Bears eat plants such as berries, and plants get their energy from the sun. So his energy source's energy source is sunlight, which also makes it his energy source
        
             
        
        
        
The correct order of phases in the menstrual cycle is; 
 menses, .estrogenic phase, ovulation, and progestational phase.
The menstrual cycle is complex and is controlled by many different glands and hormones that these glands produce. 
There are four phases of menstrual cycle; namely, menstruation, the follicular phase, ovulation and the luteal phase. 
        
             
        
        
        
Answer:
As a cell grows in size, the surface area gets bigger, but the volume gets bigger faster. Thinking about this as a ratio (division), the volume is the denominator and the surface area is the numerator. If the volume is getting very big, then the ratio itself will be getting very small.
 
        
             
        
        
        
Answer:
they carry out experiments to understand it
Explanation:
Scientists raise hypotheses which are tested by experiments made under controlled conditions in order to explain a particular topic. When a hypothesis is confirmed by the experimental data, the evidence obtained from this experiment provides the basis to increase the scientific knowledge about a particular issue. In consequence, experimentation can be considered as a critical step in the scientific method and research aims to advance knowledge of a particular phenomenon by confirming a hypothesis, which must be testable (i.e. verifiable as a result of further experimentations).