The exam paper explores biological concepts, including genetic variation, codominance, HIV replication, and carbon use efficiency. It assesses allele frequency using the Hardy-Weinberg equation, the role of CCR5 in HIV treatment, and protein digestion through endopeptidases and exopeptidases. Topics include nitrogen cycle dynamics in anaerobic marshes, sucrose transport in genetically modified plants, and physiological impacts on growth. Extended essays examine complementary molecule shapes and ion roles in metabolism. Keywords include “codominance,“ “Hardy-Weinberg equilibrium,“ “HIV remission,“ “nitrogen cycle,“ “sucrose co-transporter,“ “rubisco inhibition,“ and “plant growth physiology.“