Module: | Pre-fertilization: Micro/Megasporogenesis
Q33: Consider the following statements regarding the release and geometry of microspore tetrads:
1. Following meiosis, the four microspores are initially held together in a cluster by a thick wall composed of callose.
2. The enzyme callase, which is secreted by the tapetal cells, dissolves this wall to release the individual microspores.
3. All angiosperms strictly produce tetrahedral microspore tetrads, regardless of being monocots or dicots.
Which of the above statements is/are correct?
2. The enzyme callase, which is secreted by the tapetal cells, dissolves this wall to release the individual microspores.
3. All angiosperms strictly produce tetrahedral microspore tetrads, regardless of being monocots or dicots.
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.
During microsporogenesis, the microspore mother cell divides meiotically to form a tetrad.
Structurally, these four haploid cells do not immediately separate; they are tightly bound by a beta-glucan carbohydrate wall known as callose.
To release the pollen grains for maturation and eventual shedding, the surrounding nutritive layer, the tapetum, secretes a specific hydrolytic enzyme called callase.
This causally breaks down the callose barrier.
Statement 3 is a classical botanical distractor.
While tetrahedral tetrads are indeed the most common geometry, especially in dicotyledons, they are not universal.
Monocotyledons frequently produce isobilateral tetrads, and other geometries like linear, T-shaped, and decussate are well documented in various angiosperm families.
During microsporogenesis, the microspore mother cell divides meiotically to form a tetrad.
Structurally, these four haploid cells do not immediately separate; they are tightly bound by a beta-glucan carbohydrate wall known as callose.
To release the pollen grains for maturation and eventual shedding, the surrounding nutritive layer, the tapetum, secretes a specific hydrolytic enzyme called callase.
This causally breaks down the callose barrier.
Statement 3 is a classical botanical distractor.
While tetrahedral tetrads are indeed the most common geometry, especially in dicotyledons, they are not universal.
Monocotyledons frequently produce isobilateral tetrads, and other geometries like linear, T-shaped, and decussate are well documented in various angiosperm families.