Albert, a student researcher, varies the amount of food given to rats in an experiment to measure the effect on their learning behavior. In albert's study, the amount of food given is the independent variable.
An independent variable is under the control of the experimenter. Independent variable does not depend on the other variables involved in the experiment. Since the amount of food is varied, it is not depending on other variables like size of mice, weight, etc. 
 
        
             
        
        
        
Answer: ATP
Explanation:Each organelle supports different activities in the cell. Mitochondria, for example, are organelles that provide eukaryotes with most of their energy by producing energy-rich molecules called ATP. Prokaryotes lack mitochondria and instead produce their ATP on their cell surface membrane.
          hope i helped
 
        
                    
             
        
        
        
Tissue is a group of cells that have similar structure and that function together as a unit. ... There are four main tissue types in the body: epithelial, connective, muscle, and nervous. Each is designed for specific functions
        
             
        
        
        
I'm not sure but think its A
 
        
                    
             
        
        
        
Density and distribution of stars are directly affected when the change occur in the size of the circle.
<h3>Effect on density </h3>
The density and distribution of "stars" changed as the circle gets larger because when the circle gets larger, its volume increase which results in the decrease in the density. The distribution of stars also changed due to more space or volume present in the medium.
<h3>Distribution</h3>
If the universe is more condensed, then the stars are more closer together but when the universe is more expand then the stars are present farther away from each other so we can conclude that density and distribution of stars are directly affected when the change occur in the size of the circle.
Learn more about density here: brainly.com/question/6838128
Learn more: brainly.com/question/26243555