text dict |
|---|
{
"text": "The warm-air vent is placed near the floor of the room. Warm air is less dense than cold air so it rises. If the warm-air vent were placed near the ceiling instead, how would this affect the transfer of thermal energy throughout the room?."
} |
{
"text": "The branch of biology that studies animal behavior is called ethology. Ethologists usually study how animals behave in their natural environment. They try to determine the cause of behaviors, how behaviors develop, and how and why behaviors evolve."
} |
{
"text": "Power may be measured in a unit called the horsepower. One horsepower is the amount of work a horse can do in 1 minute, which equals 745 watts of power."
} |
{
"text": "Cnidarians have an incomplete digestive system with a single opening. The opening is surrounded by tentacles, which are covered with nematocyst cells and used to capture prey. Digestion takes place in the digestive cavity. Nutrients are absorbed and gases are exchanged through the cells lining this cavity.... |
{
"text": "The second equation is equivalent to the first. Voltage is not the same as energy. Voltage is the energy per unit charge. Thus a motorcycle battery and a car battery can both have the same voltage (more precisely, the same potential difference between battery terminals), yet one stores much more energy tha... |
{
"text": "The energy of electromagnetic waves depends on their frequency. Low-frequency waves have little energy and are normally harmless. High-frequency waves have a lot of energy and are potentially very harmful."
} |
{
"text": "There is not just one distinguishing feature that separates a living thing from a non-living thing. A cat moves but so does a car. A tree grows bigger, but so does a cloud. A cell has structure, but so does a crystal. Biologists define life by listing characteristics that living things share. Something tha... |
{
"text": "Another exception to Mendel's laws is a phenomenon called codominance . For example, our blood type shows codominance. Do you know what your blood type is? Are you A? O? AB? Those letters actually represent alleles. Unlike other traits, your blood type has three alleles, instead of two!."
} |
{
"text": "The two stages of photosynthesis are the light reactions and the Calvin cycle. Do you see how the two stages are related?."
} |
{
"text": "There are three main ocean zones based on distance from shore. They are the intertidal zone , neritic zone , and oceanic zone . Distance from shore influences how many nutrients are in the water. Why? Most nutrients are washed into ocean water from land. Therefore, water closer to shore tends to have more ... |
{
"text": "Some regions of the electron cloud are denser than others. The denser regions are areas where electrons are most likely to be. These regions are called orbitals . Each orbital has a maximum of just two electrons. Different energy levels in the cloud have different numbers of orbitals. Therefore, different ... |
{
"text": "6.3 The Laws of Thermodynamics In studying energy, scientists use the term “system” to refer to the matter and its environment involved in energy transfers. Everything outside of the system is called the surroundings. Single cells are biological systems. Systems can be thought of as having a certain amount... |
{
"text": "(a) Initially, the system (a copper penny and concentrated nitric acid) is at atmospheric pressure. (b) When the penny is added to the nitric acid, the volume of NO2 gas that is formed causes the piston to move upward to maintain the system at atmospheric pressure. In doing so, the system is performing wor... |
{
"text": "Some predator species are known as keystone species. A keystone species is one that plays an especially important role in its community. Major changes in the numbers of a keystone species affect the populations of many other species in the community. For example, some sea star species are keystone species ... |
{
"text": "The population growth rate is how fast a population is growing. The letter r stands for the growth rate. The growth rate equals the number of new members added to the population in a year for each 100 members already in the population. The growth rate includes new members added to the population and old me... |
{
"text": "All of the outer planets have numerous moons. They also have planetary rings made of dust and other small particles. Only the rings of Saturn can be easily seen from Earth."
} |
{
"text": "Uranus is a lot like Jupiter and Saturn. The planet is composed mainly of hydrogen and helium. There is a thick layer of gas on the outside. Further on the inside is liquid. But Uranus has a higher percentage of icy materials than Jupiter and Saturn. These materials include water, ammonia, and methane. Ura... |
{
"text": "isolating the individual components, preservationists are better able to determine the condition of an object and those books and documents most in need of immediate protection. The simplest class of organic compounds is the hydrocarbons, which consist entirely of carbon and hydrogen. Petroleum and natural... |
{
"text": "Scientists study meteorites to learn about Earth’s interior. Meteorites formed in the early solar system. These objects represent early solar system materials. Some meteorites are made of iron and nickel. They are thought to be very similar to Earth's core ( Figure below ). An iron meteorite is the closest... |
{
"text": "The trigeminal pathway carries somatosensory information from the face, head, mouth, and nasal cavity. As with the previously discussed nerve tracts, the sensory pathways of the trigeminal pathway each involve three successive neurons. First, axons from the trigeminal ganglion enter the brain stem at the l... |
{
"text": "The amount of kinetic energy in a moving object depends directly on its mass and velocity. An object with greater mass or greater velocity has more kinetic energy. You can calculate the kinetic energy of a moving object with this equation:."
} |
{
"text": "When done regularly, aerobic activities, such as cycling, make the heart stronger. Other aerobic activities include mowing lawn, shoveling snow and cross country skiing."
} |
{
"text": "The story is quite different for gases. Gases take the shape of their container, and they are relatively easy to compress. There are fewer gas particles per unit volume than for the same substance in the liquid or solid form. In fact, the liquid form of a given material is generally several hundred times m... |
{
"text": "Moving air, like moving water, causes erosion. Moving air is called wind."
} |
{
"text": "Group 14 is called the carbon group. This group contains two metalloids: silicon and germanium. Carbon is a nonmetal, and the remaining elements in this group are metals."
} |
{
"text": "The aphotic zone is water deeper than 200 meters. This is where too little sunlight penetrates for photosynthesis to occur. As a result, producers must make \"food\" by chemosynthesis , or the food must drift down from the water above."
} |
{
"text": "Radiation has several important uses, including diagnosing and treating cancer."
} |
{
"text": "Many adults and some children suffer from a deficiency of lactase. These individuals are said to be lactose intolerant because they cannot digest the lactose found in milk. A more serious problem is the genetic disease galactosemia, which results from the absence of an enzyme needed to convert galactose to... |
{
"text": "Because electricity can be so dangerous, safety features are built into modern electric circuits and devices. They include three-prong plugs, circuit breakers, and GFCI outlets. You can read about these three safety features in the Figure below . You can learn more about electric safety features in the hom... |
{
"text": "Catabolic Reactions Catabolic reactions break down large organic molecules into smaller molecules, releasing the energy contained in the chemical bonds. These energy releases (conversions) are not 100 percent efficient. The amount of energy released is less than the total amount contained in the molecule. ... |
{
"text": "Selective precipitation can also be used in qualitative analysis. In this method, reagents are added to an unknown chemical mixture in order to induce precipitation. Certain reagents cause specific ions to precipitate out; therefore, the addition of the reagent can be used to determine whether the ion is p... |
{
"text": "Climate change in Earth history was due to natural processes. Recent global warming is due mainly to human actions. The burning of fossil fuels releases greenhouse gases into the air. This creates greater greenhouse effect and global warming."
} |
{
"text": "The haploid life cycle ( Figure below ) is the simplest life cycle. It is found in many single-celled organisms. Organisms with a haploid life cycle spend the majority of their lives as haploid gametes. When the haploid gametes fuse, they form a diploid zygote. It quickly undergoes meiosis to produce more ... |
{
"text": "Gravity keeps the Moon orbiting Earth. Gravity keeps the planets orbiting the Sun."
} |
{
"text": "Ionic bonds are formed by the attraction between oppositely charged ions."
} |
{
"text": "The hypothalamus also produces hormones that directly regulate body processes. For example, it produces antidiuretic hormone. This hormone travels to the kidneys and stimulates them to conserve water by producing more concentrated urine."
} |
{
"text": "Take a close look at this gorilla hand. The similarities to a human hand are remarkable. Comparing anatomy, and characterizing the similarities and differences, provides evidence of evolution."
} |
{
"text": "What is this intricate orb? It is the greatly magnified skeleton of single-celled ocean organisms call radiolarian. The skeleton is made of an element that is extremely common on Earth. In fact, it is the second most abundant element in Earth’s crust. It is also one of the most common elements in the entir... |
{
"text": "Watch this short video (http://openstaxcollege. org/l/transgenic) explaining how scientists create a transgenic animal. Although the classic methods of studying the function of genes began with a given phenotype and determined the genetic basis of that phenotype, modern techniques allow researchers to star... |
{
"text": "The majority of arthropods are insects (Class Insecta). In fact, more than half of all known organisms are insects. There may be more than 10 million insect species in the world, although most of them have not yet been identified. In terms of their numbers and diversity, insects clearly are the dominant an... |
{
"text": "Obesity With obesity at high rates in the United States, there is a public health focus on reducing obesity and associated health risks, which include diabetes, colon and breast cancer, and cardiovascular disease. How does the food consumed contribute to obesity? Fatty foods are calorie-dense, meaning that... |
{
"text": "Saturn’s composition is similar to Jupiter's. The planet is made mostly of hydrogen and helium. These elements are gases in the outer layers and liquids in the deeper layers. Saturn may also have a small solid core. Saturn's upper atmosphere has clouds in bands of different colors. These clouds rotate rapi... |
{
"text": "Alkenes Organic compounds that contain one or more double or triple bonds between carbon atoms are described as unsaturated. You have likely heard of unsaturated fats. These are complex organic molecules with long chains of carbon atoms, which contain at least one double bond between carbon atoms. Unsatura... |
{
"text": "The two materials do have at least one thing in common. The atoms in the materials are held together by covalent bonds. These bonds consist of electrons shared between two or more atoms. Unlike ionic bonds, where electrons are either lost or gained by an atom to form charged ions, electrons in covalent com... |
{
"text": "Viscosity (η) is the resistance of a liquid to flow. Some liquids, such as gasoline, ethanol, and water, flow very readily and hence have a low viscosity. Others, such as motor oil, molasses, and maple syrup, flow very slowly and have a high viscosity. The two most common methods for evaluating the viscosi... |
{
"text": "Atoms have a mass that is based largely on the number of protons and neutrons in their nucleus."
} |
{
"text": "Annelids called polychaete worms live on the ocean floor. They may be filter feeders, predators, or scavengers. The amazing feather duster worm in Figure below is a polychaete that has a fan-like crown of tentacles for filter feeding."
} |
{
"text": "Biogeography is the study of how and why plants and animals live where they do. It provides more evidence for evolution. Let’s consider the camel family as an example."
} |
{
"text": "Muscles That Position the Pectoral Girdle Muscles that position the pectoral girdle are located either on the anterior thorax or on the posterior thorax (Figure 11.22 and Table 11.8). The anterior muscles include the subclavius, pectoralis minor, and serratus anterior. The posterior muscles include the tra... |
{
"text": "The two major types of seed plants are the gymnosperms (seeds in cones) and angiosperms (seeds in ovaries of flowers). Figure below shows how the seeds of gymnosperms and angiosperms differ. Do you see the main difference between the two seeds? The angiosperm seed is surrounded by an ovary ."
} |
{
"text": "Glucose is the energy-rich product of photosynthesis, a universal food for life. It is also the primary form in which your bloodstream delivers energy to every cell in your body."
} |
{
"text": "The oxygen enters the bloodstream from the alveoli , tiny sacs in the lungs where gas exchange takes place ( Figure below ). The transfer of oxygen into the blood is through simple diffusion."
} |
{
"text": "Fungi are simple eukaryotic organisms that consist of one or more cells. They include mushrooms and yeasts. Human diseases caused by fungi include ringworm and athlete’s foot. Both are skin diseases that are not usually serious. A ringworm infection is pictured below ( Figure below ). A more serious fungus... |
{
"text": "A car’s gas pedal, like the one in Figure below , is sometimes called the accelerator. That’s because it controls the acceleration of the car. Pressing down on the gas pedal gives the car more gas and causes the car to speed up. Letting up on the gas pedal gives the car less gas and causes the car to slow ... |
{
"text": "Bronchitis is an inflammation of the bronchi, the air passages that conduct air into the lungs. The bronchi become red and swollen with infection. Acute bronchitis is usually caused by viruses or bacteria, and may last several days or weeks. It is characterized by a cough that produces phlegm, or mucus. Sy... |
{
"text": "Primates are generally divided into prosimian and non-prosimian primates."
} |
{
"text": "In some places, the oceanic crust comes up to a continent. The moving crust pushes that continent away from the ridge axis as well. If the moving oceanic crust reaches a deep sea trench, the crust sinks into the mantle. The creation and destruction of oceanic crust is the reason that continents move."
} |
{
"text": "Looking at different types of competition, ecologists developed the competitive exclusion principle . The principle states that species less suited to compete for resources will either adapt, move from the area, or die out. In order for two species within the same area to coexist, they may adapt by develop... |
{
"text": "You can follow the operation of an electricity-generating fission reactor in the image above. The reactor core is submerged in a pool of water. The heat from the fission reaction heats the water, which is pumped into a heat exchange container. There the heated water boils the water in the heat exchanger. T... |
{
"text": "A single-replacement reaction is one in which an element replaces another element in a compound. An element is in either the solid, liquid, or gas state and is not an ion. The example below shows the reaction of solid magnesium metal with aqueous silver nitrate to form aqueous magnesium nitrate and silver ... |
{
"text": "Metallic Solids Metals are characterized by their ability to reflect light, called luster, their high electrical and thermal conductivity, their high heat capacity, and their malleability and ductility. Every lattice point in a pure metallic element is occupied by an atom of the same metal. The packing eff... |
{
"text": "Introduction Plants are as essential to human existence as land, water, and air. Without plants, our day-to-day lives would be impossible because without oxygen from photosynthesis, aerobic life cannot be sustained. From providing food and shelter to serving as a source of medicines, oils, perfumes, and in... |
{
"text": "It is estimated that 100 trillion bacteria live in the gut. This is more than the human cells that make up you. It has also been estimated that there are more bacteria in your mouth than people on the planet. There are over 7 billion people on the planet."
} |
{
"text": "Mammals have the ability to regulate body temperature. This is an advantage, as Earth’s climate went through sudden and dramatic changes. Mastodons, saber tooth tigers, hoofed mammals, whales, primates and eventually humans all lived during the Cenozoic Era ( Figure below )."
} |
{
"text": "The majority of the human genome is non-coding sequence. These sequences include regulatory sequences, and DNA with unknown functions. These sequences include tandem repeat elements known as satellite DNA , and transposons. Satellite DNA consists of very large arrays of tandemly repeating, non-coding DNA. ... |
{
"text": "Oceanographers use bathymetric maps to show the features of the bottom of a body of water."
} |
{
"text": "Migration Migration is the long-range seasonal movement of animals. It is an evolved, adapted response to variation in resource availability, and it is a common phenomenon found in all major groups of animals. Birds fly south for the winter to get to warmer climates with sufficient food, and salmon migrate... |
{
"text": "Composite volcanoes are also called stratovolcanoes. This is because they are formed by alternating layers (strata) of magma and ash ( Figure below ). The magma that creates composite volcanoes tends to be thick. The steep sides form because the lava cannot flow too far from the vent. The thick magma may a... |
{
"text": "When geologic and climatic conditions are changing, evolution may occur more quickly. Thus, long periods of little change may be interrupted by bursts of rapid change. This model of the timing of evolution is called punctuated equilibrium . It is better supported by the fossil record than is gradualism."
} |
{
"text": "Chinook winds ( Figure below ) occur when air is forced over a mountain range. Warm air rises over the Sierra Nevada in California, for example, because it is pushed eastward by the westerly winds. The air cools as it rises and precipitates. The air is now dry. It sinks down the far side of the mountains a... |
{
"text": "Clouds block sunlight in the day. Clouds trap heat in the atmosphere at night."
} |
{
"text": "The nervous system is made up of nerves. A nerve is a bundle of nerve cells. A nerve cell that carries messages is called a neuron. The messages carried by neurons are called nerve impulses."
} |
{
"text": "There are several traits shared by all arthropods. Arthropods have a complete digestive system. They also have a circulatory system and a nervous system. In addition, they have special organs for breathing and excreting wastes. Other traits of arthropods include:."
} |
{
"text": "Complex Tissue Structure A hallmark trait of animals is specialized structures that are differentiated to perform unique functions. As multicellular organisms, most animals develop specialized cells that group together into tissues with specialized functions. A tissue is a collection of similar cells that ... |
{
"text": "Most biochemical molecules are macromolecules, meaning that they are very large. Some contain thousands of monomer molecules."
} |
{
"text": "The Spinal Cord The description of the CNS is concentrated on the structures of the brain, but the spinal cord is another major organ of the system. Whereas the brain develops out of expansions of the neural tube into primary and then secondary vesicles, the spinal cord maintains the tube structure and is ... |
{
"text": "Laboratory testing has come to the local drug store or grocery store because of developments in chemistry. You can test your blood glucose using a simple portable device that runs a chemical test on the blood sample and tells you how much glucose is present, allowing a diabetic patient to regulate how much... |
{
"text": "As food is pushed through the GI tract by peristalsis, it undergoes digestion. Digestion is the process of breaking down food into nutrients. There are two types of digestion: mechanical digestion and chemical digestion."
} |
{
"text": "Any useful hypothesis will allow predictions based on reasoning. Reasoning can be broken down into two categories: deduction and induction. Most reasoning in science is formed through induction."
} |
{
"text": "Astronomers use imaging satellites to study and make maps of the Moon and other planets."
} |
{
"text": "Density is an important physical property of matter. It reflects how closely packed the particles of matter are. When particles are packed together more tightly, matter has greater density. Differences in density of matter explain many phenomena, not just why helium balloons rise. For example, differences ... |
{
"text": "Populations of viruses do not grow through cell division because they are not cells. Instead, they use the machinery and metabolism of a host cell to produce new copies of themselves. After infecting a host cell, a virion uses the cell’s ribosomes, enzymes, ATP, and other components to replicate. Viruses v... |
{
"text": "Some parasites kill their host, but most do not. It’s easy to see why. If a parasite kills its host, the parasite is also likely to die. Instead, parasites usually cause relatively minor damage to their host."
} |
{
"text": "An amorphous solid is a solid that lacks an ordered internal structure."
} |
{
"text": "Getting the same result when an experiment is repeated is called replication. If research results can be replicated, it means they are more likely to be correct."
} |
{
"text": "human body system that includes the skin, nails, and hair."
} |
{
"text": "In the chest, the trachea divides as it enters the lungs to form the right and left bronchi . The bronchi contain cartilage, which prevents them from collapsing. Mucus in the bronchi traps any remaining particles in air. Tiny, hair-like structures called cilia line the bronchi and sweep the particles and m... |
{
"text": "Many objects have color because they contain pigments. A pigment is a substance that colors materials by reflecting light of certain wavelengths and absorbing light of other wavelengths. A very common pigment is the dark green pigment called chlorophyll, which is found in plants. Chlorophyll absorbs all bu... |
{
"text": "Craters and rifts become lakes when they fill with water. Where does the water come from?."
} |
{
"text": "Nuclear power is a controversial subject in California and most other places. Nuclear power has no pollutants including no carbon emissions. However, power plants are not always safe. The long-term disposal of wastes is a problem that has not yet been solved. The future of nuclear power is murky. Find out ... |
{
"text": "The esophagus is a long, narrow tube that carries food from the pharynx to the stomach. It has no other purpose. Food moves through the esophagus because of peristalsis. At the lower end of the esophagus, a circular muscle, called a sphincter, controls the opening to the stomach. The sphincter relaxes to l... |
{
"text": "The temperature at which condensation of water vapor occurs is called the dew point. The dew point varies depending on air temperature and moisture content."
} |
{
"text": "Alkenes have double bonds; alkynes have triple bonds. Both undergo addition reactions."
} |
{
"text": "Weathering may concentrate some resources. In tropical climates, chemical weathering can be intense. Some minerals dissolve and water carries them away. This leaves behind the materials that are not soluble. Bauxite is aluminum oxide that collects this way. Bauxite is our main source of aluminum ore."
} |
{
"text": "Several lethal viruses that cause viral hemorrhagic fever have been discovered, two of which are shown in the Figure below . Ebola outbreaks have been limited mainly to remote areas of the world. However, they have gained extensive media attention because of the high mortality rate—23 percent to 90 percent... |
{
"text": "In eukaryotic cells, DNA and RNA synthesis occur in a separate compartment from protein synthesis. In prokaryotic cells, both processes occur together. What advantages might there be to separating the processes? What advantages might there be to having them occur together? The size of the genome in one of ... |
{
"text": "Cell division is simpler in prokaryotes than eukaryotes because prokaryotic cells themselves are simpler. Prokaryotic cells have a single circular chromosome, no nucleus, and few other organelles. Eukaryotic cells, in contrast, have multiple chromosomes contained within a nucleus, and many other organelles... |
{
"text": "The axon of many neurons has an outer layer called a myelin sheath (see Figure above ). Myelin is a lipid produced by a type of a glial cell known as a Schwann cell. The myelin sheath acts like a layer of insulation, similar to the plastic that encases an electrical cord. Regularly spaced nodes, or gaps, i... |
{
"text": "New species arise in the process of speciation. Allopatric speciation occurs when some members of a species become geographically separated. They then evolve genetic differences. If the differences prevent them from interbreeding with the original species, a new species has evolved. Sympatric speciation oc... |
{
"text": "Fossil evidence shows that amphibians evolved about 365 million years ago from a lobe-finned lungfish ancestor. As the earliest land vertebrates, they were highly successful. Some of them were much larger than today’s amphibians. For more than 100 million years, amphibians remained the dominant land verteb... |
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