar while the energy can be transferred to animals when they are being eaten.

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Chapter 2: Energy Conversion [Energy]

Energy is the ability to do work. The Sun is the main source of energy on Earth.

Energy cannot be created or destroyed. It is converted from one form into another form or transferred to other objects. There are many forms of energy.

Energy causes objects to move or change in its state of matter.

Forms of energy

Potential energy are energy stored in objects can be converted into other forms of energy	Gravitational potential energy The energy an object possess due to its position from the ground Factors affecting the amount of gravitational potential energy an object has: Mass of the object Higher mass -> More G.P.E. Height of the object from the ground Higher height from ground -> More G.P.E.
	Elastic potential energy The energy an elastic object has when it is stretched or compressed Example of elastic objects: Springs and Rubber bands The greater the extent an elastic object is stretched or compressed, the greater the amount of elastic potential energy is stored
	Chemical potential energy The energy that is stored in food, fuel or battery The energy can be converted to other forms through different ways: Food: Respiration Chemical potential energy (in food) -> Kinetic energy (legs) + Other forms of energy Fuel: Burning Power station: Chemical potential energy (fossil fuel) -> heat energy (water) -> kinetic energy (steam) -> kinetic energy (turbine) -> electrical energy (generator) Batteries: Closed circuit Chemical potential energy (battery) -> electrical energy (wires) -> Light + Heat energy (bulb)
Kinetic energy	The energy possessed by a moving object due to its motion. Factors affecting the amount of kinetic energy a moving object has: Mass of moving object Higher mass -> More kinetic energy Speed of moving object Higher speed -> More kinetic energy

When an object stops moving, all of its kinetic energy has been converted to other forms of energy such as heat and sound energy.

Other forms of energy

• Light energy

• Heat energy

• Electrical energy

• Sound energy

Sources of energy

• Sun

  • renewable source

• Running water

  • renewable source

• Wind

  • renewable source

• Fossil fuel

  • non-renewable source

  • releases carbon dioxide when burnt -> greenhouse gas -> global warming and air pollution

Energy conservation

We need to conserve energy by using the minimum amount of energy that we need. It is so that the sources of energy can be used longer.

Ways to conserve:

• Using a fan instead of air-con

• Switching off electrical appliances when they are not in use

• Taking public transport instead of private vehicles

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Chapter 3: Forces [Interactions]

A force is a push or a pull. The standard unit of measurement is the Newton (N).

A push is a force acting away from us.

A pull is a force acting towards us.

Effects of a force (A force can):

• Move a stationary object

• Stop a moving object

• Change the speed or direction of a moving object

• Change the shape or size of an object

A force has both magnitude (the amount) and direction.

A stationary object will remain stationary (at rest) if:

1. The forces acting on the object balanced each other (balance in terms of both magnitude and direction)

2. There are no forces acting on the object -> Only in space

When forces act on an object in the same direction, the forces are not balanced. The object will move and will move in the same direction as the forces.

When forces of different magnitude (amount) act on an object in the opposite direction, the forces are not balanced. The object will move and will move in the direction of the greater force(s).

When forces of the same magnitude (amount) act on an object in the opposite direction, the forces are balanced. The object will not move (remain stationary).

Types of forces:

• Non-contact forces: forces acting on an object even when objects are not in contact (without physical touching)

  • Gravitational force

  • Magnetic force

• Contact forces: forces acting on an object only when two objects are in contact (physically touching)

  • Frictional force

  • Elastic spring force

Gravitational force

The force of attraction between two objects that has mass.

Factors affecting the amount of gravitational force between two objects:

• Mass of objects

  • Greater mass of object, greater the gravitational force objects exert on each other

• Distance between objects

  • Greater the distance, less the gravitational force objects exert on each other

Weight on earth is the amount of gravitational force that Earth exerts on objects.

Gravitational force is not always the force of attraction by Earth. It is true that gravitational force exists between any two objects that has mass. But we don't see objects moving towards each other. It is because the amount of gravitational force between them is very weak as they have very little mass. In contrast, Earth has a huge mass so it exerts a strong gravitational force on objects near the Earth surface and you will notice objects falling toward the ground.

In PSLE syllabus, the amount of gravitational force (the weight) acting on any object near the Earth surface is the same regardless of the height from the ground.

• weight of an object will change when it is on different planets

Weight	Mass
the amount of gravitational force acting on an object	the amount of matter in an object
is a force	not a force
standard measurement: Newton (N)	standard measurement: Kilogram (kg)
will change depending on the gravitational force of the planets	is the same regardless of location

Magnetic force

The force of attraction and repulsion by a magnet.

It can act on magnetic materials and magnets. The magnetic force is the strongest at the poles of the magnet.

The magnetic force of attraction and repulsion can pass through magnetic materials but cannot pass through magnetic materials.

Elastic spring force

The force that an elastic object exerts on other objects attached to it when it is stretched or compressed, to return the elastic object back to its original length.

The direction of the elastic spring force will be opposite to the direction of the force applied on the elastic object.

The greater amount of force applied on an elastic object, the greater extent it is stretched or compressed. The elastic object will later exert a greater elastic spring force back.

A more stiff spring will be stretched or compressed by less extent compared to a less stiff spring when the same forces are applied to them.

Every elastic object has an elastic limit, when overstretched or over-compressed, the object will not be able to return to its original length (deformed). It may eventually crack or snap.

Frictional force

A contact force that opposes motion between two surfaces that are in contact with each other.

Factors affecting the amount of friction acting on an object:

1. Type of surface

   1. the rougher the surface, the more frictional force between the surfaces

2. The force pressing the two surfaces together/ the mass

Surface area of contact does not affect the amount of friction between two solid surfaces.

Friction always acts in the opposite direction to an object's motion and cause it to slow down.

Air resistance is the frictional force between the air and the object.

Factors affecting the amount of air resistance on an object:

1. Surface area of a moving object

   1. Bigger surface area in contact with air, more air resistance

2. Speed of a moving object

   1. As the speed of a moving object increases, air resistance increases

Water resistance is the frictional force between the water and the object.

Ways to reduce friction

• applying a layer of oil which is a lubricant

• having a streamlined body shape

• using ball bearings or wheels

Advantage of friction	Disadvantage of friction
allow us to grip onto objects	causes wear and tear (e.g. shoes, tyres, machine parts)
allow us to walk without slipping	slow down moving objects unnecessarily
allow vehicles to move, change direction and stop	causes fire
generate useful heat which allows us to stay warm	causes machines to overheat

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Chapter 4: Interactions within the environment [Interactions]

Living together

Organism -> Population -> Community -> Ecosystem

An organism is a living thing. (not just animals!)

• A species: a group of organisms that can reproduce together

A population is a group (2 or more) of organisms of the same kind, living and reproducing at a given place and time.

A habitat is a place that many populations of different species live and reproduce together.

A community is a group of populations belonging to different species living and interacting in the same place (habitat).

An ecosystem: is a community of organisms interacting with one another and with their physical environment.

In a community, organisms interact with one another for survival. They are interdependent.

The conditions in a habitat are different from other habitats. An organism will need to adapt and survive. They can also move to other places or they will die.

Different types of communities

Type of community
Seashore community	Seashore habitat is a land that is near the sea sandy soil or rocks on the shore Plankton, dead plants and animals wash in by the water Sandy soil: Crabs, barnacles, Mudskipper, snail, seagrasses, seaweed Large rocks: starfish, clam, mussel, jellyfish, mosses
Mangrove community	Mangrove swamps are muddy. Covered with seawater when the tide comes in Near coastal wetlands or the mouths of river Plants have special roots that are exposed to the surrounding air to take in oxygen. The roots hold the plants firmly to the soft mud Frogs, crabs, snakes, crocodiles, mudskippers
Pond community	consists of aquatic plants and animals Plants: Floating: water hyacinth, water lettuce, duckweed Partially submerged (roots grow in the soil at bottom of pond): lotus, water lily, arrowhead fully submerged: hydrilla, Elodea Animals: Near water surface: butterfly, mosquito, dragonfly, frog On water surface: pond skater, water cricket In the water: fish, tadpole, water spider, dragonfly nymph Plants carry out photosynthesis and give out oxygen for animals to respire animals also feed on plants and other animals Fungi, microorganisms such as algae
Garden community	a piece of land with grass, flowers or shrubs Animals: Birds, Bee, Grasshopper, Beetle, Lizard, Garden snail, Earthworm, Squirrel, Slug Fungi and microorganisms: Mushrooms, bacteria Plants: Moss, rose plant, orchids, bird's nest fern
Field community	An open area that contains grass and non-woody plants The plants is able to trap sunlight to carry out photosynthesis to produce sugar Animals: Snake, Grasshoppper, Snail, Butterfly, Bee, Dragonfly, Ant, Earthworm Fungi and microorganisms: Mushrooms, bacteria Plants: Mimosa, Milkweed, Lalang A leaf litter community can be found in a field community form from fallen leaves, bark and dead plant parts Insufficient sunlight hot and humid environment It provides food and shelter for animals Decomposers break down leaf litter for food, mineral salts from the dead plants returns to the soil
Tree community	A tree can be a habitat to various populations It can be part of a larger community Ferns, birds, squirrels, ants

All living things interact with their environment continuously.

Factors in the environment that affect the survival of an organism:

• Physical characteristics

  • Temperature

    • Most organisms are adapted to live within a temperature range.

    • A sudden change in temperature (for example cause by global warming) can greatly affect the population of plants and animals

    • Temperature of the environment can be measured using a laboratory thermometer or a temperature sensor connected to a datalogger

    • Temperature can affect the amount of water available to living things

      • 0°C or lower: Water freezes into ice. Amount of water decreases

      • Above 0°C: Rate of evaporation increases. Amount of water decreases

  • Light

    • Plants need trap light for photosynthesis

    • The amount of light can affect the temperature in a habitat

    • Some animals such as earthworms prefer to live in shady or dark places

    • A light sensor can be connected to a datalogger to measure the amount of light in an environment

  • Water

    • Water is needed for plants to carry out photosynthesis

    • All living things need water to carry out respiration and release energy in order to perform life processes

    • Water helps to transport substances such as oxygen, carbon dioxide, digested food to all parts of the body

    • Water helps to disperse the fruits and seeds

    • When the amount of water decreases, soil will be dry:

      • Plants will wilt

      • animals will dehydrate

    • When the amount of water increases, soil is waterlogged:

      • Plants roots are unable to breathe

      • Flooding may cause plants to be uprooted

      • Animals will drown in a flood

• Availability of food

  • Food provides living things with energy to do life processes

  • Plants make their own food while other organisms depend directly (consume plants) or indirectly on the food produced by plants

• Other organisms present

  • Animals interact with other organisms living in the same habitat

    • The interactions can help or harm them

    • For example, animals that feed on plants can affect the survival of the plants while animal-eaters affect the survival of animals in the habitat

    • Decomposers help to dispose the dead matters and animal waste

Food Chains and Food Web

The Sun is the main source of energy for all organisms on Earth.

Producer - plants that make their own food using light through photosynthesis

Consumer - organisms that cannot make their own food (feed on plants and other consumers)

Producer	Consumers
Plants	Plant eaters (Herbivores)	Animal eaters (Carnivores)	Both plant and animal eaters (Omnivores)

Animals, Fungi and Bacteria are consumers.

Animals (Consumer)

Prey - an animal that is hunted and eaten by another animal

Predator - an animal that hunts and eats other animals

*Prey - predator is a form of food relationship between 2 animals

*An animal can be both a prey to one animal while a predator of another animal

Food Chain

A food chain shows the transfer of energy from one organism to another in an ecosystem.

It shows who eats whom, starting from plants that produce their own food and moving up to animals that eat other organisms.

Example of food chain:

Grass -> Grasshopper -> Frog -> Snake -> Eagle

Every food chain begins with a producer. It shows the predator-prey relationship between organisms. They are also energy chains.

*We do not consider grasshopper as the predator of grass because grass is not an animal so there is no such prey-predator relationship between grass and grasshopper.

Food chains in a community can be linked together to form a food web.

Food Web

A food web is a network of interconnected food chains.

Each food web can have multiple producers. All the organisms depends on each other for food, grow, reproduce and stay alive.

Example of food web:

Producers	Consumers
Grass, Leaves	Prey	Predator
	Grasshopper	Frog
	Frog	Snake
	Rabbit	Snake
	Mouse	Snake
	Snake	Eagle
	Caterpillar	Bird
	Bird	Eagle

Food Chains in this food web:

1) Grass -> Grasshopper -> Frog -> Snake -> Eagle

2) Grass -> Rabbit -> Snake -> Eagle

3) Grass -> Mouse -> Snake -> Eagle

4) Leaves -> Caterpillar -> Bird -> Eagle

Any changes in the population of any organism will affect the population sizes of the other organisms.

Example:

Changes in population of grasshopper	Population Size	Explanation
Increase	Population of Frog, Snake, Eagle increases	There will be more grasshopper for frogs to feed on. Frogs increase. Subsequently, more frogs for snake to feed on. Hence, population of snake and eventually population of eagle will increase as well.
	Population of grass will decrease	There will be more grasshopper to feed on grass.

Activities that can affect the balance of population size of organisms:

• Overhunting

• Outbreak of diseases

• Introduction of new population

Loss of energy in a food chain

Energy is lost along the food chain. Energy can be lost to the surroundings as organisms carry out life processes such as respiration.

Also, not all of the energy is transferred from one organism to another because not the entire organism is consumed. Hence, the population size of organisms decreases along the food chain.

The energy that is leftover from a dead organism will be passed on to decomposers and used to carry out life processes.

Transfer of harmful substances in a food chain

Harmful substances can be transferred from one organism when it remained in the body of the organisms.

It can accumulate in the food chain and causes the organism at the top to have the largest amount of these substances in their body.

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Chapter 5: Adaptations [Interactions]

Adaptations allow organisms to survive better in their environment.

Types of adaptations:

Structural adaptations: The physical characteristics of an organism's body which enable it to increase its chances of survival.

Behavioural adaptations: The actions or a response of an organism that increase its chances of survival.

Adaptations can help organisms to:

• cope with the physical conditions such as temperature of surroundings

• escape from predators more easily

• obtain more food

• reproduce (finding and attracting mates)

• reproduce (dispersing seeds/fruits)

Adapting to hot environment - Animals

Adaptations	Purpose
Large ears [Structural]	Large ears have more blood vessels to increase the surface area of the ears. It allows the animals to lose heat faster to the surrounding air and keeps it cool.
Burrowing into the sand [Behavioural]	The soil is cooler underground which helps the animals to stay cool and also allows them to prevent getting spotted by predators.
Aestivation [Behavioural]	Slows down life processes to allow the animal to conserve energy and water which can be lost in a hot environment.
Only active at night [Behavioural]	At night, the temperature is lower so the animals will hunt only at night to avoid the warmest part of the day.

Adapting to cold environment - Animals

Adaptations	Purpose
Thick fur [Structural]	They trap air which is a poor conductor of heat. It cause the animal's body to lose heat to the surroundings at a slower rate. Hence, keeping the animal warm.
Thick feathers [Structural]
Blubber (a layer of fat) [Structural]	The thick layer of fat under its skin is a poor conductor of heat. It cause the animal's body to lose heat to the surroundings at a slower rate. Hence, keeping the animal warm.
Small ears [Structural]	Small ears have a smaller surface area in contact with the cold surroundings. It allows the animals to lose heat slower to the surrounding air and keeping it warm.
Dark skin [Structural]	It allows the animal to absorb more heat from the Sun and stay warm in the cold surroundings.
Migrating [Behavioural]	Some animals move from colder places to warmer places during certain months. They can escape the cold and find more food.
Hibernation [Behavioural]	Animals will eat large amount of food before hibernating to store fats. During hibernation, they become less active, life processes slow down to conserve energy which can be obtained from food but there is insufficient food in winter.
Fluffing of feathers [Behavioural]	This action helps to trap more air in the spaces between the feathers. Air is a poor conductor of heat. It causes the animal's body to lose heat to the cold surroundings at a slower rate. Hence, keeping the animal warm.

Adaptations of animals

Adaptations	Purpose
Blowholes [Structural]	It allows mammals to take in oxygen from the surrounding air when they are near the water surface.
Gill chambers [Structural]	It allows the animals to store water and keep the gills wet. They will take in dissolved oxygen from the water.
Streamlined body shape [Structural]	It allows the animals to fly faster in the air and swim faster in the water.
Echolocation [Structural]	it allows the animals to locate their prey, communicate with their species and spot obstructions ahead when they are moving.
Specialised nostrils [Structural]	The nostrils at the tip of the snout are out of the water when their body is underwater. It allows them to breathe and smell while almost entirely submerged.
Breathing tubes [Structural]	Mosquito larvae have breathing tubes out of the water which allows them to take in oxygen from the air.
Air bubbles [Structural]	They use their bodies to form air bubbles which they take in oxygen directly when they are in water.
Moist skin [Structural]	It allows some animals to breathe through their skin when in water
Hollow bones [Structural]	Reduce the body weight of the animal so it needs less energy to move or fly.
Feathers [Structural]	They are light and strong so that the birds can fly more easily. It also helps to keep the bird warm.
Sticky tongue [Structural]	Their tongue can stick onto the prey and allows the animal to hunt for food.
Strong claws and jaws [Structural]	To catch and consume their prey. The claws help it to grip their prey more tightly.
Camouflage [Behavioural]	Animals camouflage and blend in with it’s surroundings which allows them to hide from their predators or to ambush its prey.
Mimicry [Behavioural]	Mimicry refers to animal pretending to be another animal. It prevents them from getting eaten by its predators and also to deceive its prey.
Wide and blunt teeth (Herbivores) [Structural]	For chewing grass, leaves and other plant materials.
Pointed and sharp teeth [Structural]	Grip their prey firmly and tear its flesh.
Webbed feet [Structural]	Help the animal to swim faster in water.
Long tubular beak [Structural]	They can be used to reach deep into the flowers to drink nectar.
Hooked beaks [Structural]	Strong and sharp cutting edges to tear the flesh of prey.
Short, coned-shaped beaks [Structural]	Crack open nuts and seeds for food

Adaptations of plants

Adaptations	Purpose
Strong woody stem and branches [Structural]	Hold the leaves in a suitable position to trap the most amount of sunlight.
Plants with weak stem has twining stem/ clasping roots/ tendrils to climb on trees for a support [Structural]	The stems are unable to support the rest of the plant so they rely on other objects and reach upwards. The leaves will be exposed to more sunlight, trap more light to undergo a higher rate of photosynthesis. The plants can produce more sugar and grow better.
Large leaves/ leaves that float on water [Structural]	Large leaves increase the surface area exposed to the sunlight. Trap more light to undergo a higher rate of photosynthesis. The plants can produce more sugar and grow better.
Closing stomata during the day and opening at night [Behavioural]	During the day, the temperature of the surroundings is higher. The stomata is closed to reduce water loss through the stomata as the rate of evaporation is higher. At night, temperature is lower so the stomata is opened to allow for gaseous exchange with the surrounding air.
Swollen leaf steams filled with air [Structural]	The air in the stem allows the plants to float on water. It allows them to trap more sunlight as compared to when it is submerged. (same photosynthesis explanation)
Air spaces in leaves [Structural]	Fully submerged plants have air spaces in their leaves and stem to help to hold the plant up in the water.
Spread out roots/ Long roots [Structural]	This increases the surface area of roots to the soil allowing the plant to absorb more water through the roots.

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Chapter 6: Man's impact on the environment [Interactions]

Negative impacts

• Depletion of natural resources

• Deforestation

  • Soil erosion

  • Global warming

  • Disrupted rainfall

• Pollution (land/water/air)

Depletion of natural resources

Natural resources such as fossil fuels are non-renewable resources. They are used as energy sources in power stations and for vehicles. They are also important for us to obtain food and materials. Once depleted, they cannot be replaced.

Increasing world population causes the demand for natural resources and man has been using them faster than they can be replaced naturally.

Renewable resources are resources that can replenish naturally faster than we use them. Examples are wind, solar energy and water.

Deforestation is the clearing of large areas of forest by cutting and burning down trees.

Deforestation will lead to:

• Soil erosion

• Global warming

• Disrupted rainfall

	Cause	Effects
Soil erosion wearing away and removal of the top layer of soil	Loss of trees  Without the roots of trees to hold the soil firmly together, the chances of soil erosion increases  There are no leaves to form a canopy over the soil and prevent the heavy rains and strong winds, the chances of soil erosion increases	1.Agricultural Impact the most nutrient-rich topsoil is washed off by rain or blown off by the wind, the less fertile soil will produce less crops and may cause land to become barren 2.Increased risk of landslides 3.Soil may be washed into water bodies which blocks light from reaching the submerged plants. Plants receive less less for photosynthesis and produce less sugar Buriand oxygen. Less dissolved oxygen for fish to take in during respiration. 4.Lead to water pollution and death of aquatic organisms.
Global warming	Cutting of trees There are fewer trees to take in carbon dioxide during  photosynthesis. Hence, the amount of carbon dioxide in the air increases. Burning of trees/ fossil fuels The burning of fossil fuels in factories and power stations  release greenhouse gases such as carbon dioxide. The increase in carbon dioxide which is a greenhouse gas, traps more heat from the Sun within Earth. This causes an increase in the greenhouse effect and lead to a rise in average global temperature resulting in global warming.	1.Rise in global temperature causes polar ice caps to melt. -> rising sea levels -> flooding in coastal areas 2.Extinction of temperature sensitive wildlife such as corals which will disrupt food chains. 3.Extreme weather changes such as more intense storms, droughts and wildfires which destroy crops, homes and habitats.
Disrupted rainfall	Less trees to loss water vapour through the stomata. Less water vapour will lose heat and condense to form less water droplets. Less clouds will be formed and less rain will fall back to Earth's surface. Hence, the amount of water decreases.	1.Leads to drought 2.Extinction of plants and animals as all living things need water for respiration. Those that cannot adapt will not survive 3.Dry conditions will have a higher chance of wildfires

Pollution

It is caused by releasing pollutants into the environment.

Air pollution

Cause

Effects

Clearing of forest through burning (Deforestation) Burning of trash Smoking Burning of fiels in power stations, factories and vehicles

Acid Rain Acidic gas dissolve in rainwater to form acid clouds. The rain will fall back to Earth's surface as acid rain Corrodes buildings and statues by reacting with stone Causes soil to become too acidic for plants to grow well as roots is unable to function well Water bodies become acidic, killing fish and aquatic plants Health problems Excessive dust and smoke irritate eyes, damages lungs and cause breathing issues like asthma Toxic fumes from burning plastics release harmful chemicals that cause cancer when we breathe in

Water pollution

Cause

Effects

Dumping of untreated sewage and waste Factories dump rubbish and sewage directly into water bodies Oil spills Oil from ships leak into the ocean Soil erosion from deforestation fertilisers and chemicals washed into rivers

Health Issues Bacteria from untreated sewage cause diseases; people in poorer areas obtain water from polluted rivers and drink them Toxic waste like oil and mercury poisions humans and animals through the food chain when eaten Destruction of aquatic life Bacteria in sewage take in dissolved oxygen in the water for respiration. Less oxygen for organisms to take in Oil coats birds' feathers, stopping them from flying, floating or stay warm Animals mistake plastics for food/ trap in trash such as fish nets Excess fertilisers from farms cause algae to grow rapidly on water surface. Algae block sunlight so water plants cannot photosynthesise. Algae also use up the dissolved oxygen. Dead aquatic organisms decompose and further reduce the amount of oxygen in the water

Land pollution

Cause

Effects

Dumping of rubbish in open areas which releases harmful substances Littering such as plastics and trash harming soil organisms Excessive use of herbicides and pesticides to kill insects and plants chemicals build up in food chain

Health Problems Rubbish harbours harmful germs that spread diseases from infections Food waste attract pests such as rats and flies which carry diseases to humans Environmental Problems Non-biodegradable rubbish cannot be broken down easily by decomposers It piles up in landfills and take up space Food Chain effects Insects eat herbicides and pesticides in small amounts. Larger animal eat many insects, the poisons will accumulate along the food chain It will harm the predators and upsets the ecosystem balance

Positive impacts

1.Conservation

• Reduce

• Reuse

• Recycle

2.Reforestation

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