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Scientists have built machines called particle accelerators. These amazing tools smash particles that are smaller than atoms into each other head-on. This creates new particles. Scientists use particle accelerators to learn about nuclear fusion in stars. They can also learn about how atoms came together in the early universe. Two well-known accelerators are SLAC, in California, and CERN, in Switzerland.
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The abiotic factors, such as the amount of rainfall and the temperature, are going to influence other abiotic factors, such as the quality of the soil. This, in turn, is going to influence the plants that migrate into the ecosystem and thrive in that biome. Recall that migration is the movement of an organism into or out of a population. It can also refer to a whole new species moving into a habitat . The type of plants that live in a biome are going to attract a certain type of animal to that habitat. It is the interaction of the abiotic and biotic factors that describe a biome and ecosystem. In aquatic biomes, abiotic factors such as salt, sunlight and temperature play significant roles.
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Currents also flow deep below the surface of the ocean. Deep currents are caused by differences in density at the top and bottom. More dense water takes up less space than less dense water. It has the same mass but less volume. Water that is more dense sinks. Less dense water rises. What can make water more dense?.
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Mollusks have a hard outer shell. There is a layer of tissue called the mantle between the shell and the body.
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Roots are covered with thin-walled dermal cells and tiny root hairs. These features are well suited to absorb water and dissolved minerals from the soil.
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The Heart The heart is a complex muscle that consists of two pumps: one that pumps blood through pulmonary circulation to the lungs, and the other that pumps blood through systemic circulation to the rest of the body’s tissues (and the heart itself). The heart is asymmetrical, with the left side being larger than the right side, correlating with the different sizes of the pulmonary and systemic circuits (Figure 16.10). In humans, the heart is about the size of a clenched fist; it is divided into four chambers: two atria and two ventricles. There is one atrium and one ventricle on the right side and one atrium and one ventricle on the left side. The right atrium receives deoxygenated blood from the systemic circulation through the major veins: the superior vena cava, which drains blood from the head and from the veins that come from the arms, as well as the inferior vena cava, which drains blood from the veins that come from the lower organs and the legs. This deoxygenated blood then passes to the right ventricle through the tricuspid valve, which prevents the backflow of blood. After it is filled, the right ventricle contracts, pumping the blood to the lungs for reoxygenation. The left atrium receives the oxygen-rich blood from the lungs. This blood passes through the bicuspid valve to the left ventricle where the blood is pumped into the aorta. The aorta is the major artery of the body, taking oxygenated blood to the organs and muscles of the body. This pattern of pumping is referred to as double circulation and is found in all mammals. (Figure 16.10).
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Lung cancer is a disease in which the cells found in the lungs grow out of control. The growing mass of cells can form a tumor that pushes into nearby tissues. The tumor will affect how these tissues work. Lung cancer is the most common cause of cancer-related death in men, and the second most common in women. It is responsible for 1.3 million deaths worldwide every year ( Figure below ). The most common symptoms are shortness of breath, coughing (including coughing up blood), and weight loss. The most common cause of lung cancer is exposure to tobacco smoke.
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Potassium Potassium is the major intracellular cation. It helps establish the resting membrane potential in neurons and muscle fibers after membrane depolarization and action potentials. In contrast to sodium, potassium has very little effect on osmotic.
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Protein A large part of protein digestion takes place in the stomach. The enzyme pepsin plays an important role in the digestion of proteins by breaking down the intact protein to peptides, which are short chains of four to nine amino acids. In the duodenum, other enzymes— trypsin, elastase, and chymotrypsin—act on the peptides reducing them to smaller peptides. Trypsin elastase, carboxypeptidase, and chymotrypsin are produced by the pancreas and released into the duodenum where they act on the chyme. Further breakdown of peptides to single amino acids is aided by enzymes called peptidases (those that break down peptides). Specifically, carboxypeptidase, dipeptidase, and aminopeptidase play important roles in reducing the peptides to free amino acids. The amino acids are absorbed into the bloodstream through the small intestines. The steps in protein digestion are summarized in Figure 34.17 and Table 34.6.
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The rate of decay of a radioactive substance is constant over time.
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Terrestrial ecosystems, also known for their diversity, are grouped into large categories called biomes. A biome is a largescale community of organisms, primarily defined on land by the dominant plant types that exist in geographic regions of the planet with similar climatic conditions. Examples of biomes include tropical rainforests, savannas, deserts, grasslands, temperate forests, and tundras. Grouping these ecosystems into just a few biome categories obscures the great diversity of the individual ecosystems within them. For example, the saguaro cacti (Carnegiea gigantean) and other plant life in the Sonoran Desert, in the United States, are relatively diverse compared with the desolate rocky desert of Boa Vista, an island off the coast of Western Africa (Figure 20.3).
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The modern day formulation of gun powder is called black powder. It is still commonly used today. Its formulation is still quite similar to what was used in 9 th century China. Black powder is considered a low explosive. It is a mixture that burns quickly, but the resulting shock wave travels at subsonic speeds. The speed at which it burns is dependent on the accessibility of oxygen atoms to the carbon source. In contrast, high explosives like nitroglycerin detonate instead of burning, creating shock waves that are supersonic (faster than the speed of sound).
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An organ is a structure composed of two or more types of tissues that work together to do a specific task. Most modern plants have several organs that help them survive and reproduce in a variety of habitats. Major organs of most plants include roots, stems, and leaves. These and other plant organs generally contain all three major tissue types.
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