- Life Sciences
two bean-shaped guard cells surrounding a pore in the epidermis of a leaf that allow gases to enter and leave the leaf. The guard cells regulate the size of the pore in order to control the exchange of respiratory gases and the rate of transpiration.
small fluid-filled spaces in the matrix of bone and cartilage in which cartilage and bone cells...
the inner most layer of the cortex of roots and some stems of plants.