Correct Answer: Cell
The cell is the fundamental structural and functional unit of all living organisms. Every plant and animal is made up of one or more cells that perform essential life processes such as respiration, growth, reproduction, and metabolism. Cells contain specialized structures called organelles, including the nucleus, mitochondria, ribosomes, and endoplasmic reticulum, each performing specific functions. Plant cells also possess a cell wall, chloroplasts, and a large central vacuole, whereas animal cells lack these structures. Groups of similar cells form tissues, tissues combine to form organs, and organs work together in organ systems. The discovery of cells led to the development of the Cell Theory, one of the most important principles in modern biology.
- Basic Unit: Cell.
- Found In: Plants and animals.
- Functions: Growth, metabolism, and reproduction.
- Foundation: Cell Theory.
- Correct Answer: Cell.