2. What other mechanisms would cause the differences in coleoptile length between light and dark grown seedlings?

3. Carbon dioxide needed for photosynthesis enters the leaf via the stomata but water is also lost when these pores are open. Water is often limiting and to limit water loss through stoma they are more abundant in the lower epidermis. Speculate why stoma in the lower epidermis loss less water than those in the upper epidermis.