BiologyQ&A by dot point

Cellular differentiation as the process by which cells express only the genes needed for their function, the difference between embryonic and tissue (adult) stem cells, the meaning of potency, and the therapeutic and research uses of stem cells along with cancer cells.

Evolution by natural selection and the three patterns of selection (stabilising, directional and disruptive), the role of gene transfer and genetic drift, speciation, and the use of genomic sequencing and phylogenetics to compare organisms.

Gene expression through transcription and translation, the role of mRNA, tRNA and ribosomes, RNA splicing of the primary transcript, and how one gene can give rise to different proteins.

Single gene mutations (substitution, insertion and deletion), the effects of frame-shift and point mutations, chromosome structure mutations (deletion, duplication, translocation and inversion), and how mutations provide the raw material for evolution.

The replication of DNA by DNA polymerase, requiring a template, primers, free nucleotides and ATP, the formation of leading and lagging strands, and the use of the polymerase chain reaction (PCR) to amplify DNA.

The structure of DNA as a double-stranded antiparallel molecule of nucleotides, with complementary base pairing and a sugar-phosphate backbone, and the organisation of the genome in eukaryotes and prokaryotes.

The stages of cellular respiration (glycolysis, the citric acid cycle and the electron transport chain), the role of ATP, NAD and dehydrogenase enzymes, the net energy yield of glycolysis, and the use of alternative respiratory substrates and fermentation in the absence of oxygen.

The use of microorganisms in research and industry, their diverse metabolism and ability to use a range of substrates, growth in culture media and the phases of a growth curve, the production of primary and secondary metabolites, and the control of growth conditions in fermenters.

Improving wild strains of microorganisms by mutagenesis and selective breeding, recombinant DNA technology and the use of plasmids and artificial chromosomes as vectors, the role of restriction endonucleases, ligase and marker genes, and the need for regulatory sequences and import of useful genes.

Survival strategies that maintain metabolism when conditions are adverse, including dormancy (predictive and consequential), hibernation, aestivation and daily torpor, and migration as a way of avoiding unfavourable conditions, together with how migration is studied.

Metabolic pathways as integrated networks of enzyme-controlled reactions, anabolic and catabolic reactions, the control of pathways by enzymes, induced fit, competitive and non-competitive inhibition, feedback inhibition, and the role of membranes in metabolism.

Metabolic rate and the ways it is measured, the relationship between metabolic rate and body structures in different animal groups, and the contrast between conformers and regulators in how they maintain their internal environment, including the costs and benefits of each strategy.

The costs and benefits of intensive and free-range farming, the link between animal welfare and productivity, the use of indicators of poor welfare such as stereotypy and misdirected behaviour, and how observed behaviour is used to assess the welfare of farmed animals.

The components of biodiversity (genetic diversity, species diversity and ecosystem diversity), the measurement of species diversity from richness and relative abundance, the threats posed by human activity, and the meaning and causes of mass extinction.

The threats that weeds, pests and diseases pose to crop productivity, the characteristics of annual and perennial weeds, the use of chemical control by selective and systemic pesticides, the problems of pesticides, and the use of cultural, biological and integrated pest management.

Food supply, sustainable food production and the demands of a growing human population, the dependence of food production on photosynthesis, the capture and conversion of light energy in the light reactions and carbon fixation, and the factors limiting productivity in crops and livestock.

The improvement of crops and livestock by breeding, the aims of breeding programmes, inbreeding and the problem of inbreeding depression, crossbreeding and F1 hybrids, the role of genetic technology and genome sequencing, and the use of field trials to test new varieties.

Symbiosis as a co-evolved intimate relationship between members of two species, including parasitism and mutualism, and social behaviour including social hierarchy, co-operative hunting, social defence, altruism, kin selection and the social organisation of insects and primates.