Practice free Sexual Reproduction in Flowering Plants (Botany) NEET multiple-choice questions online with instant answers and detailed explanations. No login required.
Where does the 'triple fusion' specifically take place within the embryo sac?
Triple fusion is the fusion of one male gamete with the two polar nuclei. The polar nuclei are located in the large central cell of the embryo sac. Therefore, triple fusion occurs in the central cell.
A typical angiosperm embryo sac at maturity is described as 8-nucleate but 7-celled. Which nuclei are involved in forming the 7th cell and what is its role in double fertilization?
The NCERT text states: 'the remaining two nuclei, called polar nuclei are situated below the egg apparatus in the large central cell.' This large central cell, containing the two polar nuclei, fuses with one male gamete during triple fusion to form the primary endosperm nucleus, which later develops into the endosperm.
Which of the following sequences correctly traces the path of a pollen tube from the stigma to the ovule during fertilization?
The pollen grain germinates on the stigma, and the pollen tube grows through the tissues of the style and reaches the ovary. From the ovary, it enters the ovule through the micropyle, and then specifically enters one of the synergids. (Ref: 'Pollen tube grows through the tissues of the stigma and style and reaches the ovary... Pollen tube, after reaching the ovary, enters the ovule through the micropyle and then enters one of the synergids through the filiform apparatus').
Double fertilization is a unique characteristic feature of:
The chapter is titled 'Sexual Reproduction in Flowering Plants' (Angiosperms) and discusses double fertilization as a key event in their reproductive cycle. Double fertilization involving the formation of both a zygote and primary endosperm nucleus is exclusive to angiosperms.
If a pollen grain is shed at a two-celled stage (vegetative cell and generative cell), when does the generative cell divide to form two male gametes?
The NCERT text states: 'In such plants [where pollen grains are shed at two-celled condition], the generative cell divides and forms the two male gametes during the growth of pollen tube in the stigma.'
What is the primary product of triple fusion in angiosperms?
Triple fusion involves the fusion of one male gamete with the two polar nuclei, forming the Primary Endosperm Nucleus (PEN). This PEN then develops into the endosperm, which serves as nutritive tissue for the developing embryo.
The two male gametes involved in double fertilization are produced from which cell of the pollen grain?
The generative cell of the pollen grain undergoes mitosis to produce the two male gametes. The vegetative cell, on the other hand, develops into the pollen tube.
After fertilization, what does the ovule develop into?
Following fertilization, the ovule matures and develops into a seed. The ovary, enclosing the ovules, develops into the fruit.
Double fertilization constitutes two main events. What are they?
Double fertilization is characterized by two distinct fusion events: (1) Syngamy, the fusion of one male gamete with the egg cell to form the zygote, and (2) Triple fusion, the fusion of the other male gamete with the two polar nuclei to form the primary endosperm nucleus.
What is the ultimate fate of the synergids after the pollen tube enters the embryo sac and discharges its contents?
The entry of the pollen tube through the filiform apparatus into one of the synergids often leads to the degeneration of that synergid. The other synergid may also degenerate shortly after fertilization.
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