| Abiotic stresses | physical, as opposed to biological, challenges that plants face. For example, frost, drought and salinity are physical problems, while insects and weeds are biological challenges. |
| Arabidopsis | The first flowering plant to have its entire genome sequenced. It is used as a model species because it has little ‘junk’ DNA. |
| Assay | A test to analyse or quantify a substance in a sample. |
| BAC (bacterial artificial chromosome) | a vector used to clone DNA fragments. Different BACs work in different organisms. |
| Base | Part of a nucleotide, which is the building block of DNA. The four bases are adenine (A), guanine (G), cytosine (S) and thymine (T). One of the key features of DNA is that adenine always bonds with thymine, while guanine always bonds with cytosine. The complementary set of bases is known as a ‘base pair’. |
| Base Pair | Two nucleotides paired by hydrogen bonding, forming the ‘rungs’ of the DNA ladder. The number of base pairs is used to describe the length of a DNA strand. |
| Bioinformatics | The use of computers and electronic databases to collate, organise and analyse large amounts of biological information. |
| Biotechnology | the use of living organisms to make or change products. |
| Boron | A biologically dynamic semi-metallic element that occurs abundantly in the ore borax. |
| Breeding | the directed development of crops through the selection of parent plants expressing desired traits. |
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