Module: | Pollination & Outbreeding Devices
Q64: Consider the following statements regarding the structure and function of the obturator:
1. The obturator is a specialized, often glandular outgrowth arising from the placenta or the funicle that grows directly toward the micropyle of the ovule.
2. Its primary biological function is to act as a physical bridge and chemical guide, ensuring the pollen tube successfully navigates into the micropyle.
3. Following double fertilization, the obturator differentiates into a massive, permanent woody structure to mechanically protect the mature seed.
Which of the above statements is/are correct?
2. Its primary biological function is to act as a physical bridge and chemical guide, ensuring the pollen tube successfully navigates into the micropyle.
3. Following double fertilization, the obturator differentiates into a massive, permanent woody structure to mechanically protect the mature seed.
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 incorrect.
The journey of the pollen tube does not end once it exits the style and enters the open ovarian cavity; it must still find the microscopic micropyle of a specific ovule.
To bridge this physical gap, many angiosperms develop an obturator.
Structurally, this is a hood-like swelling of tissue originating from the funicle or placenta.
It physically spans the empty space and secretes chemical attractants, acting as a guided rail that conducts the pollen tube precisely to the micropylar opening.
Statement 3 is a developmental falsehood.
Like the synergids, suspensor, and antipodal cells, the obturator is a temporary reproductive accessory structure.
Once the pollen tube has entered the ovule and fertilization is achieved, its causal purpose is fulfilled, and it rapidly degenerates and disappears entirely before the seed matures.
The journey of the pollen tube does not end once it exits the style and enters the open ovarian cavity; it must still find the microscopic micropyle of a specific ovule.
To bridge this physical gap, many angiosperms develop an obturator.
Structurally, this is a hood-like swelling of tissue originating from the funicle or placenta.
It physically spans the empty space and secretes chemical attractants, acting as a guided rail that conducts the pollen tube precisely to the micropylar opening.
Statement 3 is a developmental falsehood.
Like the synergids, suspensor, and antipodal cells, the obturator is a temporary reproductive accessory structure.
Once the pollen tube has entered the ovule and fertilization is achieved, its causal purpose is fulfilled, and it rapidly degenerates and disappears entirely before the seed matures.