What adaptive advantages are conferred on a plant whose stems are positively phototropic and whose roots are positively gravitropic?

Many plants have storage structures under the soil that are quite diverse. How would you decide if the one of these structures was a modified stem or a modified root? Explain.

What are two environments in which CAM plants have an adaptive advantage? why is it that they have this adaptive advantage?

Tobacco plants invest a lot of resources into the production of secondary compounds know as alkaloids (e.g., nicotine) that we believe act as defenses against herbivores. The researchers did an experiment where they added a hormone that reduces the production of alkaloids. In graph (a), the data show that the hormone reduced the proportion of alkaloids as a function of leaf mass relative to controls- so the hormone worked. They also measured the lifetime seed production of the plants in both treatments without any herbivores present (b). They had the following results. What might you conclude/hypothesize/investigate based on the data in graph (b) (a) Chemical defenses (percent of leaf mass) 1.8% 1.4 1.0 0.6 0.2 No hormone added Hormone added (b) Lifetime seed mass (g/plant) -18 14 10 No hormone added Hormone added It would be good to test whether the hormone is very specific or whether it might also cause changes in other metabolic processes The hormone has no effect on the lifetime…