Can you give the medical term for the following definitions?

Question

1. living together of two organisms

2. congenital absence if one half of the brain

3. increased heart rate alternating with slow rate

Answer 1

1. symbiosis

2. hemianencephaly(woops)

3. paroxysmal tachycardia

Answer 2

1.  Symbiosis

2.  Hemianencephaly

3.  Could be sinus arrhythmia, sick sinus syndrome, pulsus paradoxus

Answer 3

the first one is  a symbiosis relationship. If one is harmed while te other benefits if parasitism, if one is happy and the other isn't affected its comesalism, and if they're both helping each other then its mutualism. The others I have no clue.