Answer:
Cystic fibrosis mutation is recessive to normal allele because only one functional or normal allele is enough to produce a functional protein. So, if mutation is present in one allele then also, a normal protein can be made from normal allele. The presence of normal protein prevents the expression of disease.
In addition, mutated allele only results in the loss of function of protein which can be compensated by the expression of normal allele. It does not add any toxic effect to the protein. Consequently, the disease is inherited in autosomal recessive fashion.
In contrast, Huntington mutation not only alters the structure of the functional protein but also adds toxicity to it. The altered protein is enable to interact with 100s of other proteins and inhibit or decrease their function. So, if only one allele is present then also, the mutated protein will be produced and it will result in the phenotype. Consequently, it is inherited as autosomal dominant fashion.
 
        
             
        
        
        
Air that resists vertical movement is said to be stable. The vertical movement of air is referred to as convection, while advection involves the horizontal movement of air and heat energy transference, Temperature differences at the Erath's surface occur wherever there are differences in surfaces substances. 
        
             
        
        
        
Answer:
Crossing over is the phenomenon by which homologous chromosomes exchange DNA segments between them during the process of meiosis.
 If crossing over did not occur, there will be no genetic variation among parents and offsprings. 
If the process of meiosis did not occur, there will be lesser chances of genetic variations to occur. Each chromosome will be either from the father or the mother with no genetic diversity present in it. As a result,  genetic diversity will reduce.