Question

The occurrence of more than four spores from a spore mother cell is called as
A.Polyspermy
B.Polyspory
C.Polyembryony
D.Polysiphony

Answer 1

Hint:The stamen which is the male reproductive unit of a flower has anther and filament. The anther is a bilobed structure. It is a four-sided (tetragonal) structure called tetra-eusporangiate consisting of four microsporangia located at the corners, two on each side. These micro sporangia after development become pollen sacs. The process of formation of micro-spores is called microsporogenesis.

Complete step by step answer: Microspores are produced from pollen mother cell (PMC), through the process of meiosis. After the development of anther, the cells of sporogenous tissue undergo meiotic divisions leading to the formation of microspore tetrads which are haploid.
When there are more than four pollen spores in the tetrad the condition is called Polyspory, this condition is seen in Cuscuta.
Polyspermy- This condition is seen in diploid organisms where one egg gets fertilized by more than one sperm and results in an unviable zygote. This is prevented by a fast block of Polyspermy followed by a slow block.
Polyembryony- It is the phenomenon where two or more embryos develop from a single fertilized or unfertilized egg. When this occurs in humans it leads to the birth of identical twins. It also occurs in plants, generally seen in Citrus and mango.
Polysiphony- In the case of plants this refers to more than one pollen tube emerging from a single pollen grain often joined together.
So the correct option is (B).

Note: Each cell of sporogenous tissue is called the pollen mother cell giving rise to microspore tetrads. These microspores develop to form pollen grains. Sporogenous tissues are a group of compactly arranged homogenous meristematic cells which are present at the center of each microsporangium. Spore mother cell is the same as a pollen mother cell which gives rise to microspores.