Biology A level
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| 🇬🇧 | 🇬🇧 |
| Whatis osmosis | Csrfe fdskfdsn fdsal fd/// |
| Monomer Definition | - A single molecule - e.g glucose |
| What is osmosis | A process by which molecules of a solvent tend to pass through a semipermeable membrane from a less concentrated solution into a more concentrated one. |
| What is active transport | The movement of molecules across a cell membrane from a region of lower concentration to a region of higher concentration |
| Cxzc | Cxzcd |
| Polymer Definition | - Many monomers bonded together - e.g starch |
| Fdhfd | Fdf |
| Bdvs | Vfsdv |
| What is a buffer solution | - Organic substances that maintain a constant pH |
| Fdsf | Fdsfds |
| Dsfsa | Fdsaf |
| Why is buffer solution used | - A change in pH will slow the reaction - Buffer solution keeps a constant pH |
| Fdsf | Fdsfd |
| Fdsaf | Fafds |
| What is a peptide bond | - A chain of amino acids bonded together or just amino acids bonded together |
| What is hydroxylation | - Introducing hydroxyl into a compound - Oxidation reaction |
| Sad | Dsad |
| Cdaca | Csacsa |
| Hydrolysis reactions | - Breaking bonds by the adding of water |
| Adaptations of starch | - Coils in a spiral shape and is compact so it takes little space in cell - good for storage - Insoluble - does not dissolve in cell |
| Adaptations of cellulose | - Molecules attach, individual strands of cellulose, together to form rope-like structures - Hydrogen bonds strong in large numbers |
| What monomers form cellulose molecules | - Beta glucose (b - glucose) |
| What monomer form starch molecules | - Alpha glucose (a - glucose) |
| Emulsion test | - Sample is obtained - crushing/grinding - Mixed with ethanol - Water is added - Forms emulsion - Turns cloudy, milky white if lipids are present |
| Products of the hydrolysis of sucrose | - Glucose - Fructose |
| How the structure of cellulose is linked to function | - The strength of the cellulose fibres and hydrogen bonds in cell wall maintains shape and rigidity |
| Condensation reactions | - The formation of bonds by the removal of water |
| Hydrogen bonding | - An attraction between the negative and positive region of two polarised molecules |
| Difference between unsaturated and saturated fatty acids | - Unsaturated fatty acids contain at least one double bond in the fatty acid chain - Saturated fatty acids lack double bonds between carbon atoms |
| What is a glyosidic bond | - A condensation reaction between two monosaccharides |
| Monosaccharides | - One sugar |
| Disaccharides | - Two sugars |
| Polysaccharides | - Multiple sugars |
| Rewa | Rewa |
| What is a reducing sugar | - A sugar that can donate electrons to another molecule e.g. Benedict's reagent |
| Test for reducing sugars | - Food sample dissolved in water in test tube - Equal volume of Benedict's reagent added - Heated in water bath - If it turns orange-brown sugar is present |
| What is a non-reducing sugar | - A sugar that cannot donate electrons to another molecule - So it can't be detected with Benedict's reagent |
| Test for non-reducing sugars | - The non-reducing sugars must be broken down from disaccharides to monosaccharides - Add dilute hydrochloric acid - Heat in water bath - Neutralise it with sodium hydrogen carbonate (Benedict's reagent will not work in acidic conditions) - Heat it again with Benedict's reagent - If sugar is present turns orange-brown |
| Properties of monosaccharides | - Soluble - Sweet tasting |
| Examples of monosaccharides | - Glucose - Galactose - Fructose |
| Examples of disaccharides | - Maltose - Lactose - Sucrose |
| Properties of disaccharides | - Soluble - Sweet taste |
| Examples of polysaccharides | - Starch - Cellulose |
| What monomers make MALTOSE | - Glucose + glucose |
| Properties of polysaccharides | - Insoluble - Suitable for storage |
| What monomers make LACTOSE | - Glucose + galactose |
| What monomers make SUCROSE | - Glucose + fructose |
| Test for starch | - Add iodine - Turns blue-black if present |
| Describe the structure of glycogen | - Alpha glucose - Long, branched chains - Its compact - Has 1-4 glyosidic bonds |
| Adaptations of starch | - Coils in a spiral shape and is compact so it takes little space in cell - good for storage - Insoluble - doesn't affect water potential by osmosis - Chains may be branched or unbranched |
| Adaptations of cellulose | - Molecules attach together in parallel to form rope-like structures - forming microfibrils (made by fibres) - Hydrogen bonds strong in large numbers - Unbranched chains - Long straight chains |
| What monomers form cellulose molecules | - Beta glucose (b - glucose) |
| What monomer form starch molecules | - Alpha glucose (a - glucose) |
| How the structure of cellulose is linked to function | - The strength of the cellulose fibres and hydrogen bonds in cell wall maintains shape and rigidity |
| Adaptations of glycogen | - Insoluble - doesn't diffuse out of cells - Compact - suitable for storage - More branched than starch - more rapidly hydrolysed (broken down) by enzymes |
| What are the two components of starch | - Amylose - Amylopectin |
| Amylose | - a - glucose - Unbranched - 1,4 (carbon atoms) glycosidic bonds |
| Amylopectin | - a - glucose - Branched - 1,4 and some 1,6 glycosidic bonds |
| Enzyme that breaks down maltose | - Maltase |
| Enzyme that breaks down sucrose | - Sucrase |
| Enzyme that breaks down lactose | - Lactase |
| Difference in the structure of the starch molecule and the cellulose molecule | - Starch formed from α-glucose but cellulose formed from β-glucose - Position of hydrogen and hydroxyl groups on carbon atom 1 inverted |
| Describe how the molecules of cellulose are similar to molecules of starch | - Both insoluble - Both made up of glucose - Both contain glyosidic bonds |
| Hydrogen bonds are important in cellulose molecules. Explain why | - Holds chains together - Forms microfibrils, providing strength - Hydrogen bonds strong in large numbers |
| Describe the structure of glycogen | - a - glucose - Long, branched chains - Its compact - Has 1-4 glyosidic bonds |
| Difference between unsaturated and saturated fatty acids | - Unsaturated fatty acids contain at least one double bond in the hydrocarbon chain - Saturated fatty acids lack double bonds between carbon atoms - Saturated FA unable to accept more hydrogen |
| Emulsion test | - Sample is obtained - crushing/grinding - Mixed with ethanol - Water is added - Forms emulsion - Turns cloudy, milky white if lipids are present |
| Roles of lipids | - Energy - Insoluble - waterproofing - Insulation - fats are low conductors of heat - Protection - often stored |
| What is a triglyceride | - A group of lipids - They have three fatty acids combined with glycerol - Contains unsaturated fatty acid tails which are hydrophobic and insoluble |
| Mono-unsaturated meaning | - One double bond between carbon atoms |
| Poly-unsaturated meaning | - More than one double bond between carbon atoms |
| What are phospholipids | - A group of lipids - Made up of two fatty acids, a phosphate and a molecule of glyercol |
| Structure of a phospholipid | - The fatty acid molecules repel water (hydrophobic) - non polar tail - The phosphate molecules attract water (hydrophilic) - polar head |
| Fatty acids | - Carboxyl group - Attached to a long non-polar hydrocarbon chain (hydrophobic) |
| Structure of a triglyceride related to its function | - Lots of C-H bonds (stores energy) - Non-polar and insoluble (does not affect water potential) |
| Structure of phospholipids related to function | - Polar heads forms a bilayer in water - Water holds phospholipids in place - Can form glycolipids |
| Triglycerides have a hydrophobic tail. Explain how this feature of a lipid is important for its function. | - Hydrophobic tails force them to clump together as insoluble droplets - So they can be stored, as a source of energy - Without affecting water potential by osmosis |
| What is a peptide bond | - A condensation reaction between amino acids - bonding them together |
| Monomers that make up proteins | - Amino acids |
| What is a dipeptide | - Two amino acids bonded together |
| What is a polypeptide | - Multiple amino acids bonded together |
| What chemical groups are the central carbon atom in an amino acid attached to | - Amino group - Carboxyl - an acidic group - Hydrogen atom - R group |
| Polymerisation of amino acids meaning | - Many amino acids monomers joined together in a series of condensation reactions - Forming a polypeptide |
| The primary structure of proteins | - The sequence of amino acids in the polypeptide chain |
| The secondary structure of proteins | - Hydrogen bonds form between the amino acids in the chain - It either coils into an alpha helix or folds into a beta pleated sheet |
| Different bonds in the tertiary structure | - Disulfide bridges - strong not easily broken (sulfur-sulfur, covalent bonds), binds chains together - Ionic bonds - not involved in peptide bonds - weak - Hydrogen bonds - numerous but easily broken |
| The tertiary structure of proteins | - The chains are coiled or folded even further - More bonds form - Single polypeptide chained proteins form their final 3D structure at this point |
| The quaternary structure of proteins | - Some proteins are made of many polypeptide chains - These chains are assembled again - Forming their final 3D structure |
| Test for proteins | - Add sodium hydroxide solution - solution needs to be alkaline - Add copper sulfate solution - Turns purple if protein is present |
| Functions of proteins | - Enzymes - Antibodies - Transport proteins - Structural proteins |
| Types of proteins | - Fibrous proteins - Globular proteins |
| Fibrous proteins | - Insoluble - Structural - Many disulfide bridges - e.g collagen |
| Globular proteins | - Soluble - SPECIFIC 3D shape - Metabolism - e.g enzymes |
| How disulfide bridges provide strength | - Chemical bonds formed between sulphur-containing groups - Form stronger disulphide bonds - Binds chain to each other |
| Explain why differences in primary structure result in proteins with different properties | - Different sequences of amino acids - Means bonds in different places which gives a different tertiary structure (shape) |
| What are enzymes | - Biological catalysts - Speed up an reaction without changing themselves - can be reused - Globular proteins |
| Conditions that must be satisfied for reaction to take place | - Molecules must collide with sufficient energy to alter arrangement of atoms - activation energy - The free energy of the products must be less than the substrates |
| Activation energy meaning | - The minimum amount of energy required for reactions to take place |