Answer:
1 heat and no resources for new organisms 2 frogs may bred to be a different color there are disadvantages and advantages to natural selection the bird eats the lighter color frog and the darker frog lives
make sense?
Explanation:
I believe the correct response is D. A single variable.
Answer:
The fourth plant that receives pure water is the control group.
Explanation:
The election of a control group is essential in an experiment. Its principal purpose is to allow the discrimination of the results obtained by the treatment in the study, in this case, <em>the different concentrations of salty water that each plant receives</em>. The control group provides a reference point. It must be selected from the same population of the treatment groups. Both groups must be similar in every variable that might influence the results, <u>except for the study treatment.</u>
An obligatory parasite is a parasite that can not complete its life cycle without exploiting a suitable host
