A cactus closes the pores in its stem when the air around it becomes very dry. This reduces the amount of water the cactus loses. Which part of this control system is the effector?
The dry air that surrounds the stem of the cactus
The cells that detect how dry the surrounding air is
The water that is stored inside the stem of the cactus
The cells that close the pores in the stem of the cactus
40 exam-style questions on AQA GCSE Biology 5.1 Homeostasis, covering 5.1 Homeostasis. Each one has a worked solution and a mark scheme showing where the marks go.