15. 7
16. 30 (but not sure)
17.Conditions such as high light intensity result in an increased stomata index
19. They grow toward the sunlight to be able to generate energy by photosynthesis
20. If you plant a seed on its side, the shoot and root will emerge horizontally, but quickly change their direction in growth.
21. When the soil of a plant runs too low of available water, the water chains in the xylem become thinner and thinner due to less water...Occasionally, vascular fungal diseases will clog the xylem tissue and cause wilting.