Answer:
Mitochondria
Step-by-step explanation:
Mitochondria is also called as powerhouse of the cell because ATP production occurs here. ATP is an energy rich molecule that is utilized by the cells in energy requiring metabolic processes. In absence of ATP, these processes do not occur and the cells ultimately die which proves fatal for the organism.
Cyanide is carbon and nitrogen containing compound. It is highly toxic because it affects mitochondria due to which ATP production is hampered. It inhibits mitochondrial enzyme cytochrome c oxidase. Cytochrome c oxidase or complex IV is a part of electron transport chain in mitochondria at the end of which ATP is generated. When the enzyme is inhibited, electron transport chain is also disturbed resulting in inhibition of ATP production.