Answer:
Constant variables
Explanation:
Elaina's investigation lacked the critical ingredient of constant variables which are important components of every scientific investigation. In every research, there are 3 important variables, namely:
1. Dependent variables: the actual variable to be measured during the course of investigations and whose values are dependent on another variable (independent variable) supplied by the investigators.
2. Independent variable: one of the variables that are supplied by investigators whose values are often manipulated to see the kind of changes it will cause to the dependent variable.
3. Constant variables: other variables that are neither independent nor dependent but constant for all the various experimental groups in investigations.
In a food web there is a hierarchy, if any one of the parts of a food web is changed it can effect the parts above that may consume it, or the parts below that it may consume. Since the food web relies on balance and a hierarchy, if something changes it could disrupt the balance and flow of energy in the food web.
Write pangea in google images and search (: I cant draw if for you, but if i could, i would!