P3 & 4 Revision Notes

Science revision notes

BODY SYSTEMS

1.         Each part of a body system is called an organ.

2.         A simple system has a few parts. A complex system has many parts.

3.         Two or more organs work together to form an organ system.

4.         Our skeletal systems support our bodies and give us the shape.

5.         Our respiratory system, which consists of the nose, windpipe and

            lungs, helps to take in oxygen from the air.

6.         Our circulatory system, which consists of the heart, blood and blood

            vessels, carries air, food, water around our bodies.

7.         Digestion is the process of breaking down food into smaller pieces so that it

            can be used by the body.

8.         Digestion begins in the mouth and ends at the anus.

9.         In the stomach, the food is mixed with digestive juices and further 

            broken down into soupy liquid.

10.       The small intestine is the body’s main digestive organ.  Digestion is

            completed here. Digested food is then absorbed into the blood stream.  

11.       The large intestine absorbs water from the undigested food that goes there.

Magnets

Unlike poles attract each other and like poles repel each other.

It is strongest at its poles.

Magnetic force can pass through non-magnetic materials.

It has a north pole and south pole.

Magnet can attract magnetic materials (steel, iron, nickel and cobalt).

Magnet can repel another magnet.

Magnet will always come to rest in the north-south direction.

The 3 ways of making a temporary magnet are: stroking, electricity and induction method .

Magnet can lose its magnetism (demagnetised) when it is dropped, heated and hit with a hammer.

Stroking a magnetic object with a magnet must be in one direction only.

When a magnet is cut into two halves, two smaller magnets each with a North and South pole is formed

Electromagnets are used at recycling plants to separate iron and steel from rubbish. 

Matter

It has mass and occupies space.

Matter exists in three states: solid, liquid and gas.

A solid has a definite shape, definite volume and cannot be compressed.

A liquid has no definite shape, definite volume and cannot be compressed.

A gas has no definite shape, no definite volume and can be compressed.

Heat

Heat travels from a hotter place to a colder place.

A hotter object always loses heat to a colder object until both are of same temperature.

Materials that allow heat to pass through easily are good conductors of heat.

Materials that do not allow heat to pass through are poor conductors of heat.

Most metals are good conductors of heat.

Poor conductors of heat take a long time to gain and lose heat.

Matters expand when heated and contract when cooled.   

Light

Light travels in a straight line.

Light can be reflected.

When light falls on an object, it reflects off the object and travels to our eye so that we can see.

Transparent objects allow most light to pass through.

Translucent objects allow some light to pass through.

Opaque objects do not allow light to pass through.

When an object blocks the path of light, a shadow is formed.

An object can cast a shadow of different sizes and shapes depending on: position of the object and light.

The nearer the object is to the light, the shadow is bigger and less sharp.

The further the object is to the light, the shadow is smaller and sharper.

When the light is above the object, a short shadow is formed (eg. at noon time).

When the light is slanted to one side of the object, a longer shadow is formed.

PLANT SYSTEMS

1.         Most leaves have a stalk, blade and veins.

2.         The leaf blade is the main body of a leaf.

3.         A stalk connects the leaf blade to a branch or stem.

4.         The leaves trap sunlight to make food for the plant.

5.         Leaves carry out photosynthesis to make food for the plants and produce oxygen.

6.         The leaves need carbon dioxide, water, chlorophyll and sunlight for photosynthesis.

7.         The stem holds up the plant to get sunlight.

8.         There are tubes in the stem that carry water, mineral salts and food around the plant.

10.       The roots hold the plant firmly to the ground.

11.       Roots absorb water and mineral salts from the soil for the plant.

LIFE CYCLES

1.         A cycle refers to a pattern of change that repeats itself.

2.         Life cycle consists of all the stages of a living thing’s life.

3.         Living things reproduce so that their kind will always be around on Earth.

4.         Insects with 4-stage life cycle : eg. bee, butterfly, housefly.

5.         Insects with 3-stage life cycle : eg. cockroach, dragonfly, grasshopper.

6.         The 4-stage life cycle has: egg, larva, pupa and adult. 

7.         The 3-stage life cycle has: egg, nymph and adult.

8.         Moulting is the process whereby an animal sheds its outer covering.

FUNGI AND BACTERIA

1.         Mushrooms are not plants nor animals. They belong to the group 'fungi'.

2.         Fungi do not have seeds. They reproduced by spores.

3.         Fungi cannot make their own food. They feed on plants and animals.

4.         Examples of fungi include mould, yeast, puffballs and bracket fungus.

5.         Bacteria are micro-organisms. They are so small that we cannot see them with our   eyes alone.  We need a microscope to see them.