Heart rate is controlled by the two branches of the autonomic (involuntary) nervous system. The sympathetic nervous system (SNS) and the parasympathetic nervous system (PNS). The sympathetic nervous system (SNS) releases the hormones (catecholamines - epinephrine and norepinephrine) to accelerate the heart rate.
Yes, Organisms compete for the resources they need to survive like food, air, water, space. In areas where these are sufficient, organisms live in comfortable co-existence, and in areas where resources are abundant, the ecosystem boasts high species richness (diversity).
Answer: oil and vinegar salad dressing
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