Mutations. Definition. A Mutation occurs when a DNA gene is damaged or changed in such a way as to alter the genetic message carried by that gene. A Mutagen is an agent of substance that can bring about a permanent alteration to the physical composition of a DNA gene such that the genetic message is changed.
        
             
        
        
        
Skin remains red after a bad sun burn because:
inflammation causes increased blood flow.
Explanation:
When our skin is exposed to sun rays , the epidermal layer starts getting damaged. The damage to the cell caused by  sun rays triggers the  melanin secretion. Increased secretion of melanin results in darkening of the exposed region .
However, the damage and inflammation to the skin increases blood flow to the skin, this causes reddening of the skin.
 
        
             
        
        
        
Answer:
The genotypic ratio shows the number of times a characteristic of an organism will be seen in the offspring when genes for certain traits are crossed. ... The genotypic ratio for this cross is written 1:2:1. In animals and plants, each gene has 2 alleles or variations, one from each parent
Explanation:
 
        
             
        
        
        
Mass/volume 
<span>for an irregular solid, the easiest way to determine volume is to fill a graduated cylinder to a certain level, record the level of water, then carefully place your solid in the cylinder and record the height of the water after the solid is in.
</span><span>the volume of a regular solid by measuring the lengths of its sides and determining the volume by multiplying length x height x width </span>
        
             
        
        
        
 A.) carbohydrates are large molecules made up of monosaccharides and are used by organisms for energy storage. 
Hope I helped! :)