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L_0016 | groundwater | DD_0009 | The picture shows the groundwater and how it moves. Rivers and lakes hold a lot of Earths liquid freshwater. Twenty times more of Earths liquid freshwater is found below the surface than on the surface. Groundwater (or ground water) is the water present beneath Earth's surface in soil pore spaces and in the fractures of rock formations. A unit of rock or an unconsolidated deposit is called an aquifer when it can yield a usable quantity of water. The depth at which soil pore spaces or fractures and voids in rock become completely saturated with water is called the water table. Groundwater is recharged from, and eventually flows to, the surface naturally. Natural discharge often occurs at springs and seeps, and can form oases or wetlands. Groundwater is also often withdrawn for agricultural, municipal, and industrial use by constructing and operating extraction wells. The study of the distribution and movement of groundwater is hydrogeology, also called groundwater hydrology. | image | teaching_images/aquifers_6510.png |
L_0016 | groundwater | DD_0010 | This diagram depicts how the groundwater is formed. WIth the diagram, we can understand how the groundwater is formed. First, the water is poured down from the cloud to the earth's surface. The water is recharged to the top layer of the earth called piezometric surface. Below the piezometric surface, the layer containing water is called unconfined aquifer. The top level of the unconfined aquifer is called water table level. Under the unconfined aquifer, there is a layer that the water cannot penetrate. We call the layer as impermeable layer. Under the impermeable layer, a thick layer containing water is called confide aquifer. The earth region that supports the confined aquifer is called confining bed. The hole to obtain water in the unconfined aquifer is called artesian bore. | image | teaching_images/aquifers_6524.png |
L_0016 | groundwater | DD_0011 | This diagram shows the structure of groundwater storage in the earth. The top layer of the earth is call unsaturated zone and does not have water stored. The below the unsaturated zone, there is an unconfined aquifer which contains the water closest to the earth surface. The boundary between the unsaturated zone and unconfined aquifer is called water table. The unconfined water layer absorbers the water from the surface and provide the water to the river or to the ground by a pump. The water circulation period in the unconfined aquifer is from days to years. Under the unconfined aquifer, there is a confining bed. Under the confining bed, there is confined aquifer. This is deeper layer than unconfined aquifer and the water returning cycle to the ground is century long. Under the confined aquifer, there is another confining bed. Below the confined aquifer, there is another confined aquifer. The water returning cycle to the ground is millennium long. | image | teaching_images/aquifers_6953.png |
L_0017 | introduction to the oceans | DD_0012 | This diagram represents the layers of the ocean. The oceans are divided into two broad realms; the pelagic and the benthic. Pelagic refers to the open water in which swimming and floating organisms live. Organisms living there are called the pelagos. From the shallowest to the deepest, biologists divide the pelagic into the epipelagic the mesopelagic the bathypelagic the abyssopelagic and the deepest, the hadopelagic. The last three zones have no sunlight at all. The Habitat zone is formed by 5 mini zones: Abbysal, Bathyal, Hadal, Neritic, and Oceanic. One-third of the Earth is made up of the Abbysal zone. It is very cold and dark in this zone. In the Bathyal zone, the food and temperature easily fall into the deepest zones of the ocean. The Hadal zone is the deepest zone in the ocean. It has high-pressure conditions and it's really cold. The Neritic zone is rich in plants, animals, and nutrients that are carried by currents of land. In the Oceanic zone, there is an abundant life of plankton. | image | teaching_images/ocean_zones_7130.png |
L_0017 | introduction to the oceans | DD_0013 | This diagram shows the ocean floor. Like land terrains, the ocean floor also has ridges, valleys, plains and volcanoes. The seabed (also known as the seafloor, sea floor, or ocean floor) is the bottom of the ocean. The oceanic zone begins in the area off shore where the water measures 200 meters (656 feet) deep or deeper. It is the region of open sea beyond the edge of the continental shelf and includes 65% of the ocean's completely open water. The photic zone or sunlight zone is the depth of the water in a lake or ocean that is exposed to such intensity of sunlight which designates compensation point. The aphotic zone is the portion of a lake or ocean where there is little or no sunlight. It is formally defined as the depths beyond which less than 1% of sunlight penetrates. The abyssal zone is the layer of the pelagic zone of the ocean. At depths of 4,000 to 6,000 metres (13,123 to 19,685 feet), this zone remains in perpetual darkness and never receives daylight. The continental shelf is the area of the seabed around a large landmass where the sea is relatively shallow compared with the open ocean. This is geologically part of the continental crust. Studying the ocean floor is difficult because the environment is so hostile but scientists have discovered good ways to study the ocean floor through the years. Some ways are by using a sonar and special vehicles (some of which can even be done remotely). | image | teaching_images/ocean_zones_8125.png |
L_0018 | ocean movements | DD_0014 | The diagram shows the relationship between the moon and tides around Earth. Tides are daily changes in the level of ocean water. They occur all around the globe. High tides occur when the water reaches its highest level in a day. Low tides occur when the water reaches its lowest level in a day. Tides keep cycling from high to low and back again. The main cause of tides is the pull of the Moons gravity on Earth. The pull is the greatest on whatever is closest to the Moon. Although the gravity pulls the land, only the water can move. As a result, a tidal bulge (high tide) is formed due to gravity. Earth itself is pulled harder by the Moons gravity than is the ocean on the side of Earth opposite the Moon. As a result, there is a tidal bulge of water on the opposite side of Earth due to inertia. This creates another high tide. With water bulging on two sides of Earth, there's less water left in between. This creates low tides on the other two sides of the planet. | image | teaching_images/tides_133.png |
L_0018 | ocean movements | DD_0015 | This diagram illustrates the components and behavior of a wave propagating through water. The highest point in a wave is called the Crest, whereas the lowest point is called the Trough. Waves are periodic, meaning they maintain the same pattern as they propagate. The distance from one crest to another is called the Wavelength. The wavelength can also be measured from any point in the wave to the next point at the same elevation. Beneath the wave crests, water molecules tend to move in an orbital path. Two important properties of a wave are its Frequency and Period. The frequency of a wave is related to how fast the wave is moving. Frequency is defined as the number of times a particular point in a wave, say a crest, passes by a given point each second. Period is defined as the time it takes for a wave to move through one wavelength or cycle. | image | teaching_images/ocean_waves_7117.png |
L_0018 | ocean movements | DD_0016 | This diagram represents the different positions of the Sun and moon in relation to the Earth, with two different types of tides. The positions of the Sun and moon affect tides, because the Sun's gravity determines how much influence the moon has on tides. Spring tides occur during new moon and full moon, because the Sun and moon are in a straight line, and their combined gravity causes extreme tides on Earth (high or low). Neap tides happen when the moon is in 1st quarter or third quarter, because since the Sun and moon are not in line here, the gravity is weaker and the tides do not have as great of a range. So, spring tides and neap tides are essentially opposite concepts. As you can see in Diagram A, the light blue area around the Earth represents the amount of tide, and there are extreme highs and lows. In Diagram B, the light blue area is more averaged out around the globe. | image | teaching_images/tides_151.png |
L_0018 | ocean movements | DD_0017 | This is a diagram showing how a mechanical wave moves. The wave travels in the direction from A to B. The number of waves that pass point A in one second is called wave frequency. The time is takes for a wave crest to pass point A and reach point B is called the wave period. The distance from point A to point B is a wavelength, which measures the crest of the first wave to the crest of the second. The trough is the low point of the wave, and the crest is the high point. There are three types of mechanical waves that move through a medium: transverse, longitudinal, and surface. | image | teaching_images/ocean_waves_9152.png |
L_0018 | ocean movements | DD_0018 | This image shows how spring tide occurs, a tide just after a new or full moon, when there is the greatest difference between high and low water. The times and amplitude of tides at a locale are influenced by the alignment of the Sun and Moon. Approximately twice a month, around new moon and full moon when the Sun, Moon, and Earth from a line, the tidal force due to the sun reinforces that due to the Moon. The tide's range is then at its maximum; this is called the spring tide. | image | teaching_images/tides_2614.png |
L_0019 | the ocean floor | DD_0019 | This diagram shows an abbreviated version of underwater landscape. The ground under an ocean gets slowly deeper shortly after passing the beach, which is called the continental shelf. After this it slopes down steadily in the continental slope. After the slop is an abyssal plain, which is significantly deeper but not as deep as a trench-here, there is no sunlight. A volcanic arc comes before an underwater volcano, which forms a volcanic island that may or may not be dormant. A continental slope can also be considered a continental rise if it is seen from the opposite direction. | image | teaching_images/parts_ocean_floor_9206.png |
L_0019 | the ocean floor | DD_0020 | The following diagram is that of an ocean floor. The major features on the ocean floor are continental shelf, continental slope, continental rise and the coast. The continental shelf in the ocean floor is nearest to the edges of continents. It has a gentle slope. The continental slope lies between the continental shelf and the abyssal plain. It has a steep slope with a sharp drop to the deep ocean floor. The abyssal plain forms much of the floor under the open ocean. Magma erupts through the ocean floor to make new seafloor. The magma hardens to create the ridge. | image | teaching_images/parts_ocean_floor_7237.png |
L_0023 | layers of the atmosphere | DD_0021 | The Earth has five different layers in its atmosphere. The atmosphere layers vary by temperature. As the altitude in the atmosphere increases, the air temperature changes. The lowest layer is the troposphere, it gets some of its heat from the sun. However, it gets most of its heat from the Earth's surface. The troposphere is also the shortest layer of the atmosphere. It holds 75 percent of all the gas molecules in the atmosphere. The air is densest in this layer. | image | teaching_images/layers_of_atmosphere_7066.png |
L_0023 | layers of the atmosphere | DD_0022 | The diagram shows the 5 layers of Earth's atmosphere and their relative distance from the Earth's surface. Troposphere is the shortest layer closest to Earth's surface at about 15km away from the surface. The stratosphere is the layer above the troposphere and rises to about 50 kilometers above the surface. The mesosphere is the layer above the stratosphere and rises to about 80 kilometers above the surface. Temperature decreases with altitude in this layer. The thermosphere is the layer above the mesosphere and rises to 500 kilometers above the surface. The International Space Station orbits Earth in this layer. The exosphere is the layer above the thermosphere. This is the top of the atmosphere. | image | teaching_images/layers_of_atmosphere_8102.png |
L_0033 | cycles of matter | DD_0025 | This is a diagram of the nitrogen cycle. Nitrogen is present in the earth's soil, atmoshpere, and biosphere. The amount of nitrogen on the earth is fixed, and it can't be created or destroyed. It can only change the forms it takes in chemical compounds. Nitrogen gas in the atmosphere enters the soil and ocean through t the action of nitrogen fixing bacteria. These bacterial convert nitrogen gas to ammonium, nitrites, and then to nitrates. Once in the soil, these nitrates can enter the terrestrial food web, or return to the atmosphere by the action of denitrifying bacteria. Nitrates in the ocean can the marine ecosystem, or can be converted back to nitrogen gas by denitrifying bacteria. Humans add nitrogen to the soil when they use fertiizers. These fertilizers can enter the marine food web as runoff. | image | teaching_images/cycle_nitrogen_6718.png |
L_0033 | cycles of matter | DD_0026 | The element carbon is the basis of all life on Earth. Biochemical compounds consist of chains of carbon atoms and just a few other elements. Like water, carbon is constantly recycled through the biotic and abiotic factors of ecosystems. The carbon cycle includes carbon in sedimentary rocks and fossil fuels under the ground, the ocean, the atmosphere, and living things. The diagram represents the carbon cycle. It shows some ways that carbon moves between the different parts of the cycle. | image | teaching_images/cycle_carbon_63.png |
L_0033 | cycles of matter | DD_0027 | This is a diagram of the carbon cycle. Carbon is found in all living things on Earth. Carbon is cycled between the living (biotic) and nonliving (abiotic) parts of the ecosystem. Carbon is found in sedimentary rocks and fossil fuels, the atmosphere and in living things. Animals and plants release carbon in the form of carbon dioxide during the process of respiration. Carbon dioxide in the air is taken up by plants during photosynthesis. Photosynthesis produces glucose, a carbohydrate. Glucose is broken down by animals for energy. | image | teaching_images/cycle_carbon_70.png |
L_0033 | cycles of matter | DD_0028 | This diagram shows the carbon cycle. Here are examples of how carbon moves through human, animal, and plant activity. All living things contain carbon, as do the ocean, air, rocks, and underground fossil fuels, which are made in a process that takes millions of years. Plants take in sunlight and carbon dioxide, and create energy through photosynthesis. When they decay, and are buried underground, plants and other organisms turn into fossil fuel. When we burn fossil fuels, carbon dioxide is quickly released into the air. Plants can also release carbon dioxide just like animals do, through respiration. | image | teaching_images/cycle_carbon_5008.png |
L_0033 | cycles of matter | DD_0029 | This is an illustration of the nitrogen cycle. Nitrogen exists in several forms in the earth's soil, atmoshpere, and organisms. The earth has a fixed amount of nitrogen, and is endlessly cycled through these forms in the nitrogen cycle. Animals get their nitrogen directly by eating plants, or indirectly by eating organisms that have eaten plants. Plants can't use the form of nitrogen gas in the air. Plants can only use nitrogen in chemical compounds called nitrates. Plants absorb nitrates from the soil through their roots in a process called assimilation. Most plants use nitrates that are produced by bacteria that live in soil. A certain type of plants called legumes have nitrogen-fixing bacterial living in their roots, and don't need the bacteria in the soil. Bacteria that can change nitrogen gas in the atmosphere to nitrates are called Nitrogen-fixing bacteria. The nitrates in the detritus of organisms have their nitrogen returned to the soil as ammonium by the decomposition action of detrivores. Nitrifying bacteria change some ammonium in the soil into nitrates that can be used by plants. The rest of the ammonium is changed into nitrogen gas by denitrifying bacteria. Denitrifying bacteria convert ammonium to nitrogen gas that is released into the atmoshpere. | image | teaching_images/cycle_nitrogen_6719.png |
L_0047 | air pollution | DD_0030 | This diagram shows the natural ozone destruction. It consists in 3 steps, the first one occurs when the uv radiation shocks the ozone molecule and this one gets divided into the oxygen molecule and the oxygen atom. Then, the ozone molecule is added to the oxygen atom getting as result those oxygen molecules. | image | teaching_images/ozone_formation_7149.png |
L_0048 | effects of air pollution | DD_0031 | This diagram depicts how the acid rain forms. There are factories, vegetation, houses, river and ocean in the picture. Houses and venation is on the earth's surface. First, the acidic gases are emitted from the factories. Those acid gases include sulphur dioxide and nitrogen oxides. The acid gases are included in cloud forming process by wind. The clouds containing acid gases dissolve in rainwater to form the acid rain. The acid rain poured to the earth's surface. The acid rain is absorbed to the earth and is flowing to the river. Now, the river contains the acid rain. The river flows to the ocean. The river of acid rain kills plantlife, pollutes rivers and streams, and erodes stonework. This process continues as long as the factories emit the acid gases. | image | teaching_images/acid_rain_formation_6507.png |
L_0048 | effects of air pollution | DD_0032 | This diagram shows how acid rain is caused by air pollution. Acid rain is mainly caused when air pollutants such as sulphur and nitrogen oxides mix with water vapor in the atmosphere. Nitrogen and sulphur oxides are generated on the earth's surface by man-made sources such as factories. A natural source of nitrogen oxides are volcanoes. These air pollutants generated then move upwards into the earth's atmosphere and get deposited back on the earth as dry or wet deposits. Wet deposits happen when gases and particulate matter mixes with water vapor which causes acid-rain/precipitation. Dry deposits come back to earth in the form of acidic gases and particulate matter. | image | teaching_images/acid_rain_formation_8000.png |
L_0055 | the sun | DD_0033 | This diagram shows the internal structure of the sun. The atmosphere lies on top and has the following layers. The corona is the outermost layer. Then lies the chromosphere, a reddish gaseous layer immediately above the photosphere of the sun or another star which, together with the corona, constitutes its outer atmosphere. The photosphere is about 300 km thick. Most of the Sun's visible light that we see originates from this region. Then lies the convection zone and the radiation zone. Then is the core which is made up of a very hot and dense mass of atomic nuclei and electrons. | image | teaching_images/sun_layers_6305.png |
L_0055 | the sun | DD_0034 | The diagram represents the various parts of the sun. There are three main parts to the Sun's interior: the core, the radiative zone, and the convective zone. The core is at the center. It is the hottest region, where the nuclear fusion reactions that power the Sun occur. Moving outward, next comes the radiative (or radiation) zone. Its name is derived from the way energy is carried outward through this layer, carried by photons as thermal radiation. The third and final region of the solar interior is named the convective (or convection) zone. It is also named after the dominant mode of energy flow in this layer; heat moves upward via roiling convection, much like the bubbling motion in a pot of boiling oatmeal. The boundary between the Sun's interior and the solar atmosphere is called the photosphere. It is what we see as the visible “surface” of the Sun. The photosphere is not like the surface of a planet; even if you could tolerate the heat you couldn't stand on it. The sun has its own atmosphere. The lower region of the solar atmosphere is called the chromosphere. A thin transition region, where temperatures rise sharply, separates the chromosphere from the vast corona above. The uppermost portion of the Sun's atmosphere is called the corona, and is surprisingly much hotter than the Sun's surface (photosphere). | image | teaching_images/sun_layers_6304.png |
L_0056 | the sun and the earthmoon system | DD_0035 | The diagram shows the phases of the moon as it moves in orbit around the earth. Although we can see the moon in the night sky, it does not actually produce its own light. Instead, it reflects the light of the sun onto the earth, much like a mirror would. When the moon is fully lit by the sun, we can see the entire face of the moon. This is called a full moon. However, as the moon moves around its orbit, we see less reflected light due to its changing position. The moon is waning when the reflected surface of the moon is becoming smaller. When we can see only half of the waning moon, we call this the last quarter. When the moon reaches the other side of the earth, it becomes completely dark because the earth blocks the suns light. However, as the moon continues to move around the earth, the suns light will gradually reach the moon again, and the moon reappears in the night sky. The moon is waxing when the reflected surface of the moon is becoming bigger. When we can see half of the waxing moon, we call this the first quarter. The moon will continue to grow until it again becomes a full moon. A full lunar cycle takes about 29.5 days. | image | teaching_images/earth_moon_phases_6008.png |
L_0056 | the sun and the earthmoon system | DD_0036 | This diagram shows 8 phases of the moon. When the side of the moon facing the earth is not illuminated by the Sun the moon phase is called New Moon. When the side of the moon facing the earth is fully lit by the sun, the moon phase is known as Full Moon. The first quarter and last quarter are phases when exactly half of the moon is lit by the sun. The intermediate stages are known as Crescent and Gibbous. | image | teaching_images/earth_moon_phases_2534.png |
L_0056 | the sun and the earthmoon system | DD_0037 | The diagram shows the different phases of moon. The moon does not produce any light of its own. It only reflects light from the sun. As the moon moves around the earth, we see different parts of the moon lit up by the sun. This causes the phases of the moon. A full moon occurs when the whole side facing earth is lit. This happens when earth is between the moon and the sun. About one week later, the moon enters the quarter-moon phase. Only half of the moon's lit surface is visible from earth, so it appears as a half circle. When the moon moves between earth and the sun, the side facing earth is completely dark. This is called the new moon phase. Sometimes you can just barely make out the outline of the new moon in the sky. This is because some sunlight reflects off the earth and hits the moon. Before and after the quarter-moon phases are the gibbous and crescent phases. During the crescent moon phase, the moon is less than half lit. It is seen as only a sliver or crescent shape. During the gibbous moon phase, the moon is more than half lit. It is not full. The moon undergoes a complete cycle of phases about every 29.5 days. | image | teaching_images/earth_moon_phases_2549.png |
L_0056 | the sun and the earthmoon system | DD_0038 | This image shows the different phases of moon. The phases of the Moon are the different ways the Moon looks from Earth over about a month. As the Moon orbits around the Earth, the half of the Moon that faces the Sun will be lit up. The different shapes of the lit portion of the Moon that can be seen from Earth are known as phases of the Moon. A new moon is when the Moon cannot be seen because we are looking at the unlit half of the Moon. A waxing crescent moon is when the Moon looks like crescent and the crescent increases (“waxes”) in size from one day to the next. The first quarter moon (or a half moon) is when half of the lit portion of the Moon is visible after the waxing crescent phase. A waxing gibbous moon occurs when more than half of the lit portion of the Moon can be seen and the shape increases (“waxes”) in size from one day to the next. A full moon is when we can see the entire lit portion of the Moon. A waning gibbous moon occurs when more than half of the lit portion of the Moon can be seen and the shape decreases (“wanes”) in size from one day to the next. The last quarter moon (or a half moon) is when half of the lit portion of the Moon is visible after the waning gibbous phase. A waning crescent moon is when the Moon looks like the crescent and the crescent decreases (“wanes”) in size from one day to the next. | image | teaching_images/earth_moon_phases_139.png |
L_0056 | the sun and the earthmoon system | DD_0039 | Illustrated in the diagram are the 8 different phases of the moon. The moon does not produce its own light. However, the moon becomes visible to us due to its capability to reflect light from the sun. As it moves around the Earth, we see these phases that result from the different angles the moon makes with the sun. A New Moon occurs when the side of the moon facing the earth is not illuminated by the sun. After a few days, a thin crescent shape of the moon becomes visible in the night sky. The crescent moon waxes, or appears to grow fatter, each night. When half of the moon is illuminated, it is called a First Quarter moon. The moon continues to wax, forms a gibbous shape, until it eventually becomes a Full Moon. This now means that the moon has completed one half of a month. During the second half, the shape of the moon starts to wane, growing thinner every night. Once the moon reaches the Third Quarter, it shows the other half of its disc that is illuminated by the sun. It continues to wane while nearing its approach to the New Moon Phase. The Moon undergoes a complete cycle of phases about every 29.5 days. | image | teaching_images/earth_moon_phases_2736.png |
L_0057 | introduction to the solar system | DD_0040 | The diagram shows the Solar System. The Sun and all the objects held by its gravity make up the solar system. There are eight planets in the solar system: Mercury, Venus, Earth, Mars, Jupiter, Saturn, and Neptune. Pluto, Eris, Ceres, Make and Haumea are dwarf planets. The ancient Greeks believed Earth was at the center of the universe and everything else orbited Earth. Copernicus proposed that the Sun at the center of the universe and the planets and stars orbit the Sun. Planets are held by the force of gravity in elliptical orbits around the Sun. The solar system formed from a giant cloud of gas and dust about 4.6 billion years ago. This model explains why the planets all lie in one plane and orbit in the same direction around the Sun. | image | teaching_images/solar_system_1428.png |
L_0057 | introduction to the solar system | DD_0041 | This diagram shows our Solar system. Our solar system consists of an average star we call the Sun, the planets Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto. It includes: the satellites of the planets; numerous comets, asteroids, and meteoroids; and the interplanetary medium. Jupiter is the largest planet and Saturn and Neptune have rings around them. Earth lies after Mercury and Venus. All the planets revolve around the sun. Pluto is the farthest and Mercury is nearest to the sun. | image | teaching_images/solar_system_6293.png |
L_0057 | introduction to the solar system | DD_0042 | There are eight planets in the Solar System. From closest to farthest from the Sun, they are: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. The first four planets are called terrestrial planets. They are mostly made of rock and metal, and they are mostly solid. The last four planets are called gas giants. This is because they are large planets that are mostly made of gas. Even though they are made of gas, they have much more mass than the terrestrial planets. Pluto had been called a planet since it was discovered in 1930, but in 2006 astronomers meeting at the International Astronomical Union decided on the definition of a planet, and Pluto did not fit. Instead they defined a new category of dwarf planet, into which Pluto did fit, along with some others. These small planets are sometimes called plutinos. | image | teaching_images/solar_system_1435.png |
L_0057 | introduction to the solar system | DD_0043 | This diagram shows a few of the objects in our solar system. The first object shown in the upper row is the sun which is a star and is at the center of our solar system. The next three objects are the planets mercury, venus, earth. The objects in the second row are the moon which is the Earth's moon followed by the planets mars, jupiter and saturn. Jupiter is the largest planet. The planet saturn contains rings around it. Mercury is the planet closest to the sun in our solar system. Earth is the planet that we live on. The two planets not shown in this diagram are neptune and pluto. | image | teaching_images/solar_system_6303.png |
L_0068 | types of rocks | DD_0044 | This diagram shows how rocks can change from one type to another when they undergo certain processes. For magma, when it solidifies, it becomes an igneous rock. Igneous rocks can then turn into metamorphic rocks when they undergo metamorphism. They can also turn back into magma when they undergo melting. Otherwise, when igneous rocks go through erosion, they become sediment. Sediment can also be obtained from metamorphic and sedimentary rocks when they undergo erosion, too. Sediments can then undergo lithification to become sedimentary rocks. Sedimentary rocks can also become metamorphic rocks when they undergo metamorphism. And finally, metamorphic rocks can turn into magma when they undergo melting. | image | teaching_images/cycle_rock_6744.png |
L_0068 | types of rocks | DD_0045 | The diagram shows types of rocks and rock formation cycles. There are three major rock types. Rock of these three rock types can become rock of one of the other rock types. All rocks on Earth change, but these changes usually happen very slowly. Some changes happen below Earths surface. Some changes happen above ground. Any type of rock can change and become a new type of rock. Magma can cool and crystallize. Existing rocks can be weathered and eroded to form sediments. Rock can change by heat or pressure deep in Earths crust. There are three main processes that can change rock: Cooling and forming crystals. Deep within the Earth, temperatures can get hot enough to melt rock. This molten material is called magma. As it cools, crystals grow, forming an igneous rock. The crystals will grow larger if the magma cools slowly, as it does if it remains deep within the Earth. If the magma cools quickly, the crystals will be very small. Weathering and erosion. Water, wind, ice, and even plants and animals all act to wear down rocks. Over time they can break larger rocks into smaller pieces called sediments. | image | teaching_images/cycle_rock_6723.png |
L_0068 | types of rocks | DD_0046 | The Rock Cycle illustrates how rocks continually change form. There are three basic types of rocks: igneous, sedimentary and metamorphic, and each of these rocks can be changed into any one of the other types. The names of the rock types refer to the way the rocks are formed. Arrows in the diagram display how one type of rock may change to another type of rock. All igneous rocks start out as melted rock(magma) and then crystallize, or freeze. When an igneous rock is exposed on the surface, it goes through the process of weathering and erosion that breaks the rock down into smaller pieces. Wind and water carry the smaller pieces of igneous rock into piles called sediment. Through the process of compaction and cementation, the sediment gets buried and the pieces of rock become cemented together to form a new type of rock called a sedimentary rock. If a sedimentary rock is exposed at the surface, it can be eroded away and eventually changed into a new sedimentary rock. However, if a sedimentary(or an igneous) rock gets buried deep in the Earth, heat and pressure will cause profound physical and/or chemical change. This process is called metamorphosis, and the new rock is called a metamorphic rock. Metamorphic rock can also be weathered and eroded and eventually changed into a sedimentary rock. Or, if a metamorphic rock is forced deeper into the Earth, the rock can melt and become magma. Igneous rock and sedimentary rock can also be forced deep into the Earth and melt into magma. Once magma cools, it forms igneous rocks again. | image | teaching_images/cycle_rock_6748.png |
L_0076 | continental drift | DD_0054 | The diagram shows the changes of Pangaea, which is a supercontinent of continents on the earth. The left upper sub figure shows the configuration of Pangaea in 200 million years ago. The right upper sub figure shows the configuration of Pangaea in 180 million years ago. The left lower sub figure shows the configuration of Pangaea in 65 million years ago. The right lower sub figure shows the current configuration of Pangea. | image | teaching_images/continental_drift_8043.png |
L_0076 | continental drift | DD_0055 | This diagram shows one of the pillars of Wegener's theory of the previous existence of Pangaea: the localization of fossils. Fossils are the remains or impression of prehistoric animals. Many fossils of the same organisms have been found on widely separated places. Wegener thought the existence of Pangaea allowed movement to said organisms that would be impossible nowadays. The diagram shows the area where some species had lived and the suspected routes allowed by the existence of the supercontinent. | image | teaching_images/continental_drift_8044.png |
L_0076 | continental drift | DD_0056 | The diagram shows how the earth looked according to the continental drift hypothesis. All the continents were fused together as one big land mass called pangaea. Panthalassa was the vast global ocean that surrounded the supercontinent Pangaea. Gondwana is the part of Pangaea that lay in the Southern Hemisphere. Gondwana included most of the landmasses in today's Southern Hemisphere- South America, Africa, India, Australia, and Antarctica. The part of Pangaea that lay in the Northern Hemisphere was called Laurasia. It included most of the present-day North America, Greenland, Europe, and Asia. Tethys Sea was an ocean that existed between the continents of Gondwana and Laurasia. | image | teaching_images/continental_drift_9081.png |
L_0079 | stress in earths crust | DD_0063 | Rocks are present all over earth and sometimes stress causes damage to them. Stress can occur to rocks when force is applied to them. There are four types of rock stresses. They are: confining stress, compression stress, tension stress and shear stress. Confining stress occurs when other rocks push down on a rock below them. Compression stress occurs when rocks are pressed together. Tension stress occurs when rocks are forced apart. Shear stress occurs when two or more rocks are forced in opposite directions. | image | teaching_images/faults_1737.png |
L_0079 | stress in earths crust | DD_0064 | The diagram shows different types of geological faults. Reverse fault is the geologic fault in which the hanging wall has moved upward relative to the footwall. Hanging wall is the block of rock that lies above an inclined fault while footwall is the block of rock that lies on the underside of an inclined fault. Reverse faults occur where two blocks of rock are forced together by compression. Normal fault is the geologic fault in which the hanging wall has moved downward relative to the footwall. Normal faults occur where two blocks of rock are pulled apart, as by tension. Strike-slip fault is the geologic fault in which the blocks of rock on either side of the fault slide horizontally in opposite directions along the line of the fault plane. | image | teaching_images/faults_186.png |
L_0079 | stress in earths crust | DD_0065 | The image below shows different types of faults. A fault is a planar fracture or discontinuity in a volume of rock, across which there has been significant displacement as a result of rock mass movement. Large faults within the Earth's crust result from the action of plate tectonic forces, with the largest forming the boundaries between the plates, such as subduction zones or transform faults. Energy release associated with rapid movement on active faults is the cause of most earthquakes. In strike-slip faults the fault surface is usually near vertical and the footwall moves either left or right or laterally with very little vertical motion. Strike-slip faults with left-lateral motion are also known as sinistral faults. In a normal fault, the block above the fault moves down relative to the block below the fault. This fault motion is caused by tensional forces and results in extension. | image | teaching_images/faults_1747.png |
L_0111 | climate zones and biomes | DD_0073 | The diagram shows a biome pyramid. It consists of four regions: Arctic region, Subarctic region, Temperate region and Tropical region. The Arctic region consists of Tundra. The Subarctic region consists of Boreal forest. The Temperate region consists of Temperate forest, Grassland, Chapparal, and Desert. The Tropical region consists of Tropical forest, Grassland, and Desert. The temperature and the dryness of a place decide its region. As the temperature increases, there is a change in the different regions. The hottest and driest region is the Desert. The coldest and the driest region is the Tundra. The coldest and the least dry region is the Tropical forest. | image | teaching_images/biomes_6557.png |
L_0111 | climate zones and biomes | DD_0074 | This is a map showing ten different biomes and where they can be found in on a world map. A biome is a group of similar ecosystems with the same general abiotic factors and primary producers. The oceans on the map are all classified as marine biomes, while the rivers and lakes are freshwater biomes. The northernmost parts of North America, Europe, and Asia are ice, tundra, and taiga biomes. The central parts of North America, Europe, and Asia are classified as grassland and temperate forest. The southern parts of North America, Europe, and Asia, as well as the northern parts of Africa, are classified as savana, desert, and temperate forest. South America and the south eastern part of Africa are classified as tropical rainforest, desert, and savana. Australia is made up mostly of desert and grassland. Antarctica is entirely iced. | image | teaching_images/biomes_8018.png |
L_0111 | climate zones and biomes | DD_0075 | This is a map showing where different biomes are found around the world. A biome can be defined a group of similar ecosystems with sharing abiotic factors and primary producers. In this map we can see bands of color stretching East to West, showing how similar latitudes often share similar biomes. Near the equator we see deserts and rainforests. In the North we see tundra and taiga. Most of central Europe is temperate broadleaf forest. In USA we see mostly temperate forest in the East, temperate steppe in the middle, and in the West there is a lot of montane forest as well as arid desert. | image | teaching_images/biomes_6562.png |
L_0148 | eclipses | DD_0078 | This diagram shows a lunar eclipse. In a lunar eclipse, the earth lies in between the sun and the moon. The shadow of the Earth can be divided into two distinctive parts: the umbra and penumbra. There is no direct solar radiation within the umbra. However solar illumination is only partially blocked in the outer portion of the Earth's shadow, called the penumbra. This is because of the Sun's large angular size. In this diagram, the moon lies in the umbra of the earth. This leads to a total lunar eclipse. | image | teaching_images/earth_eclipses_1631.png |
L_0148 | eclipses | DD_0079 | This image shows the types of solar eclipses. When a new moon passes directly between the Earth and the Sun, it causes a solar eclipse. When the sun, moon and Earth are lined up, the Moon casts a shadow on the Earth and blocks our view of the Sun. When the Moons shadow completely blocks the Sun, it is a total solar eclipse. If only part of the Sun is out of view, it is a partial solar eclipse. An anular eclipse occurs when the edge of the sun remains visible as a bright ring around the moon. | image | teaching_images/earth_eclipses_4570.png |
L_0148 | eclipses | DD_0080 | The diagram shows the lunar eclipse. The lunar eclipse occurs when the moon passes behind the earth into its umbra region. During the total lunar eclipse, moon travels completely inside the earth's umbra. But in partial lunar eclipse, only a portion of the moon passes through earth's umbra region. When moon passes through earth's penumbra region, it is penumbral eclipsed. Since earth's shadow is large lunar eclipse lasts for hours and anyone with the view of moon can see the eclipse. Partial lunar eclipse occurs at least twice a year but total lunar eclipse is rear. The moon glows with dull red coloring during total lunar eclipse. | image | teaching_images/earth_eclipses_1671.png |
L_0148 | eclipses | DD_0081 | This diagram shows solar eclipse. Moon rotates around the earth on an orbit that is shown in the picture. During solar eclipse, the moon lies between sun and earth so there will be a shadow on earth. Certain regions of earth will be dark due to the shadow of the moon since sun rays do not reach those regions. Moon is smaller than earth so the shadow covers a small region of the earth. The areas marked by Penumbera experience a partial eclipse, while Umbra areas experience full eclipse. | image | teaching_images/earth_eclipses_1654.png |
L_0184 | greenhouse effect | DD_0082 | This diagram illustrates the basic processes behind the greenhouse effect. The greenhouse effect is a natural process that warms the Earth, and, in fact, is quite necessary for our survival. In the shown diagram, arrows display how the greenhouse effect works. Electromagnetic radiation from the Sun passes through the Earths atmosphere. The Earth absorbs these short wavelengths and warms up. Heat is then radiated from the Earth as longer wavelength infrared radiation. Some of this infrared radiation is absorbed by greenhouse gases in the atmosphere. Absorption of heat causes the atmosphere to warm and emit its own infrared radiation. The Earths surface and lower atmosphere warm until they reach a temperature where the infrared radiation emitted back into space, plus the directly reflected solar radiation, balance the absorbed energy coming in from the Sun. The equilibrium of incoming and outgoing radiation is what keeps the Earth warm and habitable. | image | teaching_images/greenhouse_effect_6945.png |
L_0184 | greenhouse effect | DD_0083 | When sunlight heats Earth's surface, some heat radiates back into the atmosphere. Some of this heat is absorbed by gases in the atmosphere. This is the greenhouse effect, and it helps to keep Earth warm. The greenhouse effect also allows Earth to have temperatures that can support life. Gases that absorb heat in the atmosphere are called greenhouse gases. They include carbon dioxide and water vapor mainly and a small amount of methane and ozone as well. Human actions have increased the levels of greenhouse gases in the atmosphere. The diagram here illustrates exactly what is written above. Apart from Earth, in the Solar System, there also greenhouse effects on Mars, Venus, and Titan. Thus, if it were not for greenhouse gases trapping heat in the atmosphere, the Earth would be a very cold place. | image | teaching_images/greenhouse_effect_6940.png |
L_0283 | radioactive decay as a measure of age | DD_0084 | The following diagram provides an example of Alpha Decay, where a Radium atom transforms or decays into a radon atom. Alpha decay is a type of radioactive decay in which an atomic nucleus emits an alpha particle (helium nucleus) and thereby transforms or 'decays' into an atom with a mass number that is reduced by four and an atomic number that is reduced by two. Alpha decay only occurs in very heavy elements such as uranium, thorium and radium. The nuclei of these atoms are very neutron rich (i.e. have a lot more neutrons in their nucleus than they do protons) which makes emission of the alpha particle possible. After an atom ejects an alpha particle, a new parent atom is formed which has two fewer neutrons and two fewer protons. Thus, when Radium-226 decays by alpha emission, Radon-222 is created. | image | teaching_images/radioactive_decay_8173.png |
L_0283 | radioactive decay as a measure of age | DD_0085 | Gamma decay is the process by which the nucleus of an atom emits a high energy photon, that is, extremely short-wavelength electromagnetic radiation. It is one of three major types of radioactivity (the other two being alpha decay and beta decay). Gamma decay is similar to the emission of light (usually visible light) by decay in the orbits of the electrons surrounding the nucleus. In each case the energy states, and the wavelengths of the emitted radiation, are governed by the law of quantum mechanics. But while the electron orbits have relatively low energy, the nuclear states have much higher energy. Gamma decay is a process of emission of gamma rays that accompanies other forms of radioactive decay, such as alpha and beta decay. Nuclei are not normally in excited states, so gamma radiation is typically incidental to alpha or beta decay the alpha or beta decay leaves the nucleus in an excited state, and gamma decay happens soon afterwards. Gamma radiation is the most penetrating of the three kinds. Gamma ray photons can travel through several centimeters of aluminum. | image | teaching_images/radioactive_decay_7517.png |
L_0283 | radioactive decay as a measure of age | DD_0086 | The diagram below shows the beta decay of carbon 14. The carbon-14 nucleus has a neutron within it change into a proton Then we see both a beta minus particle (an electron with high kinetic energy) and an antineutrino ejected from the nucleus. Carbon 14 has two extra neutrons in its nucleus and that is a higher energy configuration and is a bit unstable, so it can release an electron and have a neutron turn into a proton-forming Nitrogen 14 instead, which is more stable. | image | teaching_images/radioactive_decay_8168.png |
L_0287 | revolutions of earth | DD_0087 | The diagram shows different imaginary lines around the earth. At the very north is the north pole and at the very south is the south pole of the earth. An imaginary line around the earth near the north pole is the arctic circle. It is located at 66.5 north of equator. An imaginary line around the earth near the south pole is the Antarctic circle. It is located at 66.5 south of equator. Equator is an imaginary line that goes round the Earth and divides it into two halves. The northern half is called northern hemisphere and the southern half is called southern hemisphere. Tropic of cancer and tropic of Capricorn are the two imaginary lines around the Earth on either side of the equator. The Tropic of Cancer is 23 26 north of it and the Tropic of Capricorn is 23 26 south of it. | image | teaching_images/earth_poles_8061.png |
L_0287 | revolutions of earth | DD_0088 | This Diagram shows the Earth's rotation. Which is the amount of time that it takes to rotate once on its axis. This is, apparently, accomplished once a day every 24 hours. However, there are actually two different kinds of rotation that need to be considered here. For one, there's the amount of time it takes for the Earth to turn once on its axis so that it returns to the same orientation compared to the rest of the Universe. Then there's how long it takes for the Earth to turn so that the Sun returns to the same spot in the sky. Earth's rotation is slowing slightly with time; thus, a day was shorter in the past. This is due to the tidal effects the Moon has on Earth's rotation. Atomic clocks show that a modern-day is longer by about 1.7 milliseconds than a century ago, slowly increasing the rate at which UTC is adjusted by leap seconds. | image | teaching_images/earth_poles_163.png |
L_0291 | rotation of earth | DD_0089 | The diagram shows the rotation of the Earth on its axis and how the Sun illuminates its surface. It helps us understand how day and night work. One rotation takes 24 hours, exactly the length of a day. Dividing the Earth into two parts along the Greenwich meridian, the part facing the Sun is illuminated by the daylight, whereas the other part is in the dark. By rotating, the part of the Earth in the dark ends up receiving the daylight and vice versa. When we say the Sun rises in the east it means that the east is facing the Sun. In the same way the west, which is the part in the dark, is where the Sun sets and the Moon and the stars appear. The changing of day and night is the result of the Earth rotating. | image | teaching_images/earth_day_night_86.png |
L_0291 | rotation of earth | DD_0090 | This diagram shows the earth rotating around its axis and the sun's rays hitting the earth. The side of the earth facing the sun has daylight. The side of the earth facing away from the sun is dark and has night. The earth rotates around its axis, once every 24 hours. Hence every part of the earth experiences day and night every 24 hours. There are 5 major circles of latitude that mark the diagram of the earth. There are the Arctic Circles, Tropic of Cancer, Equator, Tropic of Capricorn and the Antarctic Circle. The arctic circle is the northern most circle and the Antarctic circle is the southern most circle. The equator is the latitude in the middle that divides the earth into the northern and southern hemispheres. The tropic of cancer lies between the Arctic circle and the equator. The tropic of capricorn lies between the Antarctic circle and the equator. | image | teaching_images/earth_day_night_2744.png |
L_0301 | seasons | DD_0091 | The diagram below shows the earth's seasons. During part of the year, Earth is closer to the sun than at other times. However, in the Northern Hemisphere, we are having winter when Earth is closest to the sun and summer when it is the farthest away! Compared with how far away the sun is, this change in Earth's distance throughout the year does not make much difference to our weather's Earth orbits the sun, its tilted axis always points in the same direction. So, throughout the year, different parts of Earth get the suns direct rays. | image | teaching_images/seasons_6279.png |
L_0301 | seasons | DD_0092 | The earth revolves around the sun. Its takes one year to make one full revolution. This diagram shows different configurations of the earth and the sun over the course of one year that lead to the four prominent seasons: spring, summer, fall and winter. Since the earth is inclined at an angle of 23.5 degrees, at certain times of the year, the northern hemisphere gets longer days and shorter nights, which causes the season of summer. At the same time the southern hemisphere gets shorter days and longer nights, which leads to winter. June 21 is the longest day of the year in the Northern hemisphere, and is known as the Summer Solstice in the Northern Hemisphere. December 22 is the shortest day of the year in the Northern Hemisphere and is known as the Winter Solstice in the Northern Hemisphere. | image | teaching_images/seasons_6281.png |
L_0301 | seasons | DD_0093 | The diagram below shows the earth's seasons. During part of the year, Earth is closer to the sun than at other times. However, in the Northern Hemisphere, we are having winter when Earth is closest to the sun and summer when it is the farthest away! Compared with how far away the sun is, this change in Earth's distance throughout the year does not make much difference to our weather. Earth's axis is an imaginary pole going right through the center of Earth from “top” to “bottom.” Earth spins around this pole, making one complete turn each day. That is why we have day and night, and why every part of Earth's surface gets some of each. | image | teaching_images/seasons_647.png |
L_0301 | seasons | DD_0094 | The diagram shows the earth's equinox phenomenon. An equinox is an astronomical event in which the plane of Earth's equator passes through the center of the Sun which occurs twice each year during spring and autumn as shown below. On an equinox, day and night are of “approximately” equal duration all over the planet. The equinoxes, along with solstices, are directly related to the seasons of the year. In the northern hemisphere, the vernal equinox (March) conventionally marks the beginning of spring and is considered the New Year in the Persian calendar or Iranian calendars as Nouroz (means new day). On the other hand, the autumnal equinox (September) marks the beginning of autumn. In the southern hemisphere, the vernal equinox occurs in September and the autumnal equinox in March. | image | teaching_images/seasons_672.png |
L_0362 | the microscope | DD_0097 | The image below shows the different parts of an Optical microscope. The Optical microscope is a type of microscope which uses visible light and a system of lenses to magnify images of small samples. Optical microscopes are the oldest design of microscope and were possibly invented in their present compound form in the 17th century. Basic optical microscopes can be very simple, although there are many complex designs which aim to improve resolution and sample contrast. All modern optical microscopes designed for viewing samples by transmitted light share the same basic components of the light path. In addition, the vast majority of microscopes have the same 'structural' components. The eyepiece, or ocular lens, is a cylinder containing two or more lenses; its function is to bring the image into focus for the eye. The eyepiece is inserted into the top end of the body tube. Eyepieces are interchangeable and many eyepieces can be inserted with different degrees of magnification. | image | teaching_images/parts_microscope_7187.png |
L_0362 | the microscope | DD_0098 | This diagram shows the parts of a compound light microscope. The eyepiece is used to view a microscopic item placed on the stage. It can be used to view cells, bacteria, and small objects like insect wings. When holding a microscope, always use the arm and the base. Handle it carefully, as these are expensive and fragile objects. Use the condenser focus and objective lenses to make the object being viewed clearer. The course focus and fine focus can be used to adjust how close the lenses are to the stage. These focus pieces also make the image clearer. | image | teaching_images/parts_microscope_7193.png |
L_0362 | the microscope | DD_0099 | The diagram shows the anatomy of a microscope. There are two optical systems in a compound microscope: The Ocular Lens and the Objective Lens. Eyepiece or Ocular is what you look through at the top of the microscope. Eyepiece Tube holds the eyepieces in place above the objective lens. Objective Lenses are the primary optical lenses on a microscope. They range from 4x-100x and typically, include, three, four or five on lens on most microscopes. Objectives can be forward or rear-facing. Nosepiece houses the objectives. The objectives are exposed and are mounted on a rotating turret so that different objectives can be conveniently selected. Coarse and Fine Focus knobs are used to focus the microscope. Stage is where the specimen to be viewed is placed. Stage Clips are used when there is no mechanical stage. Aperture is the hole in the stage through which the base (transmitted) light reaches the stage. Illuminator is the light source for a microscope, typically located in the base of the microscope. Condenser is used to collect and focus the light from the illuminator on to the specimen. Iris Diaphragm controls the amount of light reaching the specimen. It is located above the condenser and below the stage. Condenser Focus Knob moves the condenser up or down to control the lighting focus on the specimen. | image | teaching_images/parts_microscope_7174.png |
L_0370 | flatworms and roundworms | DD_0117 | This diagram shows the earthworm anatomy. The segmented body parts provide important structural functions. Segmentation can help the earthworm move. Each segment or section has muscles and bristles called setae. The bristles or setae help anchor and control the worm when moving through soil. The bristles hold a section of the worm firmly into the ground while the other part of the body protrudes forward. The earthworm uses segments to either contract or relax independently to cause the body to lengthen in one area or contract in other areas. Segmentation helps the worm to be flexible and strong in its movement. If each segment moved together without being independent, the earthworm would be stationary. | image | teaching_images/parts_worm_7295.png |
L_0370 | flatworms and roundworms | DD_0118 | Flatworms are invertebrates. They belong to Phylum Platyhelminthes. There are over 25,000 species of flatworms in the world. Not all flatworms are as long as tapeworms. Some are actually only around a millimeter in length. Flatworms reproduce sexually, in most species the individual able to provide both egg and sperm for reproduction. Flatworms go from egg, to larva to adulthood. Flatworm adaptations include mesoderm, muscle tissues, a head region, and bilateral symmetry. Flatworms are free-living heterotrophs or parasites. Roundworms are invertebrates in Phylum Nematoda. Roundworms have a pseudocoelom and complete digestive system. They are free-living heterotrophs or parasites. | image | teaching_images/parts_worm_7321.png |
L_0370 | flatworms and roundworms | DD_0119 | The diagram shows the earthworm's internal anatomy with its key parts and definitions. An earthworm is a tube-shaped, segmented worm found in the phylum Annelida. The body of the earthworm is segmented which looks like many little rings joined or fused together. Segmentation helps the worm to be flexible and strong in its movement. An earthworm's digestive system runs through the length of its body. The digestive system consists of the mouth, the crop, the gut and the gizzard. Earthworms are hermaphrodites where each earthworm contains both male and female sex organs. Some other key features of the earthworm include its brain, which consists of a large cluster of nerve cells connected to a ventral nerve cord which runs the length of the body, and its heart, which is a set of typically five muscular swellings that pump blood through their bodies. | image | teaching_images/parts_worm_7310.png |
L_0375 | fish | DD_0127 | This diagram depicts the anatomy of a fish. Several parts of the fish such as the cheek, gills, fins and guts are shown in the diagram. The gills are present towards the front of the fish and are a respiratory organ for the extraction of oxygen from water and for the excretion of carbon dioxide. There are several types of fins on a fish. The tail fin is located at the end of the fish and is used for propulsion. The pectoral fins are located at the sides of the fish. The pelvic fins are located below the pectoral fins. The dorsal fins are located at the back of the fish whereas the anal fin is located behind the anus, towards the back of the fish. | image | teaching_images/parts_fish_2842.png |
L_0375 | fish | DD_0128 | Here is a diagram of the external parts of a fish. The caudal fin is used for steering. The adipose, anal, and dorsal fins are used for swimming and balance. The pelvic fin helps fish move up and down. The pectoral fin works like a brake, and also helps fish to move left and right. The lateral line is used to detect movement and vibration in the surrounding water. The gill plate/operculum is a flexible bony plate that covers the gills. The preopercle is part of the operculum. The maxillary holds the upper teeth. | image | teaching_images/parts_fish_2913.png |
L_0384 | the integumentary system | DD_0129 | This picture shows the layers and structure of the skin. The skin is made up of two distinct layers called the epidermis and dermis. The upper layer of the skin is called the epidermis. It is thick and tough and forms a protective layer. The epidermis consists of cells that contain a lot of keratin. The cells of the epidermis also contains cells that produce melanin which is the pigment that gives the skin much of its color. Below the epidermis, is the dermis. It is made of tough connective tissue. The dermis contains the hair follicles and sebaceous glands. Hair follicles are structures where hairs originate. Each hair grows out of a follicle, passes up through the epidermis, and extends above the skin surface. Sebaceous glands are commonly called oil glands. They produce an oily substance called sebum. Sebum is secreted into hair follicles. Then it makes its way along the hair shaft to the surface of the skin. Sebum waterproofs the hair and skin and helps prevent them from drying out. The red string like object in the diagram is the arrector pili muscle. It is a small muscle connecting a hair follicle to the dermis that contracts to make the hair stand erect in response to cold or fear. | image | teaching_images/hair_follicles_6986.png |
L_0384 | the integumentary system | DD_0130 | This is the diagram of an active hair follicle. A hair follicle is a mammalian skin organ that produces hair. Hair production occurs in phases, including growth (anagen), cessation (catagen), and rest (telogen) phases. Stem cells are responsible for hair production. The shape of the hair follicle has an effect on the hair shape and texture of the individual's hair. The papilla is a large structure at the base of the hair follicle. The dermal papilla is made up mainly of connective tissue and a capillary loop. Cell division in the papilla is either rare or non-existent. Around the papilla is the germinal matrix. The root sheath is composed of an external and internal root sheath. Other structures associated with the hair follicle include the cup in which the follicle grows known as the sebaceous glands. Hair follicle receptors sense the position of the hair. | image | teaching_images/hair_follicles_6985.png |
L_0384 | the integumentary system | DD_0131 | The image below shows the Layers and structures of the skin. Skin has three layers: The epidermis, the outermost layer of skin, provides a waterproof barrier and creates our skin tone. Below the dermis lies a layer of fat that helps insulate the body from heat and cold, provides protective padding, and serves as an energy storage area. The fat is contained in living cells, called fat cells, held together by fibrous tissue. | image | teaching_images/skin_cross_section_7574.png |
L_0384 | the integumentary system | DD_0132 | The diagram shows the layers and structures of the skin. Skin, glands, hair and nails belong to the Integumentary System. This system serves as a protective barrier that prevents internal body parts from exposure to harmful elements like ultraviolet light, extreme temperature and toxins. The skin covers the entire external surface of the human body and thus, it is the major organ of the Integumentary System. Skin has three main layers: epidermis, dermis and hypodermis. The outermost layer of the skin is the epidermis. There are no blood vessels, nerve endings, or glands in this skin layer. Nonetheless, this layer of skin is very active. It contains melanocytes that produce melanin, a brown pigment which gives the skin its color. Attached under the epidermis is the more complex structure called the dermis. This layer contains nerve endings, blood vessels and two types of glands, the sebaceous and sweat glands. The sweat produced by these glands travels out of the body through a pore on the surface of the skin. Sebaceous glands produce sebum which waterproofs the hair. Hair follicles, where hairs originate, are also found in the dermis. Each hair grows out of a follicle, passes up through the epidermis, and extends above the skin surface. Lastly, the hypodermis is the deepest layer of the skin which contains cells that serve as fat and energy storage for the body's use. | image | teaching_images/skin_cross_section_7589.png |
L_0385 | the skeletal system | DD_0133 | This diagram depicts the human skeleton. The axial skeleton includes the skull, vertebral column, and thoracic cage. The skull consists of 28 bones: 8 cranial vault bones, 14 facial bones, and 6 auditory ossicles. From a lateral view, the parietal, temporal, and sphenoid bones can be seen. From a frontal view, the orbits and nasal cavity can be seen, as well as associated bones and structures, such as the frontal bone, zygomatic bone, maxilla, and mandible. The interior of the cranial vault contains three fossae with several foramina. Seen from below, the base of the skull reveals numerous foramina and other structures, such as processes for muscle attachment. The vertebral column contains 7 cervical, 12 thoracic, and 5 lumbar vertebrae, plus 1 sacral and 1 coccygeal bone. Each vertebra consists of a body, an arch, and processes. Regional differences in vertebrae are as follows: cervical vertebrae have transverse foramina; thoracic vertebrae have long spinous processes and attachment sites for the ribs; lumbar vertebrae have rectangular transverse and spinous processes, and the position of their facets limit rotation; the sacrum is a single, fused bone; the coccyx is four or fewer fused vertebrae. The thoracic cage consists of thoracic vertebrae, ribs, and sternum. There are 12 pairs of ribs: 7 true and 5 false (two of the false ribs are also called floating ribs). The sternum consists of the manubrium, body, and xiphoid process. The appendicular skeleton consists of the bones of the upper and lower limbs and their girdles. The pectoral girdle includes the scapula and clavicle. The upper limb consists of the arm (humerus), forearm (ulna and radius), wrist (eight carpal bones), and hand (five metacarpals, three phalanges in each finger, and two phalanges in the thumb). The pelvic girdle is made up of the sacrum and two coxae. Each coxa consists of an ilium, ischium, and pubis. The lower limb includes the thigh (femur), leg (tibia and fibula), ankle (seven tarsals), and foot (metatarsals and phalanges, similar to the bones in the hand). | image | teaching_images/parts_skeleton_7256.png |
L_0385 | the skeletal system | DD_0134 | The image below shows the Human Skeleton. The human skeleton is the internal framework of the body. It is composed of around 300 bones at birth, this total decreases to 206 bones by adulthood after some bones have fused together. The human skeleton performs six major functions; support, movement, protection, production of blood cells, storage of minerals and endocrine regulation. Bones are the main organs of the skeletal system. Some people think bones are like chalk: dead, dry, and brittle. In reality, bones are very much alive. They consist of living tissues and are supplied with blood and nerves. | image | teaching_images/parts_skeleton_7266.png |
L_0385 | the skeletal system | DD_0135 | This diagram shows some major bones of the human skeletal system. There are 206 bones in a normal human body. The hands and feet contain many those bones--the hand bones are called carpals, metacarpals, and phalanges. The foot bones are called tarsals, metatarsals, and phalanges. The skeletal system has several functions for humans. It gives the body structure and shape. It gives protection to vital organs--for example the skull protects the brain and the ribcage protects the heart and lungs. It helps with movement--muscles attach to the bones and together they help us move. The final function is blood production. Red and white blood cells are made in the bone marrow of the long bones. | image | teaching_images/parts_skeleton_7270.png |
L_0386 | the muscular system | DD_0136 | The diagram shows the huma's body muscular system. Most muscles are attached to bones with tendons. Many muscles derive their name from their anatomical region. For example, the Rectus Abdominis is found in the abdominal region. Other muscles, like the Tibialis Anterior are named after the bone they are attached to, in this case the tibia. Other muscles are classified by form. The Deltoid have a delta or a triangular shape. | image | teaching_images/human_system_muscular_6165.png |
L_0386 | the muscular system | DD_0137 | This diagram shows the structure of human back. The human back is the large posterior area of the human body, rising from the top of the buttocks to the back of the neck and the shoulders. It is the surface opposite to the chest, its height being defined by the vertebral column (commonly referred to as the spine or backbone) and its breadth being supported by the ribcage and shoulders. The spinal canal runs through the spine and provides nerves to the rest of the body. Trapezius is either of a pair of large triangular muscles extending over the back of the neck and shoulders and moving the head and shoulder blade. The triceps brachii muscle is the large muscle on the back of the upper limb of many vertebrates. The latissimus dorsi of the back is the larger, flat, dorso-lateral muscle on the trunk, posterior to the arm. Gluteus is any of three muscles in each buttock which move the thigh, the largest of which is the gluteus maximus. | image | teaching_images/human_system_muscular_6166.png |
L_0386 | the muscular system | DD_0138 | The diagram shows the entire muscular system of the human body. Muscles are the main organs of the muscular system. Their main function is movement of the body. Muscles are the only tissue in our bodies that can contract and therefore move the other parts of the body. They are composed primarily of muscle fibers. Many muscles derive their name from their anatomical region. The rectus abdominis, for example, is found in the abdominal region. A function of the muscular system is to produce body heat. As a result of contraction, our muscular system produces waste heat. | image | teaching_images/human_system_muscular_6159.png |
L_0386 | the muscular system | DD_0139 | This diagram depicts the structure of muscle cells. Muscle cells are also known as muscle fibers. The diagram illustrates components such as striated myofibrils, which is exclusive to that kind of cell. Myofibrils consist of filaments. There are thin filaments and thick filaments. Each cell is covered by a plasma membrane sheath which is called the sarcolemma. Tunnel-like extensions from the sarcolemma pass through the muscle fibre from one side of it to the other in transverse sections through the diameter of the fibre. The cell contains sarcoplasm, which is the cytoplasm of muscle cells. | image | teaching_images/muscle_fiber_7082.png |
L_0386 | the muscular system | DD_0140 | This diagram represents the structure of a skeletal muscle. Each skeletal muscle fiber is a single cylindrical muscle cell. Each muscle is surrounded by a connective tissue sheath called the epimysium. Fascia, connective tissue outside the epimysium, surrounds and separates the muscles. Portions of the epimysium project inward to divide the muscle into compartments. Each compartment contains a bundle of muscle fibers. Each bundle of muscle fiber is called a fasciculus and is surrounded by a layer of connective tissue called the perimysium. Within the fasciculus, each individual muscle cell, called a muscle fiber, is surrounded by connective tissue called the endomysium. The connective tissue covering furnish support and protection for the delicate cells and allow them to withstand the forces of contraction. The coverings also provide pathways for the passage of blood vessels and nerves. Commonly, the epimysium, perimysium, and endomysium extend beyond the fleshy part of the muscle, the belly or gaster, to form a thick ropelike tendon or a broad, flat sheet-like aponeurosis. The tendon and aponeurosis form indirect attachments from muscles to the periosteum of bones or to the connective tissue of other muscles. | image | teaching_images/muscle_fiber_7083.png |
L_0389 | the digestive system | DD_0141 | Below is a diagram of the digestive system. The digestive system, as you can see, is made up of several organs and parts of the body. The digestive system breaks down food and absorbs nutrients into your body. The mouth is the first digestive organ that food enters, and the saliva starts the digestion of the food. The esophagus is the long narrow tube that carries food from the oral cavity to the stomach. The stomach stores the food until the small intestine is empty. The liver and gallbladder produce and store other secretions from the food. For instance, the liver produces bile secretions. The large intestine is where the food enters after it leaves the small intestine, and the large intestine is connected to the anus. The anus is where the body releases the food as waste (feces.) | image | teaching_images/human_system_digestive_3675.png |
L_0389 | the digestive system | DD_0142 | This diagram shows major organs and general functions of the digestive system. The digestive system is the body system that breaks down food and absorbs nutrients. It also eliminates solid food wastes that remain after food is digested. It has several organs such as the liver, stomach, pancreas, colon and intestines. Food enters the digestive system through the mouth and exits the system through the anus. In the stomach, chemicals called enzymes change the food into smaller molecules that the body can use. The pancreas is the part of the digestive system that produces important enzymes and hormones that help break down foods. It is located in the abdominal cavity behind the stomach. In the small intestine, our bodies absorb the nutrients from our food. Finally, colon mixes the solid waste material with water so we can easily eliminate it from our bodies through the anus. | image | teaching_images/human_system_digestive_6091.png |
L_0389 | the digestive system | DD_0143 | This diagram shows the digestive system in humans. Each part of the system plays an important role--although some organs such as the gallbladder can be removed without causing any long term effects on the person. The mouth is the beginning of the digestive process. This is where mechanical breakdown occurs--the teeth, tongue, and saliva break down the food so it can travel down the esophagus more easily. The purpose of the esophagus is to move the food down the digestive tract. The stomach mixes the food with enzymes and continues the breakdown. The intestines continue the breakdown and move the food to the rectum. The duodenum is the first part of the small intestine. It is also the shortest part. This is where most chemical digestion takes place. It then moves to the large intestine and then finally the rectum. The rectum is where the remaining food waste leaves the body. | image | teaching_images/human_system_digestive_3678.png |
L_0389 | the digestive system | DD_0144 | The diagram shows the human digestive system. It has several organs such as the liver, stomach, pancreas and intestines. Food enters the digestive system through the mouth and exits the system through the anus. The esophagus is a long tube that connects the mouth and the stomach. In the stomach, chemicals called enzymes change the food into smaller molecules that the body can use. The pancreas is the part of the digestive system that produces important enzymes and hormones that help break down foods. It is located in the abdominal cavity behind the stomach. In the small intestine, our bodies absorb the nutrients from our food. Finally, the large intestine mixes the solid waste material with water so we can easily eliminate it from our bodies through the anus. Overall, there are 9 main organs in the Digestive system. | image | teaching_images/human_system_digestive_3679.png |
L_0390 | overview of the cardiovascular system | DD_0145 | This diagram shows the cross-section of the human heart. The human heart is divided into the left and right halves. The heart has an upper chamber called the atrium and a lower chamber called the ventricle in each half. The red arrows show oxygenated blood coming from the lungs into the left atrium which then flows into the left ventricle and leaves the heart through the aorta. The blue arrows show deoxygenated blood coming to the heart from the through the anterior and posterior vena cava, flows through the right atrium, right ventricle and enters into the lungs. | image | teaching_images/human_system_circulatory_3648.png |
L_0390 | overview of the cardiovascular system | DD_0146 | The diagram shows the different components that make up the heart. The heart is the key organ in the circulatory system. As a hollow, muscular pump, its main function is to propel blood throughout the body. The septum is the wall of muscle divides it down the middle, into a left half and a right half. There are 4 chambers in the heart: top chamber is called atrium; bottom chambers are called ventricles. Blood can flow from the atrium to ventricle because of openings called valves. Valves open in one direction like trapdoors to let the blood pass through, then they close, so the blood cannot flow backwards into the atria. There are also valves at the bottom of the large arteries that carry blood away from the heart: the aorta and the pulmonary artery. These valves keep the blood from flowing backward into the heart once it has been pumped out. Blood vessels of the body carry blood in a circle: moving away from the heart in arteries, traveling to various parts of the body in capillaries, and going back to the heart in veins. All the blood from the body is eventually collected into the two largest veins: the superior vena cava, which receives blood from the upper body, and the inferior vena cava, which receives blood from the lower body region. | image | teaching_images/human_system_circulatory_6068.png |
L_0390 | overview of the cardiovascular system | DD_0147 | The diagram shows the circulatory system. It is the system that circulates blood and lymph through the body consisting of the heart, blood vessels, blood, lymph, and the lymphatic vessels and glands. Arterial circulation is the part of your circulatory system that involves arteries, like the aorta and pulmonary arteries. Arteries are blood vessels that carry blood away from your heart. (The exception is the coronary arteries, which supply your heart muscle with oxygen-rich blood.) Venous circulation is the part of your circulatory system that involves veins, like the vena cavae and pulmonary veins. Veins are blood vessels that carry blood to your heart. Veins have thinner walls than arteries. | image | teaching_images/human_system_circulatory_1379.png |
L_0393 | the respiratory system | DD_0148 | The diagram shows the structures of the respiratory system. They include the nose, trachea, lungs, and diaphragm. The diaphragm is a large, sheet-like muscle below the lungs. When you inhale, air enters the respiratory system through your nose and ends up in your lungs, where gas exchange with the blood takes place. In the nose, mucus and hairs trap any dust or other particles in the air. The air is also warmed and moistened so it wont harm delicate tissues of the lungs. Next, air passes through the pharynx, a passageway that is shared with the digestive system. From the pharynx, the air passes next through the larynx, or voice box. After the larynx, air moves into the trachea, or wind pipe. This is a long tube that leads down to the lungs in the chest. In the chest, the trachea divides as it enters the lungs to form the right and left bronchi (bronchus, singular). These passages are covered with mucus and tiny hairs called cilia. The mucus traps any remaining particles in the air. The cilia move and sweep the particles and mucus toward the throat so they can be expelled from the body. Air passes from the bronchi into smaller passages called bronchioles. The bronchioles end in clusters of tiny air sacs called alveoli (alveolus, singular). The alveoli in the lungs are where gas exchange between the air and blood takes place. Shown also is the rib (or ribs) the protect the lungs and other vital organs within the chest. | image | teaching_images/human_system_respiratory_6195.png |
L_0393 | the respiratory system | DD_0149 | The diagram shows the structures of the human respiratory system which is a series of organs responsible for taking in oxygen and expelling carbon dioxide. There are 3 major parts of the respiratory system: the airway, the lungs, and the muscles of respiration. The airway includes the nose, mouth, pharynx, larynx, trachea, bronchi, and bronchioles. In this diagram, we focus on the functions of the nose, mouth, trachea, lungs, and diaphragm. The nose is the primary opening for the respiratory system, made of bone, muscle, and cartilage. The nasal cavity is a cavity within your nose filled with mucus membranes and hairs. Also called the oral cavity, the mouth is the secondary exterior opening for the respiratory system. Most commonly, the majority of respiration is achieved via the nose and nasal cavity, but the mouth can be used if needed. Also known as the wind pipe, the trachea is a tube made of cartilage rings that are lined with pseudo-stratified ciliated columnar epithelium. The lungs work together with the other parts of the respiratory system to allow oxygen in the air to be taken into the body while also enabling the body to get rid of carbon dioxide in the air breathed out. The diaphragm is an important muscle of respiration which is situated beneath the lungs. It contracts to expand the space inside the thoracic cavity, whilst moving a few inches inferiorly into the abdominal cavity. | image | teaching_images/human_system_respiratory_3749.png |
L_0393 | the respiratory system | DD_0150 | This image shows the parts of the human respiratory system. Respiration involves taking in air filled with oxygen into the human body or lungs and releasing carbon dioxide from the body. Respiration involves breathing through the nose/nasal cavity. The air then travels down into the lungs through the pharynx, followed by the larynx and finally through the trachea. The lungs are located in the chest cavity or thoracic cavity along with the heart. The chest cavity are covered by ribs on the outside. The pleura lines the thoracic cavity and envelopes the lungs. The trachea is subdivided into two bronchi before it enters the lungs. The bronchi are further divided into tiny bronchioles inside the lungs. The bronchioles have a tree like structure. The lungs are separated from the abdominal cavity by the diaphragm. The diaphragm contracts while breathing in and relaxes when breathing outs. The process of respiration is controlled by the respiratory centers located in the brain. | image | teaching_images/human_system_respiratory_1327.png |
L_0393 | the respiratory system | DD_0151 | The diagram shows the parts of the respiratory system. The human respiratory system is a series of organs responsible for taking in oxygen and expelling carbon dioxide. As we breathe, oxygen enters the nose or mouth and passes the sinuses, which are hollow spaces in the skull. Sinuses help regulate the temperature and humidity of the air we breathe. The trachea, also called the windpipe, filters the air that is inhaled, according to the American Lung Association. It branches into the bronchi, which are two tubes that carry air into each lung. The bronchial tubes are lined with tiny hairs called cilia. Cilia move back and forth, carrying mucus up and out. Mucus, a sticky fluid, collects dust, germs and other matter that has invaded the lungs. We expel mucus when we sneeze, cough, spit or swallow. | image | teaching_images/human_system_respiratory_3601.png |
L_0398 | the nervous system | DD_0152 | This diagram depicts the parts of a neuron. A neuron is a basic building block of the nervous system that is responsible for receiving and transmitting information. Dendrites are treelike extensions at the beginning of a neuron that help increase the surface area of the cell body. The cell body is where the signals from the dendrites are joined and passed on. The nucleus is present within the cell body. It produces RNA that supports important cell functions. The axon is the elongated fiber that connects the cell body to the axon endings and transmits the neural signal. The axon is often covered with a fatty substance called the myelin sheath that acts as an insulator. | image | teaching_images/parts_neuron_7232.png |
L_0398 | the nervous system | DD_0153 | The diagram below shows the human nervous system. The nervous system conducts stimuli from sensory receptors to the brain and spinal cord and that conducts impulses back to other parts of the body. As with other higher vertebrates, the human nervous system has two main parts: the central nervous system (the brain and spinal cord) and the peripheral nervous system (the nerves that carry impulses to and from the central nervous system). The nervous system consists of the brain, spinal cord, sensory organs, and all the nerves that connect these organs with the rest of the body. Together, these organs are responsible for the control of the body and communication among its parts. The brain and spinal cord from the control center known as the central nervous system. | image | teaching_images/human_system_nervous_6184.png |
L_0398 | the nervous system | DD_0154 | This diagram shows the structure of a cell. It has the cell body, dived into the dendrite, nucleus, and also the axon. Other parts of the cell are the myelin sheath, node of Ranvier and lastly the synaptic know | image | teaching_images/parts_neuron_7206.png |
L_0398 | the nervous system | DD_0155 | This is a diagram of the anatomy of a brain. The brain is made up of several parts, as you can see in the picture. The brain has four lobes. The frontal lobe is used for the basic purpose of reasoning. The parietal lobe is used for the sense, touch. The temporal lobe is used for hearing. The occipital lobe is used for sight. The cerebellum is the next largest part of the brain. It controls body position, coordination, and balance. | image | teaching_images/human_system_nervous_6178.png |
L_0398 | the nervous system | DD_0156 | The diagram shows the anatomy of a multipolar neutron. A multipolar neuron (or multipolar neurone) is a type of neuron that possesses a single (usually long) axon and many dendrites, allowing for the integration of a great deal of information from other neurons. These dendritic branches can also emerge from the nerve cell body. Multipolar neurons constitute the majority of neurons in the brain and include motor neurons and interneurons. It is found majority in the cerebral cortex. The nerve endings of an axon don't actually touch the dendrites of other neurons. The messages must cross a tiny gap between the two neurons, called the synapse. There are two types of synaptic cells: presynaptic and postsynaptic. The presynaptic cell is the neuron sending the signal. The postsynaptic cell is the structure receiving the signal. | image | teaching_images/parts_neuron_7230.png |
L_0398 | the nervous system | DD_0157 | The diagram shows the various parts of the human brain. The three main parts of the brain are the cerebrum, cerebellum and medula. The cerebrum is divided down the middle from the front to the back of the head. The two halves of the cerebrum are called the right and left hemispheres. Each hemisphere is further subdivided into lobes which are shown in this diagram. The lobes shown are frontal lobe, parietal lobe, temporal lobe and occipital lobe. The cerebrum is the largest part of the brain, the next largest part is the cerebellum. The spinal cord is a long, tube-shaped bundle of neurons. Cererbum controls conscious functions, such as thinking, sensing, speaking, and voluntary muscle movements. Cerebellum controls body position, coordination, and balance. The main function of the spinal cord is to carry nerve impulses back and forth between the body and brain. | image | teaching_images/human_system_nervous_2864.png |
L_0399 | the senses | DD_0158 | Below is a diagram of the ear. The ear is made up of several parts, as shown in the diagram. Sound waves travel through the ear. Sound waves enter the auditory canal. Then they travel to the ear drum where it sends the vibrations from the sound waves to the inner ear. The sound waves then liquify and go into the cochlea. They then travel through the ear nerves, and is sent to the brain. | image | teaching_images/human_system_ear_2866.png |