Answer:
A: light availability
B: nutrients
Explanation:
Both nutrients and light availability affect the primary productivity of the freshwater ecosystem, therefore, scientists study both factors to track associated changes. This is because photosynthesis is driven by sunlight and nutrients availability. It is suggested that the abundance of autotrophs (e.g. phytoplanktons) in an aquatic ecosystem increases as light and nutrients availability increase. Thus, there will be more food available for secondary and tertiary consumers to feed upon. Resultantly, the aquatic environment will turn a biodiversity hotspot where many species of living organisms start dwelling. Thus, scientists mainly ecologists would focus on these two parameters at first that lead to consideration of other parameters.
For more information, you may want to read this scholarly article
https://aslopubs.onlinelibrary.wiley.com/doi/abs/10.4319/lo.2006.51.1.0288
The answer should be A, inside the bag.
Permeable means allowing certain material to pass through. So if it's permeable to water and iodine, it means it can allow water and iodine to pass through the bag, but doesn't allow starch to go in.
Because iodine can pass through the bag, it can get into the bag filled with starch. But since starch couldn't diffuse out of the bag, the color change is only can be observed inside the bag. When no starch is gone out from the bag, there is no color reaction in the rest of the beaker.
So that answer is A.
An obligatory parasite is a parasite that can not complete its life cycle without exploiting a suitable host
