Answer:
in the wall of the right atrium of the heart.
Explanation:
The sinoatrial node (SA), consisting of spindle-shaped cells, initiates the electrical activity of the heart. From its location in the right atrium in proximity to the superior vena cava, the electrical activity spreads to the atria, whose cells are larger than those of the SA.
Answer:
The options needed to complete the question are
A. adaptive radiation.
B. alloploidy.
C. autoploidy.
D. hybridization.
The RIGHT ANSWER IS A.
A. adaptive radiation.
Explanation:
Adaptive radiation
It's a form of evolutionary biology. In Adaptive radiation there is a relatively fast evolution of many species from a single common ancestor I.e a specie changes rapidly from an ancestral species into a different or groups of new forms.
It mostly occurs when an organism lives a new area and different traits affect its survival. E.g development of mammals after the extinction of dinosaurs.
B. Temperature and Precipitation