|
Hornwort Families
Hornworts are a group of non-vascular Embryophytes (land plants) constituting the division Anthocerotophyta (). The common name refers to the elongated horn-like structure, which is the sporophyte. As in mosses and liverworts, hornworts have a gametophyte-dominant life cycle, in which cells of the plant carry only a single set of genetic information; the flattened, green plant body of a hornwort is the gametophyte stage of the plant. Hornworts may be found worldwide, though they tend to grow only in places that are damp or humid. Some species grow in large numbers as tiny weeds in the soil of gardens and cultivated fields. Large tropical and sub-tropical species of ''Dendroceros'' may be found growing on the bark of trees. The total number of species is still uncertain. While there are more than 300 published species names, the actual number could be as low as 100-150 species. Description Like all bryophytes, the dominant life phase of a hornwort is the haploid gametophyte. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ceratophyllum
''Ceratophyllum'' is a cosmopolitan genus of flowering plants including four accepted living species in 2016, commonly found in ponds, marshes, and quiet streams in tropical and in temperate regions. It is the only extant genus in the family Ceratophyllaceae, itself the only extant family in the order Ceratophyllales. They are usually called coontails or hornworts, although hornwort is also used for unrelated plants of the division Anthocerotophyta. ''Ceratophyllum'' grows completely submerged, usually, though not always, floating on the surface, and does not tolerate drought. The plant stems can reach 1–3 m in length. At intervals along nodes of the stem they produce rings of bright green leaves, which are narrow and often much-branched. The forked leaves are brittle and stiff to the touch in some species, softer in others. Roots are completely absent and are missing even in the embryonic stage, but sometimes they develop modified leaves with a rootlike appearance, which anch ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Numbers
A number is a mathematical object used to count, measure, and label. The original examples are the natural numbers 1, 2, 3, 4, and so forth. Numbers can be represented in language with number words. More universally, individual numbers can be represented by symbols, called ''numerals''; for example, "5" is a numeral that represents the number five. As only a relatively small number of symbols can be memorized, basic numerals are commonly organized in a numeral system, which is an organized way to represent any number. The most common numeral system is the Hindu–Arabic numeral system, which allows for the representation of any number using a combination of ten fundamental numeric symbols, called digits. In addition to their use in counting and measuring, numerals are often used for labels (as with telephone numbers), for ordering (as with serial numbers), and for codes (as with ISBNs). In common usage, a ''numeral'' is not clearly distinguished from the ''number'' that it ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alga
Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic eukaryotic organisms. It is a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from unicellular microalgae, such as ''Chlorella,'' ''Prototheca'' and the diatoms, to multicellular forms, such as the giant kelp, a large brown alga which may grow up to in length. Most are aquatic and autotrophic (they generate food internally) and lack many of the distinct cell and tissue types, such as stomata, xylem and phloem that are found in land plants. The largest and most complex marine algae are called seaweeds, while the most complex freshwater forms are the ''Charophyta'', a division of green algae which includes, for example, ''Spirogyra'' and stoneworts. No definition of algae is generally accepted. One definition is that algae "have chlorophyll ''a'' as their primary photosynthetic pigment and lack a sterile covering of cells around t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plant
Plants are predominantly photosynthetic eukaryotes of the kingdom Plantae. Historically, the plant kingdom encompassed all living things that were not animals, and included algae and fungi; however, all current definitions of Plantae exclude the fungi and some algae, as well as the prokaryotes (the archaea and bacteria). By one definition, plants form the clade Viridiplantae (Latin name for "green plants") which is sister of the Glaucophyta, and consists of the green algae and Embryophyta (land plants). The latter includes the flowering plants, conifers and other gymnosperms, ferns and their allies, hornworts, liverworts, and mosses. Most plants are multicellular organisms. Green plants obtain most of their energy from sunlight via photosynthesis by primary chloroplasts that are derived from endosymbiosis with cyanobacteria. Their chloroplasts contain chlorophylls a and b, which gives them their green color. Some plants are parasitic or mycotrophic and have lost the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
RuBisCO
Ribulose-1,5-bisphosphate carboxylase-oxygenase, commonly known by the abbreviations RuBisCo, rubisco, RuBPCase, or RuBPco, is an enzyme () involved in the first major step of carbon fixation, a process by which atmospheric carbon dioxide is converted by plants and other photosynthesis, photosynthetic organisms to fuel, energy-rich molecules such as glucose. In chemical terms, it catalysis, catalyzes the carboxylation of ribulose-1,5-bisphosphate (also known as RuBP). It is probably the most abundant enzyme on Earth. Alternative carbon fixation pathways RuBisCO is important biology, biologically because it catalyzes the primary chemical reaction by which Total inorganic carbon, inorganic carbon enters the biosphere. While many autotrophic bacteria and archaea fix carbon via the reductive acetyl CoA Pathway, reductive acetyl CoA pathway, the 3-hydroxypropionate cycle, or the reverse Krebs cycle, these pathways are relatively small contributors to global carbon fixation compared t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Organelle
In cell biology, an organelle is a specialized subunit, usually within a cell, that has a specific function. The name ''organelle'' comes from the idea that these structures are parts of cells, as organs are to the body, hence ''organelle,'' the suffix ''-elle'' being a diminutive. Organelles are either separately enclosed within their own lipid bilayers (also called membrane-bound organelles) or are spatially distinct functional units without a surrounding lipid bilayer (non-membrane bound organelles). Although most organelles are functional units within cells, some function units that extend outside of cells are often termed organelles, such as cilia, the flagellum and archaellum, and the trichocyst. Organelles are identified by microscopy, and can also be purified by cell fractionation. There are many types of organelles, particularly in eukaryotic cells. They include structures that make up the endomembrane system (such as the nuclear envelope, endoplasmic reticulum, and G ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pyrenoid
Pyrenoids are sub-cellular micro-compartments found in chloroplasts of many algae,Giordano, M., Beardall, J., & Raven, J. A. (2005). CO2 concentrating mechanisms in algae: mechanisms, environmental modulation, and evolution. Annu. Rev. Plant Biol., 56, 99-131. and in a single group of land plants, the hornworts.Villarreal, J. C., & Renner, S. S. (2012) Hornwort pyrenoids, carbon-concentrating structures, evolved and were lost at least five times during the last 100 million years. ''Proceedings of the National Academy of Sciences'',109(46), 1873-1887. Pyrenoids are associated with the operation of a carbon-concentrating mechanism (CCM). Their main function is to act as centres of carbon dioxide (CO2) fixation, by generating and maintaining a CO2 rich environment around the photosynthetic enzyme ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO). Pyrenoids therefore seem to have a role analogous to that of carboxysomes in cyanobacteria. Algae are restricted to aqueous env ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cell (biology)
The cell is the basic structural and functional unit of life forms. Every cell consists of a cytoplasm enclosed within a membrane, and contains many biomolecules such as proteins, DNA and RNA, as well as many small molecules of nutrients and metabolites.Cell Movements and the Shaping of the Vertebrate Body in Chapter 21 of Molecular Biology of the Cell '' fourth edition, edited by Bruce Alberts (2002) published by Garland Science. The Alberts text discusses how the "cellular building blocks" move to shape developing embryos. It is also common to describe small molecules such as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chloroplast
A chloroplast () is a type of membrane-bound organelle known as a plastid that conducts photosynthesis mostly in plant and algal cells. The photosynthetic pigment chlorophyll captures the energy from sunlight, converts it, and stores it in the energy-storage molecules ATP and NADPH while freeing oxygen from water in the cells. The ATP and NADPH is then used to make organic molecules from carbon dioxide in a process known as the Calvin cycle. Chloroplasts carry out a number of other functions, including fatty acid synthesis, amino acid synthesis, and the immune response in plants. The number of chloroplasts per cell varies from one, in unicellular algae, up to 100 in plants like ''Arabidopsis'' and wheat. A chloroplast is characterized by its two membranes and a high concentration of chlorophyll. Other plastid types, such as the leucoplast and the chromoplast, contain little chlorophyll and do not carry out photosynthesis. Chloroplasts are highly dynamic—they circulat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plastid
The plastid (Greek: πλαστός; plastós: formed, molded – plural plastids) is a membrane-bound organelle found in the Cell (biology), cells of plants, algae, and some other eukaryotic organisms. They are considered to be intracellular endosymbiotic cyanobacteria. Examples include chloroplasts (used for photosynthesis), chromoplasts (used for pigment synthesis and storage), and leucoplasts (non-pigmented plastids that can sometimes differentiate). The event which led to permanent endosymbiosis in the Archaeplastida clade (of Embryophyte, land plants, red algae, and green algae) probably occurred with a cyanobiont (a symbiotic cyanobacteria) related to the genus ''Gloeomargarita lithophora, Gloeomargarita'', around 1.5 billion years ago. A later primary endosymbiosis event occurred in photosynthetic ''Paulinella'' amoeboids about 90–140 million years ago. This plastid belongs to the "PS-clade" (of the cyanobacteria genera ''Prochlorococcus'' and ''Synechococcus''). Chloroplas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thallus
Thallus (plural: thalli), from Latinized Greek (), meaning "a green shoot" or "twig", is the vegetative tissue of some organisms in diverse groups such as algae, fungi, some liverworts, lichens, and the Myxogastria. Many of these organisms were previously known as the thallophytes, a polyphyletic group of distantly related organisms. An organism or structure resembling a thallus is called thalloid, thallodal, thalliform, thalline, or thallose. A thallus usually names the entire body of a multicellular non-moving organism in which there is no organization of the tissues into organs. Even though thalli do not have organized and distinct parts (leaves, roots, and stems) as do the vascular plants, they may have analogous structures that resemble their vascular "equivalents". The analogous structures have similar function or macroscopic structure, but different microscopic structure; for example, no thallus has vascular tissue. In exceptional cases such as the Lemnoideae, where ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rosette (botany)
In botany, a rosette is a circular arrangement of leaves or of structures resembling leaves. In flowering plants, rosettes usually sit near the soil. Their structure is an example of a modified stem in which the internode gaps between the leaves do not expand, so that all the leaves remain clustered tightly together and at a similar height. Some insects induce the development of galls that are leafy rosettes. In bryophytes and algae, a rosette results from the repeated branching of the thallus as the plant grows, resulting in a circular outline. Taxonomies Many plant families have varieties with rosette morphology; they are particularly common in Asteraceae (such as dandelions), Brassicaceae (such as cabbage), and Bromeliaceae. The fern '' Blechnum fluviatile'' or New Zealand Water Fern (''kiwikiwi'') is a rosette plant. Function in flowering plants Often, rosettes form in perennial plants whose upper foliage dies back with the remaining vegetation protecting the plant. Ano ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
