Can any any one help?

Is a hamster and guinea pig part of the same species ?

In this experiment, the was intentionally manipulated. it is the independent variable. the dependent variables that were measured were the

Ascience research group is testing a new type of plant food. one trial is conducted in a controlled experiment. the data from the trial show that the plant that received the new food grew faster than the control plant. the group announces that the new plant food makes plants grow faster. what is the main weakness in this scientific claim?