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Genetic drift is a random change in allele frequencies that occurs in a small population. When a small number of parents produce just a few offspring, allele frequencies in the offspring may differ, by chance, from allele frequencies in the parents. | allenai/sciq |
Aerobic exercise helps improve the cardiovascular system, while anaerobic exercise causes muscles to get bigger and stronger. | allenai/sciq |
Vertebral Column Developmental anomalies, pathological changes, or obesity can enhance the normal vertebral column curves, resulting in the development of abnormal or excessive curvatures (Figure 7.21). Kyphosis, also referred to as humpback or hunchback, is an excessive posterior curvature of the thoracic region. This... | allenai/sciq |
The two main divisions of the human nervous system are the central nervous system and the peripheral nervous system. The peripheral nervous system has additional divisions. | allenai/sciq |
DNA Double-Helical Structure DNA has a double-helical structure (Figure 2.23). It is composed of two strands, or polymers, of nucleotides. The strands are formed with bonds between phosphate and sugar groups of adjacent nucleotides. The strands are bonded to each other at their bases with hydrogen bonds, and the strand... | allenai/sciq |
As for all animals, your body is made of four types of tissue: epidermal, muscle, nerve, and connective tissues. Plants, too, are built of tissues, but not surprisingly, their very different lifestyles derive from different kinds of tissues. All three types of plant cells are found in most plant tissues. Three major ty... | allenai/sciq |
(a) A jet airplane flying from Darwin, Australia, has an air speed of 260 m/s in a direction 5.0º south of west. It is in the jet stream, which is blowing at 35.0 m/s in a direction 15º south of east. What is the velocity of the airplane relative to the Earth? (b) Discuss whether your answers are consistent with your e... | allenai/sciq |
Rolling friction is friction that acts on objects when they are rolling over a surface. Rolling friction is much weaker than sliding friction or static friction. This explains why most forms of ground transportation use wheels, including bicycles, cars, 4-wheelers, roller skates, scooters, and skateboards. Ball bearing... | allenai/sciq |
Traditionally, mammals were divided into groups based on their characteristics. Scientists took into consideration their anatomy (body structure), their habitats, and their feeding habits. Mammals are divided into three subclasses and about 26 orders. Some of the groups of mammals include:. | allenai/sciq |
Alkanes contain only carbon-carbon single bonds. | allenai/sciq |
Lymph that collects in tissues slowly passes into tiny lymph vessels. Lymph then travels from smaller to larger lymph vessels. Muscles around the lymph vessels contract and squeeze the lymph through the vessels. The lymph vessels also contract to help move the lymph along. Eventually, lymph reaches the main lymph vesse... | allenai/sciq |
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27.5 Single Slit Diffraction Light passing through a single slit forms a diffraction pattern somewhat different from those formed by double slits or diffraction gratings. Figure 27.21 shows a single slit diffraction pattern. Note that the central maximum is larger than those on either side, and that the intensity decre... | allenai/sciq |
Forest and Kim Starr/Starr Environmental. Whisk ferns have yellow sporangia and no leaves . CC BY 3.0. | allenai/sciq |
The atmosphere is an exchange pool for water. Ice masses, aquifers, and the deep ocean are water reservoirs. | allenai/sciq |
The generation of electricity is critical for the operation of nearly all aspects of modern society. The following diagram illustrates the types of fuels used to generate electrical power in the Unites States. In 2009, almost 45% of the power generated in the U. S. was derived from coal, with natural gas making up anot... | allenai/sciq |
Not so fast. The mesosphere is the least known layer of the atmosphere. The mesosphere lies above the highest altitude an airplane can go. It lies below the lowest altitude a spacecraft can orbit. Maybe that's just as well. If you were in the mesosphere without a space suit, your blood would boil! This is because the p... | allenai/sciq |
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7.2 | Glycolysis By the end of this section, you will be able to: • Describe the overall result in terms of molecules produced in the breakdown of glucose by glycolysis • Compare the output of glycolysis in terms of ATP molecules and NADH molecules produced You have read that nearly all of the energy used by living cel... | allenai/sciq |
Atoms, which are always neutral in electric charge, contain electrons as well as protons and neutrons. An electron has an electrical charge of -1. If an atom has three electrons, infer how many protons it has. | allenai/sciq |
The pleura that surrounds the lungs consists of two layers, the ________. visceral and parietal pleurae. mediastinum and parietal pleurae. visceral and mediastinum pleurae. none of the above 14. Which of the following processes does atmospheric pressure play a role in? a. pulmonary ventilation b. production of pulmonar... | allenai/sciq |
Fungi are heterotrophs, meaning they obtain food from outside themselves. | allenai/sciq |
The girls in the picture above make up a small sample—there are only four of them. In scientific investigations, samples may include hundreds or even thousands of people or other objects of study. Especially when samples are very large, it’s important to be able to summarize their overall characteristics with a few num... | allenai/sciq |
The cell wall grows toward the center of the cell. The cytoplasm splits apart, and the cell pinches in two. This is called cytokinesis . | allenai/sciq |
deep sea trenches : Trenches are found in the sea. Some are near the edges of continents. Trenches are found near chains of active volcanoes. An example is the line of the very deepest blue, off of western South America. | allenai/sciq |
Skeletal muscle tissue forms skeletal muscles, which attach to bones and sometimes the skin and control locomotion and any other movement that can be consciously controlled. Because it can be controlled intentionally, skeletal muscle is also called voluntary muscle. When viewed under a microscope, skeletal muscle tissu... | allenai/sciq |
When sunlight heats Earth’s surface, some of the 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 allows Earth to have temperatures that can support life. | allenai/sciq |
Igneous rocks are classified by composition and texture. The composition can be felsic, intermediate, mafic, or ultramafic. The composition depends on the minerals the rock includes. A felsic rock will contain felsic minerals. | allenai/sciq |
Photosynthesis is the base of nearly all food chains on Earth. This is true of marine food chains, too. | allenai/sciq |
part of a vertebrate endoskeleton that encloses and protects the brain; also called the skull. | allenai/sciq |
The global pattern of precipitation is influenced by movements of air masses. For example, there is a global belt of dry air masses and low precipitation at about 30° N and 30° S latitude. | allenai/sciq |
Imagine a huge bar magnet passing through Earth’s axis, as in the Figure below . This is a good representation of Earth as a magnet. Like a bar magnet, Earth has north and south magnetic poles. A magnetic pole is the north or south end of a magnet, where the magnet exerts the most force. | allenai/sciq |
There are four major forces of evolution that cause allele frequencies to change. They are mutation, gene flow, genetic drift, and natural selection. | allenai/sciq |
A neutron is one of three main particles that make up the atom. It is found in the nucleus and is neutral in electric charge. It has about the same mass and diameter as a proton. Neutrons are found in all atoms except for most atoms of hydrogen. | allenai/sciq |
No doubt you already have a good idea of what temperature is. You might say that it’s how warm or cool something feels. In physics, temperature is defined as the average kinetic energy of the particles of matter. When particles of matter move more quickly, they have more kinetic energy, so their temperature is higher. ... | allenai/sciq |
They have lots of mitochondria. Mitochondria are called the power plants of the cell, as these organelles are where most of the cell's energy is produced. Cells that need lots of energy have lots of mitochondria. | allenai/sciq |
22.4 Gas Exchange The behavior of gases can be explained by the principles of Dalton’s law and Henry’s law, both of which describe aspects of gas exchange. Dalton’s law states that each specific gas in a mixture of gases exerts force (its partial pressure) independently of the other gases in the mixture. Henry’s law st... | allenai/sciq |
Secretory Vesicles contain materials that are to be excreted from the cell, such as wastes or hormones . Secretory vesicles include synaptic vesicles and vesicles in endocrine tissues. Synaptic vesicles store neurotransmitters. They are located at presynaptic terminals in neurons. When a signal reaches the end of an ax... | allenai/sciq |
The Celsius scale is the standard SI temperature scale. It is equal to the Kelvin scale if you minus 273 from the Celsius reading. Water has a boiling point of and a freezing point of . | allenai/sciq |
Hemoglobin Hemoglobin is a large molecule made up of proteins and iron. It consists of four folded chains of a protein called globin, designated alpha 1 and 2, and beta 1 and 2 (Figure 18.7a). Each of these globin molecules is bound to a red pigment molecule called heme, which contains an ion of iron (Fe2+) (Figure 18.... | allenai/sciq |
Assume that some members of a species become geographically separated from the rest of the species. If they remain separated long enough, they may evolve genetic differences. If the differences prevent them from interbreeding with members of the original species, they have evolved into a new species. Speciation that oc... | allenai/sciq |
A body that is lying down is described as either prone or supine. Prone describes a face-down orientation, and supine describes a face up orientation. These terms are sometimes used in describing the position of the body during specific physical examinations or surgical procedures. | allenai/sciq |
A: Energy is released when an atom gains an electron. Halogens release the most energy when they form ions. As a result, they are very reactive elements. | allenai/sciq |
Oxygen has an oxidation state of -2 in most of its compounds. Oxygen is the second most electronegative element, so it also tends to be assigned all shared electrons. Exceptions include O 2 (oxidation state = 0), peroxides, in which two oxygen atoms are connected by a single bond (oxidation state usually = -1), and any... | allenai/sciq |
Coevolution occurs when species evolve together. This often happens in species that have symbiotic relationships. Examples include flowering plants and their pollinators. | allenai/sciq |
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The trachea , or wind pipe, is a long tube that leads down to the chest. | allenai/sciq |
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The ear canal is a tube that carries sound waves into the ear. The sound waves travel through the air inside the ear canal to the eardrum. | allenai/sciq |
The blood vessels are an important part of the cardiovascular system. They connect the heart to every cell in the body. Arteries carry blood away from the heart, while veins return blood to the heart ( Figure below ). | allenai/sciq |
pressure above the liquid. Molecules in the gas phase can collide with the liquid surface and reenter the liquid via condensation. Eventually, a steady state is reached in which the number of molecules evaporating and condensing per unit time is the same, and the system is in a state of dynamic equilibrium. Under these... | allenai/sciq |
Right Atrium The right atrium serves as the receiving chamber for blood returning to the heart from the systemic circulation. The two major systemic veins, the superior and inferior venae cavae, and the large coronary vein called the coronary sinus that drains the heart myocardium empty into the right atrium. The super... | allenai/sciq |
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When we consider a chemical reaction, we need to take into account both the system and the surroundings. The system includes the components involved in the chemical reaction itself. These will often take place in a flask, a beaker, a test tube, or some other container. The surroundings include everything that is not pa... | allenai/sciq |
Two unique features of mollusks are the mantle and radula (see Figure above ). The mantle is a layer of tissue that lies between the shell and the body. It secretes calcium carbonate to form the shell. It forms a cavity, called the mantle cavity, between the mantle and the body. The mantle cavity pumps water for filter... | allenai/sciq |
Some of the largest, and most beautiful, natural crystals can be found in the Naica mine, in Mexico. These gypsum crystals were formed over thousands of years. Groundwater that is rich in calcium and sulfur flowed through an underground cave. Check it out:. | allenai/sciq |
Plants are the primary producers in terrestrial biomes. They make food for themselves and other organisms by photosynthesis. The major plants in a given biome, in turn, help determine the types of animals and other organisms that can live there. | allenai/sciq |
Birds also have wings that function as an aerofoil . The surface of the aerofoil is curved to help the bird control and use the air currents to fly. Aerofoils are also found on the wings of airplanes. | allenai/sciq |
Summary Four quantities must be known for a complete physical description of a sample of a gas: temperature, volume, amount, and pressure. Pressure is force per unit area of surface; the SI unit for pressure is the pascal (Pa), defined as 1 newton per square meter (N/m2). The pressure exerted by an object is proportion... | allenai/sciq |
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Inside of elements, you will find identical atoms. An atom is the simplest and smallest particle of matter that still has chemical properties of the element. Atoms are the building block of all of the elements that make up the matter in your body or any other living or non-living thing. Atoms are so small that only the... | allenai/sciq |
All waves can be defined in terms of their frequency and intensity. | allenai/sciq |
Monotremes can lay eggs, but most mammals give birth to live young. | allenai/sciq |
It’s much easier to precisely make mirrors than to precisely make glass lenses. For that reason, reflectors can be made larger than refractors. Larger telescopes can collect more light. This means that they can study dimmer or more distant objects. The largest optical telescopes in the world today are reflectors. Teles... | allenai/sciq |
Ionic bonding typically occurs when it is easy for one atom to lose one or more electrons and another atom to gain one or more electrons. However, some atoms won’t give up or gain electrons easily. Yet they still participate in compound formation. How? There is another mechanism for obtaining a complete valence shell: ... | allenai/sciq |
http://www. chem. ufl. edu/~itl/2045/lectures/lec_d. html. | allenai/sciq |
Earthquakes can cause tsunamis . These deadly ocean waves may result from any shock to ocean water. A shock could be a meteorite impact, landslide, or a nuclear explosion. But most come from large underwater earthquakes. | allenai/sciq |
A desmosome is a cell junction specialized for cell-to-cell adhesion. They are found in simple and stratified squamous epithelium, and in muscle tissue where they bind muscle cells to one another. These junctions are composed of complexes of cell surface adhesion proteins and linking proteins. These proteins have both ... | allenai/sciq |
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Fission is a type of radioactivity in which large nuclei spontaneously break apart into smaller nuclei. | allenai/sciq |
Bones are the main organs of the skeletal system. The skeletal system also includes cartilage and ligaments. | allenai/sciq |
Below the topsoil is the “B“ horizon. This is also called the subsoil . Soluble minerals and clays accumulate in the subsoil. Because it has less organic material, this layer is lighter brown in color than topsoil. It also holds more water due to the presence of iron and clay. There is less organic material in this lay... | allenai/sciq |
The difference between the daily high and the daily low is the tidal range. | allenai/sciq |
Germ Cells The least mature cells, the spermatogonia (singular = spermatogonium), line the basement membrane inside the tubule. Spermatogonia are the stem cells of the testis, which means that they are still able to differentiate into a variety of different cell types throughout adulthood. Spermatogonia divide to produ... | allenai/sciq |
Sensory neurons transmit nerve impulses from sense organs and internal organs to the brain via the spinal cord. In other words, they carry information about the inside and outside environment to the brain. | allenai/sciq |
CHAPTER SUMMARY 7.1 Sexual Reproduction Nearly all eukaryotes undergo sexual reproduction. The variation introduced into the reproductive cells by meiosis appears to be one of the advantages of sexual reproduction that has made it so successful. Meiosis and fertilization alternate in sexual life cycles. The process of ... | allenai/sciq |
Certain indicator compounds, such as litmus, can be used to detect acids. Acids turn blue litmus paper red. | allenai/sciq |
Most flatworms have a distinct head region that includes nerve cells and sensory organs, such as eyespots. The development of a head region, called cephalization , evolved at the same time as bilateral symmetry in animals. This process does not occur in cnidarians, which evolved prior to flatworms and have radial symme... | allenai/sciq |
Endocrine system: A high concentration of sugar in the blood triggers secretion of insulin by an endocrine gland called the pancreas. Insulin is a hormone that helps cells absorb sugar from the blood. | allenai/sciq |
Electron Shells and the Bohr Model It should be stressed that there is a connection between the number of protons in an element, the atomic number that distinguishes one element from another, and the number of electrons it has. In all electrically neutral atoms, the number of electrons is the same as the number of prot... | allenai/sciq |
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It can be. Achondroplasia is the most common form of dwarfism in humans, and it is caused by a dominant mutation. The mutation can be passed from one generation to the next. Over 95% of unrelated individuals with Achondroplasia have the same mutation, making it one of the most common mutations in the human genome. Why?... | allenai/sciq |
Overview of Transcription. Transcription uses the sequence of bases in a strand of DNA to make a complementary strand of mRNA. Triplets are groups of three successive nucleotide bases in DNA. Codons are complementary groups of bases in mRNA. | allenai/sciq |
Regions of the Vertebral Column The vertebral column originally develops as a series of 33 vertebrae, but this number is eventually reduced to 24 vertebrae, plus the sacrum and coccyx. The vertebral column is subdivided into five regions, with the vertebrae in each area named for that region and numbered in descending ... | allenai/sciq |
An element is a pure substance that cannot be separated into any other substances. There are 92 naturally occurring elements. | allenai/sciq |
Stress is the force applied to a rock. There are four types of stresses:. | allenai/sciq |
The cis isomer has the two single hydrogen atoms on the same side of the molecule, while the trans isomer has them on opposite sides of the molecule. In both molecules, the bonding order of the atoms is the same. In order for geometric isomers to exist, there must be a rigid structure in the molecule to prevent free ro... | allenai/sciq |
Chapter 42 1 Figure 42.11 C 3 Figure 42.16 If the blood of the mother and fetus mixes, memory cells that recognize the Rh antigen can form late in the first pregnancy. During subsequent pregnancies, these memory cells launch an immune attack on the fetal blood cells. Injection of anti-Rh antibody during the first pregn... | allenai/sciq |
21.5 | The Immune Response against Pathogens By the end of this section, you will be able to: • Explain the development of immunological competence • Describe the mucosal immune response • Discuss immune responses against bacterial, viral, fungal, and animal pathogens • Describe different ways pathogens evade immune re... | allenai/sciq |
Vectors in Two Dimensions A vector is a quantity that has magnitude and direction. Displacement, velocity, acceleration, and force, for example, are all vectors. In one-dimensional, or straight-line, motion, the direction of a vector can be given simply by a plus or minus sign. In two dimensions (2-d), however, we spec... | allenai/sciq |
Thermal energy can be trapped in Earth’s atmosphere by gases such as CO2, water vapor, methane, and chlorofluorocarbons before it can be radiated into space—like the effect of a greenhouse. It is not yet clear how large an increase in the temperature of Earth’s surface can be attributed to this phenomenon. Venus is an ... | allenai/sciq |
If heated water is released into a body of water, it may cause thermal pollution. Thermal pollution is a reduction in the quality of water because of an increase in water temperature. A common cause of thermal pollution is the use of water as a coolant by power plants and factories. This water is heated and then return... | allenai/sciq |
The amount of material left over after a certain number of half-lives can be easily calculated. | allenai/sciq |
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The ozone in smog may damage plants. The effects of ozone add up over time. Plants such as trees, which normally live a long time, are most affected. Entire forests may die out if ozone levels are very high. Other plants, including crop plants, may also be damaged by ozone. You can see evidence of ozone damage in Figur... | allenai/sciq |
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Comparative embryology is the study of the similarities and differences in the embryos of different species. Similarities in embryos are evidence of common ancestry. All vertebrate embryos, for example, have gill slits and tails. Most vertebrates, except for fish, lose their gill slits by adulthood. Some of them also l... | allenai/sciq |
The lungs are the main organs of the respiratory system. This is where gases are exchanged between the air and the blood. Gases are also transported by the blood and exchanged between the blood and all the cells of the body. | allenai/sciq |
Every plant and animal depends on its traits to survive. Survival may include getting food, building homes, and attracting mates. Traits that allow a plant, animal, or other organism to survive and reproduce in its environment are called adaptations . | allenai/sciq |
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