Angiosperm Life Cycle Flashcards

Study Notes

Angiosperm Life Cycle

Begins with a diploid (2n) flower on a mature sporophyte plant.
Microsporocytes in the anther undergo meiosis, creating haploid (n) microspores.
Each microspore undergoes mitosis, forming a generative cell and a tube cell, resulting in an immature microgametophyte (pollen grain).

Pollen Grain Development

The generative cell undergoes a second mitotic division, yielding two sperm nuclei.
In the ovule, a megasporocyte develops and undergoes meiosis, resulting in four haploid (n) megaspores.
Three megaspores degenerate; the remaining one undergoes three mitotic divisions to form an eight-nucleate embryo sac, known as the mature megagametophyte.

Pollination and Fertilization

Upon pollination, the pollen grain germinates on the stigma, and a pollen tube extends down the style towards the ovary through the micropyle.
One sperm nucleus combines with the egg, forming a diploid (2n) zygote.
The second sperm nucleus fuses with two polar nuclei to create a triploid endosperm, which serves as nutrition for the developing embryo.

Seed Development and Dormancy

The embryo develops within the embryo sac, with the integuments of the ovule forming a protective seed coat.
Once mature, the seed is released from the fruit; embryo development pauses until favorable conditions arise.
Upon suitable conditions, seed germination occurs, and the embryo grows into a mature diploid (2n) sporophyte, ready to produce flowers and continue the alternation of generations cycle.

Description

Explore the fascinating journey of angiosperms through their life cycle with these flashcards. Learn about the different stages, starting from the diploid flower to the development of microspores. Ideal for students of botany and biology who want to deepen their understanding of plant reproduction.