• The biological importance of water as a solvent and as a medium for living organisms, including change of state and specific heat capacity.

  • The elements which make up carbohydrates. Monosaccharides are the basic molecular units (monomers) of which other carbohydrates are composed; they include the reducing sugars, glucose and fructose. The structural formula of glucose.
  • The condensation of glucose to form the disaccharide, maltose, and of glucose and fructose to form the disaccharide, sucrose (a non-reducing sugar).

  • The formation of the polysaccharides starch, glycogen and cellulose. Hydrolysis of disaccharides and polysaccharides. Relationship of structure to function in starch, glycogen and cellulose molecules.

  • The elements which make up lipids (fats and oils). Glycerol and fatty acids combine by condensation to produce triglycerides. The structural formulae of glycerol and fatty acids.
  • The R group of a fatty acid may be saturated or unsaturated. In phospholipids, one of the fatty acids of a triglyceride is substituted by a phosphate group.

  • The elements which make up proteins. Amino acids are the monomers of which proteins are composed. The structural formula of an amino acid.

  • The condensation of amino acids to form dipeptides, polypeptides and proteins. Hydrolysis of proteins. The primary, secondary and tertiary structures of proteins. The relationship of structure to function in fibrous and globular proteins.

  • Use structural formulae that may be given to explain the processes of condensation and hydrolysis.

  • Biological processes are regulated by the action of enzymes. Enzymes as proteins that act as catalysts. The importance of enzymes in lowering activation energy so that the chemical reactions necessary to support life can proceed sufficiently quickly and within an acceptable temperature range. The mode of action of enzymes in terms of the formation of an enzyme-substrate complex.

  • The properties of enzymes related to their tertiary structure. The effects of change in temperature, pH, substrate concentration, and competitive and non-competitive inhibition on the rate of enzyme action.

  • Comparison of prokaryotic and eukaryotic cells.
  • The ultrastructure of eukaryotic cells and their organelles, to include cell wall, cell membrane, nucleus, mitochondrion, chloroplast, rough and smooth endoplasmic reticulum, Golgi body and ribosome
  • The ultrastructure of a typical bacterial cell, to include cell wall, cell membrane, genetic material, ribosomes, flagellum, plasmid, capsule.
  • Know the functions of these organelles. Be able to recognise the organelles in cells in electron micrographs.

The Cell Membrane

  • The entry and exit of substances to cells is controlled by cell membranes. The fluid-mosaic model of cell membrane structure. The function of proteins in membranes as receptors and carriers. The relationship between membrane structure and the ability of membranes to control the movement of substances through them.

  • Diffusion as the passive movement of substances in the direction of a concentration gradient. The role of carrier and channel proteins in facilitated diffusion.
  • Osmosis as a special case of diffusion across a partially permeable membrane, net movement of water depending on difference in water potentials. Hypotonic, hypertonic and isotonic solutions, and the importance of ion concentrations in maintaining cell turgor
  • Active transport as the movement of molecules or ions through a membrane by carrier proteins against a concentration gradient, and as a process requiring the transfer of energy.
From Cells to Organisms
  • The effect of surface area and distance on the rate of diffusion. The relationship between the size of an organism or structure and the surface area:volume ratio, and the significance of this for the exchange of substances and of heat.

  • The cells of multicellular organisms may differentiate and become adapted for specific functions. Tissues are aggregations of similar cells, and organs are structures performing specific physiological functions. Changes to body shape and the development of systems in larger organisms are adaptations to facilitate exchanges as the surface area:volume ratio reduces.

Gas Exchange

  • The development of internal gas exchange surfaces in larger organisms to maintain adequate rates of exchange. Organisms with internal gas exchange surfaces need mechanisms for conveying gases between the environment and these surfaces. The structure, location and adaptation for function of the gas exchange surfaces and related structures, related to the environment in which they live, in:

  • mammals (alveoli, bronchioles, bronchi, trachea, lungs) including the ventilation syste
  • bony fish (gill lamellae and filaments), including the ventilation system and the countercurrent principle
  • dicotyledonous plant leaves (mesophyll and stomata). The structure of a palisade mesophyll cell from a plant, as seen with a light microscope. Be able to describe and explain the adaptations of palisade mesophyll cells.

Digestion in Humans

  • The generalised structure of the human gut wall. Be able to relate the generalised structure of the gut wall in the oesophagus, stomach, duodenum and ileum to the functions of these organs.

  • The structure of an epithelial cell from the small intestine, as seen with a light microscope. Be able to describe and explain the adaptations of epithelial cells from the small intestine, and to use examples from the human digestive system to illustrate the features of tissues and organs.

  • The sites of production and action of amylases; endopeptidases; exopeptidases; lipase; maltase; bile. Mechanisms for the absorption of food by the ileum, including the roles of diffusion, facilitated diffusion and active transport.

Digestion in Fungi

  • Extracellular digestion exemplified by a saprophytic fungus.


  • The identification of reducing and non-reducing sugars, starch, proteins and lipids by means of simple biochemical tests, using Benedictís solution, iodine solution, the biuret test and the emulsion test.
  • The separation and identification of compounds by means of chromatography, including Rf values and two-way chromatography.
  • The principles of the use of starch-agar plates for assaying carbohydrase activity.
  • The use of electron microscopy as a means of investigating cell structure.
  • The use of differential centrifugation as a means of investigating cell function.