Final answer:
The cross-section of a cilium cut near the tip at the beginning of the recovery stroke would likely show microtubules in a state of transition with axonemal dyneins inactive and the cilium possibly exhibiting a bent or twisted shape, reflecting its repositioning for the next power stroke.
Step-by-step explanation:
If a student asked how the image of a cross-section of a cilium might differ if cut near the tip at the beginning of the recovery stroke, it is important to consider the structure of a cilium. A cilium is a hair-like appendage found on certain cells that can execute rhythmic waving or beating motions. When they are in the recovery stroke, cilia are bent and repositioning themselves in preparation for the next power stroke, which enables them to propel fluids or cells through the surrounding medium.
During the recovery stroke, the arrangement of microtubules within the cilium would be slightly different than during the power stroke. If you were to view a cross-section near the tip of a cilium during the recovery stroke, you might expect to see the axonemal dyneins, which are motor proteins that facilitate the sliding of microtubules for ciliary movement, in an inactive state as they transition between strokes. The nine outer doublet microtubules and two central singlet microtubules might also appear less rigid compared to when the cilium is fully extended during the power stroke.
The exact morphology would depend on the level of contraction and flexion of the cilia at the moment of the cross-section. Therefore, the image could show a more pronounced curvature of the ciliary shaft or possibly a twisting shape due to the intricate coordination required between microtubules for ciliary movement.