Question

Xanthomonas citri contains
(A) Single polar flagellum
(B) Bipolar flagellum
(C) Tuft of flagella
(D) No flagella

Answer 1

Hint:Xanthomonas citri is a Gram-negative bacterium, further classified as rod shaped proteobacteria.Although it is harmless for humans, it is a phytopathogen, known for being the causing agent of citrus canker.

Complete answer:
The various citrus plants are mostly affected by this bacterium. Even though it is not dangerous for humans, it is considered as a phyto-pathogen, and is the causative agent for citrus canker disease in citrus plants such as lime. The leaves, twigs and fruits are mostly affected by this disease, and causes falling of leaves and fruits before they get properly ripened. This disease could be effectively prevented by the process of defoliation of the canker focal trees. According to this process, where the canker is prevalent, the prime way of controlling includes planting of windbreaks, protecting the leaves and fruits by using copper sprays and controlling the leaf-miners. The flagellums are threadlike adjuncts, particularly a whip-like expansion of definite cells or organisms that acts like a locomotory organ. The flagella of bacteria are helical in shape and contain the protein flagellin. The base of the flagella close to the surface of the cell is adhered to the basal body packed in the cellular envelope. The flagellum revolves in either clockwise or anti-clockwise path, in a motion identical to a propeller.Xanthomonas citri is able to move with the help of a single polar flagellum.

Therefore, option (A) is the correct answer

Note:Based on the positioning of their flagellum, the bacteria could be categorized into four groups: monotrichous (comprising one flagellum), amphitrichous (comprising single flagellum at both the ends), lophotrichous (comprising of many flagella as a bunch), and peritrichous (comprising of the flagella that are scattered all over the cell except polar ends).