AQA AS Biology With Complete Questions And Answers(Graded A+)

AQA AS Biology With Complete Questions And Answers(Graded A+) Monomer - One of many small molecules that combine together to form a polymer Polymer - Large molecule made up of many repeating smaller molecules (monomers). Polymerisation - The process of making a polymer Condensation - Chemical process in which two molecules combine to form a more complex one with the elimination of a simple substance, usually water. Many biological polymers (e.g. polysaccharides, polypeptides) are formed by condensation. Hydrolysis - The breaking down of large molecules into smaller ones by the addition of water molecules. Carbohydrate - Compounds made from carbon, hydrogen and oxygen. Either monosaccharides, disaccharides and polysaccharides. Monosaccharide - A single sugar e.g. glucose Disaccharide - Made up of two sugar units that are formed by a condensation reaction. Monosaccharides are joined by a glycosidic bond. Polysaccharide - Made of many sugar units that are formed by a condensation reaction. Monosaccharides are joined by a glycosidic bond. Reducing Sugar - A sugar that serves as a reducing agent. All monosaccharides are reducing sugars along with some disaccharides. Reducing sugar test - Heat solution with Benedict's reagent to test for reducing sugars. If it goes brick red then a reducing sugar is present. Benedict's reagent - Blue solution which is used to test for reducing and non-reducing sugars. Glycosidic bond - Bond between sugar molecules in disaccharides and polysaccharides. Non-reducing sugar - A sugar which cannot serve as a reducing agent. An example is sucrose. Non-reducing sugar test - Following a negative reducing sugars test. Heat the solution with HCl to hydrolyse the non-reducing sugar into it's monosaccharides. Then perform the Benedict's test again. If you get a positive result after hydrolysis then a non-reducing sugar is present. Starch - A polysaccharide found in plant cells made up of alpha-glucose - comprised of amylose (alpha-1,4 glyosidic bonds) and amylopectin (alpha-1,4- and alpha-1,6-glyosidic bonds). Glycogen - A highly branched polysaccharide made up of alpha-glucose found in animal cells (alpha-1,4- and alpha-1,6-glyosidic bonds). Cellulose - A polysaccharide made up of beta-glucose found in plant cells (beta-1,4-glycosidic bonds). Alpha glucose - An isomer of glucose that can bond together to form starch or glycogen. Beta glucose - An isomer of glucose that can bond together to form cellulose. Lipid - A class of organic compounds that are fatty acids are their derivatives and are insoluble in water but soluble in organic solvents. They include triglycerides, phospholipids, waxes and steroids. Triglyceride - An individual lipid molecule made up of a glycerol molecule and three fatty acids. Contains ester bonds. Fatty acid - A carboxylic acid with a hydrocarbon tail. Glycerol - A molecule which combines with three fatty acids to form triglycerides. It is 3 carbon chain with 3 hydroxyl groups. Saturated fatty acid - A fatty acid in which there are no double bonds between the carbon atoms Mono-unsaturated fatty acid - Fatty acid which possesses a carbon chain with a single double bond between carbon atoms. Poly-unsaturated fatty acid - Fatty acid which possesses a carbon chain with many double bonds between carbon atoms. Phospholipid - Triglyceride in which one of the three fatty acid molecules is replaced by a phosphate molecule. Phospholipids are important in the structure an functioning of plasma membranes. Protein - A polymer which is made up of amino acids linked by peptide bonds. May also contain prosthetic groups as part of its quaternary structure. Amino acid - A monomer which makes up proteins. Has a central carbon atom which is bonded to: a carboxylic acid group, an amino group, a hydrogen atom and a R group. R-group - Each of the 20 amino acids has a different R group - determines the bonding that the amino acid can carry out. Peptide bond - The type of bond that is formed between two amino acids. Polypeptide - Many amino acids joined together by peptide bonds. Primary protein structure - The sequence of amino acids that makes up the polypeptides of a protein. Secondary protein structure - The way in which the chain of amino acids of the polypeptides of a protein is folded. Tertiary protein structure - The folding of a whole polypeptide chain in a precise way, as determined by the amino acids of which it is composed. Disulfide bridge - Bond formed between Sulphur atoms in R groups of amino acids.