Why is the heart able to act as one unit? why can all of the cells contract at the same time?

Long term continuous groundwater monitoring, especially with warning systems and anthropic activity monitors

D.) domain, kingdom, phylum, class, order, family, genus then species

From our previous experiment, we examined how many drops a penny can hold - and place drops of salt water on the penny after recording 5 trials each, take the average of each solution.