What must happen before a chemical reaction can begin?

Does the sun release radiant energy?

Indicate the coat color and the proportion of offspring with that color for each of the following crosses of rabbits. assume all are homozygous. chinchilla x chinchilla 1/2 agouti, 1/2 chinchilla 3/4 agouti, 1/4 chinchilla all chinchilla

Anurse is caring for a 42-year-old client who is scheduled for an amniocentesis during the fifteenth week of gestation because of concerns regarding down syndrome. what other fetal problem does an examination of the amniotic fluid reveal at this time?