Answer:
Answer is Sinoatrial node, SA.
Explanation:
The sinoatrial node, SA, is known to be a group of cells which are found at the top of the heart.
The electrical signal that is initiated by the sinoatrial node bring about or stimulates the atria and then the ventricle of the heart.
It should be noted that, the sinoatrial node are regarded as the pacemaker cells.
Option B
Blue and yellow are co-dominant traits and none of these traits are expressed individually in the off springs. Green color is produced after the combination of yellow and blue trait.
1. light morph
2. Dark morph
<h2>
Answer:</h2>
The Mesozoic era is featured by the arousal of <u>b. birds</u>.
<h2>
Explanation:</h2>
The Mesozoic Time is the age of the dinosaurs and kept going nearly 180 million a long time from around 250 to 65 million a long time back. It includes periods called the Triassic, Cretaceous, and Jurassic periods. A mass-extinction stamped the starting and conclusion of the Mesozoic Period. The occasion that caused the move from the Paleozoic time to the Mesozoic period was the most prominent termination this soil has seen.
There's noteworthy prove that birds developed inside theropod dinosaurs, particularly, that winged creatures are individuals of Maniraptora, a category which belongs to dinosaurs period.
