biology

• The four key inorganic ions in living organisms are Magnesium ions (Mg 2+ ), Iron ions (Fe 2+ ), Calcium ions (Ca 2+ ), and Phosphate ions (PO 4 3- ).
• Mg 2+ is used to produce chlorophyll in plants.
• Fe 2+ is found in haemoglobin and is involved in the transport of oxygen in animals.
• PO 4 3- is used to produce ADP and ATP in living organisms.
• Ca 2+ is used to strengthen tissues such as bones and teeth in animals and cell walls in plants.
• The emulsion test for fats and oils involves adding ethanol to the sample, allowing the mixture to settle, adding an equal volume of water, and recording any observations.
• The positive result of an emulsion test is the formation of a white, cloudy emulsion.
• The positive result of a biuret test is a colour change from pale blue to purple.
• The iodine-potassium iodide test for starch involves adding iodine-KI solution and observing a colour change from orange to blue-black in the presence of starch.
• Water is a polar molecule because O is more electronegative than H, attracting the electron density in the covalent bond more strongly, forming δ- O and δ+ H.
• Weak intermolecular forces of attraction form between a lone pair on a δ- O and a δ+ H on an adjacent molecule.
• A metabolite is a molecule formed or used in metabolic reactions.
• Water is a reactant in photosynthesis and hydrolysis reactions and a product in aerobic respiration and condensation reactions.
• Water acts as a temperature buffer, enabling endotherms to resist fluctuations in core temperature and to maintain optimum enzyme activity.
• Water's high surface tension is due to the ordered arrangement and cohesion of molecules at the surface of water.
• Water's high latent heat of vaporisation is important for organisms as it has a cooling effect in homeostasis.
• α-glucose is a monosaccharide.
• Deoxyribose is a monosaccharide.
• Water is a polar universal solvent that enables chemical reactions to take place within cells, the transport of materials in the plasma and the removal of metabolic waste.
• β-glucose is a monosaccharide.
• Monosaccharides are simple sugars with the general formula C n (H 2 O) n.
• LDLs block receptor sites, reducing cholesterol absorption and are known as ‘bad’ lipoproteins.
• Examples of monosaccharides include Glyceraldehyde, Ribose, Deoxyribose, α- and β- glucose, Fructose, Galactose.
• The general structure of an amino acid consists of an amine group (-NH2), a variable side chain (R), a carboxyl group (-COOH), and an H atom.
• The high blood cholesterol level caused by LDLs leads to formation of atherosclerosis plaques.
• The high surface tension of water is important for organisms as it enables the transport of water and nutrients through plants stems and small blood vessels in the body, and allows small insects to 'walk' on water.
• The quaternary structure of a protein involves interactions of more than one polypeptide chain and may involve addition of prosthetic groups, e.g. metal ions or phosphate groups.
• The structure of fibrous proteins relates to their function.
• Monounsaturated fatty acids contain one C=C bond.
• The tertiary structure of a protein is the folding of a protein to make a three-dimensional structure, held in place by various interactions and bonds: disulfide bonds, ionic bonds, hydrogen bonds, and hydrophobic interactions.
• Polypeptides are formed by many amino acid monomers joining together in condensation reactions, forming peptide bonds (-CONH-).
• The secondary structure of a protein is the local interactions of the amino acids in the polypeptide chain resulting in α-helices or β-pleated sheets, held in place by various interactions and bonds: disulfide bonds, ionic bonds, hydrogen bonds, and hydrophobic interactions.
• Polyunsaturated fatty acids contain more than one C=C bond.
• The primary structure of a protein is the individual sequence of amino acids in a protein.
• A low density lipoprotein (LDL) is a combination of triglycerides from saturated fats and protein.
• Unsaturated fats have one or more C=C bonds, are liquid at room temperature due to weak intermolecular forces, and are used for thermal insulation, for example in adipose tissue.
• Polyunsaturated fats have more than one C=C bond, are liquid at room temperature, and are used for thermal insulation, for example in adipose tissue.
• One molecule of glycerol forms ester bonds with three fatty acids via condensation reactions to form a triglyceride.
• Linear polysaccharide found in the exoskeletons of insects and crustaceans as well as fungal cell walls is called chitin.
• The glycerol backbone of a phospholipid is attached to two hydrophobic fatty acid tails and one hydrophilic polar phosphate head, forming a phospholipid bilayer in water and making it a component of cell membranes.