For those wanting to know what the new Snapchat emoji symbols mean, there is several different things that they repersent and these emojis have replaced the âBest Friendsâ feature with Friend Emojis smilies.
(plural tetrads) 1  A group of four things. ( 2 chemistry) A tetravalent atom or radical. ( biology) Two pairs of sister chromatids (a dyad pair) aligned in a certain way and often on the equatorial plane during the meiosis process.
The arrangement or classification of objects according to certain criteria. Systematics is a broader term applied to all comparative biology, including taxonomy. For classifying plants and animals, where the term taxonomy is most often applied, the criteria are characters of structure and function. A given character usually has two or more states.