Which of the following is true?* 5 points
The waves in the ECG cycle represent the number of heartbeats.
The time of electrical recovery in the ventricles before a new heartbeat starts is
known as ventricular depolarization.
Electrical impulses in the heart cause the muscle to contract.
Muscle tissue in most body organs are able to stimulate their own contractions.

1. Electrical impulses in the heart cause the muscle to contract.

2. To keep the blood flowing in only one direction

Explanation:

In the first question, the correct answer is ''Electrical impulses in the heart cause the muscle to contract''. Every muscle in our body contracts because of electrical impulses and this is also true for our hearts. Or any hearts in nature that we know of.

In the second question, the answer is ''To keep the blood flowing in only one direction''. We have those valves and without them, we wouldn't be able to function as we do.