IB MYP 4-5 Biology Chapter 9 : Patterns–Practice Questions

Ans: Magicicada reduces predation by synchronously emerging every 13 or 17 years; because too many emerge for predators to consume; predators cannot rely on Magicicada as a source of food because it is too infrequent; 13/17 is a prime number so predators with a 2/3/4/5 year cycle will not always coincide with Magicicada emergence.
Gecarcoidea: too many eggs released for predators to eat; many therefore survive; males can shed their sperm when eggs are in the water; increasing the chance of fertilization.
Plasmodium: tertian and quartan fevers; parasite might benefit from synchronizing its life cycle with the human 24–hour circadian rhythm; fevers usually occur in the evening; Anopheles mosquitos tend to bite and suck out blood in the evening; Plasmodium (gameto– cytes) are sucked out with the blood; gametocytes may emerge into the blood in the evening; to maximize chances of dispersal; at the same time causing evening fevers; Plasmodium vivax might be reproduced faster than Plasmodium malariae hence 2/3 day cycles; immune system might not control the parasite as effectively if it remains inside body cells apart from brief periods every 2nd/3rd day; so Plasmodium synch– ronizes its emergence; overwhelming the capacity of the immune system; cause of tertian and quartan fevers not known even after 100 years of research.