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Ciencias naturales ¶

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Inicio. Atlas de Histología Vegetal y Animal. Bienvenid@s Éste es un sitio web dedicado a la biología celular y a la histología de plantas y animales. Las páginas web están pensadas para que sirvan de apoyo a estudiantes de enseñanzas medias y universitarios, así como a cualquier persona interesada en estos temas. El sitio web está organizado en secciones, y éstas están ordenadas de manera secuencial para facilitar la comprensión de los diferentes temas. Sin embargo, se puede consultar cada una de ellas libremente, sin seguir necesariamente el orden establecido en la página. Nuestro deseo es que sirva como herramienta docente y como lugar donde se pueda aprender a conocer a la célula eucariota y cómo se organiza para formar tejidos, y últimamente a los organismos.

Todo el contenido de este sitio se publica bajo licencia Creative-Commons: by-nc-sa. In Images: A 'Google Maps' for the Mouse Brain. Tiny slices Credit: Allen Institute for Brain Science Researchers recently created a type of Google Maps for the mouse brain. The project, called the Allen Mouse Common Coordinate Framework, began with 234,500 individual sections from 1,675 whole mouse brains. These were collected as part of the Allen Mouse Brain Connectivity Atlas. An average brain A computer program then averaged all 1,675 specimens into a single 3D image, which then became the archetypal average mouse brain for the project.

Not your average mouse Here, one view of this average mouse brain. Glowing brain cells Next, anatomists painstakingly tracked fluorescently labeled neurons to identify boundaries between brain regions. The team then created an antomical model that revealed the boundary regions in the mouse brain, shown here in different colors. Detailed brain regions Another view of the boundaries between brain regions in a mouse, as defined by data from the Allen Brain Atlas Mouse Connectivity project. Anatomical structure. Foraging. Plant Identification. La struttura del DNA - Lezione animata. Tree of Life Web Project. The Tree of Life Web Project (ToL) is a collaborative effort of biologists and nature enthusiasts from around the world. On more than 10,000 World Wide Web pages, the project provides information about biodiversity, the characteristics of different groups of organisms, and their evolutionary history (phylogeny).

Each page contains information about a particular group, e.g., salamanders, segmented worms, phlox flowers, tyrannosaurs, euglenids, Heliconius butterflies, club fungi, or the vampire squid. ToL pages are linked one to another hierarchically, in the form of the evolutionary tree of life. Starting with the root of all Life on Earth and moving out along diverging branches to individual species, the structure of the ToL project thus illustrates the genetic connections between all living things.

Opinion: Why Finding Water on Mars Matters. Today's NASA announcement challenges our other assumptions about the universe. By Jared Petty Most of my life I’ve taken the hostility of outer space for granted. Textbooks and teachers taught me about an acidic atmosphere on Venus, bone-crushing gravity on Jupiter, frigid darkness on Pluto, and the arid, dead stone of the Martian wastes. I remember standing in the Smithsonian as a child staring at the lifeless landscapes photographed by the Viking missions, red rocky deserts stretching on to the edge of forever.

That image cemented an idea which I accepted for a long time to be a matter of fact, that Mars was an inhospitable, empty rock spinning through space. Got feedback on our player? We want to hear it. The facts did not change, of course...water has long flowed on Mars whether we knew about it or not. The international scientific community has long embraced the possibility of interstellar life.

Is there life on Mars? NASA Discovers Evidence for Liquid Water on Mars. For years, scientists have known that Mars has ice locked away within its rusty exterior. More elusive, though, is figuring out how much of that water is actually sloshing around in liquid form. Now, NASA scientists have found compelling evidence that liquid water—life-giving, gloriously wet H 20—exists on Mars. We’re not talking gushing rivers or oceans here.

These scientists have been investigating “recurring slope lineae,” patches of precipitated salt that appear to dribble down Mars’ steep slopes like tears rolling gently down a cheek. Ojha and his team have watched these lineae form every Martian summer, growing wider week after week until they slowly fade come winter—exactly the times and places where conditions are right for liquid water to exist on Mars. Ojha notes that they haven’t actually observed water flowing on Mars. Still, the water left a distinctive chemical trace. The team doesn’t know where the water is coming from, or how much of it there is yet. Quetzalcoatlus. Quetzalcoatlus northropi /kɛtsəlkoʊˈætləs/ is a pterosaur known from the Late Cretaceous of North America (Maastrichtian stage) and one of the largest-known flying animals of all time.

It is a member of the family Azhdarchidae, a family of advanced toothless pterosaurs with unusually long, stiffened necks. Its name comes from the Mesoamerican feathered serpent god, Quetzalcoatl. Description[edit] Size[edit] Size comparison of Q. northropi (green), Q. sp (blue), and a human. When it was first named as a new species in 1975, scientists estimated that the largest Quetzalcoatlus fossils came from an individual with a wingspan as large as 15.9 m (52 ft), choosing the middle of three extrapolations from the proportions of other pterosaurs that gave an estimate of 11 m, 15.5 m, and 21 m, respectively (36 ft, 50.85 ft, 68.9 ft). Skull[edit] Skull reconstruction of Q. sp. Skull material (from smaller specimens, possibly a related species) shows that Quetzalcoatlus had a very sharp and pointed beak. Richard Dawkins El Gen Egoista. Confirmed by science: You really can change your DNA - and here's how.

Geologic & Evolutionary History of Earth. Natural science. Domains, Species Kingdoms etc.