Plants respire all the time, whether it is dark or light, because their cells need energy to stay alive. But they can only photosynthesize when they have light.
The oxidation of water occurs during photosynthetic electron transport during the light reactions of photosynthesis. In the absence of a source of light energy (dark reactions have no direct requirement for light energy), oxygen is not produced.
 
        
             
        
        
        
It represents the genotype. 
For example, Pp is heterozygous genotype, pp is recessive homozygous genotype, PP is dominant homozygous genotype. <span>But, combination and dominance between alleles can show different phenotypes. For example, complete dominance is when phenotype of the dominant allele is expressed in heterozygous. Codominance is when both alleles are expressed equally in heterozygous (phenotype is a combination of both).</span>
        
             
        
        
        
Usually and animal that catches its pray also eats dead animals is classified as carnivore. Do you need clearer classification?
        
             
        
        
        
1. They are much like empty atoms