Every living thing grows, reproduces and eventually dies. The stages it goes through are its life cycle.
Some animals change shape as they grow. In complete metamorphosis an insect has four stages: egg → larva → pupa → adult. In incomplete metamorphosis there are three stages: egg → nymph → adult.
Frogs are amphibians: eggs (frogspawn) hatch into tadpoles that grow legs and lungs. Birds and mammals do not change shape; the young look like small adults. Mammals give birth to live young and feed them milk.
How many stages are in complete metamorphosis?
Which is the correct order for a butterfly?
A grasshopper has no pupa stage. Its life cycle is:
A tadpole becomes a:
Which feature do mammals share?
The pupa stage is when the insect:
A life cycle shows:
Which animal goes through a larva stage?
A young bird that has just hatched is a:
Which stage comes after the egg in a frog’s life cycle?
Why do adults reproduce?
Flowers are a plant’s reproductive organs. Pollination and seed dispersal help plants make new plants.
The stamen is the male part: the anther makes pollen. The carpel is the female part: the stigma catches pollen and the ovary contains ovules. Petals attract insects.
Pollination is when pollen moves from an anther to a stigma, carried by insects or wind. After fertilisation, the ovule becomes a seed. Seeds travel away from the parent plant by wind, water, animals or by explosion.
Which part of a flower makes pollen?
Which part of a flower catches pollen?
Pollination is the transfer of pollen from:
Brightly coloured petals help a plant to:
A dandelion seed is dispersed by:
Seeds with hooks are usually dispersed by:
The ovary of a flower contains:
Why must seeds be dispersed?
A coconut is dispersed mainly by:
A pea pod disperses seeds by:
After fertilisation the ovule becomes a:
When you stir salt into water it seems to vanish. It has dissolved, forming a solution.
A solute (such as salt) dissolves in a solvent (such as water) to make a solution. Something that dissolves is soluble; something that does not is insoluble. The mass of a solution equals the mass of the solute plus the solvent.
A solvent can only hold so much solute. When no more will dissolve, the solution is saturated. Stirring, crushing and heating make solids dissolve faster, and warm water usually dissolves more.
In a salt solution, the salt is the:
In a sugar solution, the water is the:
Which substance is insoluble in water?
A saturated solution is one where:
Which does NOT help sugar dissolve faster?
Compared with cold water, hot water usually dissolves:
A solution is made of:
Which is a soluble substance?
You dissolve 30 g of salt in 100 g of water. The mass of the solution is:
How can you get salt back from salt solution?
Which process separates sand from water?
A mixture contains two or more substances that are not joined chemically. They can be separated again.
In a mixture the substances keep their own properties. Sand and water, salt and iron filings and air are mixtures. Because nothing new is made, we can separate them using their physical differences.
Choose a method that uses a difference in properties. Filtering separates an insoluble solid from a liquid. Evaporation separates a dissolved solid from a liquid. A magnet removes magnetic materials. Sieving separates different-sized pieces.
A mixture is:
Filtering separates:
To get salt from salt water you should:
Which pair can be separated using a magnet?
A sieve separates substances that have:
What is the best way to separate pebbles from sand?
Which is a mixture?
Which method separates a solid that has dissolved?
Iron filings mixed with sand are best separated using:
Mud and water are separated by:
When a mixture is separated, the substances:
Light travels in straight lines. When it meets a surface or a new material, it can bounce or bend.
Light reflects (bounces) off surfaces. A smooth, shiny surface such as a mirror gives a clear image. The law of reflection says the angle of incidence equals the angle of reflection, both measured from the normal (a line at 90° to the surface).
When light passes from one material into another, for example from air into water, it changes speed and bends. This is refraction. It makes a straw look bent in a glass of water and makes pools look shallower than they are.
Reflection of light is when light:
The angle of incidence equals the:
Refraction is when light:
A straw looks bent in a glass of water because of:
Which surface gives the clearest reflection?
The normal is a line at what angle to the surface?
Light hits a mirror at 40° to the normal. At what angle does it reflect?
Which is a source of light?
Why does the Moon appear bright?
Light travels in:
When light goes from air into water it:
Earth is one of eight planets travelling round the Sun. Their movements give us days, seasons and years.
The Sun is a star at the centre. In order outward the planets are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune. The inner four are small and rocky; Jupiter and Saturn are huge gas giants; Uranus and Neptune are ice giants.
Earth rotates (spins) on its axis once in about 24 hours, giving day and night. It revolves (orbits) around the Sun once in about 365 days, a year. Because the axis is tilted, we have seasons. The Moon orbits Earth in about a month.
What is at the centre of the Solar System?
Which planet is third from the Sun?
Which of these is a gas giant?
Earth’s rotation causes:
One revolution of Earth around the Sun takes about:
Seasons happen mainly because Earth:
How many planets are in the Solar System?
Which planet is closest to the Sun?
The Moon orbits:
One rotation of Earth takes about:
Which is NOT a rocky planet?
A force can start something moving, stop it, or change its shape. Forces are at work whenever anything moves.
A force is a push or a pull, measured in newtons (N) with a forcemeter. Forces can change an object’s speed, direction or shape. Gravity pulls objects towards Earth, and friction and air resistance slow moving things down.
In a fair test, you change one thing and keep everything else the same.
Force is measured in:
Gravity pulls objects:
Friction usually:
In a fair test you change:
A box has a 10 N push to the right and a 6 N push to the left.
What is the overall force, in N?
Enter an exact answer, without rounding.Two children pull a sled forward with 15 N each.
What is the total force, in N?
Enter an exact answer, without rounding.Which is a force?
A parachute works by increasing:
Balanced forces on a still object mean it:
A forcemeter is used to measure:
Which shoes grip best on ice?
Every sound you hear starts with something shaking. That shake travels through the air and into your ears.
Sounds are made by vibrations, which travel through solids, liquids and gases. Sound cannot travel through a vacuum, because there is nothing to vibrate.
Loudness depends on the size of the vibrations: bigger vibrations make louder sounds. Pitch is how high or low a sound is: faster vibrations make higher notes.
Sounds are made by:
Sound cannot travel through:
A louder sound has:
A higher pitch comes from:
Sound travels about 340 metres in 1 second through air.
How far does it travel in 3 seconds, in m?
Enter an exact answer, without rounding.You see lightning, and hear thunder 6 seconds later. Sound travels about 1 km in 3 seconds.
About how far away is the storm, in km?
Enter an exact answer, without rounding.Tightening a guitar string makes its pitch:
Sound travels fastest through:
Which part of the ear vibrates first?
Ear defenders work by:
Why do we see lightning before we hear thunder?
Questions from every topic in this course. Pick an answer for each one, then hit Check My Answers.
Which is an insect with an incomplete life cycle?
Why do adults reproduce?
Which part is the male part of a flower?
After fertilisation the ovule becomes a:
The substance that dissolves is called the:
Which process separates sand from water?
Which method uses differences in size?
When a mixture is separated, the substances:
A pool looks shallower than it is because of:
When light goes from air into water it:
Earth takes about 365 days to:
Which is NOT a rocky planet?
Unbalanced forces can make an object:
Which force pulls you down a slide?
Plucking a string harder makes the sound:
Sound needs something to travel through, called a: