Given below are two statements. [2023]
Statement I: In bacteria, the mesosomes are formed by the extensions of the plasma membrane.
Statement II: The mesosomes, in bacteria, help in DNA replication and cell wall formation.
In the light of the above statements, choose the most appropriate answer from the options given below:
Statement I is correct but statement II is incorrect.
Statement I is incorrect but statement II is correct.
Both statement I and statement II are correct.
Both statement I and statement II are incorrect.
Which of the following statements about inclusion bodies is incorrect? [2020]
They are not bound by any membrane.
These are involved in ingestion of food particles.
They lie free in the cytoplasm.
These represent reserve material in cytoplasm.
(2)
Reserve material in prokaryotic cells are stored in the cytoplasm in the form of inclusion bodies. These are not bound by any membrane system and lie free in the cytoplasm, e.g., phosphate granules, cyanophycean granules and glycogen granules.
Select the wrong statement. [2016]
Bacterial cell wall is made up of peptidoglycan.
Pili and fimbriae are mainly involved in motility of bacterial cells.
Cyanobacteria lack flagellated cells.
Mycoplasma is a wall-less microorganism.
(2)
Pili and fimbriae are bacterial appendages which are not involved in locomotion. Actually, pili are long, fewer and thick tubular outgrowths which develop in response to or fertility factor in Gram-negative bacteria. Being long, they are helpful in attaching to the recipient cell and forming a conjugation tube. Fimbriae are small bristle-like fibers sprouting from the cell surface in large numbers. There are 300–400 of them per cell. They are involved in attaching bacteria to solid surfaces.
Which of the following structures is not found in a prokaryotic cell? [2015]
Mesosome
Plasma membrane
Nuclear envelope
Ribosome
(3)
A prokaryotic cell is characterized by the absence of an organized nucleus and membrane-bound cell organelles. DNA is naked, i.e., without a nuclear envelope, and lies variously coiled in the cytoplasm. It is commonly called nucleoid or genophore. Mesosomes, plasma membrane, and 70S ribosomes are present in a prokaryotic cell.
The structures that help some bacteria to attach to rocks and/or host tissues are [2015]
mesosomes
holdfast
rhizoids
fimbriae
(4)
Pili and fimbriae are bacterial appendages which are not involved in locomotion. Actually, pili are long, fewer and thick tubular outgrowths which develop in response to or fertility factor in Gram-negative bacteria. Being long, they are helpful in attaching to the recipient cell and forming a conjugation tube. Fimbriae are small bristle-like fibers sprouting from the cell surface in large numbers. There are 300–400 of them per cell. They are involved in attaching bacteria to solid surfaces.
Which one of the following is not an inclusion body found in prokaryotes? [2015]
Glycogen granule
Polysome
Phosphate granule
Cyanophycean granule
(2)
Polysome is not an inclusion body. It is an aggregation of ribosomes formed under conditions of high concentration of magnesium. An inclusion body is any of various particulate structures, usually proteins, formed after viral infections in a prokaryotic or eukaryotic cell.
Which structures perform the function of mitochondria in bacteria? [2014]
Nucleoid
Ribosomes
Cell wall
Mesosomes
(4)
Mesosome is a characteristic circular to villiform specialization of the bacterial cell membrane that develops as an ingrowth. It consists of vesicles, tubules and lamellae. Mesosomes may be septal or lateral. Septal mesosome connects the nucleoid with the plasma membrane and assists in replication and septum formation during cell division. Lateral mesosome is not connected with the nucleoid and contains respiratory enzymes, performing functions similar to eukaryotic mitochondria. Hence, it is also called chondrioid. They also increase the surface area of the plasma membrane and enzymatic contact.
The motile bacteria are able to move by [2014]
fimbriae
flagella
cilia
pili
(2)
Flagellum is the organ of motility in bacteria. Bacterial flagella are unistranded, equivalent to a single microtubular fibre and formed of protein called flagellin. They perform rotatory movements.
