Biology in Human Welfare and Applied Biology: Biotechnology, Ecology and Environment
Domain 9: Biology in Human Welfare and Applied Biology - what is tested
This domain tests biotechnology tools and applications, ecological organisation, ecosystem function, biodiversity and environmental issues. Expect questions on recombinant DNA, PCR, transgenic organisms, food chains, nutrient cycles, pollution and conservation.
Core rules
- Recombinant DNA technology uses restriction enzymes to cut DNA, ligase to join it, vectors such as plasmids, and host cells for cloning. Selectable markers identify transformed cells.
- PCR amplifies DNA using denaturation, primer annealing and extension by Taq polymerase. It needs primers, nucleotides and template DNA.
- Applications include human insulin from recombinant bacteria, Bt crops, gene therapy and vaccines.
- Ecology levels: organism, population, community, ecosystem, biome. Energy flows through food chains; only about 10% passes to the next trophic level.
- Biodiversity is richest in tropical rainforests and coral reefs; hotspots are conservation priorities. Threats include habitat loss, pollution, invasive species and climate change.
- Environmental issues: eutrophication, biomagnification, ozone depletion and solid waste.
Worked example
Explain how a human gene can be expressed in a bacterium to make insulin. The insulin gene is cut with a restriction enzyme and inserted into a plasmid vector cut with the same enzyme; DNA ligase seals the join. The recombinant plasmid is put into E. coli, and selection identifies transformed cells. The bacteria transcribe and translate the human gene because the genetic code is nearly universal. Reasoning: the same codon-amino acid relationship allows prokaryotic machinery to read a eukaryotic coding sequence; introns must be absent, so cDNA is used.
Traps
Saying restriction enzymes join DNA; confusing PCR with gene cloning; claiming Bt toxin harms humans because it kills insects; saying energy increases up the food chain; treating all introduced species as invasive; forgetting that hotspots are not the only conservation areas.