Mass transport and blood vesselsEdexcel International A Level Biology: Mind map

Exam questions on Mass transport and blood vessels

1. An amoeba is a single-celled organism less than 1 mm across and it obtains oxygen by diffusion across its cell surface membrane. A horse is a large mammal with a high metabolic rate and cannot obtain oxygen for its cells in this way.
   A flatworm is a thin, flat animal that has no circulatory system. Explain why it can survive without one.2 marks
2. Blood flows from the heart to the leg muscles of a runner through an artery, passes through capillaries in the muscle and returns to the heart through a vein.
   Explain how the structure of a capillary makes it suitable for exchanging oxygen and glucose with the muscle cells.2 marks
3. A student examines cross-sections of an artery and a vein from the same mammal. The artery has a much thicker wall than the vein, and the vein has a wider lumen than the artery.
   Explain how the structure of the vein is suited to carrying blood back to the heart.3 marks