Alternation of generationsAlternation of generations (also known as metagenesis or heterogenesis) is the predominant type of life cycle in plants and algae. In plants, both phases are multicellular: the haploid sexual phase – the gametophyte – alternates with a diploid asexual phase – the sporophyte. A mature sporophyte produces haploid spores by meiosis, a process which reduces the number of chromosomes to half, from two sets to one.
SporeIn biology, a spore is a unit of sexual (in fungi) or asexual reproduction that may be adapted for dispersal and for survival, often for extended periods of time, in unfavourable conditions. Spores form part of the life cycles of many plants, algae, fungi and protozoa. They were thought to have appeared as early as the mid-late Ordovician period as an adaptation of early land plants.
PlantPlants are the eukaryotic organisms that constitute the kingdomPlantae(/'plænteɪ/). They are predominantly photosynthetic or came from photosynthetic ancestors, meaning that they obtain their energy from sunlight by using the green pigment chlorophyll in their chloroplasts to produce sugars from carbon dioxide and water. Over the course of time, some plants have evolved to be parasitic, meaning they take energy from other organisms.
Biological life cycleIn biology, a life cycle (or biological life cycle when the context is not clear) is a series of stages of the life of an organism. It begins as a zygote, often in an egg, and concludes as an adult that reproduces, producing an offspring in the form of a new zygote. The same series of stages occurs in the new biological generation, the process repeating in a cyclic fashion.
EukaryoteDomain of life whose cells have nucleiThe eukaryotes () are cellularorganisms of the domainEukaryota or Eukarya, which have a distinct cell nucleus (formed by a nuclear membrane), membrane-bound organelles and organization supported by a cytoskeleton. Extant eukaryotes are traditionally grouped into four kingdoms: animals, plants, fungi and protists.
CladeIn biology, a clade (/kleɪd/) (from Ancient Greek κλάδος (kládos) 'branch'), also known as a monophyletic group or natural group, is a group of organisms that is composed of a common ancestor and all of its descendants. Clades are the fundamental unit of cladistics, a modern approach to taxonomy adopted by most biological fields. The common ancestor may be an individual, a population, or a species (extinct or extant).
EmbryoAn embryo ( EM-bree-oh) is the initial stage of development for a multicellular organism. In organisms that reproduce sexually, embryonic development is the part of the life cycle that begins just after fertilization of the female egg cell by the male sperm cell. The resulting fusion of these two cells produces a single-celled zygote that undergoes many cell divisions that produce cells known as blastomeres.
SeedIn botany, a seed is a plant structure containing an embryo and stored nutrients in a protective coat called a testa. More generally, the term seed means anything that can be sown, which may include seed and husk or tuber. Seeds are the product of the ripened ovule, after the embryo sac is fertilized by sperm from pollen, forming a zygote. The embryo within a seed develops from the zygote and grows within the mother plant to a certain size before growth is halted.
SporangiumA sporangium (from Late Latin, from Ancient Greek (sporá)'seed' and (angeîon)'vessel'; pl.: sporangia) is an enclosure in which spores are formed. It can be composed of a single cell or can be multicellular. Virtually all plants, fungi, and many other groups form sporangia at some point in their life cycle. Sporangia can produce spores by mitosis, but in land plants and many fungi, sporangia produce genetically distinct haploid spores by meiosis.
Sexual reproductionSexual reproduction is a type of reproduction that involves a complex life cycle in which a gamete (haploid reproductive cells, such as a sperm or egg cell) with a single set of chromosomes combines with another gamete to produce a zygote that develops into an organism composed of cells with two sets of chromosomes (diploid).
Multicellular organismA multicellular organism is an organism that consists of more than one cell, and more than one cell type, unlike unicellular organisms. All species of animals, land plants and most fungi are multicellular, as are many algae, whereas a few organisms are partially uni- and partially multicellular, like slime molds and social amoebae such as the genus Dictyostelium.
Sex organA sex organ, also known as a reproductive organ, is a part of an organism that is involved in sexual reproduction. Sex organs constitute the primary sex characteristics of an organism. Sex organs are responsible for producing and transporting gametes, as well as facilitating fertilization and supporting the development and birth of offspring. Sex organs are found in many species of animals and plants, with their features varying depending on the species.*As an Amazon Associate I earn from qualifying purchases.