A-Level Biology: Gene Expression and Technology

The final section of A-Level Biology moves from what genes are to how they are controlled and engineered — the content that connects the course to modern medicine and biotechnology. This quiz covers regulation, cancer biology and the full gene-technology toolkit.

The regulation questions cover the control layer: transcription factors, with oestrogen's mechanism tested precisely — a steroid crossing the membrane to bind an intracellular receptor that then acts in the nucleus — epigenetic control through DNA methylation and histone acetylation, and RNA interference tested by its actual effect, targeted mRNA degradation and translational repression.

The cancer questions demand the oncogene distinction that examiners consistently probe: proto-oncogenes mutating into permanently active oncogenes that drive division, versus tumour suppressor genes whose loss removes the brakes — tested as a multi-select alongside the benign-malignant distinction defined by invasion and metastasis. The stem-cell potency ladder (totipotent through unipotent, plus induced pluripotent cells as reprogrammed somatic cells) rounds out the regulation half.

The technology questions cover the toolkit tool by tool: restriction endonucleases and ligase with their exact bond-level jobs, marker genes for identifying transformed cells, PCR tested by phase — the annealing step's temperature and purpose — DNA probes and hybridisation, and genetic fingerprinting through the variability of VNTRs.

Each explanation states mechanism and purpose together, the pairing this section's application questions reward. It completes the A-Level Biology collection alongside the Genes and Protein Synthesis and Inheritance quizzes.

• Explain transcription-factor control, including oestrogen's intracellular mechanism
• Describe epigenetic control via methylation and acetylation, and RNAi's effect
• Distinguish oncogenes from tumour suppressor genes and benign from malignant tumours
• Rank stem-cell potency and define induced pluripotent cells
• Assign the correct roles to restriction enzymes, ligase, PCR phases, probes and VNTRs

Topic scope follows the control of gene expression content of the DfE A level biology subject content as delivered in current exam-board specifications: transcription factors, epigenetics, cancer genetics, stem cells and recombinant DNA technology.