Basically, the P-P chain turns 4 protons into: 1 neutrino, 1 gamma ray, 1 positron, 1 helium nucleus. 
A gamma ray = energy. 
The chain converts hydrogen into helium and makes energy. 
This is all occurring through fusion reactions where 2 protons basically smash into each other. But, it could also be e.g. a proton smashing with a deuterium nucleus. Or, other nuclei smashing together to make something else.
Hope this helps! 
        
             
        
        
        
Answer:
The correct answer would be:
- Genotype ratio: 1 (PP) : 2 (Pp) : 1 (pp)
- Phenotypic ratio: 3 (polka-dot tails) : solid colored tail
The genotype of both parents is Pp (heterozygous).
Thus, both the parent would produce two types of gametes which are P and p.
The cross would result in the production of offspring with three types of genotype PP, Pp, and pp in 1:2:1.
Offspring with PP and Pp will have a polka-dotted tail as it is the dominant trait.
Thus, the phenotype ratio would be 3 (polka-dotted tail) : 1 (solid colored tail).
 
        
             
        
        
        
I believe its Uranus and Neptune, please tell me if I'm wrong. 
Reason: an ice planet is made up of a semi icy surface like perhaps water, oxygen, or any other element stronger than hydrogen. Neptune and Uranus both meet this match, they are made up of elements that are actually stronger than hydrogen.
 
        
             
        
        
        
Mechanical stress applied to bone increases osteoblast activity in bone tissue, and the removal of mechanical stress decreases osteoblast activity.
Explanation:
Osteoblasts are cells , that are produced in the bone marrow and are responsible for formation of bones and bone matrix.
Whenever a mechanical stress is applied on the bones , a series of reactions are triggered. As a result the activities of osteoblast increases to synthesize more and more bone matrix to provide strength.
Again on the other hand a decrease in mechanical causes a decrease in the activities of the osteoblasts.
 
        
             
        
        
        
The circumference of earth is 24,901 mi