Answer:
Explanation:
Four conditions are needed for natural selection to occur: reproduction, heredity, variation in fitness or organisms, variation in individual characters among members of the population. 
ORR 
Struggle for existence, variation and inheritance. These are said to be the necessary and sufficient conditions for natural selection to occur.
 
        
             
        
        
        
Answer:
Each layer has a different temperature range and contains different mixtures of gases and moisture. Human activities on Earth's surface can create changes in the atmosphere. Pollution, acid rain, and holes in the ozone disrupt how the atmosphere normally functions.
 
        
             
        
        
        
Answer: That a STD is not contagious but can be given by blood bond in other words like if you kiss someone and they have blood on there lip or a sore you can get it like that or if you have finger to finger for example holding hands and they have a little wound there would be a 57% chance they would get the STD. Hopes this helps!
Explanation:
 
        
                    
             
        
        
        
Answer:
Explanation:
It is beneficial to know if mutation is the cause of a particular ailment or an individual carries a mutated gene because it gives a clear direction on what the problem is an how it can be resolve of possible.
We have the sex cell and somatic cells, some mutation affects sex cells, while some somatic cells. If a mysterious affect sex cell there is every possibility of it being inherited by the offspring hence adequate knowledge about a mutant gene being in the body can help guide against some further re-occurence.
Negative effect is fear, it creates fear in an individual who has it.
It can lead to depression when an individual becomes traumatize due to his state.