Question

Rod-shaped bacteria are called
A. Cocci
B. Bacilli
C. Spirilla
D. Vibrios

Answer 1

Hint: Bacteria are unicellular microorganisms that can survive in a wide range of different environmental conditions. The bacterial cell is a type of prokaryotic cell with simple internal structure and organisation. The bacteria serve as the reason for various infectious diseases but some may also be beneficial to humans.

Complete answer:
Bacteria are a group of prokaryotic organisms which are generally microscopic in nature. The structure and properties of the bacterial cell are much simpler than that of other organisms as there is no definite nucleus or membrane bound organelles. They are single celled microorganisms and are not visible through naked eyes.

The bacterial cell ranges to a few micrometres in length. They are found to inhabit as well as grow in different environments ranging from the soil, water, acidic hot springs and even the deepest reservoirs of the earth’s surface. The cells lack various complex organelles such as mitochondria, chloroplasts and don’t possess a true nucleus as that is found in the eukaryotic cells. In the bacterial cell, the genetic material lies freely within the cytoplasm. The genetic material or the DNA is not bound by any nuclear membrane.

Bacteria are known to display various forms of shapes and sizes which are often referred to as morphologies. The cells are only about one micrometre to five micrometre which is about one-tenth of the size of the eukaryotic cells. The bacterial cells are observed in varieties of shapes such as spherical, long rod-shaped, curved or spiral-shaped. The various types of bacterial cell shapes are created due to the properties of the cell wall and the cytoskeleton.

The rod shaped bacteria are known as bacilli. They are elongated in shape like a rod and so are also called rod-shaped bacteria. When they are present in pairs and are arranged next to each other, they are called diplobacilli. Sometimes, they form a chain like structure by lying side by side to each other and are known as streptobacilli.

Hence, The correct answer is option (B).

Note: The bacteria belong to the domain of microscopic, prokaryotic microorganisms. They are among the simplest types of unicellular organisms. They are omnipresent as they are found in a variety of habitats. Bacteria are known to inhabit various different habitats. They have different modes of nutrition such as autotrophic, heterotrophic, and saprophytic and can also be parasitic and pathogenic. The bacteria that have a rod-shaped structure are known as bacilli.