AQA AS BIOLOGY END OF COURSE 2025/2026 QUESTIONS
AND ANSWERS GRADED A+
✔✔Polyunsaturated Fatty Acid (PUFA) - ✔✔Fatty acid that possesess carbon chains
with many double bonds.
✔✔Primary Structure Of A Protein - ✔✔The sequence of amino acids that makes up the
polypeptides of a protein.
✔✔Prokaryotic Cell - ✔✔A cell of an organism belonging to the kingdom Prokaryotae
that is characterised by lacking a nucleus and membrane bound organelles.
✔✔Quaternary Structure Of A Protein - ✔✔A number of polypeptide chains linked
together, and sometimes associated with non-protein groups, to form a protein.
✔✔Saturated Fatty Acid - ✔✔A fatty acid in which there are no double bounds between
carbon atoms.
✔✔Secondary Structure Of A Protein - ✔✔The way in which the chain of amino acids of
the polypeptides of a protein is folded.
✔✔Serum - ✔✔Clear liquid that is left after blood has clotted and the clot has been
removed. It is therefore blood plasma without the clotting factors.
✔✔Sinoatrial Node (SAN) - ✔✔An area of the heart muscle in the right atrium that
controls and coordinates the contraction of the heart.
✔✔Stroke Volume - ✔✔The volume of blood pumped at each ventricular contraction of
the heart.
✔✔Substrate - ✔✔A substance that is acted on or used by another substance or
process.
✔✔Supernatant Liquid - ✔✔The liquid portion of a mixture left at the top of the tube
when suspended particles have been separated out at the bottom during centrifugation.
✔✔Systole - ✔✔The stage in the cardiac cycle in which the heart muscle contracts. It
occurs at two stages, when the atria contract, and when the ventricles contract.
✔✔Tertiary Structure Of A Protein - ✔✔The folding of a whole polypeptide chain in a
precise way, as determined by the amino acids.
✔✔Thrombosis - ✔✔Formation of a blood clot within a blood vessel that may lead to a
blockage.
, ✔✔Tidal Volume - ✔✔The volume of air breathed in and out during a single breath
when at rest.
✔✔Tissue - ✔✔A group of similar cells organised into a structural unit that serves a
particular function.
✔✔Tissue Fluid - ✔✔Fluid that surrounds the cells of the body. Its composition is similar
to that of blood plasma execpt it lacks proteins. It supplies nutrients to the cells and
removes waste products.
✔✔T cell (T Lymphocyte) - ✔✔Type of white blood cell that is produced in the bone
marrow but matures in the thymus gland. They coordinate the immune response and kill
infected cells.
✔✔Transmission - ✔✔The transfer of a pathogen from one individual to another.
✔✔Triglyceride - ✔✔An individual lipid molecule made up of a glycerol molecule and
three fatty acids.
✔✔Tumour - ✔✔A swelling in an organism that is made up of cells that continue to
divide in an abnormal way.
✔✔Turgid - ✔✔A plant cell that is full of water. Additional entry of water is prevented by
the cell wall stopping further expansion.
✔✔Ultrafiltration - ✔✔Filtration assisted by blood pressure.
✔✔Unsaturated Fatty Acids - ✔✔A fatty acid in which there are one or more double
bonds between carbon atoms.
✔✔Vaccination - ✔✔The introduction of a vaccine containing appropriate disease
antigens into the body, by injection or mouth, in order to induce artificial immunity.
✔✔Water Potential - ✔✔The pressure created by water molecules. It is the measure of
the extent to which a solution gives out water.
✔✔Absorption - ✔✔The taking in of soluble molecules.
✔✔Assimilation - ✔✔Incorporating absorbed molecules into body tissues.
✔✔ Activation Energy - ✔✔Energy required to bring about a reaction. It is lowered by
the presence of enzymes.
AND ANSWERS GRADED A+
✔✔Polyunsaturated Fatty Acid (PUFA) - ✔✔Fatty acid that possesess carbon chains
with many double bonds.
✔✔Primary Structure Of A Protein - ✔✔The sequence of amino acids that makes up the
polypeptides of a protein.
✔✔Prokaryotic Cell - ✔✔A cell of an organism belonging to the kingdom Prokaryotae
that is characterised by lacking a nucleus and membrane bound organelles.
✔✔Quaternary Structure Of A Protein - ✔✔A number of polypeptide chains linked
together, and sometimes associated with non-protein groups, to form a protein.
✔✔Saturated Fatty Acid - ✔✔A fatty acid in which there are no double bounds between
carbon atoms.
✔✔Secondary Structure Of A Protein - ✔✔The way in which the chain of amino acids of
the polypeptides of a protein is folded.
✔✔Serum - ✔✔Clear liquid that is left after blood has clotted and the clot has been
removed. It is therefore blood plasma without the clotting factors.
✔✔Sinoatrial Node (SAN) - ✔✔An area of the heart muscle in the right atrium that
controls and coordinates the contraction of the heart.
✔✔Stroke Volume - ✔✔The volume of blood pumped at each ventricular contraction of
the heart.
✔✔Substrate - ✔✔A substance that is acted on or used by another substance or
process.
✔✔Supernatant Liquid - ✔✔The liquid portion of a mixture left at the top of the tube
when suspended particles have been separated out at the bottom during centrifugation.
✔✔Systole - ✔✔The stage in the cardiac cycle in which the heart muscle contracts. It
occurs at two stages, when the atria contract, and when the ventricles contract.
✔✔Tertiary Structure Of A Protein - ✔✔The folding of a whole polypeptide chain in a
precise way, as determined by the amino acids.
✔✔Thrombosis - ✔✔Formation of a blood clot within a blood vessel that may lead to a
blockage.
, ✔✔Tidal Volume - ✔✔The volume of air breathed in and out during a single breath
when at rest.
✔✔Tissue - ✔✔A group of similar cells organised into a structural unit that serves a
particular function.
✔✔Tissue Fluid - ✔✔Fluid that surrounds the cells of the body. Its composition is similar
to that of blood plasma execpt it lacks proteins. It supplies nutrients to the cells and
removes waste products.
✔✔T cell (T Lymphocyte) - ✔✔Type of white blood cell that is produced in the bone
marrow but matures in the thymus gland. They coordinate the immune response and kill
infected cells.
✔✔Transmission - ✔✔The transfer of a pathogen from one individual to another.
✔✔Triglyceride - ✔✔An individual lipid molecule made up of a glycerol molecule and
three fatty acids.
✔✔Tumour - ✔✔A swelling in an organism that is made up of cells that continue to
divide in an abnormal way.
✔✔Turgid - ✔✔A plant cell that is full of water. Additional entry of water is prevented by
the cell wall stopping further expansion.
✔✔Ultrafiltration - ✔✔Filtration assisted by blood pressure.
✔✔Unsaturated Fatty Acids - ✔✔A fatty acid in which there are one or more double
bonds between carbon atoms.
✔✔Vaccination - ✔✔The introduction of a vaccine containing appropriate disease
antigens into the body, by injection or mouth, in order to induce artificial immunity.
✔✔Water Potential - ✔✔The pressure created by water molecules. It is the measure of
the extent to which a solution gives out water.
✔✔Absorption - ✔✔The taking in of soluble molecules.
✔✔Assimilation - ✔✔Incorporating absorbed molecules into body tissues.
✔✔ Activation Energy - ✔✔Energy required to bring about a reaction. It is lowered by
the presence of enzymes.
