Final answer:
The life cycles of sexually reproducing multicellular organisms share stages of reproduction, development, and inheritance of genetic material. Fertilization and death are common and crucial events. Life cycle continuity is maintained via the cell cycle, which is highly conserved across eukaryotes.
Step-by-step explanation:
The commonalities among the life cycles of sexually reproducing multicellular organisms include the basic stages of reproduction, growth, development, and eventual maturation. Each organism begins its life cycle as a single cell, which then proliferates to many cells that stay together after dividing. Multicellular organisms often undergo substantial structural changes, especially in the early stages of development. Reproduction typically involves the formation and union of gametes, such as sperm and egg, leading to the development of a new multicellular organism.
Two events that are common to all sexually reproducing organisms are fertilization and death. Fertilization involves the union of an egg and sperm to form a zygote, which then divides and differentiates into a multicellular organism. Death is seen as the end of an individual organism's life cycle, followed by the potential for its offspring to begin their own cycles. Additionally, the fundamental inheritance of genetic material from one generation to the next ensures continuity and variety among organisms.
Comparatively, animal and plant life cycles have distinct characteristics. Animals typically have a more straightforward life cycle involving sexual reproduction, while plants can exhibit more complex life cycles that include both sexual and asexual reproduction, such as alternation of generations with distinct haploid and diploid stages.
The continuity of life is further supported by the cell cycle, an orderly series of events facilitating reproduction of cells and therefore, the reproduction of the organism as a whole. These mechanisms of the cell cycle are conserved across a diverse range of eukaryotic organisms, including protists, plants, and animals.