Which one of the following is an example of a eukaryote?
a)e. coli bacteria
b)virus
c)yeast

a tetrad is the foursome during meiosis made by two homologous chromosomes that have each already replicated into a pair of sister chromatids.

if the type of the food available changes, then the frequency of beak types will change, because birds with beaks more suited to the available food will be more successful over time.