Algae are the most ancient group of plants on the planet. One of the representatives of this systematic unit is ulotrix. Reproduction, habitat and life processes of this plant are the subject of our article.
Green Algae Department
This group of lower plants has about 15 thousand species. Among them there are unicellular representatives. These are chlorella and chlamydomonas. Volvox is a colony of green algae, which is shaped like a ball. Its diameter is small - only 3 mm. In this case, one colony can have 50 thousand cells.
Ulotrix, the reproduction and structure of which we are considering, is a multicellular algae. Ulva, spirogyra, cladophora, hara have a similar structure.
Structure and reproduction of ulotrix
Lower plants do not form tissues. The body of multicellular species is called thallus, or thallus. The function of attachment to the substrate is performed by filamentous formations - rhizoids. Their cells are also not differentiated.
Ulotrix thallus has a filamentous unbranched shape. Heconsists of cells arranged in a single row. These algae live in marine and fresh water bodies, attaching themselves as rhizoids to snags, stones and other underwater objects. Ulothrix threads grow up to 10 centimeters long. Together they form a green mud.
An obligatory component of each ulotrix cell is a parietal chloroplast with several pyrenoids. The latter are an area in which organic substances synthesized during photosynthesis are deposited in reserve.
Ulotrix cells are eukaryotic. This means that their genetic material is contained in a well-formed nucleus. It is encoded in nucleic acid molecules - DNA. This structure of the genetic apparatus determines the variety of ways in which ulotrix reproduces.
Vegetative propagation
This method of propagation of ulotrix is characteristic of all plants. Its essence lies in the development of a new organism from the multicellular part of the mother. In the case of ulotrix, these are fragments of threads. This method of vegetative propagation is called fragmentation.
Ulotrix: reproduction by spores
Another asexual process is sporulation. During this process, only thallus cells can take part. Each of them is divided into several parts. They are called spores - cells of asexual reproduction.
For ulotrix, this method is quite effective. This is because the divisionabsolutely every cell of the thread is capable. The number of spores that is formed in this case varies widely - from 4 to 32. At first, they move freely in the water column, protected by a mucous capsule. During this period they are called zoospores. Each of them is equipped with four flagella, which allow them to move freely in the water column.
The significance of this phase of the life cycle lies in the dispersal of plants. Next, each spore must attach to a solid substrate. Only under this condition will it grow into the ulotrix thread. First, the zoospore loses flagella, its cell wall thickens and the cell proceeds to division.
Development of gametes
The next step in the life cycle of spirogyra is the sexual process. Each cell of the thread also forms a significant number of gametes - from 4 to 64. Sexual reproduction of the ulotrix is isogamous. This characteristic means that germ cells of the same structure participate in it. They are not divided into male and female. These gametes are identical in shape and size. They are denoted by a plus or minus sign.
When isogamy occurs, the fusion of germ cells by copulation, the result of which is a zygote. Each gamete forms two flagella, with the help of which it enters the water. This is where fertilization takes place. An interesting fact is that gametes formed on different threads are capable of fusion. This phenomenon is called heterothallism.
In the life cycle of ulotrix there is a change of generations. This phenomenon has an adaptivecharacter. When adverse conditions occur, filamentous algae cells become round. Their walls secrete a large amount of mucus. This state of the cells is called palmeloid. Then they are separated, their mitotic division occurs. When environmental conditions are normalized, the newly formed cells turn into motile zoospores. Filamentous thalli develop from them.
So, ulotrix is a representative of the group of lower plants, the department of Green algae. Its body is a filamentous thallus, consisting of undifferentiated cells. Ulothrix lives in fresh, and sometimes in s alty water bodies. Leads an attached lifestyle. It is attached to underwater objects with the help of filamentous rhizoids. Ulothrix reproduces in three ways: vegetatively, by sporulation and by fusion of motile gametes.
