<span>The average heart rate is the number of heart beats counted in 15 seconds divided by 15 seconds. The instantaneous heart rate is the time it takes for a single heart beat. Since the heart can beat at varying rates, these values are not necessarily the same.</span>
        
             
        
        
        
It is convenient to divide the photosynthetic process in plants into four stages, each occurring in a defined area of the chloroplast: (1) absorption of light, (2) electron transport leading to the reduction of NADP+ to NADPH, (3) generation of ATP, and (4) conversion of CO2 into carbohydrates (carbon fixation).
        
                    
             
        
        
        
Answer: it can change because...
Explanation: the tilt of the earths axis is a little over 25 degreas so when the earth is tilted twards the sun the day is longe and vise versa because of this the seasons are created
 
        
             
        
        
        
They are both built over time