The initiates the electrical impulse that triggers a heartbeat, while the delays the spread of this impulse from the atria to the ventricles. This delay allows the ventricles to finish filling before they start to contract.

sinus node

AV node

Hope this helps

the awnser is d i think

1. a host loses nutrients to a parasite

2. a parasite only benefits when the host is alive (cause if the host dies the parasite dies with it )

3. producers to consumers

4. the tapeworm is a parasite

5. they convert energy from the sun (photosynthesis)

6. sunflower-robin (i think im 80% sure)

7. producer

8. consumer

9. prey

10. fresh water snails ( cause the green algea is the producer and the snails are the primary consumers and the small fish consumer so is the big fish)