Molecular Bonding Condensation Reactions – a reaction that joins two molecules and H2O is removed Hydrogen Bond – A weak interaction between a slightly positively charged atom and a slightly negatively charged atom e.g. between the bases of DNA, between the O(-) of...
Transport in Animals Transport – the movement of substances such as oxygen, nutrients, hormones, waste and heat around the body Three factors influence the need for transport systems: Size Surface area/volume ratio Level of metabolic activity Features of a good...
4.3 Classification and Evolution Biological Classification Binomial system – a system that uses the genus name and the species name to avoid confusion when naming organism Classification – the process of placing living things into groups Reasons for classification:...
2.1.3 Enzymes (a) state that enzymes are globular proteins, with a specific tertiary structure, which catalyse metabolic reactions in living organisms All enzymes are globular proteins with a specific tertiary structure, which catalyse metabolic reactions in all...
Nucleic Acids The monomer units in nucleic acids are called nucleotides. They consist of a pentose sugar (deoxyribose/ribose) a phosphate group and a nitrogenous base that is either a pyrimidine or a purine. These three components are joined in condensation reactions...
Communicable Diseases Organisms that cause disease Pathogen – a microorganism that causes disease Transmission of Pathogens Lifecycle of a pathogen: Travel from one host to another (transmission) Entering the hosts tissues Reproducing Leaving the hosts tissues Direct...
Cellular Control state that genes code for polypeptides including enzymes Gene – a length of DNA that codes for one or more polypeptides, including enzymes. Polypeptide – a polymer consisting of a chain of amino acids residues joined by peptide bonds. Protein – a...
Microscopes Light microscope – Light microscopes shine light through a specimen and then uses focused lenses to magnify it. Laser scanning microscope – These use laser light to scan an object, point by point, before using the information to assemble an image on the...
Practical Biochemistry Tests STARCH: Add a solution of iodine to sample If starch is present, iodine changes colour from yellow-brown to blue-black REDUCING SUGARS: Add Benedicts solution (alkaline copper sulphate) to sample Heat in a water bath of 80oc If reducing...
Maintaining Biodiversity (a) outline the reasons for the conservation of animal and plant species, with reference to economic, ecological, ethical and aesthetic reasons How are humans reducing biodiversity? Disruption of food chains - over-harvesting Killing to remove...
Cell Membranes (a) outline the roles of membranes within cells and at the surface of cells (b) state that plasma (cell surface) membranes are partially permeable barriers Plasma membranes are partially permeable meaning they let some molecules through but not...
Diet and Food Production define the term balanced diet A balanced diet is a diet that contains appropriate amounts of all necessary nutrients required for healthy growth and activity. This includes: Carbohydrates – for energy Fats – for energy and insulation...
Enzymes Biological Catalysts Enzymes are biological catalysts that speed up metabolic reactions and remain unchanged at the end of the reaction. The number of reactions that an enzyme can catalyse per second is known as the turnover number Active site- the indented...
Biological Membranes Plasma membranes are partially permeable as they allow some but not all substances to pass through them. Very small molecules diffuse through the plasma membrane Some substances dissolve in the lipid layer to pass through Larger substances pass...
Transport in Plants Plants need a transport system to: Move water and minerals from the roots up to the leaves Move sugars from the leaves to the rest of the plant The Vascular Tissues Water and soluble mineral ions travel upwards in the xylem tissue Assimilates such...
Ecosystems define the term ecosystem Ecosystem – all living organisms and non-living components in a specific habitat, and the interrelationships between them. Habitat - the place where an organism lives. Population - all of the organisms of one species , who...
Biotechnology state that biotechnology is the industrial use of living organisms (or parts of living organisms) to produce food, drugs or other products Biotechnology – the industrial use of living organisms (or parts of living organisms) to produce food, drugs or...
Populations and Sustainability (a) explain the significance of limiting factors in determining the final size of a population Population size is a balance between death rate and rate of reproduction. A habitat cannot support a population larger than its carrying...
Genomes and Gene Technologies outline the steps involved in sequencing the genome of an organism Genome – all the genetic information within an organism OR all the genetic information within an individual. Genome sequencing – the technique used to give the base...
Cloning in Plants and Animals outline the differences between reproductive and non-reproductive cloning Clones – genes, cells or whole organisms that carry identical genetic material because they are derived from the same original DNA. Reproductive cloning generates...
Respiration (a) outline why plants, animals and microorganisms need to respire, with reference to active transport and metabolic reactions Respiration– the process whereby energy stored in complex organic molecules (carbohydrates, fats and proteins) is used to make...
Animal Behaviour explain the advantages to organisms of innate behaviour Behaviour – the responses of an organism to its environment, which increase its chances of survival. An organism must be able to detect changes in the environment, which form stimuli, then carry...
Plant Responses explain why plants need to respond to their environment in terms of the need to avoid predation and abiotic stress Like animals, plants must also need to respond to external stimuli. This is important to: Avoid predation. Avoid abiotic (non-living)...
Excretion (a) define the term excretion Excretion - the removal of metabolic waste from the body, of by-products or unwanted substances from normal cell processes. Functions of the Liver: control of: blood glucose levels, amino acid levels, lipid levels synthesis of:...
Communication outline the need for communication systems within multicellular organisms, with reference to the need to respond to changes in the internal and external environment and to co-ordinate the activities of different organs All living things to maintain a...
Hormones (a) define the terms: (b) explain the meaning of the terms first messenger and second messenger, with reference to adrenaline and cyclic AMP (cAMP) First messenger - the hormone that transmits a signal around the body. Second messenger - molecules called cAMP...
Nerves outline the roles of sensory receptors in mammals in converting different forms of energy into nerve impulses Sensory receptors – specialised cells that can detect changes in our surroundings. They are energy transducers that convert one form of energy...
Biodiversity (b) explain how biodiversity may be considered at different levels; habitat, species and genetic. Habitat - The range of habitats in which different species live. Each habitat will be occupied by a range of organisms. Species - The differences between...
Classification (b)explain the relationship between classification and phylogeny By grouping things into their evolutionary relationships in natural classification phylogeny, which studies the relationship, we can see what organisms are closely related to each other...
Evolution (a) define the term variation Variation is the presence of differences between individuals. This can be within a species or between species. (b) discuss the fact that variation occurs within as well as between species The variation that occurs between...
Exchange Surfaces For exchange to be effective: The surface area of an organism must be large compared with its volume. Thin exchange surface to give a short diffusion pathway Partially permeable to allow selected materials to cross Movement of the environmental...
Transport in Animals (a) explain the need for transport systems in multicellular animals in terms of size, level of activity and surface area: volume ratio (b) explain the meaning of the terms: (c) explain the meaning of the terms: d) describe, with the aid of...
Transport in Plants (a) explain the need for transport systems in multicellular plants in terms of size and surface area: volume ratio Multicellular plants have a small surface area: volume ratio so diffusion would be too slow to provide necessary substances like...
Nucleotides and Nucleic Acids (a) state that deoxyribonucleic acid (DNA) is a polynucleotide, usually double stranded made up of nucleotides containing the bases adenine (A), thymine (T), cytosine (C) and guanine (G) Nucleic acids come in two forms: DNA...
Cell Structure (a) state the resolution and magnification that can be achieved by a light microscope, a transmission electron microscope and a scanning electron microscope Light Microscope - uses a number of lenses to produce an image that can be viewed directly at...
Cell Division, Cell Diversity and Cellular Organisation (a) state that mitosis occupies only a small percentage of the cell cycle and that the remaining percentage includes the copying and checking of genetic information (b) describe, with the aid of diagrams and...
Biological Membranes (a) outline the roles of membranes within cells and at the surface of cells (b) state that plasma (cell surface) membranes are partially permeable barriers Plasma membranes are partially permeable meaning they let some molecules through but not...