Your answer is b Changes in the tempurature and salinity of water
F1 would be red because the first round is dominant-recessive the only other answer is pink.
Answer:
SA node
Explanation:
The SA node (called the pacemaker of the heart) sends out an electrical impulse. The upper heart chambers (atria) contract. The AV node sends an impulse into the ventricles. The lower heart chambers (ventricles) contract or pump.
Feel free to ask if you still don't understand
