Http://www.collective-evolution.com/2014/07/07/new-study-finds-88-percent-of-earths-ocean-surface-no...
This should be of use here.
Several genes determine your skin color; this is a DNA-generated phenotype. However, if you spend a lot of time in the sun, your skin will be darker. This is an environmental influence on your phenotype.
A) single loop
Fish have a two-chambered heart in which a single-loop circulatory pattern takes blood from the heart to the gills and then to the body.
A vaccine promotes immunity by injecting the user with the virus or illness to help the body figure out what to do and thus build a defense from it hoped I helped (:
