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test · 389k rows

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What form of energy is light? Here are the choices: A. seismic B. electromagnetic C. hydro D. mechanical		B: electromagnetic.
What is a common chemical substance on planet earth? Here are the choices: A. nitrogen B. hydrogen C. oxygen D. water	Water is a common chemical substance on planet Earth. In fact, Earth is sometimes called the "water planet" because almost 75% of its surface is covered with water. If you look at Figure below , you will see where Earth’s water is found. The term water generally refers to its liquid state, and water is a liquid over a ...	D: water.
Blood calcium levels are tightly regulated by the what system? Here are the choices: A. nervous B. cardiovascular C. digestive D. endocrine	Of course, calcium is critical for many other biological processes. It is a second messenger in many signaling pathways, and is essential for muscle contraction, nerve impulse transmission, and blood clotting. Given these roles, it is not surprising that blood calcium levels are tightly regulated by the endocrine syste...	D: endocrine.
This bodily defense function attacks pathogens and includes inflammatory response and phagocytosis? Here are the choices: A. vomitting B. first line of defense C. third line of defense D. second line of defense	The second line of defense attacks pathogens that manage to enter the body. It includes the inflammatory response and phagocytosis by nonspecific leukocytes.	D: second line of defense.
Lodgepole cones remain closed until exposed to what? Here are the choices: A. extreme heat B. predators C. UV light D. precipitation		A: extreme heat.
What is the change of state from a gas to a liquid? Here are the choices: A. condensation B. fermentation C. combustion D. vaporation	A puddle of water left undisturbed eventually disappears. The liquid molecules escape into the gas phase, becoming water vapor. Vaporization is the process in which a liquid is converted to a gas. Evaporation is the conversion of a liquid to its vapor below the boiling temperature of the liquid. If the water is instead...	A: condensation.
The steropodon may have been an ancestor of which animal? Here are the choices: A. geckos B. wooly mammoth C. platypus D. lioness	The first monotremes may have evolved about 150 million years ago. Early monotreme fossils have been found in Australia. An example is a genus called Steropodon , shown in Figure below . It may have been the ancestor of the platypus. Early monotremes retained some of the traits of their therapsid ancestors. For example...	C: platypus.
Closely associated with "work", what is characterized by its many forms and the fact that it is conserved? Here are the choices: A. heating B. energy C. matter D. fuel	Introduction to Work, Energy, and Energy Resources Energy plays an essential role both in everyday events and in scientific phenomena. You can no doubt name many forms of energy, from that provided by our foods, to the energy we use to run our cars, to the sunlight that warms us on the beach. You can also cite examples...	B: energy.
What is the time it takes for radioactive substance to decay? Here are the choices: A. decay rate B. full-life C. half-life D. deterioration rate	The disintegration of unstable nuclei does not occur all at once. The rate of disintegration is a statistical process. The most convenient way to consider it is by a concept known as half-life . The time required for half of the atoms in any given quantity of a radioactive substance to decay is the half-life of that el...	C: half-life.
What type of biomes are found in the salt water of the ocean? Here are the choices: A. marine B. major C. surreal D. active	Marine biomes are found in the salt water of the ocean.	A: marine.
What is formed when an enzyme binds its substrate? Here are the choices: A. vessel - substrate complex B. lock and key model C. enzyme - substrate complex D. nucleus - substrate complex	View an animation (http://openstaxcollege. org/l/hexokinase2) of induced fit. When an enzyme binds its substrate, an enzyme-substrate complex is formed. This complex lowers the activation energy of the reaction and promotes its rapid progression in one of multiple possible ways. On a basic level, enzymes promote chemic...	C: enzyme - substrate complex.
What type of rock is a sandstone? Here are the choices: A. landform rocks B. limestone rocks C. igneous rocks D. sedimentary rocks	If you look up close, you would be able to see grains of sand. From this distance, you can see different layers from where the sand was laid down. This rock is sandstone. The sand grains are cemented together to make sandstone. Sandstone is a common type of sedimentary rock.	D: sedimentary rocks.
Which acids provide the molecular blueprints for all proteins produced in living systems? Here are the choices: A. nucleic acids B. periodic acids C. amino acids D. nitrous acids	The final type of biomolecules that we will be looking at are the nucleic acids. Like carbohydrates and proteins, nucleic acids are complex polymers of a few simple building blocks. Nucleic acids provide the molecular blueprints for all proteins produced in living systems. We will explore the process by which this info...	A: nucleic acids.
Cephalopods have three hearts that pump blood of what color? Here are the choices: A. Green B. Red C. blue D. purple	Cephalopods include the octopus and squid. They have a prominent head and a well-developed brain. Typically the foot has been modified into a set of arms or tentacles. Members of this class can change color. They can also change texture and body shape, and, and if those camouflage techniques don't work, they can still ...	C: blue.
Influenza is a type of what, where glycoproteins attach to a host epithelial cell? Here are the choices: A. atoms disease B. recent disease C. nucleus disease D. viral disease	Figure 17.6 In influenza virus infection, glycoproteins attach to a host epithelial cell. As a result, the virus is engulfed. RNA and proteins are made and assembled into new virions.	D: viral disease.
What is the smallest aromatic hydrocarbon? Here are the choices: A. anthracene B. benzene C. naphthalene D. phenanthrene	Benzene is the smallest aromatic hydrocarbon. It has just one ring. You can see its structural formula in Figure below . Benzene has many uses. For example, it is used in air fresheners and mothballs because of its strong scent.	B: benzene.
A hypothesis is scientific only if it can be tested by what? Here are the choices: A. making a conclusion B. independent variable C. carbon dating D. making observations	For a hypothesis to be testable means that it is possible to make observations that agree or disagree with it. If a hypothesis cannot be tested by making observations, it is not scientific. Consider this statement:.	D: making observations.
Aging occurs as cells lose their ability to do what? Here are the choices: A. fold B. duplicate C. divide D. split	Aging occurs as cells lose their ability to divide.	C: divide.
The tyndall effect refers to the scattering of what by colloidal particles? Here are the choices: A. primary colors B. dust mites C. visible light D. dark matter	The Tyndall effect is the scattering of visible light by colloidal particles.	C: visible light.
Acids are associated with a low number on which scale? Here are the choices: A. ionic B. acidic C. metric D. ph	As indicated in http://catalog. flatworldknowledge. com/bookhub/reader/2547 - gob-ch10_s04, weak acids are relatively common, even in the foods we eat. But we occasionally come across a strong acid or base, such as stomach acid, that has a strongly acidic pH of 1–2. By definition, strong acids and bases can produce a r...	D: ph.
Said to go hand-in-hand with science, what evolves as new materials, designs, and processes are invented? Here are the choices: A. technology B. biology C. invention D. industry	Technology evolves as new materials, designs, and processes are invented.	A: technology.
What are the poles labeled? Here are the choices: A. north and south B. east and west C. west and south D. southwest and south		A: north and south.
What is considered to be the "fundamental unit" of life? Here are the choices: A. bacteria B. organ C. cell D. proton	It could easily be said that a cell is the fundamental unit of life, the smallest unit capable of life or the structural and functional unit necessary for life. But whatever it is, a cell is necessary for life. This concept will discuss some of the fundamental properties of the cell with lessons that include the cell s...	C: cell.
What two states of matter are included in the category "fluids"? Here are the choices: A. liquids and soilds B. liquids and gases C. bacteria and gases D. solids and gases	Fluid friction is friction that acts on objects that are moving through a fluid. A fluid is a substance that can flow and take the shape of its container. Fluids include liquids and gases. If you’ve ever tried to push your open hand through the water in a tub or pool, then you’ve experienced fluid friction between your...	B: liquids and gases.
When matter changes into an entirely different substance with different chemical properties, what has occurred? Here are the choices: A. chemical change B. physical change C. mechanical change D. gaseous change	A chemical change occurs whenever matter changes into an entirely different substance with different chemical properties. A chemical change is also called a chemical reaction. Many complex chemical changes occur to produce the explosions of fireworks. An example of a simpler chemical change is the burning of methane. M...	A: chemical change.
Phospholipids are unable to mix with what? Here are the choices: A. air B. nitrogen C. solids D. water	Molecules in the cell membrane allow it to be semipermeable. The membrane is made of a double layer of phospholipids (a "bilayer") and proteins ( Figure below ). Recall that phospholipids, being lipids, do not mix with water. It is this quality that allows them to form the outside barrier of the cell.	D: water.
What are molecules that the immune system recognize as foreign to the body? Here are the choices: A. viruses B. peptides C. antigens D. tumors	The average kinetic energy of atoms (each of mass and average speed ) in a gas is related to the temperature of the gas, measured in Kelvin. The Boltzmann constant is a constant of nature, equal to.	C: antigens.
The end result of diffusion is an equal concentration, or equilibrium , of molecules on both sides of what? Here are the choices: A. the organelle B. the membrane C. the cell D. the organism	Diffusion will continue until the concentration gradient has been eliminated. Since diffusion moves materials from an area of higher concentration to the lower, it is described as moving solutes "down the concentration gradient. " The end result of diffusion is an equal concentration, or equilibrium , of molecules on b...	B: the membrane.
What paired organs that are part of the urinary system play the prime role in excretion? Here are the choices: A. lungs B. kidneys C. ovaries D. liver	Each of the above organs of excretion is also part of another body system. For example, the large intestine and liver are part of the digestive system, and the lungs are part of the respiratory system. The kidneys are the main organs of excretion. They are part of the urinary system.	B: kidneys.
The fungus benefits from the constant supply of food produced by what? Here are the choices: A. the photosynthesizer B. the host C. the phytoflagellate D. the spermatophyte	A lichen is a mutualistic relationship between a fungus and a photosynthetic organism. The other organism is usually a cyanobacterium or green alga. The fungus grows around the bacterial or algal cells. The fungus benefits from the constant supply of food produced by the photosynthesizer. The photosynthesizer benefits ...	A: the photosynthesizer.
Gases can be classifed as real or what? Here are the choices: A. noble B. shape C. ideal D. dense	Did you notice that none of these statements relates to the identity of the gas? This means that all gases should behave similarly. A gas that follows these statements perfectly is called an ideal gas. Most gases show slight deviations from these statements and are called real gases. However, the existence of real gase...	C: ideal.
What is a mutation? Here are the choices: A. change in the nucleotide sequence of dna B. change in the swetha sequence of dna C. change in the distinct sequence of dna D. change in the rna sequence of dna	28.7 Patterns of Inheritance There are two aspects to a person’s genetic makeup. Their genotype refers to the genetic makeup of the chromosomes found in all their cells and the alleles that are passed down from their parents. Their phenotype is the expression of that genotype, based on the interaction of the paired all...	A: change in the nucleotide sequence of dna.
What are biological catalysts that speeds up biochemical reactions? Here are the choices: A. enzymes B. carbohydrates C. hormones D. proteins	This super fast train can obviously reach great speeds. And there's a lot of technology that helps this train go fast. Speaking of helping things go fast brings us to enzymes. Life could not exist without enzymes. Essentially, enzymes are biological catalysts that speed up biochemical reactions.	A: enzymes.
What type of reaction is a transfer of a proton from one molecule or ion to another? Here are the choices: A. ionic bonding B. thermal reaction C. acid-base D. ionization	An acid-base reaction according to the Brønsted-Lowry definition is a transfer of a proton from one molecule or ion to another. When ammonia is dissolved in water, it undergoes the following reversible reaction.	C: acid-base.
What part of the plant, in general, is responsible for transport and storage of water and minerals? Here are the choices: A. petals B. pistil C. leaves D. stems	Stems are needed for transport and storage. Their vascular tissue carries water and minerals from roots to leaves. It carries dissolved sugar from the leaves to the rest of the plant. Without this connection between roots and leaves, plants could not survive high above the ground in the air. In many plants, ground tiss...	D: stems.
One gram of carbohydrates provides how many calories of energy? Here are the choices: A. one B. eight C. two D. four	Carbohydrates include sugars, starches, and fiber. Sugars and starches are used by the body for energy. One gram of carbohydrates provides 4 Calories of energy. Fiber, which is found in plant foods, cannot be digested but is needed for good health.	D: four.
Mushrooms and other fungi obtain energy from what? Here are the choices: A. the soil B. the sun C. the air D. other organisms	Mushrooms and other fungi obtain energy from other organisms. That’s why you often see fungi growing on a fallen tree; the rotting tree is their source of energy ( Figure below ).	D: other organisms.
How are protozoa that cause giardiasis spread? Here are the choices: A. insects B. starch and water C. food and water D. lakes and rivers	Protozoa that cause giardiasis are spread by contaminated food or water. They live inside the intestine. They may cause abdominal pain, fever, and diarrhea.	C: food and water.
What can prevent the passage of molecules and ions between cells, such as in the blood-brain barrier? Here are the choices: A. solid junctions B. tight junctions C. special junctions D. fatty junctions	In addition to holding cells together, tight junctions play a role in the transport of materials. Tight junctions prevent the passage of molecules and ions through the space between cells. So these molecules and ions must actually enter cells (either by diffusion or active transport) in order to proceed through a tissu...	B: tight junctions.
Give an example of air pollution while painting indoors. Here are the choices: A. variety fumes B. gas fumes C. fuel fumes D. paint fumes	If you are painting indoors, there are more important concerns than just getting messy. You should also be concerned about breathing in the fumes from the paints. Making sure to get plenty of fresh air while painting is very important. Paint fumes can have serious health effects. Paint fumes are just one example of ind...	D: paint fumes.
What plays a variety of important roles in biochemical systems? Here are the choices: A. bacteria B. mutation C. reactants D. protein	Proteins play a variety of important roles in biochemical systems. Some of the most common protein functions are listed below:.	D: protein.
What type of plants grow on other plants? Here are the choices: A. legumes B. epiphytes C. parasites D. bryophytes	Plants called epiphytes grow on other plants. They obtain moisture from the air and make food by photosynthesis. Most epiphytes are ferns or orchids that live in tropical or temperate rainforests (see Figure below ). Host trees provide support, allowing epiphyte plants to obtain air and sunlight high above the forest f...	B: epiphytes.
What provides a protective covering for the body and helps maintain homeostasis? Here are the choices: A. unadorned system B. lysogenic system C. endorcrine system D. integumentary system	Because the organs of the integumentary system are external to the body, you may think of them as little more than “accessories,” like clothing or jewelry. But the organs of the integumentary system serve important biological functions. They provide a protective covering for the body and help the body maintain homeosta...	D: integumentary system.
Uranium is an important part of the process used to harness which type of power? Here are the choices: A. gravitational B. wind C. solar D. nuclear	Nuclear Fuels Nuclear fuel consists of a fissionable isotope, such as uranium-235, which must be present in sufficient quantity to provide a self-sustaining chain reaction. In the United States, uranium ores contain from 0.05–0.3% of the uranium oxide U3O8; the uranium in the ore is about 99.3% nonfissionable U-238 wit...	D: nuclear.
Budding and fission in annelids are examples of what type of reproduction? Here are the choices: A. sexual B. hybrid C. byproduct D. asexual	Most annelids can reproduce both asexually and sexually. Asexual reproduction may occur by budding or fission. Sexual reproduction varies by species. Some species go through a larval stage before developing into adults. Other species grow to adult size without going through a larval stage.	D: asexual.
What is the process by which plants make their own food? Here are the choices: A. mitochondrial process B. respiration C. ATP cycle D. photosynthesis		D: photosynthesis.
In what part of the carbon cycle does carbon move between living things and the air? Here are the choices: A. biotic cycle B. endothermic cycle C. abdaspac cycle D. envelop cycle	Carbon moves through ecosystems in two cycles that overlap. In the biotic cycle, it moves between living things and the air. In the abiotic cycle, it moves between the air, ground, and oceans. By burning fossil fuels, humans have increased the amount of carbon dioxide in the air.	A: biotic cycle.
Herbivores and the bacteria that live in their intestines demonstrate a two-way beneficial relationship called what? Here are the choices: A. parasitism B. pragmatism C. syncretism D. mutualism	An example of a mutualistic relationship is between herbivores (plant-eaters) and the bacteria that live in their intestines. The bacteria get a place to live. Meanwhile, the bacteria help the herbivore digest food. Both species benefit, so this is a mutualistic relationship. The clownfish and the sea anemones also hav...	D: mutualism.
What joins within each testis to form the epididymis? Here are the choices: A. viviparous tubules B. seminiferous tubules C. hypodermic tubules D. interstitial tubules	The seminiferous tubules within each testis join to form the epididymis. The epididymis (plural, epididymes) is a coiled tube about 6 meters (20 feet) long lying atop the testis inside the scrotum. The functions of the epididymis are to mature and store mature sperm until they leave the body.	B: seminiferous tubules.
How many layers of phospholipids does the cell membrane contain? Here are the choices: A. five B. three C. four D. two	The cell membrane consists of two layers of phospholipids. It encloses the cytoplasm and controls what enters and leaves the cell.	D: two.
What process within cells makes sure that every gamete receives a copy of every chromosome? Here are the choices: A. genomes B. meiosis C. fission D. mutations	All of our cells contain DNA. Meiosis ensures that each gamete receives a copy of each chromosome.	B: meiosis.
Do amphibians and reptiles maintain a constant body temperature? Here are the choices: A. no, they have a lower body temperature than their surroundings B. no, they have about the same body temperature as their surroundings C. no, they have a higher body temperature than their surroundings D. yes	The following figures summarize the basic features of major terrestrial biomes. Think about how its biodiversity and types of plants and animals relate to its climate. For example, why do you think there are no amphibians or reptiles in tundra biomes? (Hint: Amphibians and reptiles cannot maintain a constant body tempe...	B: no, they have about the same body temperature as their surroundings.
Most vascular plants are seed plants, also known as? Here are the choices: A. fungus B. bacteria C. spermatophytes D. sporozoans	Most vascular plants are seed plants, or spermatophytes. They reproduce with seeds and pollen. Some modern seed plants are gymnosperms that produce seeds in cones.	C: spermatophytes.
Centrifuges use what to perform their task? Here are the choices: A. absorption B. magnetism C. jets D. inertia	Figure 6.17 Centrifuges use inertia to perform their task. Particles in the fluid sediment come out because their inertia carries them away from the center of rotation. The large angular velocity of the centrifuge quickens the sedimentation. Ultimately, the particles will come into contact with the test tube walls, whi...	D: inertia.
What are the two unique features of mollusks? Here are the choices: A. mantle and radula B. antennae and pseudopod C. pseudopod and mantle D. radula and antennae	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 filte...	A: mantle and radula.
Name the two types of water turtles live in. Here are the choices: A. ocean water and sea water B. ocean water and fresh water C. arctic water and ice water D. river water and lake water	Many turtles are aquatic. They may live in the ocean or in fresh water. Other turtles are terrestrial and live on land. All lizards are terrestrial. Their habitats may range from deserts to rainforests. They may live in a range of places, from underground burrows to the tops of trees. Most snakes are terrestrial, but s...	B: ocean water and fresh water.
What structures are located on roof of the nasopharynx and on each side of the pharynx? Here are the choices: A. testicles B. uvula C. tonsils D. tongues	Figure 21.10 Locations and Histology of the Tonsils (a) The pharyngeal tonsil is located on the roof of the posterior superior wall of the nasopharynx. The palatine tonsils lay on each side of the pharynx. (b) A micrograph shows the palatine tonsil tissue. LM × 40. (Micrograph provided by the Regents of the University ...	C: tonsils.
What colorful arc-shaped atmospheric phenomena are produced by a combination of refraction and reflection? Here are the choices: A. sunsets B. shadows C. lightning D. rainbows	Rainbows are produced by a combination of refraction and reflection. You may have noticed that you see a rainbow only when you look away from the sun. Light enters a drop of water and is reflected from the back of the drop, as shown in Figure 25.24. The light is refracted both as it enters and as it leaves the drop. Si...	D: rainbows.
Rabies transmission occurs when saliva from an infected mammal enters a wound. the virus travels through neurons in the peripheral nervous system to the central nervous system where it impairs this? Here are the choices: A. skeletal system B. brain function C. reproduction system D. lung function	Figure 21.5 Viruses are classified based on their core genetic material and capsid design. (a) Rabies virus has a single-stranded RNA (ssRNA) core and an enveloped helical capsid, whereas (b) variola virus, the causative agent of smallpox, has a double-stranded DNA (dsDNA) core and a complex capsid. Rabies transmission...	B: brain function.
Newton realized that the nature of gravity on earth that pulls an apple to the ground could explain the motion of these? Here are the choices: A. molecules B. moon and planets C. seasons D. atoms and quarks	As has been noted in numerous Things Great and Small vignettes, this is not the first time the large has been explained by the small and vice versa. Newton realized that the nature of gravity on Earth that pulls an apple to the ground could explain the motion of the moon and planets so much farther away. Minute atoms a...	B: moon and planets.
Where do most of the steps of cellular respiration take place? Here are the choices: A. cytoplasm B. nucleus C. mitochondria D. ribosomes	Most of the steps of cellular respiration take place in the mitochondria.	C: mitochondria.
Which metal is not solid at room temperature? Here are the choices: A. titanium B. aluminum C. silver D. mercury	All metals except for mercury are solids at room temperature. Many metals are shiny, ductile, and malleable. Most are also good conductors of heat.	D: mercury.
Induced mutations are caused by environmental factors. what term is used to describe a mutation that has no environmental cause? Here are the choices: A. cancerous mutation B. evident mutation C. numerous mutation D. spontaneous mutation	Mutagenesis may occur spontaneously or be induced. A spontaneous mutation can just happen. These mutations are not caused by an environmental factor, but occur during normal cellular processes. A spontaneous mutation may be due to a mistake during DNA replication or transcription. Mutations may also occur during mitosi...	D: spontaneous mutation.
What part of the cell does cellular respiration occur? Here are the choices: A. nuclei B. proton C. mitochondria D. glucose	Cellular respiration occurs in the mitochondria. Figure 20.13 "Respiration" shows the mitochondrion’s two membranes: outer andinner. The inner membrane is extensively folded into a series of internal ridges calledcristae. Thus there are two compartments in mitochondria: the intermembrane space, which lies between the m...	C: mitochondria.
How is the chance of survival affected when animals lack parental care? Here are the choices: A. variable B. decreased C. increased D. unaffected		B: decreased.
Elements with magic numbers of what tend to have more stable isotopes? Here are the choices: A. pressure B. nucleus C. molecules D. protons	Isotopes with magic numbers of protons and/or neutrons tend to be especially stable. Elements with magic numbers of protons tend to have more stable isotopes than elements that do not.	D: protons.
What is the term for the steep sloped side of a sand dune? Here are the choices: A. front face B. break face C. slide face D. slip face	A sand dune has a gentle slope on the side the wind blows from. The opposite side has a steep slope. This side is called the slip face.	D: slip face.
Pulleys are generally used to do what with objects? Here are the choices: A. pack B. wrap C. clean D. lift	A pulley is a simple machine that consists of a rope and grooved wheel. The rope fits into the groove in the wheel, and pulling on the rope turns the wheel. Pulleys are generally used to lift objects, especially heavy objects. The object lifted by a pulley is called the load. The force applied to the pulley is called t...	D: lift.
What term describes how close estimates are to one another? Here are the choices: A. precision B. efficiency C. precise D. Distant	Precision describes how close estimates are to one another. Estimates that are relatively close to one another are precise. Let’s assume that ten different students made an estimate of the volume shown in Figure above , and the values were: 52.9, 52.8, 52.9, 52.9, 53.3, 52.0, 52.8, 52.9, 53.0, 52.8. We can determine ho...	A: precision.
What are membrane-bound organelles that can have secretory, excretory, and storage functions? Here are the choices: A. prokaryotes B. vacuoles C. alleles D. nuclei	Vacuoles are membrane-bound organelles that can have secretory, excretory, and storage functions. Many organisms will use vacuoles as storage areas and some plant cells have very large vacuoles. Vesicles are much smaller than vacuoles and function in transporting materials both within and to the outside of the cell.	B: vacuoles.
The structural classification of joints divides them into bony, fibrous, cartilaginous, and synovial joints. the bones of fibrous joints are held together by fibrous connective tissue; the three types of fibrous joints are sutures, syndesomes, and what? Here are the choices: A. gomphoses B. articular C. synchondrosis D...	38.3 Joints and Skeletal Movement The structural classification of joints divides them into bony, fibrous, cartilaginous, and synovial joints. The bones of fibrous joints are held together by fibrous connective tissue; the three types of fibrous joints are sutures, syndesomes, and gomphoses. Cartilaginous joints are jo...	A: gomphoses.
A catalyst can increase the rate of what, in general? Here are the choices: A. mechanicl reaction B. consumption reaction C. carbon reaction D. chemical reaction	A catalyst is a substance that increases the rate of a chemical reaction. The presence of a catalyst is one of several factors that influence the rate of chemical reactions. (Other factors include the temperature, concentration, and surface area of reactants. ) A catalyst isn’t a reactant in the chemical reaction it sp...	D: chemical reaction.
Which crust lies deep inside the ocean? Here are the choices: A. shallowest B. youngest C. thickest D. oldest	The oldest crust is coldest and lies deepest in the ocean.	D: oldest.
What is the most significant cause of respiratory disease as well as cardiovascular disease and cancer? Here are the choices: A. running B. driving C. smoking D. sleeping	Smoking is the most significant cause of respiratory disease as well as cardiovascular disease and cancer. Exposure to tobacco smoke by smoking or by breathing air that contains tobacco smoke is the leading cause of preventable death in the United States. Regular smokers die about 10 years earlier than nonsmokers. The ...	C: smoking.
What type of light can you feel as heat but not see and has the longest wavelengths and lowest frequencies? Here are the choices: A. ultraviolet light B. thermal light C. solar light D. infrared light	Infrared light is light with the longest wavelengths and lowest frequencies. You can’t see infrared light, but you can feel it as heat. Besides the sun, flames and living things give off infrared light.	D: infrared light.
Ionic, molecular, covalent, and metallic are major types of what state of matter? Here are the choices: A. gas B. plasma C. liquid D. solids	Summary The major types of solids are ionic, molecular, covalent, and metallic. Ionic solids consist of positively and negatively charged ions held together by electrostatic forces; the strength of the bonding is reflected in the lattice energy. Ionic solids tend to have high melting points and are rather hard. Molecul...	D: solids.
What forces keep the moon orbiting the earth? Here are the choices: A. magnetic B. polar C. cosmic D. gravitational	This photograph was taken by Apollo 8 crewmember Bill Anders on December 24, 1968, showing the Earth rising above the lunar surface. Gravitational forces keep the moon orbiting the Earth.	D: gravitational.
Snow and ice may also undergo which process where there is intense sunlight, very cold temperatures, and dry winds? Here are the choices: A. sublimation B. increasefixation C. amplification D. crystalline	Snow and ice may also undergo sublimation under certain conditions. This is most likely to happen where there is intense sunlight, very cold temperatures, and dry winds. These conditions are often found on mountain peaks. As snow sublimates, it gradually shrinks without any runoff of liquid water. At the URL below, you...	A: sublimation.
Electromagnets can be controlled by controlling what type of current? Here are the choices: A. negative B. magnetic C. positive D. electric	Besides their strength, another pro of electromagnets is the ability to control them by controlling the electric current. Turning the current on or off turns the magnetic field on or off. The amount of current flowing through the coil can also be changed to control the strength of the electromagnet.	D: electric.
The rate of evolution is influenced by the rate of changes to what? Here are the choices: A. the environment B. the earth C. dna D. migration	The rate of evolution is influenced by how quickly the environment is changing. Long periods of gradual evolutionary change may be interrupted by short bursts of rapid change.	A: the environment.
What do you call a device that produces a very focused beam of visible light of just one wavelength and color? Here are the choices: A. laser B. light meter C. optical diffuser D. fusion relay	Did you ever see a cat chase after a laser light, like the one in Figure below ? A laser is a device that produces a very focused beam of visible light of just one wavelength and color. Waves of laser light are synchronized so the crests and troughs of the waves line up. The diagram in Figure below shows why a beam of ...	A: laser.
Bubbles in bread dough are created by what gas produced during alcoholic fermentation? Here are the choices: A. yeast dioxide B. carbon dioxide C. combustion dioxide D. acid dioxide	In alcoholic fermentation, glycolysis is followed by a step that produces alcohol and carbon dioxide. This step also forms additional molecules of ATP. It occurs in yeast, such as the yeast in bread. Carbon dioxide from alcoholic fermentation creates gas bubbles in bread dough. The bubbles leave little holes in the bre...	B: carbon dioxide.
What is the capacity to cause change? Here are the choices: A. temperature B. energy C. mass D. gravity		B: energy.
Ocean currents transfer heat from the equator towards what locations? Here are the choices: A. poles B. tropical zones C. east and west D. continents	Ocean currents transfer heat from the Equator toward the poles. This moderates Earth's temperature.	A: poles.
In sexual reproduction, two of what unite to produce an offspring? Here are the choices: A. gametes B. chromosomes C. DNA strands D. spores	In sexual reproduction, two gametes unite to produce an offspring. Which two gametes is a matter of chance. The union of gametes occurs randomly.	A: gametes.
What are the ends of long bones called? Here are the choices: A. cartilage B. marrow extension C. appendage D. epiphysis	Long bones ossify and get longer as they grow and develop. These bones grow from their ends, known as the epiphysis, and the presence of a growth plate, or epiphyseal line, signifies that the bone is still growing.	D: epiphysis.
Convection is the transfer of thermal energy by particles moving through what? Here are the choices: A. tissue B. Solid C. Metal D. fluid	Convection is the transfer of thermal energy by particles moving through a fluid. Particles transfer energy by moving from warmer to cooler areas. That’s how energy is transferred in the soup in Figure above . Particles of soup near the bottom of the pot get hot first. They have more energy so they spread out and becom...	D: fluid.
What happens when waves reach the shore? Here are the choices: A. diffuse and recede B. surge and drown C. topple and break D. repel and attract	Figure below shows what happens to waves near shore. As waves move into shallow water, they start to touch the bottom. The base of the waves drag and slow. Soon the waves slow down and pile up. They get steeper and unstable as the top moves faster than the base. When they reach the shore, the waves topple over and brea...	C: topple and break.
What is an involuntary muscle contraction that moves rapidly along an organ like a wave called? Here are the choices: A. peristalsis B. ruptured nerve C. esophagus D. apoptosis	The organs of the GI tract are lined with mucous membranes that secrete digestive enzymes and absorb nutrients. The organs are also covered by layers of muscle that enable peristalsis. Peristalsis is an involuntary muscle contraction that moves rapidly along an organ like a wave (see Figure below ). You can watch an an...	A: peristalsis.
What is the purpose of water molds in fresh water environments? Here are the choices: A. fish food B. wave production C. decomposition D. oxygen production		C: decomposition.
What corrosive substances capable of dissolving many metals can cause contamination if spilled? Here are the choices: A. bases B. acids C. salts D. ions	Acids can dissolve many metals; a spilled acid can lead to contamination.	B: acids.
What is always conserved in chemical reactions? Here are the choices: A. energy B. mass C. bonds D. force	A: All chemical equations must be balanced. This means that there must be the same number of each type of atom on both sides of the arrow. That’s because mass is always conserved in chemical reactions. Count the number of hydrogen and oxygen atoms on each side of the arrow. There are two hydrogen atoms in both reactant...	B: mass.
A polyatomic ion is an ion composed of more than one what? Here are the choices: A. nucleus B. neutron C. pair bond D. atom	A polyatomic ion is an ion composed of more than one atom. For example, the ammonium ion consists of one nitrogen atom and four hydrogen atoms. Together, they comprise a single ion with a 1+ charge and a formula of NH 4 + . The carbonate ion consists of one carbon atom and three oxygen atoms, and it carries an overall ...	D: atom.
Mutualism is an interaction between individuals of two different species that has what effect on both of them? Here are the choices: A. harmful B. abnormal C. beneficial D. neutral	They live mutualistically with other organisms. Mutualistic fungi live harmlessly with other living organisms. Recall that mutualism is an interaction between individuals of two different species, in which both individuals benefit.	C: beneficial.
What are the structural and functional units of the nervous system, which transmit nerve impulses to other cells? Here are the choices: A. neurons B. axions C. electrons D. ions	Neurons are the structural and functional units of the nervous system. They consist of a cell body, dendrites, and axon. Neurons transmit nerve impulses to other cells. Types of neurons include sensory neurons, motor neurons, and interneurons.	A: neurons.
If hot water becomes trapped, pressure may build up. when the water breaks free, it creates what? Here are the choices: A. geyser B. steam C. glacier D. groundwater	If hot water becomes trapped, pressure may build up. When the water breaks free, it creates a geyser.	A: geyser.
What electrical force is responsible for fission? Here are the choices: A. velocity B. momentum C. friction D. repulsion	The strong force predominates and can cause nuclei of complex atoms with many protons to be stable. The electric force of repulsion is responsible for fission, the breaking apart of nuclei, and therefore also for atom bombs and nuclear power. A form of fission where a helium nucleus is a product, is called alpha radiat...	D: repulsion.
Which law states that a pair of alleles is separated, or segregated, during the formation of gametes? Here are the choices: A. separation anxiety B. law of equals C. law of segregation D. de facto segregation	Mendel summarized his findings in two laws: the Law of Segregation and the Law of Independent Assortment. The Law of Segregation is based on his findings from his first set of experiments. Mendel stated that heritable factors are segregated during gamete formation. More precisely, this law states that a pair of alleles...	C: law of segregation.
Sounds or pictures can be encoded in pulses of what, which are then sent through an optical fiber? Here are the choices: A. quasars B. microwaves C. kinetic energy D. laser light	Besides entertaining a cat, laser light has many other uses. One use is carrying communication signals in optical fibers. Sounds or pictures are encoded in pulses of laser light, which are then sent through an optical fiber. All of the light reflects off the inside of the fiber, so none of it escapes. As a result, the ...	D: laser light.
What substance are physical objects are made of? Here are the choices: A. friction B. gravity C. energy D. matter	To understand minerals, we must first understand matter. Matter is the substance that physical objects are made of.	D: matter.

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