Question

WRITE ABOUT A THEME: ORGANIZATION Cells are the basic units of structure and function in all organisms. A key feature in the life cycle of plants is the alternation of multicellular haploid and diploid generations. Imagine a lineage of flowering plants in which mitotic cell division did not occur between the events of meiosis and fertilization (see Figure 30.12). In a short essay (100–150 words), describe how this change in the timing of cell division would affect the structure and life cycle of plants in this lineage.

Short answer

The life cycle of angiosperms exhibits alternation of generations. In this process, multicellular haploid forms alternate with diploid forms. In the absence of mitotic division between meiosis and fertilization, the zygote will be haploid.

Therefore, the gametophyte will not alternate with the sporophyte, and hence the life cycle would not be complete.

Step-by-step solution

Alternation of generations

Alternation of generations is a critical characteristic exhibited during the life cycle of angiosperms. In this type of life cycle, the haploid phase alternates with the diploid phase. The haploid phase is also called the gametophytic phase, and the diploid phase is called the sporophytic phase.

Important events in angiosperms

The angiosperms exhibit three major events throughout their life cycle. In their life cycle, the meiosis results in the formation of haploid gametes. The haploid gametes then divide mitotically, and then fertilization of these gametes results in a diploid zygote.

Skipped mitosis during the life cycle

During the life cycle of angiosperms, it can severely affect the life cycle when mitosis does not occur post meiosis. When mitosis does not occur, gametes will have only have the number of cells that arose from mitosis. When these gametes fuse, they will give rise to haploid zygote instead of diploid.