IB Biology Syllabus

2003-04

2.1 Chemical Elements and Water (2 hours)

2.1.1 State that the most frequently occurring chemical elements in living things are carbon, hydrogen and oxygen.

2.1.2 State that a variety of other elements are needed by living organisms including nitrogen, calcium, phosphorus, iron and sodium.

2.1.3 State one role for each of the elements mentioned in 2.1.2. Refer to the roles in both plants and animals.

2.1.4 Outline the difference between an atom and an ion.

2.1.5 Outline the properties of water that are significant to living organisms including transparency, cohesion, solvent properties and thermal properties. Refer to the polarity of water molecules and hydrogen bonding where relevant. One example to illustrate the importance of each property is sufficient.

*Thermal properties—refer to the large amounts of energy required to heat up water and change its state (and the reverse).
*Solvent properties—water is capable of dissolving many organic and inorganic substances.

2.1.6 Explain the significance to organisms of water as a coolant, transport medium and habitat, in terms of its properties. (Both plants and animals should be mentioned. No physical, chemical or quantitative details are required.)

2.2.1 Define organic. Compounds containing carbon that are found in living organisms (except hydrogencarbonates, carbonates and oxides of carbon) are regarded as organic.

2.2.2 Draw the basic structure of a generalized amino acid. (No details about the R group are required.)

2.2.3 Draw the ring structure of glucose and ribose. Diagrams as viewed below are acceptable.

2.2.4 Draw the structure of glycerol and a generalized fatty acid. The term fatty acid can refer to aliphatic and aromatic fatty acids.

2.2.5 Outline the role of condensation and hydrolysis in the relationships between monosaccharaides, disaccharides and polysaccharides; fatty acids, glycerol and glycerides; amino acids, dipeptides and polypeptides.

2.2.6 Draw the structure of a generalized dipeptide, showing the peptide linkage.

2.2.7 List two examples for each of monosaccharides, disaccharides and polysaccharides. (The names of the component monomer units of the disaccharide and polysaccharide examples are required, but not the structural formulas.)

2.2.8 State one function of a monosaccharide and one function of a polysaccharide.

2.2.9 State three functions of lipids.

2.2.10 Discuss the use of carbohydrates and lipids in energy storage.

6.5.1 Explain the four levels of protein structure, indicating each level’s significance. (Quaternary structure may involve the binding of a prosthetic group to form a conjugated protein.)

6.5.2 Outline the difference between fibrous and globular proteins, with reference to two examples of each protein type.

6.5.3 Explain the significance of polar and non-polar amino acids. (Limit this to controlling the position of proteins in membranes, creating hydrophilic channels through membranes and the specificity of active sites in enzymes. Cross reference with 1.4.)

6.5.4 State six functions of proteins, giving a named example of each. (Membrane proteins should not be included.)

2.3.1 Define enzyme and active site.

2.3.2 Explain enzyme-substrate specificity. (The lock-and –key model can be used as a basis for the explanation. The induced fit model is not expected at SL.)

2.3.3 Explain the effects of temperature, pH and substrate concentration on enzyme activity. (Cross reference with 5.6.1. For temperature and pH, refer to denaturation of the active site.)

2.3.4 Define denaturation.

2.3.5 Explain the use of pectinase in fruit juice production, and one other commercial application of enzymes in biotechnology.

6.6.1 State that metabolic pathways consist of chains and cycles of enzyme catalyzed reactions.

6.6.2 Describe the induced fit model. (This is a type of lock and key fit. Its action accounts for the fact that the active sites of some enzymes may accomodate the fit of more than one substrate.)

6.6.3 Explain that enzymes lower the activation energy of the chemical reactions that they catalyze. (Graphical representation of both exergonic and endergonic reactions should be covered, but specific energy values do not need to be recalled.)

6.6.4 Explain the difference between competitive and non-competitive inhibition, with reference to one example of each.

6.6.5 Explain the role of allostery in the control of metabolic pathways by end-product inhibition. (Allostery is a form of non-competitive inhibition.) Mention that the shape of allosteric enzymes can be altered by the binding of end products to an allosteric site, thereby decreasing its activity.