What is the gametophyte generation?
Definition. noun. (botany) A phase in the life cycle of certain plants and algae that starts with a spore up to the time that gametes are produced.
What is alternation of generation explain?
“Alternation of generations is a type of life cycle in which subsequent generations of plants alternate between diploid and haploid organisms.”
What is alternation of generation give example?
The classic example is the mosses, where the green plant is a haploid gametophyte and the reproductive phase is the brown diploid sporophyte. The two forms occur together. In bryophytes and mosses, the gametophyte is the dominant generation and the sporophyte are sporangium bearing stalks growing from the gametophyte.
What is the importance of alternation of generation?
The alternation of generations allows for both the dynamic and volatile act of sexual reproduction and the steady and consistent act of asexual reproduction. When the sporophyte creates spores, the cells undergo meiosis, which allows the gametophyte generation to recombine the genetics present.
What do you mean by isomorphic and heteromorphic alternation of generation?
In an isomorphic alternation of generations (found in some algae, for example) the sporophyte and gametophyte are morphologically similar or identical; in a heteromorphic alternation of generations they are dissimilar (e.g. in mosses the gametophyte is the dominant and conspicuous generation, whereas in higher plants …
What is the difference between isomorphic and Heteromorphic?
Species with heteromorphic life cycle have a large multicellular body in one generation but have a microscopic body in the other generation of a year. In contrast, isomorphic species have both diploid and haploid life forms with very similar morphology, having more than two generations in a year.
What is the difference between Metagenesis and alternation of generation?
Alternation of generations, also called metagenesis or heterogenesis, in biology, the alternation of a sexual phase and an asexual phase in the life cycle of an organism. The two phases, or generations, are often morphologically, and sometimes chromosomally, distinct.
What is Metagenesis with example?
The definition of metagenesis is the reproduction cycle of an organism that alternates between sexual and asexual generations. An example of metagenesis is the reproduction cycle of a cnidarian. (biology) The production of sexual and asexual organisms in alternate generations.
What is Coelenterate Metagenesis?
METAGENESIS The life cycle of Obelia represents a remarkable example of alternation of generation where the asexual and sessile phase of Obelia reproduces asexually by budding and gives rise to sexual and free-swimming medusa. This phenomenon of alternation between two diploid phases is termed as metagenesis.
What is the result of Metagenesis?
The rock reaches temperature conditions that lead to the metagenesis of organic matter. At this stage the organic matter is composed only of methane and a carbon residue, where some crystalline ordering begins to develop. Coals are transformed into anthracite.
What is the life cycle of obelia?
Through its life cycle, Obelia take two forms: polyp and medusa. They are diploblastic, with two true tissue layers—an epidermis (ectodermis) and a gastrodermis (endodermis)—with a jelly-like mesoglea filling the area between the two true tissue layers. They carry a nerve net with no brain or ganglia.
Why is Scyphozoan Medusa called jellyfish?
The Scyphozoa are an exclusively marine class of the phylum Cnidaria, referred to as the true jellyfish (or “true jellies”). The class name Scyphozoa comes from the Greek word skyphos (σκύφος), denoting a kind of drinking cup and alluding to the cup shape of the organism.
Does Hydra have medusa stage?
Unusual because in Hydra there is no medusa. Hydra can reproduce sexually. Look for ovaries near the base, testes higher on the column. Once fertilized, this egg develops a protective ornamented shell and frequently enters a stage of arrested development or dormancy.
What is the structural difference between obelia and jelly fish?
Obelia refers to a genus of sedentary colonial coelenterates with upright branching stems bearing minute cups in which the polyps sit while jellyfish refers to a free-swimming marine coelenterate with a gelatinous bell- or saucer-shaped body that is typically transparent and has stinging tentacles around the edge.
What are the similarities and differences between cnidarians and Ctenophores?
Both cnidarians and ctenophores are diploblastic animals. Cnidarians exhibit radial symmetry whereas ctenophores exhibit biradial symmetry. Both contain tentacles, surrounding their mouth. The main difference between cnidarians and ctenophores is their body symmetry.
Is sea anemone a polyp or medusa?
Unlike jellyfish, sea anemones do not have a medusa stage in their life cycle. A typical sea anemone is a single polyp attached to a hard surface by its base, but some species live in soft sediment and a few float near the surface of the water.