At which point is the actual growth rate of the population greatest?

The growth rate is the slope of the curve. The population is growing the fastest (the slope is highest) at B.

2. At which point is the actual growth rate negative?

Just like the slope of a line, the growth rate will be negative when the curve decreases from left to right. The growth rate is negative at E.

3. At which point is the logistically growing population growing at a rate that is closest to the biotic potential for a population of that size?

This would happen when the slopes of curves 1 and 2 seem to be parallel. Out of all the points, this is most likely at points A and B, but I think curve 2 is more similar to curve 1 at B.

4. What does the hatched area represent?

The hatched area is the difference in population size between a perfect environment and a real-life environment. In the real-life environment, population size is limited by space and resources. The answer is D.

5. Contest competition is competition in which mortality compensates exactly for increases in density, so there is a constant number of survivors irrespective of initial density. Exploitation competition is competition in which any adverse effects on an organism are brought about by reductions in resource levels caused by other, competing organisms.

The scenario in the problem describes territoriality, not aggregation. And the the chemicals secreted doesn't reduce resource levels of other plants. Instead, the more competitor plants there are, the more the chemicals will prevent the growth of these competitors.

Therefore the answer is C.

6. A plant species that is strongly r-adapted or r-selected would likely have small seeds (A). Organisms that are r-adapted are usually small (so the answer isn't C), have a short generation time, have lots of offspring (so the answer isn't B), disperse their offspring widely, and live in an unstable environment (so the answer isn't D). Organisms that are K-adapted usually show the opposite.

7. "r" is the rate of increase of a species (biotic potential). All of the factors mentioned influence r. I wouldn't call any of them the "major factor" because they are all important, but if I had to pick one, I would choose C, reproductive longevity. The longer the reproductive period of an individual's life, the more individuals there will be to reproduce.