The life cycle of Laminaria, a brown alga, involves alternation of generations. In Laminaria, the sporophyte is a large seaweed with several leaflike blades. The gametophytes are short, branched filaments.
The Correct Answer and Explanation is :
Laminaria, a brown alga, undergoes a typical alternation of generations between its diploid sporophyte and haploid gametophyte stages. Here’s a detailed breakdown of the life cycle:
- Sporophyte Generation (Diploid): The large, blade-like sporophyte is the dominant stage in Laminaria. It grows attached to the seafloor and consists of a complex structure with several leaf-like blades. The sporophyte is diploid (2n), meaning it has two sets of chromosomes. It produces sporangia (specialized reproductive structures) through meiosis. These sporangia release haploid spores (n) into the water.
- Germination of Spores: The haploid spores released by the sporophyte germinate and develop into the gametophyte stage. This stage is a much smaller, filamentous structure. The gametophyte is haploid (n), meaning it has only one set of chromosomes.
- Gametophyte Generation (Haploid): The gametophyte produces gametes (sperm and eggs) by mitosis. In the female gametophyte, eggs are produced, while in the male gametophyte, sperm are produced. The release of gametes into the surrounding water allows fertilization to occur, where the sperm fuses with an egg to form a diploid zygote.
- Fertilization and Return to Sporophyte: The fertilized egg (zygote) grows into a new diploid sporophyte, and the cycle begins anew. The sporophyte then matures, produces more sporangia, and the process repeats.
This alternation between a large, multicellular diploid sporophyte and a small, filamentous haploid gametophyte is characteristic of many algae and plants with an alternation of generations.
Now, I will generate an image representing the life cycle of Laminaria.
Here is the illustrated diagram representing the life cycle of Laminaria, showing the alternation of generations. It includes both the sporophyte and gametophyte stages, as well as the processes of spore production, fertilization, and the development of new sporophytes.
