Biology

   The cell Cell structure Properties Functions Cell membrane / Plasma membrane Thin membrane consisting of a lipid layer sandwiched between two protein layers   This arrangement is known as the unit membrane and the shows two lipid layers with proteins within     Substances are transported across the membrane by active transport and diffusion It controls the movement of substances into and out of the cell Cytoplasm Jelly-like substance in which are small structures scattered are called organelles Chemical processes are carried out.   Vacuole Cell sap where sugars and salts are stored   Cell wall ·          Made of cellulose ·          Between the cells is a middle lamella made of calcium pectate ...

 Introduction Classification is the orderly arrangement of organisms into groups based on their similarities. Simple criteria used are size, habitat or usefulness e.g. aquatic vs terrestrial plants. Classification can be in terms of either artificial classification or natural system of classification.  Classification results due to the need to be able to identify organisms in their taxonomic groups, enable easy and systematic study of organisms and show evolutionary relationships of organisms. Artificial classification : involves reliance on characteristics that relate to man and less of the innate/natural features of the organisms. For instance animals can be grouped as wild or domesticated depending on their usefulness to man. Natural system of classification involves grouping organisms on the basis of possessing similar natural characteristics. Organisms belonging to the same group are believed to have originated from the same ancestor at some time during evolutionary hist...