If all the zooplankton is removed from an ecosystem while keeping all other factors undisturbed, then which of the following events will occur?

If zooplankton are removed from the ecosystem while keeping all other factors undisturbed, then phytoplankton populations are likely to increase. Zooplankton are consumers of phytoplankton; they feed on them. With fewer zooplankton around to consume them, the population of phytoplankton would likely increase due to reduced predation pressure.