Ideally suited for CO 2 gain or H 2 O loss. Guard cells contain chloroplasts, neighboring epidermal cells do not. FICK'S LAW Diffusion is proportional to the driving force, and inversely proportional to the resistance. The ratio of photosynthesis to transpiration. Models of leaf size are based on the observation that it may be optimal for a plant to maximize water-use efficiency.
Heat loss occurs through convection in large leaves.
This reflects the difficulty of getting water.