Edexcel Certificate Biology Past Papers & Mark Schemes

Cell and molecular biology questions in Paper 1 frequently require precise recall of the stages of protein synthesis. Know the difference between transcription (DNA → mRNA in the nucleus) and translation (mRNA → polypeptide at ribosomes), including the roles of codons, anticodons, tRNA, and the ribosome. Be able to decode a given mRNA sequence using the genetic code table. Genetics questions in Paper 2 may include dihybrid inheritance or sex-linked traits. For dihybrid crosses, set up a 4×4 Punnett square systematically and read off phenotypic ratios. For sex-linked inheritance (e.g. colour blindness on the X chromosome), use the notation X^B and X^b to track alleles through the cross, and remember that males (XY) only need one X-linked allele to express the condition. Ecology and evolution questions often ask you to interpret data from ecological studies or graphs showing population change. When describing a trend in a graph, always use data values (numbers and units) rather than vague terms like 'went up'. When explaining a trend, apply the specific biological mechanism: a decline in prey population reduces food availability for predators, reducing predator birth rates and increasing predator death rates, so the predator population lags behind the prey decline.