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Domain Bacteria
*Key characteristics: Bacteria are prokaryotes- cells that do not enclose their DNA in membranous nuclear envelopes as eukaryotes do. Many details of their molecular genetics differ from those of Archaea and Eukarya.
*Cell Structure: Variety of cell shapes, including spherical,rodlike,and spiral; most have cell walls containing peptidoglycan. Few if any have internal organelles. Some have external flagella for cell movement.
*Genetic Organization: All essential genes are in one large DNA double helix that has its ends joined to form a closed loop. Smaller loops of DNA (plasmids) may carry nonessential genes. Simultaneous transcription and translation; introns generally not present; histone proteins absent.
*Reproduction: By binary fission; no true sexual reproduction; some achieve recombination by conjugation.
*Cell Structure: Variety of cell shapes, including spherical,rodlike,and spiral; most have cell walls containing peptidoglycan. Few if any have internal organelles. Some have external flagella for cell movement.
*Genetic Organization: All essential genes are in one large DNA double helix that has its ends joined to form a closed loop. Smaller loops of DNA (plasmids) may carry nonessential genes. Simultaneous transcription and translation; introns generally not present; histone proteins absent.
*Reproduction: By binary fission; no true sexual reproduction; some achieve recombination by conjugation.
GROUPS OF BACTERIA
Proteobacteria
(This large and diverse clade of bacteria includes Esherichicia, Salmonella,Helicobacter, and the nitrogen-fixing soil bacterium Rhizobium).
For example, a Helicobacteria pylori is a rod-shaped and has several flagella used for movement. This bacterium infects he stomach lining and causes ulcers in some people. Picture below represents a Helicobacteria pylori.
Interesting facts:
- Helicobacter pylori was named by Robin Warren and Barry J. Marshall in 1983.
- Helicobacter pylori infects more than 50% of the human population!
- George Bush was diagnosed with a stomach ulcer in the 1960's (Helicobacter Foundation).
- Helicobacter pylori (H. pylori) is a type of bacterium that is found in the stomach of about two-thirds of the world’s population.
- Helicobacter pylori was named by Robin Warren and Barry J. Marshall in 1983.
- Helicobacter pylori infects more than 50% of the human population!
- George Bush was diagnosed with a stomach ulcer in the 1960's (Helicobacter Foundation).
- Helicobacter pylori (H. pylori) is a type of bacterium that is found in the stomach of about two-thirds of the world’s population.
Spirochaetes:
The spirochaetes are name for their distinctive spiral shape. They move in a corkscrew-like fashion,twisting along as they are propelled by flagella on both ends of the cell. Most are free-living,but a few cause serious diseases,including syphilis, Lyme disease,and leptospirosis.
Interesting facts:
-Their length can vary from about five microns (millionths of an inch) to several hundred microns, depending on the species.
- Beneficially, spirochetes contribute to digestion in ruminants such as cows.
- A number of Spirochaeta species live in extreme environments and not just in humans, animals, or ticks.
- They are tightly coiled, and so look like minature springs or telephone cords.
-Their length can vary from about five microns (millionths of an inch) to several hundred microns, depending on the species.
- Beneficially, spirochetes contribute to digestion in ruminants such as cows.
- A number of Spirochaeta species live in extreme environments and not just in humans, animals, or ticks.
- They are tightly coiled, and so look like minature springs or telephone cords.
Actinobacteria:
A large number of soil bacteria belong to this group. Some form long filaments. Members include the Streptomcyes and Actinomyces, which are natural producers of many antibiotics,including streptomycin. A related group is the Firmicutes. The Firmicutes include Bacillus anthracis (anthrax), Clostridia (tetanus and botulism), and Bascillus thuringenisis, which produces a powerful insecticide used for genetic engineering in plants.
Interesting facts:
- They can be terrestrial or aquatic.
- Actinobacteria is one of the dominant bacterial phyla and contains one of the largest of bacterial genera,Streptomyces.
- Actinobacteria include some of the most common soil life freshwater life, and marine life, playing an important role in the decomposition of organic materials, such as cellulose and chitin, and thereby playing a vital part in organic matter turnover and the carbon cycle.
Cyanobacteria:
The cyanobacteria are photosynthetic prokaryotes that were once called "blue-green algae". They are among the oldest organisms on Earth, having been identified in rocks dating to more than 3 billion years ago. They are found in salt water and fresh water, in the soil, and even on the surfaces of damp rocks. They are the only organisms on Earth that are able to fix carbon and nitrogen under aerobic conditions, and this enables them to play critical roles in the global ecosystem, where they serve as key sources of carbon and nitrogen.
Interesting facts:
- They can block sunlight and kill fish by absorbing all of the oxygen in an area.
- Many of them form long filaments of attached cells.
- They can contain very powerful poisons.
- Cyanobacteria have been found among the oldest fossils on earth and are one of the largest groups of bacteria.
- Their maximum length is about 1 mm.
- They reproduce by binary fission.
- Cyanobacteria are prokaryotic (without a nucleus).
- Cyanobacteria are bacteria that grow in water and are photosynthetic (use sunlight to create food and support life).
- They lack a nucleus and organelles.
Interesting facts:
- They can block sunlight and kill fish by absorbing all of the oxygen in an area.
- Many of them form long filaments of attached cells.
- They can contain very powerful poisons.
- Cyanobacteria have been found among the oldest fossils on earth and are one of the largest groups of bacteria.
- Their maximum length is about 1 mm.
- They reproduce by binary fission.
- Cyanobacteria are prokaryotic (without a nucleus).
- Cyanobacteria are bacteria that grow in water and are photosynthetic (use sunlight to create food and support life).
- They lack a nucleus and organelles.
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Domain Archaea
Key characteristics:
- Archaea are prokaryotes that differ from bacteria in so many details of structure and metabolism that they are viewed as a different domain than bacteria. Genetically, they have more in with bacteria. Their cell walls do not contain peptidoglycan.
Cell structure: Cells similar to those of bacteria in appearance; many have flagella that are different in structure and biochemical composition from bacterial flagella. Cell membrane lipids also different from those of bacteria; few internal organelles.
Genetic Organization: As in bacteria, all essential genes are in one large DNA double helix that has its ends joined to form a closed loop. Proteins responsible for transcription and translation are similar to those of eukaryotes. Also like eukaryotes, most species contain introns, and all species contain DNA-binding histone proteins.
Reproduction: By binary fission; no true sexual reproduction, but some achieve recombination by conjuction.
Groups of Archaea:
- Archaea are prokaryotes that differ from bacteria in so many details of structure and metabolism that they are viewed as a different domain than bacteria. Genetically, they have more in with bacteria. Their cell walls do not contain peptidoglycan.
Cell structure: Cells similar to those of bacteria in appearance; many have flagella that are different in structure and biochemical composition from bacterial flagella. Cell membrane lipids also different from those of bacteria; few internal organelles.
Genetic Organization: As in bacteria, all essential genes are in one large DNA double helix that has its ends joined to form a closed loop. Proteins responsible for transcription and translation are similar to those of eukaryotes. Also like eukaryotes, most species contain introns, and all species contain DNA-binding histone proteins.
Reproduction: By binary fission; no true sexual reproduction, but some achieve recombination by conjuction.
Groups of Archaea:
Crenarchaeotes: The crenarchaeotes include organisms that live in the hottest and most acidic environments known Most of the known species have been isolated from thermal vents and hot springs.
Kararchaeotes:
- Kararchaeotes were discovered by scientists at the lineage in Obsidian pool, Yellowstone National Park, and have since discovered more species in Iceland. Their DNA sequences place them apart from other archaea.
Nanoarchaeotes:
Only a single species of this group has been discovered, in group 2002, attached to a much larger crenarchaeote! Nanoarchaeotes grow in hot vents near the coastal regions of the ocean and show definite molecular differences from other archaea.
Euryarchaeotes:
The euryarchaeotes are a very diverse group of archaea, living in a broad range of habitats. tHE Methanogens are a major group of euryarchaeotes that play essential roles in the environment. They help to break down organic compounds on oxygen-poor environments,releasing methane gas in the process.
Other facts:
- Way before extreme sports and extreme reality TV shows came the archaea- the original and ultimate extremists.
- When archaea were first discovered, biologists called them extremophiles,a term that literally means "lovers of the extreme".
- Archaea found in deep-sea ocean vents thrive in temperatures exceeding 100 degrees Celsius, while others enjoy life in the frigid waters of the Arctic.
Other facts:
- Way before extreme sports and extreme reality TV shows came the archaea- the original and ultimate extremists.
- When archaea were first discovered, biologists called them extremophiles,a term that literally means "lovers of the extreme".
- Archaea found in deep-sea ocean vents thrive in temperatures exceeding 100 degrees Celsius, while others enjoy life in the frigid waters of the Arctic.
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Kingdom Protista
Key characteristics: A protest is a eukaryote, generally single- celled, that does not fit into any of the other major taxonomic groups. The protists do not make up a true kingdom.
Organization: Great diversity of cell organelles and organization; some have cell walls, some have chloroplasts, most have mitochondria or organelles related to mitochondria or organelles related to mitochondria; those that are multicellular have relatively little differentiation into tissues.
Movement: Some move by cilia or flagella.
Reproduction: Most reproduce by cell division; many have sexual phases to their life cycle; some exchange genetic material by conjugation.
Organization: Great diversity of cell organelles and organization; some have cell walls, some have chloroplasts, most have mitochondria or organelles related to mitochondria or organelles related to mitochondria; those that are multicellular have relatively little differentiation into tissues.
Movement: Some move by cilia or flagella.
Reproduction: Most reproduce by cell division; many have sexual phases to their life cycle; some exchange genetic material by conjugation.
Phylums of Protista
Excavates: Have characteristic feeding groove, usually supported by microtubules. Most have flagella, few lack mitochondria and are unable to carry out oxidative phosphorylation, although they do possess remnants of the organelle.
Groups of Excavates:
1. Diplomonads- These organisms get their name from the fact that they possess two distinct and different nuclei. The diplomonad Giardia is a dangerous intestinal paradise that frequently contaminates freshwater streams.
2. Discicristates- Discicristates are named for the disc-shaped cristae present in their mitochondria. Some species are photosynthetic and free-living, such as Euglena, while others are dangerous parasites.
Groups of Excavates:
1. Diplomonads- These organisms get their name from the fact that they possess two distinct and different nuclei. The diplomonad Giardia is a dangerous intestinal paradise that frequently contaminates freshwater streams.
2. Discicristates- Discicristates are named for the disc-shaped cristae present in their mitochondria. Some species are photosynthetic and free-living, such as Euglena, while others are dangerous parasites.
Chromalveolates
Key characteristics:
- Chromaveolates get their name from alveoli, flattened vesicles that line the cell membrane. The prefix chromo-, meaning "pigment", reflects evidence that members of this clade share a common ancestor that had accessory pigments used in photosynthesis.
Groups of Chromalveolates:
1. Phaeophytes (Brown Algae)- Phaeophytes are mostly found in salt water. They are some of the most abundant and visible of the algae. Most species contain fucoxanthin, a greenish-brown pigment from which the group gets its common name. The multicellular brown alga known as giant kelp can grow as large as 60 meters in length.
- Chromaveolates get their name from alveoli, flattened vesicles that line the cell membrane. The prefix chromo-, meaning "pigment", reflects evidence that members of this clade share a common ancestor that had accessory pigments used in photosynthesis.
Groups of Chromalveolates:
1. Phaeophytes (Brown Algae)- Phaeophytes are mostly found in salt water. They are some of the most abundant and visible of the algae. Most species contain fucoxanthin, a greenish-brown pigment from which the group gets its common name. The multicellular brown alga known as giant kelp can grow as large as 60 meters in length.
Cercozoa, Foraminiferans, and Radiolarians
1. Cercozoa- Memebers of this clade are common in soil, where they feed on bacteria as well as decaying organic matter. Many have flagella, and some produce scales made of silica that protect their surfaces.
2. Foraminiferans- They produce intricate and beautiful shells that differ from species to species. Slender pseudopods that emerge through tiny holes in the shell enable them to capture food, including bacteria. As many as 4000 species exist
3. Radiolarians- These organisms have an intricate structure in which the nucleus is found in an inner region of the cell known as the endoplasm. The outer portion of the cell, known as the ectoplasm, contains lipid droplets and vacuoles. These organisms sometimes form symbolic relationships with photosynthetic algae, from which they obtain food.
2. Foraminiferans- They produce intricate and beautiful shells that differ from species to species. Slender pseudopods that emerge through tiny holes in the shell enable them to capture food, including bacteria. As many as 4000 species exist
3. Radiolarians- These organisms have an intricate structure in which the nucleus is found in an inner region of the cell known as the endoplasm. The outer portion of the cell, known as the ectoplasm, contains lipid droplets and vacuoles. These organisms sometimes form symbolic relationships with photosynthetic algae, from which they obtain food.
Rhodophytes
Also known as the red algae, these organisms get their name from reddish accessory pigments called phycobilins. These highly efficient pigments enable red algae to grow anywhere from the ocean's surface to depths as great as 268 meters. Most species are multicellular. Rhodophytes are the sister group to kingdom Plantae.
Amoebozoa
Members of the Amoebozoa are amoebalike organisms that move by means of cytoplasmic streaming, also called amoeboid movement, using pseudopods.
Choanozoa
Members of the clade Choanozoa can be solitary or colonial and are found in aquatic environments around the world. This clade is the sister group to kingdom Animalia.
Choanoflagellates are a major group in the clade Choanozoa. They get their name from a collar of cytoplasm that surrounds their single flagellum. Many species trap food within the collar and ingest it.
Other facts:
(Did You know that there are challenges in classifying Protists?)
- Biologists traditionally classified protists by splitting them into funguslike, plantlike, and animal- like groups.
- Biologists now think that protistss shouldn't be classified as a kingdom at all. In fact, when scientists look for the deepest and most fundamental divisions among eukaryotes,they find that all of those divisions are within the protists themselves, not between protists and other eukaryotes.
- Here, "protists" are considered a kingdom for the sake of convenience, but keep in mind that their differences are really too great for any single kingdom to contain.
Choanoflagellates are a major group in the clade Choanozoa. They get their name from a collar of cytoplasm that surrounds their single flagellum. Many species trap food within the collar and ingest it.
Other facts:
(Did You know that there are challenges in classifying Protists?)
- Biologists traditionally classified protists by splitting them into funguslike, plantlike, and animal- like groups.
- Biologists now think that protistss shouldn't be classified as a kingdom at all. In fact, when scientists look for the deepest and most fundamental divisions among eukaryotes,they find that all of those divisions are within the protists themselves, not between protists and other eukaryotes.
- Here, "protists" are considered a kingdom for the sake of convenience, but keep in mind that their differences are really too great for any single kingdom to contain.
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Kingdom Fungi
Key characteristics:
Fungi are heterotrophic eukaryotes with cell walls that contain chitin. Fungi were once thought to be plants that had lost their chloroplasts. It is now clear, however, that they are much more closely related to animals than to plants. More than 100,000 species of fungi are known. Distinctions among the phyla are made on the basis of DNA comparisons, cell structure, reproductive structures, and life cycles.
Organization:
Some are unicellular yeasts, but most have a multicellular body called a mycelium that consists of one or more slender, branching cells called hyphae.
Feeding and Digestion:
Obtain food by extracellular digestion and absorption
Reproduction:
Most have sexual phases to their life cycle and are haploid at most points during the cycle. Most produce tough, asexual spores, which are easily dispersed and able to endure harsh environmental conditions. Asexual reproduction by budding and splitting is also common.
Phylums of Fungi
Fungi are heterotrophic eukaryotes with cell walls that contain chitin. Fungi were once thought to be plants that had lost their chloroplasts. It is now clear, however, that they are much more closely related to animals than to plants. More than 100,000 species of fungi are known. Distinctions among the phyla are made on the basis of DNA comparisons, cell structure, reproductive structures, and life cycles.
Organization:
Some are unicellular yeasts, but most have a multicellular body called a mycelium that consists of one or more slender, branching cells called hyphae.
Feeding and Digestion:
Obtain food by extracellular digestion and absorption
Reproduction:
Most have sexual phases to their life cycle and are haploid at most points during the cycle. Most produce tough, asexual spores, which are easily dispersed and able to endure harsh environmental conditions. Asexual reproduction by budding and splitting is also common.
Phylums of Fungi
Basidiomycetes
The basidiomycetes, or club fungi, are named for the basidium. The basidium is a reproductive cell that resembles a club.
- Life Cycle: Basidiomycetes undergo what is probably the most elaborate life cycle of all the fungi.
Diversity:
More than 26,000 species of basidiomycetes have been described, roughly a third of all known fungal species. Examples include the stinkhorn and fly agaric mushrooms shown on the previous page, and the shelf fungus and puffball at right.
- Life Cycle: Basidiomycetes undergo what is probably the most elaborate life cycle of all the fungi.
Diversity:
More than 26,000 species of basidiomycetes have been described, roughly a third of all known fungal species. Examples include the stinkhorn and fly agaric mushrooms shown on the previous page, and the shelf fungus and puffball at right.
Ascomycetes
Basic Info:
The ascomycetes, or sac fungi, are named for the ascus, a saclike reproductive structure that contain species.
Life Cycle:
The ascomycete life cycle includes as asexual phase, in which haploid spores are released from structures called conidiophores, and a sexual phase.
Diversity:
There are more than 50,000 species of ascomycetes, making it the largest phylum of the Fungi. Some ascomycetes, such as morels and cup fungi, are large enough to be visible when they grow above ground. Others, such as the common yeasts used for baking bread, are microscopic.
The ascomycetes, or sac fungi, are named for the ascus, a saclike reproductive structure that contain species.
Life Cycle:
The ascomycete life cycle includes as asexual phase, in which haploid spores are released from structures called conidiophores, and a sexual phase.
Diversity:
There are more than 50,000 species of ascomycetes, making it the largest phylum of the Fungi. Some ascomycetes, such as morels and cup fungi, are large enough to be visible when they grow above ground. Others, such as the common yeasts used for baking bread, are microscopic.
Zygomycetes
Basic Info:
The hyphae of zygomycetes generally lack cross walls between cells. Zygomycetes get their name from the sexual phase of their reproductive cycle, which involves a structure called a zygosporangium that forms between the hyphae of two different mating types. One group within the zygomycetes, the Glomales, form symbiotic mycorrhizae with plant roots.
The hyphae of zygomycetes generally lack cross walls between cells. Zygomycetes get their name from the sexual phase of their reproductive cycle, which involves a structure called a zygosporangium that forms between the hyphae of two different mating types. One group within the zygomycetes, the Glomales, form symbiotic mycorrhizae with plant roots.
Chytrids
Members of this phylum live in water or moist soil. Their reproductive cells have flagella, making them the only fungi known to have a motile stage to their life cycle. Chytrids are especially good at digesting cellulose, the material of plant cell walls- some live in the digestive systems of cows and deer, helping them to digest plant matter. Others are pathogens- certain chytrids have recently been associated with the decline of frog populations around the world. About 1000 species are known, many of them recently discovered.
"A Closer Look"
Consumers Beware!
(Edible and Inedible Mushrooms)
- Many types of fungi have long been considered delicacies, and several different species of mushrooms are cultivated for food. When properly cooked and prepared, domestic mushrooms are tasty and nutritious.
- Wild mushrooms are a different story: Although some are edible, many are poisonous. The poisonous ones look very much like the edible mushrooms, that is why you should never pick or eat any mushroom found in the wild.
-The result of eating a poisonous mushroom can be severe illness, or even death.
(Edible and Inedible Mushrooms)
- Many types of fungi have long been considered delicacies, and several different species of mushrooms are cultivated for food. When properly cooked and prepared, domestic mushrooms are tasty and nutritious.
- Wild mushrooms are a different story: Although some are edible, many are poisonous. The poisonous ones look very much like the edible mushrooms, that is why you should never pick or eat any mushroom found in the wild.
-The result of eating a poisonous mushroom can be severe illness, or even death.
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Kingdom Plantae
Key Characteristics:
-Plants are eukaryotes with cell walls composed of cellulose. Plants carry out photosynthesis using the green pigments chlorophyll a and b, and they store the products of photosynthesis as starch.
Phylums of Plantae:
-Plants are eukaryotes with cell walls composed of cellulose. Plants carry out photosynthesis using the green pigments chlorophyll a and b, and they store the products of photosynthesis as starch.
Phylums of Plantae:
Green Algae
Key Characteristics:
The green algae are plants that do not make embryos. All other plants form embryos as part of their life cycle. The green algae include both unicellular and multicellular species, and they are primarily aquatic.
Organization: Single cells, colonies, and a few truly multicellular species.
Movement: Many swim using whiplike flagella.
Water transport: Water diffuses in from the environment.
Reproduction: Asexual and sexual, with gametes and spores; some species show alternation of generations.
Classes of Green Algae:
The green algae are plants that do not make embryos. All other plants form embryos as part of their life cycle. The green algae include both unicellular and multicellular species, and they are primarily aquatic.
Organization: Single cells, colonies, and a few truly multicellular species.
Movement: Many swim using whiplike flagella.
Water transport: Water diffuses in from the environment.
Reproduction: Asexual and sexual, with gametes and spores; some species show alternation of generations.
Classes of Green Algae:
Chlorophytes
(Classic Green Algae)
These algae usually live as single cells, like Chlamydomaonas, or in colonies, like Volvox. They are found in both fresh and salt water, and some species are even known to live in artic snowbanks.
- Chlamydomonas is a unicellular green alga. Each cell has two flagella, which are used in movement.
These algae usually live as single cells, like Chlamydomaonas, or in colonies, like Volvox. They are found in both fresh and salt water, and some species are even known to live in artic snowbanks.
- Chlamydomonas is a unicellular green alga. Each cell has two flagella, which are used in movement.
Charophytes: Stoneworts
Among the green algae, the charophytes are the closest relatives of more complicated plants. They are mostly freshwater species. Their branching filaments may be anchored to the substrate by thin rhizoids.
- Chara with antheridia (sperm-producing structures) visible.
- Chara with antheridia (sperm-producing structures) visible.
Ulvophytes
Sea Lettuces
- The ulvophytes are large organisms composed of hundreds or thousands of cells. Most form large, flattened green sheets and are often simply called seaweed. They show both haploid and diploid phases in their life cycle, but in many species, such as the common sea lettuce, Ulva, it is difficult to tell the two phases apart.
- The ulvophytes are large organisms composed of hundreds or thousands of cells. Most form large, flattened green sheets and are often simply called seaweed. They show both haploid and diploid phases in their life cycle, but in many species, such as the common sea lettuce, Ulva, it is difficult to tell the two phases apart.
Bryophtes
Key Characteristics:
Cryophytes, found mostly on land, are multicellular plants that lack true vascular tissue. This lack of vascular tissue limits their height to just a few centimeters and restricts them to moist soils.
Organization: Complex and specialized tissues, including protective external layers and rhizoids.
Movement: Adults stationary; male gametes swim to egg cells using flagella.
Water Transport: Diffusion from cell to cell; in some mosses, water flows through specialized tissue.
Reproduction: All reproduce sexually with alternation of generations, producing gametes and spores. Most reproduce asexually, too. The gametophyte stage is dominant, with the sporophyte stage dependent on the gametophyte.
Classes of Bryophytes
Cryophytes, found mostly on land, are multicellular plants that lack true vascular tissue. This lack of vascular tissue limits their height to just a few centimeters and restricts them to moist soils.
Organization: Complex and specialized tissues, including protective external layers and rhizoids.
Movement: Adults stationary; male gametes swim to egg cells using flagella.
Water Transport: Diffusion from cell to cell; in some mosses, water flows through specialized tissue.
Reproduction: All reproduce sexually with alternation of generations, producing gametes and spores. Most reproduce asexually, too. The gametophyte stage is dominant, with the sporophyte stage dependent on the gametophyte.
Classes of Bryophytes
Mosses
(Classic Bryophytes)
Mosses are found on damp, well- shaped soil, and occasionally along the sides of tree trunks.
Mosses are found on damp, well- shaped soil, and occasionally along the sides of tree trunks.
Liverworts
Liverworts are flat, almost leaf-like plants that grow on the damp forest floor. Some species are shaped almost like the liver, from which they get their name.
Hornworts
Hornworts get their name from their sporophytes, tiny green structures resembling horns. Like other bryophytes, hornworts are found mostly in damp, well-shaped areas. Only about 100 species are known.
Seedless Vascular Plants
Key Characteristics:
- This informal grouping lumps together all the plants that have true vascular tissue but lack seeds. Vascular tissue is a key adaption to life on land. By carrying water and food throughout plant structures, vascular tissue permitted the evolution of roots and tree-size plants, and it allowed plants to spread into dry areas of land.
Organization: Complex and specialized tissues, including true roots, stems, and leaves.
Movement: Adults stationary; male gametes swim to egg cells using flagella.
Water Transport: Through vascular tissue.
Reproduction: Alternation of generations, producing spores, eggs, and swimming sperm; the sporophyte is not dependent on the gametophyte as it is in bryophytes.
- This informal grouping lumps together all the plants that have true vascular tissue but lack seeds. Vascular tissue is a key adaption to life on land. By carrying water and food throughout plant structures, vascular tissue permitted the evolution of roots and tree-size plants, and it allowed plants to spread into dry areas of land.
Organization: Complex and specialized tissues, including true roots, stems, and leaves.
Movement: Adults stationary; male gametes swim to egg cells using flagella.
Water Transport: Through vascular tissue.
Reproduction: Alternation of generations, producing spores, eggs, and swimming sperm; the sporophyte is not dependent on the gametophyte as it is in bryophytes.
Classes of Seedless Vascular Plants
Ferns:
Ferns are common and abundant. Because they need standing water to reproduce, ferns are generally found in areas that are damp at least part of the year. The sporophyte phase of the life cycle is dominant. Spores are produced in prominent clusters known as sori on the under sides of leaves.
Ferns are common and abundant. Because they need standing water to reproduce, ferns are generally found in areas that are damp at least part of the year. The sporophyte phase of the life cycle is dominant. Spores are produced in prominent clusters known as sori on the under sides of leaves.
Club Mosses
Not really mosses, these vascular plants are also called lycopods. These plants were especially abundant during the Carboniferous Period 360 to 290 million years ago, when they grew as large as trees. Today, their remains make up a large part of coal deposits mined for fuel.
- The small club moss known as Lycopodium can be found growing on the forest floor throughout the temperate regions of North America. They look like tiny pine trees at first glance, but they are, in fact, small, seedless plants.
- The small club moss known as Lycopodium can be found growing on the forest floor throughout the temperate regions of North America. They look like tiny pine trees at first glance, but they are, in fact, small, seedless plants.
Horsetails
Only a single living genus of horsetails is known, Equisetum. These plants were thought to resemble horses' tails; their name is derived from this perception. Today, only 25 species are known, confined to wet areas of soil. But horsetails were once much more diverse, larger in size, and abundant. Abrasive silica, found in many horsetails, was used in colonial times as a scouring powder to help clean pots and pans.
Gymnosperms
Key Characteristics:
Gymnosperms are seed-bearing vascular
plants whose seeds are exposed to the environment, rather than being enclosed in a fruit. The seeds are usually located on the scales of cones.
Organization: True roots, stems, and leaves.
Movement: Adults stationary; within
pollen grains, male gametophytes drift in air or are carried by animals to
female structures where they release sperm that move to eggs.
Water Transport: Through vascular tissue.
Reproduction: Sexual; alternation of
generations; the sporophyte stage is dominant. Female gametophytes live within
the parent sporophyte. Pollen grains carry sperm to eggs, so open water is not
needed for fertilization.
Classes of Gymnosperms
Gymnosperms are seed-bearing vascular
plants whose seeds are exposed to the environment, rather than being enclosed in a fruit. The seeds are usually located on the scales of cones.
Organization: True roots, stems, and leaves.
Movement: Adults stationary; within
pollen grains, male gametophytes drift in air or are carried by animals to
female structures where they release sperm that move to eggs.
Water Transport: Through vascular tissue.
Reproduction: Sexual; alternation of
generations; the sporophyte stage is dominant. Female gametophytes live within
the parent sporophyte. Pollen grains carry sperm to eggs, so open water is not
needed for fertilization.
Classes of Gymnosperms
Conifers
Conifers are by far the most diverse group of living gymnosperms, represented by nearly 700 species worldwide. They include the common pine, spruce, fir, and redwood trees that make up a large share of the forests in the temperature regions of the world. Conifers have enormous economic importance. Their wood is used for residential building, to manufacture paper, and as a source of heat. Compounds from their resins are used for a variety of industrial purposes.
Cycads
Cycads are beautiful palmlike plants that have large cones. Cycads first
appeared in the fossil record during the Triassic Period, 225 million years ago. Huge of cycads thrived when dinosaurs roamed Earth. Today, only nine genera of cycades exist. Cycads can be growing naturally in tropical and subtropical places such as Mexico, the West Indies, Florida, and parts of Asia, Africa, and Australia.
appeared in the fossil record during the Triassic Period, 225 million years ago. Huge of cycads thrived when dinosaurs roamed Earth. Today, only nine genera of cycades exist. Cycads can be growing naturally in tropical and subtropical places such as Mexico, the West Indies, Florida, and parts of Asia, Africa, and Australia.
Ginkgoes
Ginkgoes were common when dinosaurs were alive, but today the group contains only one species, Ginkgo biloba. The living Ginkgo species looks similar to its fossil ancestors- in fact, G. biloba may be pne of the oldest seed plant species alive today.
Gnetophytes
About 70 present-day species of gnetophytes are known, placed in just three genera. The reproductive scales of these plants are clustered in cones.
- Welwitschia mirabilis, an inhabitant of the Namibian desert in southwestern Africa, is one of the most remarkable gnetophytes. Its huge leathery leaves grow continuously and spread across the ground.
- Welwitschia mirabilis, an inhabitant of the Namibian desert in southwestern Africa, is one of the most remarkable gnetophytes. Its huge leathery leaves grow continuously and spread across the ground.
ANGIOSPERMS
Key Characteristics:
Angiosperms are plants that bear seeds in a closed ovary. The ovary is a part of a reproductive organ known as a flower. Seeds are formed in a double fertilization event, which forms a diploid embryo and a triploid endosperm tissue. As seeds mature, ovaries develop into fruits that help to disperse the seeds.
Organization: True roots, stems, and leaves.
Movement: Adults stationary; within pollen grains, male gametophytes drift in air or are carried by animals to female structures, where they release sperm that move to eggs.
Water Transport: Through vascular tissue.
Reproduction: Sexual, with alternation of generations; also asexual. The sporophyte stage is dominant. Female gametophytes live within the parent sporophyte. Pollen carries sperm to eggs, so open water is not needed for fertilization.
Classes of Angiosperms
Angiosperms are plants that bear seeds in a closed ovary. The ovary is a part of a reproductive organ known as a flower. Seeds are formed in a double fertilization event, which forms a diploid embryo and a triploid endosperm tissue. As seeds mature, ovaries develop into fruits that help to disperse the seeds.
Organization: True roots, stems, and leaves.
Movement: Adults stationary; within pollen grains, male gametophytes drift in air or are carried by animals to female structures, where they release sperm that move to eggs.
Water Transport: Through vascular tissue.
Reproduction: Sexual, with alternation of generations; also asexual. The sporophyte stage is dominant. Female gametophytes live within the parent sporophyte. Pollen carries sperm to eggs, so open water is not needed for fertilization.
Classes of Angiosperms
Nymphaeaceae
About 50 species of water lilies are known, and they are of special interest to plant taxonomists. Their DNA and flower structure suggest that they are, along with Amborella, one of the earliest groups to have split off from the main line of flowering plant evolution. Examples of water lilies are found throughout the world.
- Water lilies are aquatic plants that produce flowers and leaves, which float on the surface of the water.
- Water lilies are aquatic plants that produce flowers and leaves, which float on the surface of the water.
Magnoliids
Magnolia trees and others
The most famous genus of these plants is Magnolia, which includes nearly 200 species. Laurels and tulip poplars are also magnoliids of their flower structure, magnoliids were once thought to be nearly as primitive as water lilies. Genetic studies now suggest that they split off from the rest of the angiosperm line after monocots and, therefore, do not represent the earliest flowering plants.
The most famous genus of these plants is Magnolia, which includes nearly 200 species. Laurels and tulip poplars are also magnoliids of their flower structure, magnoliids were once thought to be nearly as primitive as water lilies. Genetic studies now suggest that they split off from the rest of the angiosperm line after monocots and, therefore, do not represent the earliest flowering plants.
Amborella
Amborella does not represent a group of plants but instead just a single species found only on the island of New Caledonia in the South Pacific Ocean. DNA studies show that Amborella is equally separated from all other flowering plants living today, suggesting that it is descended from plants that split off from the main line of flowering plant evolution as long ago as 100 million years.
- The flowers of Amborella trichopoda are simpler than those of most other plants, and the species has a number of features that place it at the very base of flowering plant evolution.
- The flowers of Amborella trichopoda are simpler than those of most other plants, and the species has a number of features that place it at the very base of flowering plant evolution.
Monocots
The monocots include an estimated 65,000 species, roughly 20 percent of all flowering plants. They get their name from the single seed leaf found in monocot embryos, and they include some of the plants that are most important to human cultures. Monocots grown as crops account for a majority of the food produced by agriculture. These crops include wheat, rice, barley, corn, and sugar cane. Common grasses are monocots, as are onions, bananas, orchids, coconut palms, tulips, and irises.
- Onions are just one of many examples of monocot crop species.
- This African hillside I dotted with clumps of Wild Pampas Grass.
- Many orchid species are grown by enthusiasts for their rare beauty. Notice the aerial roots on this specimen, which grows as an epiphyte in its natural environment.
-This sugar cane in Vietnam has been bundled for sale.
- Onions are just one of many examples of monocot crop species.
- This African hillside I dotted with clumps of Wild Pampas Grass.
- Many orchid species are grown by enthusiasts for their rare beauty. Notice the aerial roots on this specimen, which grows as an epiphyte in its natural environment.
-This sugar cane in Vietnam has been bundled for sale.
Eudicots: "True Dicots"
Eudicots account for about 75 percent of all angiosperm species. The name means "true dicots", and these plants are the ones usually given as examples of dicot stem, leaf, and flower structure. Eudicots have distinctive pollen grains with three grooves on their surfaces, and DNA studies strongly support their classification in a single group. They include a number of important subgroups, five of which are described here.
They also include:
1. Ranunculales: A subgroup which includes, and is named after, buttercups. Also included in this subgroup are a number of well known flowers such as columbines, poppies, barberries, and moonseed. (Rocky Mountain Columbine)
2. Rosids: The rosids include, as you might expect, the roses. However, this subgroup also includes many popular fruits, such as oranges, strawberries, raspberries, and apples. Some of the best-known trees, including poplars, willows, and maples, are also members.
3. Asterrids: The nearly 80,000 astrid species include sunflowers, azaleas, snapdragons, blueberries, tomatoes, and potatoes.
4. Caryophyllales: Cacti are probably the most well- known plants in the caryophyllales subgroup. Pinks and carnations, spinach, rhubarb, and insect-eating plants, such as sundews and pitcher plants, are also members.
5. Saxifragales: Plants in the saxifragales subgroup include peonies, witch hazel, gooseberries, and coral bells.
They also include:
1. Ranunculales: A subgroup which includes, and is named after, buttercups. Also included in this subgroup are a number of well known flowers such as columbines, poppies, barberries, and moonseed. (Rocky Mountain Columbine)
2. Rosids: The rosids include, as you might expect, the roses. However, this subgroup also includes many popular fruits, such as oranges, strawberries, raspberries, and apples. Some of the best-known trees, including poplars, willows, and maples, are also members.
3. Asterrids: The nearly 80,000 astrid species include sunflowers, azaleas, snapdragons, blueberries, tomatoes, and potatoes.
4. Caryophyllales: Cacti are probably the most well- known plants in the caryophyllales subgroup. Pinks and carnations, spinach, rhubarb, and insect-eating plants, such as sundews and pitcher plants, are also members.
5. Saxifragales: Plants in the saxifragales subgroup include peonies, witch hazel, gooseberries, and coral bells.
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Kingdom Animalia (Animals)
Key Characteristics:
Animals are multicellular, heterotrophic, eukaryotic organisms whose cells lack cell walls.
Animals are multicellular, heterotrophic, eukaryotic organisms whose cells lack cell walls.
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Phylum Porifera (Sponges)
Key Characteristics:
Sponges are the simplest animals. They are classified as animals because they are multicellular, heterotrophic, lack cell walls, and have some specialized cells. They are aquatic, lack true tissues and organs, and have internal skeletons of sponging and/or spicules of calcium carbonate or silica. Sponges have no body symmetry.
Feeding and Digestion: Filter feeders; intracellular digestion.
Circulation: Via flow of water through body.
Respiration: Oxygen diffuses from water into cells as water flows through body.
Excretion: Wastes diffuse from cells into water as water flows through body.
Response: No nervous system; little capacity to respond to environmental changes.
Movement: Juveniles drift or swim freely; adults are stationary.
Reproduction: Most- sexual with internal fertilization; water flowing out of sponge disperses sperm, which fertilizes eggs inside sponge(s); may reproduce asexually by budding or producing gemmules.
Classes of Porifera
Sponges are the simplest animals. They are classified as animals because they are multicellular, heterotrophic, lack cell walls, and have some specialized cells. They are aquatic, lack true tissues and organs, and have internal skeletons of sponging and/or spicules of calcium carbonate or silica. Sponges have no body symmetry.
Feeding and Digestion: Filter feeders; intracellular digestion.
Circulation: Via flow of water through body.
Respiration: Oxygen diffuses from water into cells as water flows through body.
Excretion: Wastes diffuse from cells into water as water flows through body.
Response: No nervous system; little capacity to respond to environmental changes.
Movement: Juveniles drift or swim freely; adults are stationary.
Reproduction: Most- sexual with internal fertilization; water flowing out of sponge disperses sperm, which fertilizes eggs inside sponge(s); may reproduce asexually by budding or producing gemmules.
Classes of Porifera
Demospongiae: Typical sponges
More than 90 percent of all living sponge species are in this group, including the few freshwater species. They have skeletons made of sponging, a flexible protein. Some species have silica spicules. Some species have silica spicules.
Examples: Yellow Sponge, both sponges, Carnivorous Mediterranean Sponge, tube sponges.
Examples: Yellow Sponge, both sponges, Carnivorous Mediterranean Sponge, tube sponges.
Hexactinellida: Glass sponges
Glass sponges live in the deep ocean and are especially abundant in the Antarctic. They are called "glass" sponges because their skeletons are made of glasslike silica spicules.
Examples: Venus's Flower Basket, Cloud Sponge.
Examples: Venus's Flower Basket, Cloud Sponge.
Calcarea: Calcareous sponges
Calcareous sponges live in shallow, tropical marine waters and are the only sponges with calcium carbonate spicules.
Example: Clathrina
Example: Clathrina
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Phylum Cnidaria (Cnidarians)
-Key Characteristics: Cnidarians are aquatic, mostly carnivorous, and the simplest animals to have specialized tissues (outer skin and lining of the gastrovascular cavity) and body symmetry (radial). Their tentacles have stinging cells called nematocysts used in feeding.
-Feeding and Digestion: Predatory, stinging prey with nematocysts; digestion begins extracellularly in gastrovascular cavity and is completed intracellularly; indigestible materials leave body through single opening; many, especially reef-building corals, also depend on symbiotic algae, or zooxanthellae.
- Circulation: No internal transport system; nutrients typically diffuse through body.
-Respiration: Diffusion through body walls.
-Excretion: Cellular wastes diffuse through body walls.
-Response: Some specialized sensory cells: nerve cells in nerve net, statocysts that help determine up and down, eyespots (acelli) made of light-detecting cells.
- Movement: Polyps stationary, medusas free-swimming; some, such as sea anemones, can borrow and creep very slowly; others move using muscles that work with a hydrostatic skeleton and water in gastrovascular cavity; medusas such as jellyfish move by jet propulsion generated by muscle contractions.
- Reproduction: Most- alternate between sexual (most species by external fertilization) and asexual (polyps produce new polyps or medusae by budding).
Classes of Cnidarians
-Feeding and Digestion: Predatory, stinging prey with nematocysts; digestion begins extracellularly in gastrovascular cavity and is completed intracellularly; indigestible materials leave body through single opening; many, especially reef-building corals, also depend on symbiotic algae, or zooxanthellae.
- Circulation: No internal transport system; nutrients typically diffuse through body.
-Respiration: Diffusion through body walls.
-Excretion: Cellular wastes diffuse through body walls.
-Response: Some specialized sensory cells: nerve cells in nerve net, statocysts that help determine up and down, eyespots (acelli) made of light-detecting cells.
- Movement: Polyps stationary, medusas free-swimming; some, such as sea anemones, can borrow and creep very slowly; others move using muscles that work with a hydrostatic skeleton and water in gastrovascular cavity; medusas such as jellyfish move by jet propulsion generated by muscle contractions.
- Reproduction: Most- alternate between sexual (most species by external fertilization) and asexual (polyps produce new polyps or medusae by budding).
Classes of Cnidarians
Hydrozoa: Hydras and their relatives
Hydras and their relatives spend most of their time as polyps and are either colonial or solitary. They reproduce asexually (by budding), sexually, or they alternate between sexual and asexual reproduction.
Examples: hydra, Portuguese Man-of-War.
A Portuguese Man-of-War is actually a colony of polyps.
Examples: hydra, Portuguese Man-of-War.
A Portuguese Man-of-War is actually a colony of polyps.
Anthozoa: Corals and sea anemones
Corals and sea anemones are colonial or solitary polyps with no medusa stage. The central body is surrounded by tentacles. They reproduce sexually or asexually.
Examples: reef corals, sea anemones, sea pens, sea fans.
Examples: reef corals, sea anemones, sea pens, sea fans.
Scyphozoa: Jellyfishes
Jellyfishes spend most of their time as medusas; some species bypass the polyp stage. They reproduce sexually and sometimes asexually by budding.
Examples: Lion's Mane Jellyfish, Moon Jelly, Sea wasp.
"A Closer Look"
A common ancestor: Recent molecular studies and cladistics analyses recognize the clade Choanozoa to be the true sister group to all Metazoa-multicellular animals. Choanozoa is one group of organisms formerly called "protists" and is named for choanoflagellates (art and photo right), single- celled, colonial organisms that look like certain cells of sponges and flatworms. Current thinking suggests that the chonflagellates alive today are the best living examples of what the last common ancestor of metazoans looked like.
Examples: Lion's Mane Jellyfish, Moon Jelly, Sea wasp.
"A Closer Look"
A common ancestor: Recent molecular studies and cladistics analyses recognize the clade Choanozoa to be the true sister group to all Metazoa-multicellular animals. Choanozoa is one group of organisms formerly called "protists" and is named for choanoflagellates (art and photo right), single- celled, colonial organisms that look like certain cells of sponges and flatworms. Current thinking suggests that the chonflagellates alive today are the best living examples of what the last common ancestor of metazoans looked like.
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Phylum Arthropoda (Arthropods)
-Key Characteristics: Arthropods are the most diverse of all multicellular organism. They have segmented bodies and jointed appendages. They are supported by tough exoskeletons made of chitin, which they periodically shed as they grow. Anthropods are coelomate protostomes with bilateral symmetry.
- Feeding and Digestion: Extremely diverse; herbivores, carnivores, detritivores,, parasites, blood-suckers, scavengers, filter feeders; digestive system with two openings; many feeding specializations in different groups.
- Circulation: Open circulatory system with heart and arteries.
- Respiration: Terrestrial- tracheal tubes or book lungs; aquatic-gills or books gills (horseshoe crabs).
-Excretion: Terrestrial- Malpighian tubules; aquatic-diffusion into water.
- Response: Well-developed nervous system with brain; sophisticated sense organs.
-Movement: Muscles attached internally to jointed exoskeletons.
-Reproduction: Usually sexual, although some species may reproduce asexually under certain circumstances; many undergo metamorphosis during development.
Classes of Arthropods
- Feeding and Digestion: Extremely diverse; herbivores, carnivores, detritivores,, parasites, blood-suckers, scavengers, filter feeders; digestive system with two openings; many feeding specializations in different groups.
- Circulation: Open circulatory system with heart and arteries.
- Respiration: Terrestrial- tracheal tubes or book lungs; aquatic-gills or books gills (horseshoe crabs).
-Excretion: Terrestrial- Malpighian tubules; aquatic-diffusion into water.
- Response: Well-developed nervous system with brain; sophisticated sense organs.
-Movement: Muscles attached internally to jointed exoskeletons.
-Reproduction: Usually sexual, although some species may reproduce asexually under certain circumstances; many undergo metamorphosis during development.
Classes of Arthropods
Crustacea: Crustaceans
There are crustacean species in almost every habitat, but most are aquatic, and most of these are marine. They have two or three body sections, two pairs of antennae, and chewing mouthparts called mandibles. Many have a carapace, or "shell", that covers part or all of the body.
Examples: crabs, lobsters, crayfish, pill bugs, water fleas, barnacles.
Examples: crabs, lobsters, crayfish, pill bugs, water fleas, barnacles.
Chelicerata: Chelicerates
Living chelicerates include horseshoe crabs and arachnids, (Their extinct relatives include trilobites and giant "sea-scorpions.") Most living chelicerates are terrestrial. The body is composed of two parts-the cephalothorax and abdomen. The first pair of appendages are specialized feeding structures called chelicerae. Chelicerates have no antennae.
Merostomata: Horseshoe crabs
The class Merostomata once included many species, but only four species of horseshoe crab survive today. All are marine. They have five pairs of walking legs an a long, spinelike tail.
Arachnida: Arachinids
The vast majority of anachnids are terrestrial. They have four pairs of walking legs and no tail.
Examples: spiders, ticks, mites, scorpions, daddy longlegs.
Examples: spiders, ticks, mites, scorpions, daddy longlegs.
Uniramia: Uniramians
Most uniramians are terrestrial, although some are aquatic for all part of their lives. They have one pair of antennae, mandibles, and unbranched appendages. Uniramians include at least three fourths of all known animal species!
Uniramians include centipedes, millipedes, and insects- more than three fourths of all known animal species, including this Elephant Hawk Math.
Uniramians include centipedes, millipedes, and insects- more than three fourths of all known animal species, including this Elephant Hawk Math.
Insecta: Insects
There are more than 1,000,000 insect species in more than 25 orders. An insect body is divided into three parts-head, thorax, and abdomen. Insects have three pairs of legs and usually one or two pairs of legs and usually one or two pairs of wings attached to the thorax. Some insects undergo complete metamorphosis.
Examples: termites, ants, beetles, dragonflies, flies, moths, grasshoppers.
The Death's Head Hawk Moth is named for the skull-like shape on the adult's head. Like many insects, this moth undergoes complete metamorphosis, during which the larva, or caterpillar, turns into a pupa, and, eventually, an adult.
Examples: termites, ants, beetles, dragonflies, flies, moths, grasshoppers.
The Death's Head Hawk Moth is named for the skull-like shape on the adult's head. Like many insects, this moth undergoes complete metamorphosis, during which the larva, or caterpillar, turns into a pupa, and, eventually, an adult.
Diplopoda: Millipedes
Millipedes have a long body composed of many segments. Each segment bears two pairs of legs. Most millipedes are herbivorous.
Chilopoda: Centipedes
Centipedes have a long body composed of many segments. Each segment bears one pair of legs. They are carnivorous and have poison claws for capturing prey.