Identify the challenges plants faced when colonizing land and the adaptations th
ID: 278477 • Letter: I
Question
Identify the challenges plants faced when colonizing land and the adaptations that evolved in response. Describe the haplodiplontic life cycle, distinguishing between sporophyte and gametophyte generations (haploid, diploid and other). Explain what happened to the gametophyte and the sporophyte generation as plants became more specialized. Describe the basic anatomy/structure, reproduction and ecology of fungi. Describe the symbiotic relationship found in mycorrhizae and other fungal associations with different organisms.
Explanation / Answer
The challenges the plants face when colonizing land is fight for nutrition and other resources. With more land colonization, it leads to increase competition of the existing plants for better nutrition and food. The plants acquired traits that allowed them to colonize new environments which led them to become superior to the native plants. This led to reconstituting the morphology and led to disappearance of the native plants that are comparatively weaker. Due to the adaptations, either the plants developed superior traits or they gave up to the natural selection.
Haplodiplontic life cycle – In this the gametes are not the direct result of the meiotic division but the diploid sporophyte cells undergo meiosis which produces the haploid spores. The spores, each of it, goes through the mitotic division and leads to formation of multicellular, haploid gametophyte. The sporophytes is a multicellular generation that occurs in the life cycle of a plant that possess diploid cells that consists of two genomes or two sets of chromosomes. It leads to the production of haploid spores or meiospores through the process of meiosis. The gametophyte is again multi-cellular generation in life cycle of plant that is capable of forming gametes directly from its cells. They are haploid and have only one set of chromosome.
Fungi consist of filaments that are called hyphae and each of the hyphae consists multiple cells that is surrounded by a tubular cell wall. The mass of hyphae make the fungi body which is known as mycelium . The hyphae is divided into cells with help of internal walls known as septa. The fungi reproduce asexually by methods of fragmentation, budding or by production of spores.It also has the sexual mode of reproduction. In the sexual mode of reproduction there is fusion between two fungi. In asexual reproduction, cells of hyphae break off and grow into a new fungi. There is also production of spores that grow into new fungus.
The mycorrhiza shares a symbiotic relationship with fungus. The fungus grows on the roots of the plants and it gets easy access to food that is prepared by the plants. The fungus puts out mycelia which helps in absorbing water and nutrients that is beneficial for the myccorrhiza