Correct Option
The correct option isPresence of a single chromosome.
Explanation
Cells are broadly classified into two types: Prokaryotic and Eukaryotic. This classification is primarily based on the organization of the nucleus and the presence or absence of membrane-bound organelles. Prokaryotic cells are structurally simpler and evolutionarily primitive compared to eukaryotic cells.
Option Analysis
- Presence of a well-defined nuclear membrane. is Incorrect: Prokaryotic cells lack a well-defined nuclear membrane. Their genetic material is naked (not enveloped by a nuclear membrane) and is located in a region of the cytoplasm called the nucleoid. In contrast, eukaryotic cells possess a true nucleus with a nuclear membrane.
- Size generally in the range of 5-100 µm. is Incorrect: Prokaryotic cells are generally smaller in size, typically ranging from 1 to 10 µm. The size range of 5 to 100 µm is characteristic of eukaryotic cells.
- Presence of a single chromosome. is Correct: Prokaryotic cells typically contain a single circular chromosome composed of DNA. Eukaryotic cells usually contain more than one chromosome.
- Presence of membrane-bound organelles like plastids. is Incorrect: Membrane-bound cell organelles, such as plastids, mitochondria, Golgi bodies, and the endoplasmic reticulum, are absent in prokaryotic cells. These organelles are specific features of eukaryotic cells.
Key Takeaway: The fundamental distinction of a prokaryotic cell is the absence of a membrane-bound nucleus (presence of a nucleoid) and membrane-bound organelles, alongside the presence of a single circular chromosome.