Plants alternate between the diploid sporophyte and haploid gametophyte
Gametophyte
A gametophyte is a stage in the life cycle of plants and algae that undergo alternation of generations. It is a haploid multicellular organism that develops from a haploid spore that has one set of chromosomes. The gametophyte is the sexual phase in the life cycle of plants and algae.
What is the alternation of generations in plants?
Updated November 13, 2019. Alternation of generations describes a plant's life cycle as it alternates between a sexual phase, or generation and an asexual phase. The sexual generation in plants produces gametes, or sex cells and is called the gametophyte generation.
What is the alternation of generations between haploid and diploid phases?
The organism is diploid and there is no alternation of generations between haploid and diploid phases. In plant multicellular organisms, life cycles vacillate between diploid and haploid generations. In the cycle, the diploid sporophyte phase produces haploid spores via meiosis.
What are the different types of plant life cycle?
Plant Life Cycle: Alternation of Generations 1 Plant vs Animal Life Cycles. Plants and some animals are capable of reproducing both asexually and sexually. ... 2 Non-Vascular Plants. Alternation of generations is seen in both vascular and non-vascular plants. ... 3 Seedless Vascular Plants. ... 4 Seed-Bearing Vascular Plants. ... 5 Sources. ...
What is the primary phase of the life cycle for vascular plants?
The primary phase of the plant life cycle for vascular plants is the sporophtye generation. In vascular plants that do not produce seeds, such as ferns and horsetails, the sporophtye and gametophyte generations are independent. In ferns for example, the leafy fronds represent the mature diploid sporophyte generation.
What is Alternation of Generations?
Alternation of generations is common in plants, algae, and fungi. This can be compared to the sexual reproduction in animals where both haploid and diploid cells are found in every generation.
What is the life cycle of plants?
Therefore, the life cycle of plants is known as alternation of generations. The ability of the plants to reproduce sexually and asexually helps them to adapt to different environments. The alternation of generations depends upon the ...
What is the next generation of gametophytes?
Gametophyte Generation. This is the next generation in the alternation of generations. The spore is newly formed and has half the DNA as the parent organism. This spore undergoes mitosis multiple times to form a gametophyte. The gametophyte generation creates gametes. These gametes are produced by gametangia.
What happens when a gamete encounters a gamete of the opposite sex?
When a gamete encounters a gamete of the opposite sex, it fuses with it to form a zygote which eventually becomes a sporophyte. This is the simplest version of alternation of generations. This is widely found in ferns.
What happens when gametes fertilize?
The gametes fertilize to form a haploid zygote which matures into a mature sporophyte. This cycle keeps repeating.
Which generation is the dominant generation in a tracheophyte?
In Bryophytes, the dominant generation is haploid and the gametophyte comprises the main plant. In tracheophytes, the dominant generation is diploid and the sporophyte comprises the main plant.
How are seeds scattered?
Dispersal: The seeds are scattered by the wind and animals. Some of these seeds emerge into a new plant.
Where is the simplest form of alternations of generations found?
The simplest form of alternations of generations is found in the fern, as seen below. As seen in the diagram, the gametophyte and sporophyte are clearly different individuals. This is not always the case.
What are the complication of alternation of generations?
There are many additional factors which can complicate this basic theme of alternation of generations. The most notable complication is gender. Both sporophytes and gametophytes can have genders. Further, the sporophyte or gametophyte may not be totally independent of the other generation. Consider flowering plants for example. Some flowers have both male and female gametophytes housed within. In other flower species, the male and female flowers are separated, but may be present on the same plant. In still other flowers, individual sporophytes only give rise to a certain gender of flower.
How do sporophytes and gametophytes work together?
When the sporophyte creates spores, the cells undergo meiosis, which allows the gametophyte generation to recombine the genetics present. This allows for great diversity to arise. As plants colonized the land, they were initially isomorphic, or both the gametophytes and sporophytes looked and acted about the same. As time progressed, most plants found it beneficial to reduce one of these life cycles. Most flowering plants now have a much reduced gametophyte life cycle, while liverworts and mosses went the other way, preferring to diminish the sporophyte cycle. In the wide variety of plants alive today there is almost every variation of the alternation of generations conceivable.
How do haploid gametes form sporophytes?
To form a sporophyte, two haploid gametes come together to form a diploid zygote. Typically, haploid organisms are defined by having an “n” number of chromosomes. When two gametes of the same species come together, they each have n chromosomes.
What does it mean when a plant is dioicous?
This means that the plant has separate individuals of both gametophytes and sporophytes, and that the gametes it produces are of different sizes. This would be true of a holly or willow tree, which produces separate male and female flowers, on separate individual sporophytes.
What is the next generation of haploid spores?
Gametophyte. This represents the next generation in the alternation of generations, as the haploid spore is created. The spore is technically a new organism, and has only half the DNA as the parent organism. This spore will undergo successive rounds of mitosis to form a new multicellular individual, the gametophyte.
Do green algae have gametes?
Some species of green algae produce only one type of gamete. These are both flagellated and swim in open water until they find each other. This scheme is not particularly useful for terrestrial plants. Most terrestrial plants show anisogamy, or a difference in their gametes.
What Is Alternation of Generations
- Alternation of generations is a type of life cycle found in terrestrial plants and some algae in which subsequent generations of individuals alternate between haploid and diploid organisms. This can be contrasted to sexual reproduction in animals, in which both haploid and diploid cells are found in every generation. Alternation of generations has ...
Alternation of Generations Life Cycle
- Sporophyte
To form a sporophyte, two haploid gametes come together to form a diploid zygote. Typically, haploid organisms are defined by having an “n” number of chromosomes. When two gametes of the same species come together, they each have n chromosomes. Therefore, the diploid zygote … - Gametophyte
This represents the next generation in the alternation of generations, as the haploid spore is created. The spore is technically a new organism, and has only half the DNA as the parent organism. This spore will undergo successive rounds of mitosis to form a new multicellular indi…
Complications with Alternation of Generations
- Gendered Gametes
There are many additional factors which can complicate this basic theme of alternation of generations. The most notable complication is gender. Both sporophytes and gametophytes can have genders. Further, the sporophyte or gametophyte may not be totally independent of the oth… - Differences in the Sporophyte and Gametophyte
During the alternation of generations in some species, there is an unequal distribution in size or dominance of either the sporophyte or the gametophyte. In different species, this can be reversed. In liverworts the gametophyte is the dominant generation. Liverwort is a gametophytic plant. In f…
Evolution of The Alternation of Generations
- Fossil evidence, and the existence of many algae with simplified alternation of generation life cycles, hints that the evolutionary advantage of sexual reproduction through the alternation of generations is what made terrestrial plants adaptable enough to colonize the land. The alternation of generations allows for both the dynamic and volatile act of sexual reproduction and the stead…
Quiz
- 1. What is one advantage of the alteration of generations over an asexual species? A. Asexual species have very little genetic recombination B. There are no advantages C.It is easier to reproduce 2. What is the difference between the alternation of generations seen in plants and the sexual reproduction seen in mammals? A. Mammals only alternate every other generation B. Ma…