The diagram below shows part of the cell cycle. Normally, checkpoints exist between each phase that monitor whether a cell is ready to move onto the next phase of cell cycle. An error at which of the following checkpoints would be most likely to lead to uncontrolled cell division and cancer?
the checkpoint that prevents cells from leaving M phase until they are ready
the checkpoint that prevents cells from leaving S phase until they are ready
the checkpoint that prevents cells from leaving G1 phase until they are ready
the checkpoint that prevents cells from leaving G2 phase until they are ready

Monarch butterflies have brightly colored orange wings with black patterns on them, making them easily visible to birds that eat butterflies and moths, yet birds rarely eat the monarchs. likewise, the monarch caterpillars are brightly striped yellow and white and black, and they also are rarely eaten by birds, although some wasps will attack them and feed them to their young. what can be inferred from these observations? monarchs must threaten and attack birds, but not wasps. monarchs have a way of discouraging bird predation that does not involve hiding. monarchs’ wings are so colorful that most birds must find them difficult to eat. monarchs lay more eggs than other less conspicuous butterflies.