Glossary of terms

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Abiotic factors

= non-living conidtions in a habitat

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Activation energy

= The energy required to initiate a reaction

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Active site

= Area of an enzyme with a shape complementary to a specific substrate, allowing the enzyme to bind a substrate with specificity

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Active transport

= Movement of particles across a plasma membrane against a concentration gradient. Energy is required

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Adenosine diphosphate (ADP)

= A nucleotide composed of a nitrogenous base (adenine), a pentose sugar and two phophate groups. Formed by the hydrolysis of ATP, releasing a phosphate ion and energy.

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Adenosine triphosphate (ATP)

= A nucleotide composed of a nitrogenous base (adenine) , a pentose suagr and three phosphate groups. The univeral energy currency of cells.

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= Chemicals (antibodies) that cuase pathogens to clump together so they are easier for phagocytes to engulf and digest

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= Different versions of the same gene

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Amino acids

= Monomer used to build polypeptides and thus proteins

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Anabolism (anabolic)

= Reactions of metabolism that construct molecules from smaller units. These reactions require energy from the hydrolysis of ATP

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Analogous structures

= Structures that have adapted to perform the same function but have a different origin

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= Third stage of mitosis when chromatids are seperated to opposite poles of the cell

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Antibiotic resistant bacteria

= Bacteria that undergo mutation to become resistant to an antibiotic and then survive to increase in number

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A chemical or compound that kills or inhibits the growth of bacteria

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= Y- shaped glycoproteins made by B cells of the immne system in response to the presence of an antigen.

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identifying chemical on the surface of a cell that triggers an immune response

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Antigen-antibody complex

The complex formed when an antibody binds to an antigen

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Antigen-presenting cell (APC)

A cell that displays foreign antigens complexed with major histocompatibility complexes on their surfaces.

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Antisense strand

The strand of DNA that runs 3' to 5' and is complementary to the sense strand. It acts as a template strand during transcription.

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Anti- toxins

Chemicals (antibodies) that bind to toxins produced by pathogens so they no longer have an effect.

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The cell walls and intercellular spaces of plant cells

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Apoplast route

Movement of substances through the cell walls and cell spaces by diffusion and into cytoplasm by active transport

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an abnormal rythm of the heart

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Objects or strructures seen through a microscope that have been created during the processing of the specimen

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Artificail active immunity

immunity which results from exposure to a safe form of a pathogen, for example by vaccination

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Artificail passive immunity

immunity which results from the administration of antibodies from another animal against a dangerous pathogen

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Asexual reproduction

the production of genetically identical off spring from a single parent

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the products of photosynthesis that are transported around a plant e.g sucrose 

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Atrial fibrillation

An abnormal rhythm of the heart when the atria beat very fast and incompletly

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Atrio- ventricular node (AVN)

stimulates the ventricles to contract after imposing a slight delay to ensure atrial contraction is complete.

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Autoimmune disease

A condition or illness result from an autoimmune response

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