Biology 9700/21 May June 2018 | Cambridge AS Level Past Papers With Mark Scheme

1. Structural variability in mitochondria observed in electron micrographs due to sectioning angles and their division for energy needs in rapidly metabolizing cells.

2. Sucrose hydrolysis products (glucose and fructose), glycosidic bond cleavage, and explanation for Benedict’s test results due to non-reducing sugar properties.

3. Comparative enzyme activity analysis of free and immobilized sucrase across temperature and pH ranges, with discussion on industrial advantages such as reusability and enhanced stability.

4. Hemoglobin structure features (heme group, α-helices, polypeptide chains) and physiological oxygen saturation changes under varying carbon dioxide pressures.

5. Immune system responses to toxoid vaccines, including antigen recognition, clonal expansion, and memory cell formation, and characterization of myasthenia gravis as an autoimmune disease with chronic implications.

6. Water transport pathways (symplastic and apoplastic) in Ranunculus roots, their roles in transpiration-driven movement, and differences in transport speeds due to structural barriers.

7. Distinctions between facilitated diffusion and active transport based on energy requirements and gradient direction.