AQA AS BIOLOGY NEWEST
2024 [A+ GRADED] ACTUAL
2024
activation energy - ANS-energy required to bring about a reaction. The
activation energy is
... [Show More] lowered by the presence of enzymes.
active immunity - ANS-resistance to disease resulting from the activities
of an individual's own immune system whereby an antigen induces
plasma cells to produce antibodies.
active site - ANS-a group of amino acids that makes up the region of an
enzyme into which the substrate fits in order to catalyse a reaction.
active transport - ANS-movement of a substance from a region where it is
in a low concentration to a region where it is in a high concentration. The
process requires the expenditure of metabolic energy.
aerobic - ANS-connected with the presence of free oxygen. Aerobic
respiration requires free oxygen to release energy from glucose. See also
anaerobic.
allele - ANS-one of a number of alternative forms of a gene. For example,
the gene for the shape of pea seeds has two alleles: one for 'round' and
one for 'wrinkled'.
allergen - ANS-a normally harmless substance that causes the immune
system to produce an immune response. See also allergy.
allergy - ANS-the response of the immune system to an allergen.
Examples include hay fever and asthma.
antibiotic - ANS-a substance produced by living organisms that can
destroy or inhibit the growth of microorganisms.
antibiotic resistance - ANS-the development in microorganisms of
mechanisms that prevent antibiotics from killing them.
antibody - ANS-a protein produced by lymphocytes in response to the
presence of the appropriate antigen.
anticodon - ANS-a sequence of three adjacent nucleotides on a molecule
of transfer RNA that is complementary to a particular codon on a
messenger RNA molecule.
antigen - ANS-a molecule that triggers an immune response by
lymphocytes.
antioxidant - ANS-chemical which reduces or prevents oxidation. Often
used as an additive to prolong the shelf-life of certain foods.
apoplastic pathway - ANS-route through the cell walls and intercellular
spaces of plants by which water and dissolved substances are
transported. See also symplastic pathway.
artificial selection - ANS-breeding of organisms by human selection of
parents/gametes in order to perpetuate certain characteristics and/or to
eliminate others.
asthma - ANS-a chronic illness in which there is resistance to air flow to
the alveoli of the lungs as a result of the airways becoming inflamed due
to an allergic response to an allergen.
atheroma - ANS-fatty deposits in the walls of arteries, often associated
with high cholesterol levels in the blood.
ATP (adenosine triphosphate) - ANS-nucleotide found in all living
organisms, which is produced during respiration and is important in the
transfer of energy.
autosomes - ANS-a chromosome which is not a sex chromosome.
B cell (B lymphocyte) - ANS-type of white blood cell that is produced and
matures within the bone marrow. B lymphocytes produce antibodies as
part of their role in immunity. See also T cell.
Benedict's test - ANS-a simple biochemical reaction to detect the
presence of reducing sugars.
biodiversity - ANS-the range and variety of genes, species and habitats
within a particular region.
biomass - ANS-the total mass of living material, normally measured in a
specific area over a given period of time.
Biuret test - ANS-a simple biochemical reaction to detect the presence of
protein. [Show Less]