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Chemical remediation can also treat water in the aquifer. A chemical is pumped into the aquifer. The chemical destroys the contaminant. | sciq |
Ocean acidification occurs when excess carbon dioxide in the atmosphere causes the oceans to become acidic. Burning fossil fuels has led to an increase in carbon dioxide in the atmosphere. This carbon dioxide is then absorbed by the oceans, which lowers the pH of the water. Ocean acidification can kill corals and shell... | sciq |
To move blood through the heart, the cardiac muscle needs to contract in an organized way. Blood first enters the atria ( Figure below ). When the atria contract, blood is pushed into the ventricles. After the ventricles fill with blood, they contract, and blood is pushed out of the heart. The heart is mainly composed ... | sciq |
5. Assume a molecule must cross the plasma membrane into a cell. The molecule is a very large protein. How will it be transported into the cell? Explain your answer. | sciq |
Physical science explains much of what you observe and do in your daily life. In fact, you depend on physical science for almost everything that makes modern life possible. You couldn’t drive a car, text message, or send a tweet without decades of advances in chemistry and physics. You wouldn’t even be able to turn on ... | sciq |
Most of the energy used by living things comes either directly or indirectly from the sun. Sunlight provides the energy for photosynthesis . This is the process in which plants and certain other organisms (see Figure below ) synthesize glucose (C 6 H 12 O 6 ). The process uses carbon dioxide and water and also produces... | sciq |
Water is truly an amazing substance. It can exist in all three states under normal pressures and temperatures. At room temperature, it is a tasteless, odorless, colorless liquid, although it exhibits a blue hue when present in large volumes. Approximately 70% of the Earth’s surface is covered in water. For a small mole... | sciq |
28.4 Maternal Changes During Pregnancy, Labor, and Birth Hormones (especially estrogens, progesterone, and hCG) secreted by the corpus luteum and later by the placenta are responsible for most of the changes experienced during pregnancy. Estrogen maintains the pregnancy, promotes fetal viability, and stimulates tissue ... | sciq |
The energy yield and the types of energy produced by nuclear bombs can be varied. Energy yields in current arsenals range from about 0.1 kT to 20 MT, although the Soviets once detonated a 67 MT device. Nuclear bombs differ from conventional explosives in more than size. Figure 32.34 shows the approximate fraction of en... | sciq |
There are almost 120 known elements. As you can see from Figure below , the majority of elements are metals. Examples of metals are iron (Fe) and copper (Cu). Metals are shiny and good conductors of electricity and heat. Nonmetal elements are far fewer in number. They include hydrogen (H) and oxygen (O). They lack the ... | sciq |
The image below shows the role of the atmosphere in the water cycle ( Figure below ). Water vapor rises from Earth’s surface into the atmosphere. As it rises, it cools. The water vapor may then condense into water droplets and form clouds. If enough water droplets collect in clouds, they may come together to form dropl... | sciq |
As plant cells have some structural differences compared to an animal cell, an additional stage prior to prophase is necessary. In plant cells only, prophase is preceded by a preprophase stage. Plant cells have a large central vacuole encompassing the center of the cell. Prior to the division of the nucleus, the nucleu... | sciq |
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After birds lay their eggs, they generally keep the eggs warm with their body heat while the embryos inside continue to develop. This is called incubation, or brooding . In most species, parents stay together for at least the length of the breeding season. In some species, they stay together for life. By staying togeth... | sciq |
Slump is the sudden movement of large blocks of rock and soil down a slope. You can see how it happens in Figure below . All the material moves together in big chunks. Slump may be caused by a layer of slippery, wet clay underneath the rock and soil on a hillside. Or it may occur when a river undercuts a slope. Slump l... | sciq |
organ system that brings oxygen into the body and releases carbon dioxide into the atmosphere. | sciq |
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Birds have a relatively large, four-chambered heart. The heart beats rapidly to keep oxygenated blood flowing to muscles and other tissues. Hummingbirds have the fastest heart rate at up to 1,200 times per minute. That’s almost 20 times faster than the human resting heart rate!. | sciq |
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We use several kinds of formulas to describe organic compounds. A molecular formula shows only the kinds and numbers of atoms in a molecule. For example, the molecular formula C4H10 tells us there are 4 carbon atoms and 10 hydrogen atoms in a molecule, but it doesn’t distinguish between butane and isobutane. A structur... | sciq |
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There are three temperature scales that are commonly used. Their units are °F (degrees Fahrenheit), °C (degrees Celsius), and K (Kelvin). | sciq |
Many plants respond to the days growing shorter in the fall by going dormant. They suspend growth and development in order to survive the extreme coldness and dryness of winter. Part of this response causes the leaves of many trees to change color and then fall off (see Figure below ). Dormancy ensures that plants will... | sciq |
All substances are made of atoms. Atoms are the smallest particles of matter. They cannot be divided into smaller particles. They also cannot be created or destroyed. | sciq |
Bacteria play important roles in the nitrogen cycle. They change nitrogen gas and products of decomposition into nitrates, which plants can assimilate. Animals obtain nitrogen by eating plants or other organisms. Still other bacteria return nitrogen gas to the atmosphere. | sciq |
Hydrophobic molecules “like” to be near other hydrophobic molecules. They “fear” being near hydrophilic molecules. The opposite is true of hydrophilic molecules. They “like” to be near other hydrophilic molecules. They “fear” being near hydrophobic molecules. These “likes” and “fears” explain why some molecules can pas... | sciq |
Both types of lymphocytes are produced in the red bone marrow. They are named for the sites where they grow larger. The "B" in B cells stands for “bone. ” B cells grow larger in red bone marrow. The "T" in T cells stands for “thymus. ” T cells mature in the thymus gland. | sciq |
The name of a simple covalent compound can be determined from its chemical formula. | sciq |
Asteroids are very small, irregularly shaped, rocky bodies. Asteroids orbit the Sun, but they are more like giant rocks than planets. Since they are small, they do not have enough gravity to become round. They are too small to have an atmosphere. With no internal heat, they are not geologically active. An asteroid can ... | sciq |
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Solid carbon dioxide is called dry ice because it does not pass through the liquid phase. Instead, it does directly to the gas phase. (Carbon dioxide can exist as liquid but only under high pressure. ) Dry ice has many practical uses, including the long-term preservation of medical samples. | sciq |
Ecosystems need a constant input of energy for their organisms, but matter is recycled through ecosystems. | sciq |
Most mercury compounds decompose when heated. Most mercury compounds contain mercury with a 2+-oxidation state. When there is a large excess of mercury, it is possible to form compounds containing the Hg 2 2+ ion. All mercury compounds are toxic, and it is necessary to exercise great care in their synthesis. | sciq |
In reality, most animal behaviors are not controlled by nature or nurture. Instead, they are influenced by both nature and nurture. In dogs, for example, the tendency to behave toward other dogs in a certain way is probably controlled by genes. However, the normal behaviors can’t develop in an environment that lacks ot... | sciq |
The n = 1 shell is completely filled in a helium atom. The next atom is the alkali metal lithium with an atomic number of 3. The first two electrons in lithium fill the 1s orbital and have the same sets of four quantum numbers as the two electrons in helium. The remaining electron must occupy the orbital of next lowest... | sciq |
This window screen has a fly on it. In a way, the window screen is like a cell membrane. It lets some things pass through while keeping other things out. Air molecules and raindrops can pass through the screen, but larger objects like the fly cannot. In the first lesson of this chapter, you'll learn about different way... | sciq |
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In an individual carrying an abnormal number of X chromosomes, cellular mechanisms will inactivate all but one X in each of her cells. As a result, X-chromosomal abnormalities are typically associated with mild mental and physical defects, as well as sterility. If the X chromosome is absent altogether, the individual w... | sciq |
Most of Earth’s water is salt water in the oceans. As Figure below shows, only 3 percent of Earth’s water is fresh. Freshwater is water that contains little or no dissolved salt. Most freshwater is frozen in ice caps and glaciers. Glaciers cover the peaks of some tall mountains. For example, the Cascades Mountains in N... | sciq |
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Hertz also studied the reflection, refraction, and interference patterns of the electromagnetic waves he generated, verifying their wave character. He was able to determine wavelength from the interference patterns, and knowing their frequency, he could calculate the propagation speed using the equation υ = fλ (velocit... | sciq |
Specific antigens on the surface of red blood cells determine blood type. The best-known blood types are ABO and Rhesus (Rh) blood types. Blood type is important in cases of blood transfusion. A patient must receive blood of his or her own blood type to avoid clumping of red blood cells. | sciq |
Extrusive igneous rocks cool at the surface. Volcanoes are one type of feature that forms from extrusive rocks. Several other interesting landforms are also extrusive features. Intrusive igneous rocks cool below the surface. These rocks do not always remain hidden. Rocks that formed in the crust are exposed when the ro... | sciq |
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What is the function of a phosphatase? a. A phosphatase removes phosphorylated amino acids from proteins. A phosphatase removes the phosphate group from phosphorylated amino acid residues in a protein. A phosphatase phosphorylates serine, threonine, and tyrosine residues. A phosphatase degrades second messengers in the... | sciq |
Hypothalamic-Pituitary Axis The hypothalamus in vertebrates integrates the endocrine and nervous systems. The hypothalamus is an endocrine organ located in the diencephalon of the brain. It receives input from the body and other brain areas and initiates endocrine responses to environmental changes. The hypothalamus ac... | sciq |
Freshwater biomes have water that contains little or no salt. They include standing and running freshwater biomes. Standing freshwater biomes include ponds and lakes. Lakes are generally bigger and deeper than ponds. Some of the water in lakes is in the aphotic zone where there is too little sunlight for photosynthesis... | sciq |
You probably know that the wires strung between these high towers carry electricity. But do you know what electricity is? It actually consists of a constant stream of tiny particles called electrons. Electrons are negatively charged fundamental particles inside atoms. Atoms were discovered around 1800, but almost 100 y... | sciq |
If a solution has a higher concentration of hydronium ions than pure water, it has a pH lower than 7. A solution with a pH lower than 7 is called an acid . As the hydronium ion concentration increases, the pH value decreases. Therefore, the more acidic a solution is, the lower its pH value is. Did you ever taste vinega... | sciq |
Laura Guerin. The sensory division of the peripheral nervous system interprets signals, while the motor division sends signals . CC BY-NC 3.0. | sciq |
After each mass extinction, new species develop to fill the habitats where old species lived. This is well documented in the fossil record. | sciq |
Kidney dialysis is the process of filtering wastes from the blood using a machine. | sciq |
Summary The tendency of an element to lose or gain electrons is one of the most important factors in determining the kind of compounds it forms. Periodic behavior is most evident for ionization energy (I), the energy required to remove an electron from a gaseous atom. The energy required to remove successive electrons ... | sciq |
A tissue is a group of connected cells that have a similar function within an organism. More complex organisms such as jellyfish, coral, and sea anemones have a tissue level of organization. For example, jellyfish have tissues that have separate protective, digestive, and sensory functions. Though most animals have man... | sciq |
The particles that make up matter are also constantly moving. They have kinetic energy. The theory that all matter consists of constantly moving particles is called the kinetic theory of matter . You can learn more about it at the URL below. | sciq |
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common name of a plant-like protist, which contains chloroplasts and makes food by photosynthesis. | sciq |
Blood pressure is written as systolic/diastolic. For example, a reading of 120/80 is said as "one twenty over eighty. " These measures of blood pressure can change with each heartbeat and over the course of the day. Pressure varies with exercise, emotions, sleep, stress, nutrition, drugs, or disease. | sciq |
You already know that evolution is the change in species over time. Most evolutionary changes are small and do not lead to the creation of a new species. When populations change in small ways over time, the process is called microevolution . Microevolution results in changes within a species. | sciq |
Birds often use flashy displays to attract mates. | sciq |
The earliest continental crust is now found in the ancient cores of continents, called the cratons . Geologists can learn many things about the Precambrian by studying the rocks of the cratons. | sciq |
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Short-period comets come from the Kuiper belt, beyond Neptune. Long-period comets come from the very distant Oort cloud. | sciq |
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Atoms with unstable nuclei are radioactive. To become more stable, the nuclei undergo radioactive decay. In radioactive decay, the nuclei emit energy and usually particles of matter as well. There are several types of radioactive decay, including alpha, beta, and gamma decay. Energy is emitted in all three types of dec... | sciq |
On land, sulfur is deposited in four major ways: precipitation, direct fallout from the atmosphere, rock weathering, and geothermal vents (Figure 20.17). Atmospheric sulfur is found in the form of sulfur dioxide (SO2), and as rain falls through the atmosphere, sulfur is dissolved in the form of weak sulfuric acid (H2SO... | sciq |
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