I'm not totally sure. But in my view, <span>(4)a salt solution</span> would be used to prove that the gas produced by the yeast in the vacuum bottle could change the pH of the liquid in the flask
        
                    
             
        
        
        
I am a population.
-Hope I helped.
        
             
        
        
        
Answer:
secondary succession
Explanation:
secondary succession occurs after a major natural disturbance in the environment, but the soil is still there afterwards so its faster then primary.
 
        
             
        
        
        
A. land plants, tiny water plants
a. slug, frog, newt
b. plants, slug-insect-water fleas, frog-fish-newt, perch-fox, heron
c. water fleas, diving beetles
d. heron, perch
e. one thing that could happen if all frogs suddenly died is that there would be an overpopulation of slugs, insects, and beetles. another thing that could happen would be that foxes would only rely on getting slugs for food so the slugs would soon go extinct and the plants would possibly over populate.
hope this helps!!