Answer:
For functioning of heart, circulatory and execratory systems are required.
Explanation:
It requires at least two body systems to perform the function because the functions does not be completed solely, it requires coordination among systems which help them to fulfill their task. For example, the function of the heart requires circulatory system and execratory system for the pumping of blood throughout the body. it is an involuntary action which is not control by nervous system.
 
        
             
        
        
        
I believe it is B. 
Don’t hate me if I am wrong :,)
        
                    
             
        
        
        
Answer: Leeuwenhoek biggest contribution is to the first tenet of the cell theory. 
Explanation: the first tenet of cell theory states that every living being is made of cells and even an organism can be made of just one cell able to reproduce by itself.
Leeuwenhoek observations stablish the existence of microscopic structures alive some with movement. This helped other scientists to determinate this structures were cells that can make vital processes such as feeding, breathing or reproducing which are determinant in biological definition of life. 
 
        
                    
             
        
        
        
Answer:
Photosynthesis is the process by which plants use sunlight, water, and carbon dioxide to create oxygen and energy in the form of sugar.
Explanation: