| A | B |
|---|
| anatomy | the study of the physical structure of an organism |
| antibiotic | a compound that kills or limits the growth and reproduction of bacteria |
| anaerobic | chemical reactions that do not require the use of oxygen |
| aerobic | chemical reactions that do require the use of oxygen |
| allele | the different varieties of a gene |
| active transport | movement of molecules across the cell membrane requiring the use of energy |
| active site | the part of the enzyme where the substrate and reacted particle bonds |
| accuracy | the amount of conformity of a measurement to its actual value |
| abiotic | nonliving parts of an environment such as light, soil, water and climate |
| activation energy | the amount of energy needed to start a chemical reaction |
| adenine | one of 4 nitrogen bases found in DNA and RNA |
| amino acids | the building blocks of proteins |
| ancestry | the history of an organism's development |
| anticodon | 3 adjacent nucleotides in tRNA that bind to a codon in mRNA |
| analogous structures | parts that serve the same purpose in different species but evolved independently |
