Biology 9700/23 May June 2019 | Cambridge AS Level Past Papers With Mark Scheme

1. DNA structure and replication sequence, focusing on telomere function in protecting chromosome integrity during cell division.

2. Alveolar adaptations for efficient gas exchange, calculation of bronchus lumen diameter, and transpiration rate trends in xerophytes under varying conditions.

3. Structural and functional differences between Vibrio cholerae and human epithelial cells, along with prevention strategies for cholera transmission and impacts of HIV on immune response to Vibrio cholerae.

4. Comparative structure of phloem sieve tubes and xylem vessels, including mechanisms of sucrose transport involving companion cells and energy-dependent processes.

5. Effects of altitude on red blood cell counts, mechanisms of crenation in hypertonic solutions, and the role of carbonic anhydrase in respiratory gas transport.

6. Identification of cardiac structures, nicotine's short-term cardiovascular effects, and the implications of halted cell cycles in adult cardiac myocytes on cardiac repair and regeneration.