A biologist .....they study living things only.
Cardiac Muscle, reason its called Cardiac attack when you have that sort of " Heart Attack "
Answer: Mouth.
Explanation:
The mouth is known to be performing both the tasks of chemical digestion and mechanical digestion.
The food is ingested through mouth and the teeth perform the process of mechanical digestion by breaking down the food particles into smaller particles.
Then the saliva gets mixed into the food and the enzymes(amylase) present in the saliva helps in the digestion of carbohydrates.
So, mouth is the organ that performs the process of both mechanical and chemical digestion.