There are several ways in naturereproduction of plant organisms. Most of them are associated with the formation of specialized cells: spores or gametes. When the latter merge, a seed is formed in some groups of plants. What is different from the dispute and how it is arranged? Modern science already knows the answers to these and many other questions. Let's see and we.
Spores and Seeds: A Matter of Evolution
Жизнь возникла в воде.Many representatives of algae survived in difficult conditions precisely because of the ability to form motile cells of asexual reproduction - zoospores. Consequently, the difference of semen from spores can be traced in time frames.
The first natives to land were the highest sporeplants. Mosses, moorings, horsetails and ferns are spread by spores - asexual cells. Unlike the lower plants - algae, they have got real tissue. Therefore, this group of organisms and received such a characteristic name.
Далее в процессе эволюции в природе возникли seed plants. The seed is formed by the merger of germ cells - the gametes. This group includes gymnosperm conifers and angiosperms flowering, which occupy a dominant position in the modern plant world.
Sporulation value
Споры могут образовывать не только растения.Bacteria (unicellular prokaryotic organisms) also multiply with the participation of spores. In addition, with the help of asexual reproduction cells, they can easily survive adverse conditions. It is because of this that bacteria remain viable when exposed to high or low temperatures, ionizing radiation.
Mushrooms are also capable of sporulation. Moreover, some mold representatives of this kingdom of nature can throw them at a distance of more than a meter.
Alternation of generations
How does the life cycle of sporeplants can be considered on the example of moss. The green carpet of these plants is called the gametophyte, or the sexual generation. In its special organs, sex cells are formed. But when they merge, no seed is formed. What is different from the controversy gametes it? These are the germ cells from which a member of the asexual generation is formed - the sporophyte. In mosses, it is a dry leg with a box, within which spores mature. Once in the ground, asexual reproduction cells germinate, again forming a green gametophyte. And so it repeats again.
Seed structure
In seed plants at the confluence of male and femalethe gamete is an organ of generative reproduction - the seed. Unlike the dispute, it has an embryo (the prototype of the future plant). Its constituent parts are the germinal root, small stalk and bud. For the development of the future plant, the embryo is surrounded by a supply of nutrients, which is called endosperm, and is additionally protected by the seed coat. This double cocoon from adverse environmental conditions!
Seeds of gymnosperms are located on the scales of cones openly. But angiosperms form additional protection in the form of fruits.
How do seeds differ from spores?
Spores are separate cells. They may differ in size, shape, have flagella for movement. But they have one function - ensuring asexual reproduction of organisms.
A more progressive part of the plant is the seed. What is this education different from controversy? First of all, the fact that it is an organ consisting of tissues and specialized cells.
Water is necessary for the development and germination of the spores, and the seeds already have such a reserve in the endosperm. No wonder mosses and ferns live only in wet places.
У большинства растений семена находятся внутри fruits. They are a device for additional protection and distribution of seeds. For example, a string and a burdock have special attachments that are easily attached to animal fur. The ash lion is carried by the wind, and the henbane box itself scatters the seeds at a decent distance.
Spore cells germinate only in certainconditions. If moisture, light or heat is not enough, they die. Seeds, due to the supply of necessary substances, can wait out unfavorable factors. And with the onset of a suitable time to give rise to a new organism.
Another bonus of seeds is their ability toacquiring new traits enshrined in the genotype. This is due to the fact that the merger of germ cells creates a new combination of genetic material. Using this property, breeders create seeds with valuable qualities. Everyone is well aware of winter wheat, which germinates only in the cold and allows you to get a grain harvest year-round.
Seed and spore plants
In the modern plant world, seed plantsoccupy a dominant position, being the pinnacle of the evolutionary process. If we talk about species diversity, then only algae, moss-like, pyropod-shaped, horse-shaped and fern-like reproduce by spores. All other plants on the planet - seed. Ate and apricot, oak and cherry, roses and lilies ... Do not list all the plants.
The stock of substances, the germ of the future plantorganism, additional protection, the ability to spread - all these signs have a seed, which differs from the dispute, giving its owners a number of important advantages.
