BiologyQ&A by dot point

The cell cycle and mitosis, meiosis and the production of gametes, the sources of genetic variation, and the basics of sexual reproduction in flowering plants and mammals.

The ultrastructure of eukaryotic cells and the functions of organelles, the difference between prokaryotic and eukaryotic cells, and the fluid-mosaic model of the cell membrane.

Gas exchange surfaces and ventilation in mammals, gas exchange in plants and insects, the transport of oxygen and carbon dioxide in blood, and the structure of the circulatory and transport systems.

Diffusion, facilitated diffusion, osmosis, active transport, endocytosis and exocytosis, and the factors that affect the rate of movement across membranes.

Transport and water relations in plants: the structure and function of xylem and phloem, water uptake by roots through the apoplast and symplast pathways, the cohesion-tension theory of the transpiration stream, the factors affecting transpiration and how a potometer measures it, translocation by the mass flow hypothesis from source to sink, and the adaptations of xerophytes that reduce water loss.

The structure of viruses, why they are non-cellular, the lytic and lysogenic cycles, the replication of HIV as a retrovirus, and how viruses cause disease.

Biodiversity, classification and sampling: biodiversity at the genetic, species and habitat levels, species richness and evenness, calculating and interpreting a diversity index, the hierarchical classification of organisms and binomial nomenclature, the use of quadrats, transects and mark-release-recapture (the Lincoln index) to sample organisms, and the structural, physiological and behavioural adaptations of organisms to their habitats.

Ecosystems, energy flow and food webs, the carbon and nitrogen cycles, succession, and the principles of conservation and managing human impact.

Recombinant DNA technology and genetic engineering, the polymerase chain reaction, gel electrophoresis and DNA profiling, and the applications and ethics of gene technology.

Genes, alleles and genotypes, monohybrid and dihybrid inheritance, sex linkage, codominance, and the use of genetic diagrams and the chi-squared test.

Antigens and the difference between the cellular and humoral immune responses, the action of B and T lymphocytes, antibodies and immunological memory, and active and passive immunity and vaccination.

Natural selection and the sources of variation, the Hardy-Weinberg principle and allele frequencies, types of selection, and the mechanisms of speciation.

Gene expression and mutation: the genetic code as triplets of bases, transcription of a gene into messenger RNA, translation at the ribosome using transfer RNA, codons and anticodons, the role of gene mutation (substitution, insertion and deletion) and how mutations can be silent, harmful or beneficial, and the regulation of gene expression so that different genes are switched on in different cells.

Carbohydrates, lipids and proteins: their monomers, the condensation and hydrolysis reactions that join and break them, the bonds formed, and how molecular structure relates to biological function.

Enzymes as biological catalysts, the induced-fit model of enzyme action, the effects of temperature, pH, substrate and enzyme concentration on rate, and how inhibitors and immobilised enzymes work.

The structure of nucleotides, DNA and RNA, the base-pairing rules, semi-conservative DNA replication, and the role of ATP as the energy currency of the cell.

The dipolar nature of water and the hydrogen bonding that gives it its properties, the biological importance of those properties, and the roles of inorganic ions such as nitrate, phosphate, calcium and hydrogen ions.

The principle of homeostasis and negative feedback, the structure of the kidney and nephron, ultrafiltration and selective reabsorption, and osmoregulation by ADH.

The endocrine system and how hormones act, the control of blood glucose by insulin and glucagon, the difference between nervous and hormonal control, and the basis of diabetes.

Muscles and movement: the ultrastructure of skeletal muscle and the sarcomere (actin, myosin, the A band, I band and H zone), the sliding filament theory of contraction, the roles of calcium ions, troponin, tropomyosin and ATP in the cross-bridge cycle, the neuromuscular junction, and the supply of ATP for contraction by aerobic respiration, anaerobic respiration and creatine phosphate.

The light-dependent and light-independent stages of photosynthesis, the stages of aerobic respiration, anaerobic respiration, and the role of ATP and electron carriers.

Plant growth responses (tropisms), the role of auxin (IAA) in phototropism and gravitropism, and the commercial uses of plant growth substances.

The structure of neurones, the resting potential and action potential, the transmission of impulses along axons, and synaptic transmission across a cholinergic synapse.