Darting motility is shown by –
**Core Concept**
Darting motility is a type of ciliary movement exhibited by certain cells or organisms, characterized by rapid, irregular, and back-and-forth movements. This phenomenon is often observed in the context of cellular biology, where it relates to the movement and behavior of cilia or flagella.
**Why the Correct Answer is Right**
Darting motility is typically seen in the cilia of certain cells, such as those in the respiratory tract or the oviducts of females. The movement of cilia is essential for the clearance of mucus, debris, and other substances from these areas. The darting motion is thought to be a result of the coordinated action of multiple cilia, which work together to create a powerful and efficient movement.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because darting motility is not typically associated with the movement of microorganisms.
**Option B:** This option is incorrect because darting motility is not a characteristic of the flagella of bacteria, which typically exhibit a more uniform and whip-like movement.
**Option C:** This option is incorrect because darting motility is not a feature of the movement of muscle cells or other types of cells that exhibit smooth muscle contraction.
**Clinical Pearl / High-Yield Fact**
Darting motility is an important aspect of cellular biology and has significant implications for our understanding of cellular movement and behavior. It is also relevant in the context of respiratory medicine, where the dysfunction of cilia can lead to conditions such as bronchiectasis.
**Correct Answer: D. Cilia of respiratory epithelial cells.**