Introduction to biomolecules

    • Biomolecules is a core JC1 topic in H2 BIO A levels. This topic explores the 3 most important biomolecules that makes up a cell: carbohydrates, proteins and lipids. You will learn about the monomers such as amino acids, glucose, glycerol and fatty acids as well as their polymeric structure and functions. This includes, cellulose, amylose, amylopectin, glycogen, phosphopipids, triglyceride, haemoglobin, collagen as well as GPCR.

    A selection of materials for biomolecules

    Most common phrasing errors made by students during exams

    • Cellulose is soluble and linear
    • Haemoglobin has 2β and 2α chains
    • Collagen comprises of a triple helix
    • Phospholipids are hydrophobic molecules
    • Cellulose is a protein and collagen is a polysaccharide
    • Cellulose has β1-4 whereas starch have α1-6 glycosidic bonds
    • Chains of cellulose are cross-linked by covalent hydrogen bonds
    • Secondary structures of proteins results from hydrogen bonds between O atom of the -CO and H atom of the -NH groups

    Exam tips

    • Very often questions asks to compare 2 molecules:
      • Give point to point comparison i.e. 1 point in 1 sentence
      • What does the question want? Structure? Function? Reference to diagram? Relate structure to function?
      • If its structures, monomers and bonds formed between monomers are easy points to use
      • Don’t write vague differences e.g. collagen is a protein
      • Don’t include non-structural differences e.g. collagen forms connective tissues in animals
      • Careful not to compare different levels of organization e.g. comparing a single cellulose chain to a single collagen polypeptide chain
    • Do not confuse collagen and cellulose!
    • Haemoglobin best describes all levels of protein structures so use it whence you can
    • Did the question ask for a biomolecule’s structure? Function? Or structure relating to function?
    • Expect to know various food tests, procedures and results, questions can appear even in papers 1, 2 as well as 3
    • When describing dehydration reactions, include details of H from one monomer and OH of another monomer in forming water
    • Protein structures at tertiary and quaternary level are formed by the same 4 types of bonds BUT how the bonds form must be clarified

    BYang’s tough questions bank

    • Fizzy (carbonated) drinks are increasingly used to tenderize tough cuts of meat. Suggest a mechanism to explain the phenomenon. [4m. Created 210312]

    Questions and other matters

    • JOIN my classes so that you can get answers to your questions. You will also be able to access TYS questions from different JCs in Singapore as well as my comments and answers.
    • You can also register for my H2 BIO crash courses to get ready for exams. Here’s the SCHEDULE.
    • You may also be interested to know how to boost your performance for A levels.