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Biology LibreTexts

2: Organisms

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    • 2.1: A Diversity of Organisms
    • 2.2: Acetabularia, an unusual unicellular green algae
    • 2.3: Agaricus bisporus, the commercial mushroom
    • 2.4: Alfalfa
    • 2.5: Bracket Fungi
      If you are observant and spend much time hiking in the woods you are sure to encounter a bracket (shelf) fungus, fruiting bodies of wood decay fungi that are found both on standing and fallen trees and form a hard outgrowth with a spore producing surface facing downward.
    • 2.6: Calupera - A Large Coenocytic Green Algae
      Caulerpa is a large green algae that appears to be multicellular because it is organized into different parts, seemingly leaves, stems and roots. But it is actually just a single large cell. And since an individual organism might be two meters in extent, Caulerpa produces the largest cells on earth, except for maybe some plasmodial slime molds. They are mostly found in shallow waters in warmer oceans but a few occur in fresh water.
    • 2.7: Chlamydomonas, a small unicellular green alga
    • 2.8: Chytrids - Tiny Fungi
      Chytrids (Chytridomycota) are a group of fungi that are rarely directly encountered, primarily because they are small and they generally eat things that are small.
    • 2.9: Clubmosses - Lycopodium
      Club mosses are representatives of the Lycopodiophyta, plants that are very important in the fossil record and in the history of plant life but are not particularly diverse or common now. World-wide there are around 1000 species in the group. As is the case with many of the ferns the common names for club mosses have been much more stable than the scientific names, several of which have been changed in the last thirty years.
    • 2.10: Coccolithophores, photosynthetic unicellular algae
      Coccolithophores are some of the most important organisms that you have never heard of !! They are very small marine organisms who have a very significant impact on earth's geology and ecology. They are distinctive because they have a coating that consists of a number of ornate calcium carbonate plates.
    • 2.11: Coltsoot - Tussilago farfara
      Tussilago farafara is a common herbaceous plant throughout much of North America, occurring in disturbed habitats, usually in relatively moist sites. It is one of the first flowers to be found in the spring, often on roadsides
    • 2.12: Corn
    • 2.13: Corralorhiza - A Plant that Eats Fungi
      Corralorhiza is a representative of the orchid family. The orchids are one of the largest families of flowering plants, a group with over 25, 000 species. Although the genus Corralorhiza is restricted to North America, with roughly a dozen species, most members of the family are found in the tropics. Probably the most commonly seen orchid in the northeastern US is the pink lady slipper but there are another 10-15 species of orchids that relatively easy to find.
    • 2.14: Cryptomonads - Unicellular Photosynthetic Algae
      As the name implies, cryptophytes (crypto = hidden) are unicellular algae that are often hidden. This is a consequence of their relatively small size (10-30 um), the fact that they often occur in deeper waters, and the fact that they are often difficult to collect in an intact condition. However, they are significant contributors to aquatic food chains, both marine and fresh water, and have interesting features that relate to their evolution.
    • 2.15: Dandelion
      Dandelion is an extremely common plant through temperate North America and Europe. It is widely recognized as a weed, a word that generally means that it is an undesirable plant, undesirable because it grows in places where people are trying to grow something else, and, at least to some people, undesirable because of its looks — perhaps not so much the bright yellow flowers, but more likely because of the fruit heads and the rosettes of leaves in an otherwise uniform carpet of grass.
    • 2.16: Diatoms - Unicellular Photosynthetic Algae
      The diatoms are a phylum of unicellular photosynthetic algae and are a group significant for their unique structure and ecology.
    • 2.17: Dictyostelium - A Cellular Slime Mold
      Dictyostelium is a 'cellular slime mold', a very unfamiliar (to most) organism that has proved to be useful as a 'model organism' to study significant biological processes, in particular, development. It has a multicellular stage that develops not as a result of a cell dividing repeatedly producing daughter cells all stuck together. Instead multicellularity is the result of the aggregation of many individual cells.
    • 2.18: Ephedra - Jointfir
      Ephedra (the common name is also ephedra, and it is also called jointfir) is a representative of a small, diverse group of seed plants that unfortunately has no common name. They are simply called 'the gnetophytes' after the name for the phylum, Gnetophyta.
    • 2.19: Euglena- a unicellular algae
      Euglena is a genus of unicellular, freshwater organisms that are very common in ponds and small bodies of water, especially if they are rich in nutrients and consequently high in algae (aka 'pond scum' ). Euglena itself is sometimes photosynthetic and is a component of the green sludge in such ponds. But at other times it is non-photosynthetic and is a component of the diverse group of organisms that are eating the green sludge or perhaps eating the other things that eat the green sludge.
    • 2.20: Ginkgo
      Gingko (Ginkgo biloba) is a commonly planted tree that many have probably seen but may not have distinguished from other trees. In spite of the fact that its form is very similar to most trees it has a number of distinct features. In particular, most trees are flowering plants (angiosperms) or conifers, ginkgo is neither!
    • 2.21: Glomeromycota- important mycorrhizal fungi
      The Glomeromycota are a very common, yet rarely seen, group of fungi. They are ubiquitous partners with angiosperms, forming associations called mycorrhizae, more specifically 'endomycorrhizae', also called vesicular/arbuscular (VA) mycorrhizae. Most plants (more than 80%) are mycorrhizal and most of these form endomycorrhizae with a fungal associate in the Glomeromycota.
    • 2.22: Gonyaulax - A Dinoflagellate
      Gonyaulax is representative of a n important group of unicellular organisms, the Pyrrophyta (sometimes called Dinophyta). The common name for the group is the dinoflagellates. Like the Euglenophyta, the group contains both photosynthetic and non-photosynthetic forms. Gonyaulax and several other dinoflagellates are notable for their association with two familiar phenomena: ocean bioluminescence and red tides, although most dinoflagellates are not.
    • 2.23: Halobacterium
      Halobacterium is one of several organisms that can color high salt environments red, like the hypersaline pools in Owens Lake, California. Halobacteriumis significant not just for its tolerance of extreme salinity but also because it is a member of the Archaea and because it has some peculiar metabolic abilities.
    • 2.24: Hemlock
    • 2.25: Horsetails, the genus Equisetum
    • 2.26: Juniper
    • 2.27: Kelp - Laminaria, a brown algae
    • 2.28: Lungwort Lichen (Lobaria pumonaria)
    • 2.29: Marchantia - Thalloid Liverwort
    • 2.30: Marsilea - The 4-leaf Clover Fern
    • 2.31: Molds - Ubiquitous Fungi
    • 2.32: Nostoc - The Smallest Multicellular Organism
    • 2.33: Oedogonium- a filamentous green algae
      Oedogonium is representative of a number of organisms in a very diverse group, the green algae. In this book we consider several members of the green algae that illustrate a range in form and structure.
    • 2.34: Physarum - A Plasmodial Slime Mold
    • 2.35: Phytophthora
    • 2.36: Pinus - Pine Trees
    • 2.37: Polytrichium - Hairy Cap Moss
    • 2.38: Populus
    • 2.39: Potatoes- Solanum tuberosum
    • 2.40: Porphyra- an edible red algae
    • 2.41: Redwoods- the tallest and largest trees
    • 2.42: Rhizobium- nitrogen fixing bacteria
    • 2.43: Rhizopus
    • 2.44: Rice
    • 2.45: Rust fungi (order Pucciniales, formerly Uredinales)
    • 2.46: Sagebrush
    • 2.47: Sarracenia, a carnivorous plant
    • 2.48: Seaweed, Fucus- a brown algae
    • 2.49: Sensitive fern
    • 2.50: Soybeans (and other beans)
      Soybean, Glycine max, is an important annual crop throughout much of the temperate regions of the world but especially in the United States, which leads the world in soybean production, followed by Brazil and Argentina. Much of the U.S. production is exported. Soybean is particular notable because of the many ways it is used. It is eaten fresh and dry. The seeds can be processed to yield soy oil or to make soy milk (produced by grinding soy seeds in water, producing an emulsion of protein & oil.
    • 2.51: Sphagnum-peat moss
      The genus Sphagnum is by far the most important non-vascular plant group on earth. The 120 species in the genus are primarily found in cool, moist habitats, mostly in the Northern Hemisphere but some do occur in the southern part of the Southern Hemisphere. The genus is important because it can dominate large areas and change conditions at these sites, making them less hospitable for some species and more hospitable for others.
    • 2.52: Sunflower - Helianthus annuus
      The sunflower is a familiar plant that has the distinction of being the only widely used crop species that originated in North America. Although Native Americans domesticated the plant and selected for plants with single heads and larger seeds, its initial use after being introduced into Europe was primarily as an ornamental plant in gardens. It first became popular as a crop plant in Russia, largely as a consequence of edicts from the Eastern Orthodox Church concerning diet restrictions during
    • 2.53: Tar Spot Fungus
      The fungus Rhytisma lives inside tree leaves and produces large black spots on the leaves late in the growing season (August and September) as the leaves start to senesce. The most common species in the northeastern U.S. occur on maples but there are other species that occur on other tree species. The black spots form when the fungus produces large black masses of hyphae ( 'stroma' ) that break through the epidermis of the leaf.
    • 2.54: Thermus aquaticus
      T. aquaticusis the organism that makes PCR (polymerase chain reaction) possible. It is an 'thermophile' , capable of living in high temperatures, specifically at temperatures over 70 C (150 F). It was discovered in 1969, at a time when biologists assumed thatno living thing could surviveat temperatures over 55 C. WhileThermuscan 'only' withstand temperatures up to 80 C, other organisms can live at temperatures even closer to the boiling point of water.
    • 2.55: Wheat
      Wheat should be familiar to everyone although perhaps only as a food and not very much as an organism. Wheat is one of the oldest crop species, originating in Turkey probably close to 10, 000 years ago, although some researchers place its origin even older. As described below what we call 'wheat' is at least three different entities, differing in chromosome number, evolutionary history and also features related to harvesting and baking.
    • 2.56: Wood Ferns
      The wood ferns (genus Dryopteris) are a group of over 400 species and are commonly seen throughout temperate areas, especially in forests. Many are planted as ornamental plants and they are commonly used in landscaping and gardens. The group is known for hydridization, polyploidy and subsequent speciation which accounts for the large number of species (see discussion of speciation through polyploidy in Chapter 28).
    • 2.57: Yeast
      Brewer's (aka baker's yeast or commercial yeast), is the organism that is used to make bread rise and produce wine from the fruits of grape. It also is extremely important as a 'model organism' in biology. It was the first eukaryote to have its entire genome sequenced and studies using S. cervisiae have been highly significant in developing our understanding of meiosis, mitosis and cancer.

    Thumbnail: Forest mushrooms. (Unsplash License; Adam Nieścioruk via Unsplash)

    This page titled 2: Organisms is shared under a CC BY-NC 4.0 license and was authored, remixed, and/or curated by George M. Briggs (Milne Library) .

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