Question

Bacilli and spirilla are both capable of movement and use slender, hair-like extensions called ________?

1) Flagella
2) Cilia
3) Pseudopodia
4) Fimbriae

Answer 1

Bacilli and spirilla move using flagella, which are long, hair-like extensions that help propel the entire cell, unlike cilia which are shorter and more numerous, or pseudopodia used by other protists for movement.

Step-by-step explanation:

Bacilli and spirilla are both capable of movement and use slender, hair-like extensions called flagella. Flagella are long, hair-like structures that extend from the plasma membrane and are used to move an entire cell.

For example, sperm cells, Euglena, and some prokaryotes such as bacteria may have one, two, or many flagella to propel them forward.

In contrast, cilia are shorter, more numerous hair-like structures that move either the entire cell or substances along the outer surface of the cell, such as the cilia of cells lining the fallopian tubes or the respiratory tract. Other protists may use pseudopodia ("false feet") for movement, while fimbriae are bristle-like fibers that are not involved in locomotion.

Answer 2

Flagella are the correct slender, hair-like structures utilized by bacilli and spirilla for movement. These whip-like appendages allow bacteria to swim through the liquid environment, and the most accurate term for such bacterial appendages is flagella. Option 1 is the correct answer.

Step-by-step explanation:

Bacilli and spirilla, which are types of bacteria, are capable of movement using slender, hair-like extensions. The correct term for these extensions is flagella. Flagella are long, whip-like structures that protrude from the plasma membrane of the cell, enabling it to swim or propel itself through a liquid environment.

Bacterial flagella are typically composed of the protein flagellin and move in a rotary motion, which is different from the undulating motion seen in eukaryotic flagella and cilia. While each bacterial cell may have one or multiple flagella, cilia are usually numerous and line the entire surface of eukaryotic cells, aiding in locomotion or the movement of substances along the surface of the cell.

Pseudopodia, or "false feet," are cytoplasmic extensions used by some protists for movement or capturing food but are not associated with bacterial movement. Fimbriae are another form of bacterial appendage, but they are not involved in movement; rather, they are used for attachment to surfaces or other cells.

In summary, the correct answer to the question is Flagella, making the correct option (1). Bacilli and spirilla use flagella to swim or move through their environment.