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AQA A-LEVEL BIOLOGY| EXAM HIGH
LEVEL QUESTIONS WITH VERIFIED
ANSWERS| LATEST UPDATE 2026|
GRADED A+| 100% PASS
polymer - Answer -long molecules formed from combinations of many monomers joined together condensation reaction - Answer -a chemical reaction in which two or more molecules join and produces one water molecule hydrolysis reaction - Answer -A chemical reaction that breaks apart a larger molecule by adding a molecule of water isomers - Answer -Compounds with the same chemical formulae but different structures. carbohydrates - Answer -compounds made from carbon, hydrogen and oxygen (monosaccharides, disaccharides and polysaccharides), important energy store monosaccharide - Answer -simple sugars (glucose, fructose, galactose) disaccharide - Answer -two monosaccharides joined together by a glycosidic bond polysaccharide - Answer -many sugar units joined by a glycosidic bond maltose - Answer -α glucose + α glucose
lactose - Answer -glucose + galactose sucrose - Answer -glucose + fructose where is lactose found? - Answer -milk where is maltose found? - Answer -germinating seeds where is sucrose found? - Answer -table sugar cellulose - Answer -polymer of β glucose starch - Answer -polymer of α glucose (amylose + amylopectin) what is the structure of cellulose? - Answer -long, unbranched chains of β glucose, insoluble where is cellulose found? - Answer -plant cell walls why is cellulose strong? - Answer -chains linked by h bonds form microfibrils giving high tensile strength to prevent osmotic lysis what is the structure of starch? - Answer -long, highly-branched, compact helix and insluble where is starch found? - Answer -energy stores in plants glycogen - Answer -storage form of glucose in animals, compact, highly-branched structure limits of the Benedict's test - Answer -isn't specific or sensitive
saturated fatty acid - Answer -no double bonds between carbon atoms, maximising the number of hydrogen atoms that can attach to the carbon skeleton. unsaturated fatty acid - Answer -a fatty acid with one or more double bonds between the carbons (mono or poly) phospholipid - Answer -1 glycerol + 2 fatty acids + 1 phosphate polar - Answer -molecule with partial charges due to a difference in electronegativity hydrophobic - Answer -water repulsion hydrophillic - Answer -attracted to water what is the test for lipids? - Answer -emulsion test describe the emulsion test - Answer -mix with ethanol and add water, white cloudy emulsion = lipid amino acid - Answer -monomer of proteins amino acid structure - Answer -central carbon atom, hydrogen atom, variable (R) group, carboxyl group (COOH) and amine group (NH2) amine group - Answer --NH carboxyl group - Answer --COOH protein - Answer -polymer of amino acids linked by peptide bonds
dipeptide - Answer -product of the condensation of two amino acids polypeptide - Answer -long chain of amino acids joined by peptide bonds disulphide bridges - Answer -a strong covalent bond formed with the sulfur of cysteine monomers R group - Answer -a variable/functional group that defines an amino acid primary structure - Answer -sequence of amino acids, coded by DNA secondary structure - Answer -local folding of the chain to form either an α-helix or β-pleated sheet tertiary structure - Answer -further folding involving interactions between R-groups. quaternary structure - Answer -many polypeptide chains and sometimes an associated prosthetic group fibrous proteins - Answer -long, insoluble, structural proteins (collagen in bone, keratin in hair, actin in muscle etc) globular proteins - Answer -spherical, water-soluble proteins (enzymes, membrane proteins, haemoglobin, insulin etc) strength of bonds in proteins (weak to strong) - Answer - hydrophobic/phillic interactions, hydrogen bonds, ionic bonds, disulfide bridges
factors affecting rate of reaction - Answer -kinetic energy, temperature, enzyme/substrate concentration, pH, inhibitors kinetic energy - Answer -energy of motion temperature - Answer -increase in temperature increases rate of reaction (kinetic energy) but in enzyme-catalysed reactions, too high temperature can denature the enzyme and reduce function pH - Answer -the acidity or alkalinity of a solution by measuring H+ ions. interferes with bonds so extreme changes in pH can cause enzymes to denature and permanently lose function concentration - Answer -increasing concentration will increase the rate of reaction up to a point when there is a limiting factor so activity will plateau competitive inhibitor - Answer -binds to the enzyme's active site in place of the substrate, structure mimics the enzyme's substrate's non-competitive inhibitor - Answer -reduces the activity of an enzyme by binding to an allosteric site, causing a conformational change preventing binding of the substrate reversible inhibitor - Answer -bind to enzyme with weak bonds so only affect enzyme when attached irreversible inhibitor - Answer -attach with strong covalent bonds permanently damaging the enzyme allosteric site - Answer -specific receptor site on an enzyme remote from the active site
conformational change - Answer -alteration of the structure of a protein that impacts on its function DNA - Answer -deoxyribonucleic acid RNA - Answer -ribonucleic acid structure of DNA - Answer -double stranded helix with antiparallel chains, sugar phosphate backbone and held together by hydrogen bonds between base pairs. structure of RNA - Answer -single stranded helix, short polynucleotide chain nucleotide - Answer -pentose sugar, nitrogen containing base and phosphate group bases in DNA - Answer -A(adenine), T(thymine), C(cytosine), G(guanine) what is T replaced with in RNA? - Answer -U(uracil) complementary base pairs - Answer -hydrogen bonding between bases, A-T(2), G-C(3) pyrimidines - Answer -single rings cytosine, thymine, uracil purines - Answer -double rings adenine, guanine non-overlapping - Answer -codons are read one at a time
structure of ATP - Answer -nucleotide derivative 1 ribose, 1 adenine base, 3 phosphate groups uses of ATP - Answer -metabolism, movement, active transport, cell maintenance, synthesis, thermoregulation ATP in aerobic respiration - Answer -released as free energy with 30 molecules per glucose hydrolysis of ATP - Answer - re-synthesis of ATP - Answer - photophosphorylation - Answer -in chloroplast ATP is formed from ADP and Pi utilising the energy of sunlight oxidative phosphorylation - Answer -in mitochondria the production of ATP using energy derived from the electron transport chain in cellular respiration substrate-level phosphorylation - Answer -in cytoplasm the formation of ATP by directly transferring a phosphate group to ADP from an intermediate substrate in catabolism catabolism - Answer -metabolic pathway that break down molecules, releasing energy anabolism - Answer -metabolic pathway that construct molecules, requiring energy
