Key terms & definitions

A contraceptive method that creates a physical barrier; condoms also reduce the transfer of pathogens during sexual contact.

A layer that restricts the passage of substances, such as moisture or oxygen, or blocks light, helping to protect packaged contents.

A contraceptive device, such as a condom or diaphragm, that physically prevents sperm reaching an egg.

A contraceptive method that physically prevents sperm reaching an egg, such as a condom or diaphragm.

A contraceptive method, such as a condom, that creates a physical barrier and reduces the transfer of pathogens during sexual contact.

The ability of a material to restrict the passage of substances such as moisture or grease, or to block light.

Protection provided by a coating that separates a metal from substances such as oxygen and water.

Something that prevents or disrupts the receipt or understanding of a message.

An obstacle that makes taking part in physical activity or sport more difficult.

A legal professional specialising in advocacy and legal advice, often instructed through a solicitor.

Exchanging goods directly for other goods rather than paying with money.

The state between death and resurrection in which souls await the Day of Judgement.

The rate at which the body uses energy to maintain essential functions while at rest.

The rate at which chemical reactions occur in the body when it is at rest.

The energy used to maintain essential body functions at rest, such as breathing and circulation.

The minimum rate of energy-releasing chemical reactions needed to keep the body functioning while at rest.

The minimum rate at which the body uses energy at rest to maintain essential life processes, such as breathing and a heartbeat. It can be expressed as an energy requirement per day.

One of the four variable parts of a DNA nucleotide, represented by A, C, G or T.

A particle that accepts a proton in a proton-transfer reaction.

A substance that neutralises an acid. Examples include metal oxides, metal hydroxides and metal carbonates.

The quantity that is repeatedly multiplied in a power. In $x^5$, the base is $x$.

The number of different digits available in a number system. It determines how place values increase from right to left.

The input connection of a bipolar transistor, through which a small controlling current flows.

The area of the face chosen as the base of a cone or pyramid, often represented by $B$.

The background river flow maintained between rainfall events, largely by groundwater.

The reference period against which a change, such as temperature increase or sea-level rise, is measured.

The starting line on chromatography paper where samples are placed.

The pencil line on chromatography paper where the samples are initially placed and from which their travel distances are measured.

The starting value from which the height or length of a bar is measured.

A recorded starting level against which later results can be compared.