They determine the north and south ends
        
             
        
        
        
Answer:
Option B, they negate each other 
Explanation:
Electrical gradient force is more or less equal to the chemical gradient during an active transport. The number of electron produced during the establishment of chemical gradients, were transferred through the cellular circuit to produce electrical gradient of an equivalent amount in opposite path.
Thus, both electrical and chemical gradient are opposite to each other and hence they negate out each other.
Option B
 
        
             
        
        
        
the most often the start of a scientific investigation. is observation
 
        
             
        
        
        
Answer:
Differences in temperature or precipitation determine the types of plants that grow in a given area (Figure 1). Generally speaking, height, density, and species diversity decreases from warm, wet climates to cool, dry climates. Raunkiaer (1934) classified plant life forms based on traits that varied with climate.
Explanation: