Although optimal levels of auxin promote growth and inhibit leaf abscission, when auxin concentration get too high, the opposite things happen (growth is inhibited and abscission is promoted).  Which of the following explain the reason for these opposite effects?

The list below includes several strategies that certain tree species have to survive freezing temperatures. Choose the SECOND of the two options in the list that indicates a strategy that some tree species have to survive freezing temperatures

What is the term for plants which are tolerant of relatively high salt concentrations in the soil? 

Acid rain and acid fog can be harmful to terrestrial plants.  Which of the following is NOT a way that acid deposition harms plants?

During times of water stress, this hormone is responsible for increasing root growth (and thus water and ion uptake in the roots), while slightly inhibiting shoot growth.

Which hormone induces the aleurone layer in grain seeds to produce amylase, an enzyme which hydrolyzes starch of the endosperm?

What term is used for a dark-grown seedling having increased stem elongation, poor leaf development (apical hook for dicot), and pale color due to lack of chloroplast maturation?

Which of the following photoreceptors are responsible for the red/far-red photoreversibility of light sensitive lettuce seed germination?

The terms listed below include some environmental variables that are cues important in controlling flowering in many species.  Select the FIRST listed environmental cue that is important in controlling FLOWERING.

There are two main mechanisms by which phytochrome effects occur.  Which of the following is NOT one of those two mechanisms?