Bacilli and Spirilla are known to propel themselves with which hair-like projections?

Bacilli and Spirilla are types of bacteria characterized by their rod-like and spiral shapes, respectively. They have the ability to move independently through their environment, which is made possible by the presence of flagella. Flagella are long, whip-like structures that rotate to propel the bacteria forward, allowing them to navigate through fluids. This motility is crucial for their survival, enabling them to seek out nutrients and escape harmful conditions.

Cilia, on the other hand, are shorter hair-like projections found on some other types of cells and are used for movement or to move substances across the cell surface, but they are not typically associated with the motility of bacilli or spirilla. Pseudopodia are temporary extensions of the cell body used by some protozoa for movement and feeding, and fimbriae are short, hair-like structures that help bacteria adhere to surfaces but do not play a role in locomotion. Hence, flagella are the specific structures responsible for the propulsion of bacilli and spirilla.