Test: Prokaryotic & Eukaryotic Cells - NEET MCQ

In prokaryotes, the genetic material consists of single circular DNA molecule lying entangled in nucleoid. It is not bounded by a definite nuclear membrance. Histones are water-soluble proteins rich in arginine and lysine that help in DNA packaging in chromosomes. Prokaryotic cells lack pistone proteins.

Line in NCERT: "The genetic material is basically naked, not enveloped by a nuclear membrane. In addition to the genomic DNA (the single chromosome/circular DNA), many bacteria have small circular DNA outside the genomic DNA."

Basal body is also known as a modified centriole which serves both to create and connect the cilia and flagella to the cell.

Line in NCERT: "Both the cilium and flagellum emerge from centriole-like structure called the basal bodies."

Prokaryotic cell is usually small (0.1-5.1μm) in size whereas eukaryotic cell size is comparatively larger (5-100μm). Prokaryotic cells multiply very rapidly by asecial means like binary fission, sporulation etc.

Line in NCERT: "They are generally smaller and multiply more rapidly than the eukaryotic cells."

The correct option is B (ii) and (iii)
Mesosomes are the areas in the cell membrane of prokaryotic cell which fold inwards. It helps in cell wall formation, DNA replication, respiration and increases the surface area of the plasma membrane.

Glycocalyx (mucilage sheath) is the outermost layer of the bacterial cell envelope which consists of non-cellulosic polysacharides with or without proteins. It may occur in the form of loose sheath, called slime layer. If it is a thick coering, it is called capsule. Glycocalyx gives sticky character to the cell and is not absolutely essential for survival of bacteria. It prevents desiccation, protects from phagocytes, toxic chemicals and viruses and serves in attachment. It may give selective advantage though in certain situations.

Line in NCERT: "Glycocalyx differs in composition and thickness among different bacteria. It could be a loose sheath called the slime layer in some, while in others it may be thick and tough, called the capsule."

Glycocalyx is the outermost layer of the cell envelope. Cell wall lies between plasma membrane andd glycocalyx.

Line in NCERT: "The cell envelope consists of a tightly bound three layered structure i.e., the outermost glycocalyx followed by the cell wall and then the plasma membrane."

Plasmid is a structure in bacterial cell consisting of DNA that can exist and replicate independently of the chromosome. Plasmids provide genetic instructions for certain cell activities (e.g., antibiotic, resistance). They can be transferred from cell to cell in a bacterial colony.

Line in NCERT: "In addition to the genomic DNA (the single chromosome/circular DNA), many bacteria have small circular DNA outside the genomic DNA. These smaller DNA are called plasmids."

Mitochondria are absent in prokaryotes. Mesosomes are characteristic circular to villiform specialisation of cell membrance of bacteria that develop as an ingrowth from the plasma membrane. It helps in nucleoid replication and cell division. Lateral mesosome is not connected with nucleoid. It contains resspiratory enzymes and is, therefore, often called chondrioid. It is believed to be equal to mitochondrion of eukaryotes. However, respiratory enzymes are also present over the plasma membrane.

Line in NCERT: "In prokaryotes, there are no membrane bound organelles."

The cytoplasmic ribosomes of prokaryotes (blue green algae, bacteria and PPLOs) are 70S. They have two subunits 50S and 30S.

Line in NCERT: "The eukaryotic ribosomes are 80S while the prokaryotic ribosomes are 70S."

Fimbriae are hair like structures present in large number in bacteria. They help in attaching bacteria to solid surface or host tissues.

Line in NCERT: "In some bacteria, they are known to help attach the bacteria to rocks in streams and also to the host tissues."