Module: | Double Fertilization & Endosperm
Q74: Consider the following statements regarding cytoplasmic streaming within the growing pollen tube:
1. The rapid apical growth of the pollen tube relies heavily on a highly dynamic actin-myosin cytoskeletal network.
2. This cytoskeleton drives vigorous cytoplasmic streaming, which acts as a conveyor belt moving the male gametes and vegetative nucleus toward the tube apex.
3. The male gametes actively generate their own motive force for this journey by vigorously beating their flagella within the stylar fluid.
Which of the above statements is/are correct?
2. This cytoskeleton drives vigorous cytoplasmic streaming, which acts as a conveyor belt moving the male gametes and vegetative nucleus toward the tube apex.
3. The male gametes actively generate their own motive force for this journey by vigorously beating their flagella within the stylar fluid.
Which of the above statements is/are correct?
✅ Correct Answer: A
The correct option is A. Statements 1 and 2 are correct, but Statement 3 is biologically impossible for the described taxa.
The pollen tube represents a marvel of intracellular logistics.
Because the tube must travel significant distances (sometimes centimeters in maize), it cannot rely on simple diffusion.
Structurally, the vegetative cell cytoplasm organizes massive bundles of actin filaments.
Myosin motor proteins drag organelles, vesicles, and the male gametes along these tracks in a process called reverse fountain cytoplasmic streaming, concentrating growth materials at the extreme apex.
Statement 3 presents a severe evolutionary error.
Angiosperm (flowering plant) male gametes are strictly non-motile; they entirely lack flagella or cilia.
Their movement through the style is 100 percent passive, completely dependent on the vegetative cell's cytoplasmic streaming mechanism to drag them to the ovule.
The pollen tube represents a marvel of intracellular logistics.
Because the tube must travel significant distances (sometimes centimeters in maize), it cannot rely on simple diffusion.
Structurally, the vegetative cell cytoplasm organizes massive bundles of actin filaments.
Myosin motor proteins drag organelles, vesicles, and the male gametes along these tracks in a process called reverse fountain cytoplasmic streaming, concentrating growth materials at the extreme apex.
Statement 3 presents a severe evolutionary error.
Angiosperm (flowering plant) male gametes are strictly non-motile; they entirely lack flagella or cilia.
Their movement through the style is 100 percent passive, completely dependent on the vegetative cell's cytoplasmic streaming mechanism to drag them to the ovule.