Hi.
Your answer would be myelin sheath.
        
             
        
        
        
Answer:
Genotype ratio: 1 (RR) : 2 (RW) : 1 (WW)
Phenotype ratio: 1 Red : 2 Roan : 1 White
Explanation:
Codominance is a kind of inheritance pattern in which both alleles are equally dominant in a gene. This means that both alleles when in a heterozygous state will be simultaneously expressed. According to this question, allele for a red coat (R) and the allele for a white coat (W) results in offspring with a roan coat (RW) in cattle. 
Hence, in a cross between a a roan cow (RW) and a roan bull (RW), the following gametes will be produced: R and W. 
Using these gametes in a punnet square (see attached image), the offsprings with the following genotypes will be produced: RR, RW, RW, WW. 
Therefore, based on the results of the cross;
Genotype ratio: 1 (RR) : 2 (RW) : 1 (WW)
Phenotype ratio: 1 Red : 2 Roan : 1 White
 
        
             
        
        
        
Answer:
While exercise is a common cause of muscle fatigue, this symptom can be the result of other health conditions, too.
Causes of muscle fatigue
Addison's disease.
age.
anaerobic infections.
anemia.
anxiety.
botulism.
cerebral palsy.
chemotherapy.
 
        
             
        
        
        
Answer:12.
Containing two complete sets of chromosomes, one from each parent.
Explanation:   Once mitosis is complete, the cell has two groups of 46 chromosomes, each enclosed with their own nuclear membrane. The cell then splits in two by a process called cytokinesis, creating two clones of the original cell, each with 46 monovalent chromosomes.