Science Test Two 2026

Independent variable

What you can change in an investigation

Dependent variable

What you measure to judge the effect of changing the independent variable

Control variable

What you keep the same in an investigation

Categoric variables

Plotted using a bar chart

Continuous variables

Plotted on a scatter or line graph

Which variable is plotted on the x-axis?

The independent variable

Which variable is plotted on the y-axis?

The dependent variable

When is data valid?

Data is only valid for use in coming to a conclusion measurements are affected by a single independent variable

Anomaly

A data point in an experiments results that doesn't fit the general pattern or trend of the other results

Precise measurements

Measurements where there is very little spread about the mean value

Calculate the mean by….

Adding up all results and diving by the number of recorded results

An electrical switch looks like and does what?

If it's closed, the energy can move round freely but if it's open, the circuit doesn't work.

A cell looks like and does what?

A cell is one part of a battery.

What is an electric current?

An electric current is the rate of a flow of electric charges in a circuit.

Measuring Potential difference

A measure of the amount of energy given by the cell to the moving electrons. Unit is V (VOLTS) and measured by a voltmeter. We can use this to measure the potential difference of a cell or a battery.

Resistance

What is slowing the current down

How do we measure electric current in a circuit?

An ammeter measures the amount of electrical current flowing through a circuit. The unit of current is AMPS (A).

Series circuit

When each component connect together through wires in a circle. If one thing breaks, it is extremely likely that everything on that circuit will break too. One loop.

Parallel circuit

When each component connect together with wires in all directions, often crossing through the middle of the circle and creating pairs of parallel lines. More than one loop.

What do batteries need?

Acid and metals that are very different in reactivity.

Potential Difference

The cell or battery provides the 'push' to make the charges move. This push is called potential difference. Potential difference across a cell tells you about the size of the force on the energy transferred by the cell to the charges and the energy transferred by the charges to the components in the circuit. Some people talk about the voltage of a battery or cell. It is better to talk about the potential difference, you can think of it like a height difference.

Energy in animals and humans is needed for…

Growth and repair

Movement

Control of body temperature in mammals

Respiration

A chemical reaction that happens in all living cells. It's the way that energy is released from glucose so that all the other chemical processes needed for life can happen. Respiration and breathing are not the same thing.

Aerobic respiration

In aerobic respiration, glucose and oxygen react together in cells to produce carbon dioxide and water and releases energy.

Glucose + oxygen = carbon dioxide+water

Use of energy

We take in energy from food we eat and use it in activities like moving, keeping warm and speaking.

joules (J)

Energy is measured in Joules. You 10J of energy to lift a 1kg bag of sugar off the floor and put it on a table.

Joules - Kilojoules

A joule is too small a unit to be useful so energy on food labels, and other amounts of energy, is described in kilojoules (KJ). 1kJ=1000J

Renewable Energy Source

A renewable energy resource is an energy resource that can be replaced and will never run out. Examples are solar power, hydroelectric power, biofuels, wind, tidal and geothermal.

Non-Renewable Energy Source

A non-renewable energy source is an energy resource that will run out and can't be rapidly replaced. Examples are coal mining, nuclear power, natural gases and oil drilling.

Coal Power

Made from deceased animals that have fossilised and been covered in layers of sediment and dirt. Non renewable and you have to wait around 300 million years for it to form.

Oil and Gas Power

Organic and rich in sediment. Non renewable as made from plants and animals and engineers have to drill to extract oil from the ground.

Nuclear Power

Has a high fuel to power ratio. Has a low CO2 release but it's non-renewable, hazardous and radioactive, releasing harmful radiation.

Wind Power

Harnesses wind energy using wind turbines. Used wind to make electricity. Renewable energy resource as wind doesn't run out, but it's disruptive to people in the area and you need loads of turbines.

Solar Power

Uses warmth from the sun and doesn't produce any fuel costs or greenhouse gases. Renewable source as it never runs out. It's very expensive and too inefficient.

Geothermal Power

Harnesses warmth from rocks underground and above ground. Increased geographical range and it doesn't run out, but it's only harnessed when rocks are hot so doesn't work as well in the winter and colder months.

Hydroelectric Power

Makes dams to harness energy from the tide. More reliable than wind and solar power and is renewable as tides don't deplete over time. But it effects people and animals in the surrounding area.

Biofuels

Absorbs CO2 from the atmosphere and from plants and trees. It is a renewable source as there will always be CO2 in the atmosphere. But, it means an increase in pests and some people have ethical reasons to not do it.

Power

You can use the power of an appliance to work out how much energy it transfers per second. Power is the energy transferred per second. The unit of the power is watts (W) and the unit of energy is the joule (J). Power is defined as 'the rate at which energy is transferred'.

Equation of power

Energy transferred/ time

Or p=e/t

Or energy transfer = power x time

Or e=tp

How much energy do appliances transfer?

Energy transferred= power x time

Example:

Q. If you are in an 8kW shower for 1/4 of an hour, how much energy is transferred?

A. Energy transferred= 8kW x 1/4 hour

2kW