Hello!! The answer would be A - The SA node. It is known as the "pacemaker" because it initiates the heart's rhythmic contractions. I hope I helped!! Have a great day. :)
False. Energy is never destroyed, it can only be transformed. Energy is never lost as well.
Answer:
A. Each organism had a different parent that passed on a set of unique genetic instructions.
Explanation:
Organisms can either be single-celled or multicellular. According to this question, a student collects a sample of water from a pond near her home. She then examines a drop of the water under a microscope and noticed it contains four very differently shaped single-celled organisms.
The single-celled organisms are of different shapes because they are from different parents, which passed on a set of unique genetic instructions via their genes to them. Organisms of the same species from the same parent will possess the same shape because they contain same gene which makes them look and behave similar.
However, in this case, the four different shaped single-celled organisms are of DIFFERENT SPECIES and hence, contain individual unique genes that makes them so
<span>Opaca and Marginal zone stays outer and does not move during chick gastrulation,
The zone opaca is a thick fringe ring comprising of more than one cell, it is joined to the germ wall. The Marginal zone lies at the fringe between the range opaca and the region pellucida</span>
