In a lake with three trophic levels (non-native fish, zooplankton, algae), an algal bloom occurs when the small population of zooplankton declines due to the predation of the invasive fish. Which of the following describes why zooplankton are the keystone species in this scenario? a) Zooplankton are the smallest of all the herbivorous marine mammals in their communities.
b) The small population of zooplankton have an unequal effect on the marine community.
c) Marine mammals depend upon the work of zooplankton to convert sunlight into food.
d) Zooplankton help other populations survive by keeping out other herbivores.

Some species of wasps are social. the queen starts a colony from scratch each spring. she builds a small nest, and lays and raises a group of female workers. the workers enlarge the nest while the queen continues to lay eggs. unfertilized eggs become males that mate with newly hatched females. all of the wasps except the newly fertilized females die by the summer. which best describes this behavior? a)it is beneficial only to the males that do not fertilize eggs. b)it is beneficial only to the female workers that are not fertilized. c)it is beneficial to each one of the individual colony members. d)it is beneficial to the whole species, but not to all of the individual members.