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The nitrogen that enters living systems by nitrogen fixation is successively converted from organic nitrogen back into nitrogen gas by what?	viruses	algae	pollen	bacteria	The Nitrogen Cycle Getting nitrogen into the living world is difficult. Plants and phytoplankton are not equipped to incorporate nitrogen from the atmosphere (which exists as tightly bonded, triple covalent N2) even though this molecule comprises approximately 78 percent of the atmosphere. Nitrogen enters the living world via free-living and symbiotic bacteria, which incorporate nitrogen into their macromolecules through nitrogen fixation (conversion of N2). Cyanobacteria live in most aquatic ecosystems where sunlight is present; they play a key role in nitrogen fixation. Cyanobacteria are able to use inorganic sources of nitrogen to “fix” nitrogen. Rhizobium bacteria live symbiotically in the root nodules of legumes (such as peas, beans, and peanuts) and provide them with the organic nitrogen they need. Free-living bacteria, such as Azotobacter, are also important nitrogen fixers. Organic nitrogen is especially important to the study of ecosystem dynamics since many ecosystem processes, such as primary production and decomposition, are limited by the available supply of nitrogen. As shown in Figure 46.17, the nitrogen that enters living systems by nitrogen fixation is successively converted from organic nitrogen back into nitrogen gas by bacteria. This process occurs in three steps in terrestrial systems: ammonification, nitrification, and denitrification. First, the ammonification process converts nitrogenous waste from living animals or from the remains of dead animals.
What term describes the amount of solute in a given amount of solution?	cloudiness	density	temperature	concentration	The concentration of a solution is the amount of solute in a given amount of solution. A dilute solution has a low concentration of solute. A concentrated solution has a high concentration of solute.
Which process helps absorptive protists absorb food molecules across their cell membranes?	metabolism	activation	secretion	diffusion	Absorptive protists absorb food molecules across their cell membranes. This occurs by diffusion. These protists are important decomposers.
When matter recycles and changes state what does it gain or lose by doing so?	fuel	density	volume	energy	Matter can exist in one of several different states, including a gas, liquid, or solid state. States of matter differ in the amount of energy their molecules have. When matter recycles, it changes state by gaining or losing energy.
Where does oxygen enter the blood?	in the liver	in the heart	in the veins	in the lungs
What kind of compounds change color when bases come into contact with them, so they can be used to detect bases?	metals	liquid	parameters	indicators	Certain compounds, called indicators, change color when bases come into contact with them, so they can be used to detect bases. An example of an indicator is a compound called litmus. It is placed on small strips of paper that may be red or blue. If you place a few drops of a base on a strip of red litmus paper, the paper will turn blue. You can see this in the Figure below . Litmus isn’t the only detector of bases. Red cabbage juice can also detect bases, as you can see in this video: http://www. youtube. com/watch?v=vrOUdoS2BtQ .
Concentric circles that spread out through the water around the droplets are actually types of what moving through the water?	lines	winds	troughs	waves	No doubt you’ve seen this happen. Droplets of water fall into a body of water, and concentric circles spread out through the water around the droplets. The concentric circles are waves moving through the water.
The smallest units of matter that retain the unique properties of an element are known as what?	neutrons	protons	molecules	atoms	All matter is made of tiny particles. Protons, neutrons, and electrons form atoms that bond together to create molecules. Atoms are the smallest units that have the properties of an element. Molecules are the smallest units of a compound. Chemical bonds hold molecules together. Molecules form the different types of minerals. The silicates make up most of Earth's crust. Minerals come together to create the three major rock types. They are igneous, sedimentary, and metamorphic. Igneous rocks form from cooled magma. Sedimentary rocks form from compacted or cemented sediments. Metamorphic rocks are those that have been altered by heat and pressure. These three rock types are the material part of the rock cycle. They are connected by different processes. Different processes convert any type of rock into any other type of rock. These processes are weathering and erosion, crystallization, and burial and pressure, among others. Each rock contains a story of how it formed. For most rocks it is possible to know what it formed from.
What is a process that changes some chemical substances into other chemical substances?	cellular respiration	a bio reaction	spontaneous mutation	a chemical reaction	A chemical reaction is a process that changes some chemical substances into other chemical substances. The substances that start a chemical reaction are called reactants . The substances that form as a result of a chemical reaction are called products . During the reaction, the reactants are used up to create the products. For example, when methane burns in oxygen, it releases carbon dioxide and water. In this reaction, the reactants are methane (CH 4 ) and oxygen (O 2 ), and the products are carbon dioxide (CO 2 ) and water (H 2 O).
What type of lens and mirrors have a negative focal length?	subverging	converging	convexing	diverging	The focal length , , of a lens or mirror is the distance from the surface of the lens or mirror to the place where the light is focused. This is called the focal point or focus . For diverging lenses or mirrors, the focal length is negative.
What is the formation of organs from the germ layers called?	biosynthesis	photosynthesis	synaptogenesis	organogenesis	43.7 Organogenesis and Vertebrate Formation Organogenesis is the formation of organs from the germ layers. Each germ layer gives rise to specific tissue types. The first stage is the formation of the neural system in the ectoderm. The mesoderm gives rise to somites and the notochord. Formation of vertebrate axis is another important developmental stage.
What must two nuclei do for fusion to occur?	repel each other	explode	melt	collide	Two nuclei must collide for fusion to occur. High temperatures are required to give the nuclei enough kinetic energy to overcome the very strong repulsion resulting from their positive charges. A nuclear reactor consists of the following: 1. A nuclear fuel. A fissionable isotope must be present in large enough quantities to sustain a controlled chain reaction. The radioactive isotope is contained in tubes called fuel rods. A moderator. A moderator slows neutrons produced by nuclear reactions so that they can be absorbed by the fuel and cause additional nuclear reactions. A coolant. The coolant carries heat from the fission reaction to an external boiler and turbine where it is transformed into electricity.
What determines the ability of soil particles to bind many nutrients?	currents charges	surface pulses	layer charges	surface charges
Enthalpy is a measure of the total energy of what kind of system?	hypodermic	macroscopic	planetary	thermodynamic	Reactions can proceed by themselves if they are exergonic or exothermic, that is if they release energy. The associated free energy of the reaction is composed of two different thermodynamic quantities, enthalpy and entropy. Enthalpy is a measure of the total energy of a thermodynamic system. The change in enthalpy is positive in endothermic reactions, and negative in exothermic processes.
In eukaryotes, the new mrna is not yet ready for translation. it must go through more processing before it leaves where?	protons	Electrons	molecules	nucleus	In eukaryotes, the new mRNA is not yet ready for translation. It must go through more processing before it leaves the nucleus. This may include splicing, editing, and polyadenylation. These processes modify the mRNA in various ways. Such modifications allow a single gene to be used to make more than one protein.
What term describes the splitting of the nucleus of an atom into two smaller nuclei?	critical fission	nuclean fusion	atomic reaction	nuclear fission	Nuclear fission is the splitting of the nucleus of an atom into two smaller nuclei. This type of reaction releases a great deal of energy from a very small amount of matter. It begins when the nucleus of a radioactive atom gains a neutron.
What type of contamination causes almost 90% of diarrheal disease worldwide?	food contamination	air contamination	ground contamination	water supply contamination	Unsafe water supplies have drastic effects on human health. Waterborne diseases are diseases due to microscopic pathogens in fresh water. These diseases can be caused by protozoa, viruses, bacteria, and intestinal parasites. In many parts of the world there are no water treatment plants. If sewage or animal manure gets into a river, then people downstream will get sick when they drink the water. According to the World Health Organization (WHO), diarrheal disease is responsible for the deaths of 1.8 million people every year. It was estimated that 88% of the cases of diarrheal disease are caused by unsafe water supplies.
Why is respiratory acidosis considered to be problematic?	causes suffocation	causes acid stomach	excess oxygen in blood	excess co2 in blood	Metabolic acidosis is problematic, as lower-than-normal amounts of bicarbonate are present in the blood. The pCO2 would be normal at first, but if compensation has occurred, it would decrease as the body reestablishes the proper ratio of bicarbonate and carbonic acid/CO2. Respiratory acidosis is problematic, as excess CO2 is present in the blood. Bicarbonate levels would be normal at first, but if compensation has occurred, they would increase in an attempt to reestablish the proper ratio of bicarbonate and carbonic acid/CO2. Alkalosis is characterized by a higher-than-normal pH. Metabolic alkalosis is problematic, as elevated pH and excess bicarbonate are present. The pCO2 would again be normal at first, but if compensation has occurred, it would increase as the body attempts to reestablish the proper ratios of bicarbonate and carbonic acid/CO 2. Respiratory alkalosis is problematic, as CO2 deficiency is present in the bloodstream. The bicarbonate concentration would be normal at first. When renal compensation occurs, however, the bicarbonate concentration in blood decreases as the kidneys attempt to reestablish the proper ratios of bicarbonate and carbonic acid/CO2 by eliminating more bicarbonate to bring the pH into the physiological range.
When light strikes rhodopsin, the g-protein transducin is activated, which in turn activates what?	hydrolysis	aldosterone	photosynthesis	phosphodiesterase	Figure 36.20 When light strikes rhodopsin, the G-protein transducin is activated, which in turn activates phosphodiesterase. Phosphodiesterase converts cGMP to GMP, thereby closing sodium channels. As a result, the membrane becomes hyperpolarized. The hyperpolarized membrane does not release glutamate to the bipolar cell.
In what stage of photosynthesis does the calvin cycle occur?	first	third	fourth	second	The Calvin cycle occurs in the second stage of photosynthesis. This stage takes place in the stroma of the chloroplast. In the Calvin cycle, carbon dioxide is used to produce glucose (sugar) using the energy stored in ATP and NADPH. The energy is released from these molecules when ATP loses phosphate (P i ) to become ADP and NADPH loses hydrogen (H) to become NADP + .
All of the planets rotate on their axes in the same direction that they move around the sun, except for which one?	Saturn	Jupiter	venus	uranus	All of the planets rotate on their axes in the same direction that they move around the Sun. Except for Uranus. Uranus is tilted on its side. Its axis is almost parallel to its orbit. So Uranus rolls along like a bowling ball as it revolves around the Sun. How did Uranus get this way? Scientists think that the planet was struck and knocked over by another planet-sized object. This collision probably took place billions of years ago.
What is the process by which organisms change in small ways over time?	adaptation	spontaneous mutation	natural selection	microevolution	Microevolution is the process by which organisms change in small ways over time.
What regulates the cell cycle only when they are tightly bound to cdks?	hormones	kinases	subclades	cyclins	Cyclins regulate the cell cycle only when they are tightly bound to Cdks. To be fully active, the Cdk/cyclin complex must also be phosphorylated in specific locations. Like all kinases, Cdks are enzymes (kinases) that phosphorylate other proteins. Phosphorylation activates the protein by changing its shape. The proteins phosphorylated by Cdks are involved in advancing the cell to the next phase. (Figure 10.12). The levels of Cdk proteins are relatively stable throughout the cell cycle; however, the concentrations of cyclin fluctuate and determine when Cdk/cyclin complexes form. The different cyclins and Cdks bind at specific points in the cell cycle and thus regulate different checkpoints.
Einstein developed a theory about how electromagnetic radiation can behave as both a wave and what else?	sound	energy	bacteria	particle	In 1905, the physicist Albert Einstein developed a new theory about electromagnetic radiation. The theory is often called the wave-particle theory . It explains how electromagnetic radiation can behave as both a wave and a particle. Einstein argued that when an electron returns to a lower energy level and gives off electromagnetic energy, the energy is released as a discrete “packet” of energy. We now call such a packet of energy a photon . According to Einstein, a photon resembles a particle but moves like a wave. You can see this in the Figure below . The theory posits that waves of photons traveling through space or matter make up electromagnetic radiation.
What type of proteins are only temporarily associated with the membrane?	peripheral oxidation proteins	visual membrane proteins	sensitive rod proteins	peripheral membrane proteins	Peripheral membrane proteins are proteins that are only temporarily associated with the membrane. They can be easily removed, which allows them to be involved in cell signaling. Peripheral proteins can also be attached to integral membrane proteins, or they can stick into a small portion of the lipid bilayer by themselves. Peripheral membrane proteins are often associated with ion channels and transmembrane receptors. Most peripheral membrane proteins are hydrophilic.
Which organisms break down either organic or inorganic molecules to supply energy for the cell?	spicule organisms	photoreactive organisms	asexual organisms	chemotrophic organisms	Chemotrophic organisms break down either organic or inorganic molecules to supply energy for the cell. Some chemotrophic organisms can also use their organic energy-supplying molecules as a carbon supply, which would make them chemoheterotrophs.
What are the things moving under the earth's mantle that move the crust?	lava channels	crystals	ridges	plates	What portion of Earth makes up the “plates” in plate tectonics? Again, the answer came about in part due to war. In this case, the Cold War. The scientists set up seismometer networks during the 1950s and early 1960s. The purpose was to see if other nations were testing atomic bombs. Since seismometers measure ground shaking, they also recorded earthquakes.
Although they look like big rocks, what structures that serve as habitats for many different types of ocean life are actually alive?	southern reefs	new forming reefs	natural reefs	coral reefs	Coral reefs ( Figure below ) look like big rocks, but they are actually alive. They are built from cnidarians called corals. The corals are sessile (non-moving) polyps that can use their tentacles to feed on ocean creatures that pass by. Their skeletons are made up of calcium carbonate, which is also known as limestone. Over long periods of time, their skeletons build on each other to produce large structures known as coral reefs. Coral reefs are important habitats for many different types of ocean life.
What type of reactions are chemical reactions that release energy?	ozonic reactions	sulfuric reactions	biochemical reactions	exothermic reactions	Chemical reactions that release energy are called exothermic reactions . An example is the combustion of methane described at the beginning of this lesson. In organisms, exothermic reactions are called catabolic reactions . Catabolic reactions break down molecules into smaller units. An example is a decomposition reaction, such as the breakdown of glucose molecules for energy. Exothermic reactions can be represented by the general chemical equation:.
Fossil fuels and coal are examples of what kind of resources?	renewable	valuable	reusable	nonrenewable	Nonrenewable resources exist in fixed amounts. They can be used up. Examples include fossil fuels such as coal.
What type of compound contains atoms of two or more different elements in its ring structure?	hydrocarbon	aldehyde	polymer	heterocyclic	In some amines, the nitrogen atom replaces a carbon atom in an aromatic hydrocarbon. Pyridine (Figure 20.17) is one such heterocyclic amine. A heterocyclic compound contains atoms of two or more different elements in its ring structure.
What is formed when atoms of different elements combine in a chemical reaction?	toxins	crystals	dust	compounds	For each of the following situations, tell whether the rate of the reaction would increase or decrease, and explain your answer in terms of collision theory. The concentration of a reactant is doubled.
What type of electricity is formed when a negative charge builds up and are transferred?	direct current	neutron energy	alternating current	static electricity	Static electricity is a buildup of electric charges on objects. Charges build up when negative electrons are transferred from one object to another. The object that gives up electrons becomes positively charged, and the object that accepts the electrons becomes negatively charged. This can happen in several ways.
What important liquid is stored throughout the earth in the oceans, underground, and in ice?	air	oil	lava	water	Water cycling is extremely important to ecosystem dynamics. Water has a major influence on climate and, thus, on the environments of ecosystems, some located on distant parts of the Earth. Most of the water on Earth is stored for long periods in the oceans, underground, and as ice. Figure 46.13 illustrates the average time that an individual water molecule may spend in the Earth’s major water reservoirs. Residence time is a measure of the average time an individual water molecule stays in a particular reservoir. A large amount of the Earth’s water is locked in place in these reservoirs as ice, beneath the ground, and in the ocean, and, thus, is unavailable for short-term cycling (only surface water can evaporate).
What results when a warm air mass runs into a cold air mass?	rough front	cool front	dry front	warm front	When a warm air mass runs into a cold air mass, it creates a warm front ( Figure below ). The warm air mass is moving faster than the cold air mass. The warm air mass then flows up over the cold air mass. As the warm air rises, it cools. This brings about clouds and sometimes light precipitation. Warm fronts move slowly and cover a wide area. After a warm front passes, the warm air mass behind it brings warmer temperatures. The warm air is also likely to be more humid.
Which type of double bond has a sigma bond and a pi bond?	sodium - oxygen bond	dioxide - oxygen bond	Covalent Bonds	carbon-oxygen bond	Has a double-bonded carbon-oxygen bond (one sigma bond and one pi bond). The carbon to which the oxygen is attached has one hydrogen atom connected to it.
Has the average annual temperature on earth been rising or falling for the past 100 years?	falling	unchanged	fluctuating	rising	The average annual temperature on Earth has been rising for the past 100 years.
The majoirty of modern gymnosperms belong to what group, which includes pine trees?	clusters	stems	Pinophytes	conifers	There are only about 1,000 living species of gymnosperms, whereas there are hundreds of thousands of living species of angiosperms. Living gymnosperms are typically classified in the divisions described in the Table below . Most modern gymnosperms are trees with woody trunks. The majority are conifers such as pine trees.
A circuit must be what in order for electric devices such as light bulbs to work?	cyclical	open	down	closed	A circuit must be closed for electric devices such as light bulbs to work. The arrows in the diagram show the direction in which electrons flow through the circuit. The current is considered to flow in the opposite direction.
What type of radiation from the sun reaches earth across space striking everything on earth’s surface?	seismic	particle	static	electromagnetic	Electromagnetic radiation from the sun reaches Earth across space. It strikes everything on Earth’s surface, including these volleyball players.
What happens if a catalyst runs out?	reaction increases	variety slows	variety increases	reaction slows	Chemistry in Everyday Life Transition Metal Catalysts One of the most important applications of transition metals is as industrial catalysts. As you recall from the chapter on kinetics, a catalyst increases the rate of reaction by lowering the activation energy and is regenerated in the catalytic cycle. Over 90% of all manufactured products are made with the aid of one or more catalysts. The ability to bind ligands and change oxidation states makes transition metal catalysts well suited for catalytic applications. Vanadium oxide is used to produce 230,000,000 tons of sulfuric acid worldwide each year, which in turn is used to make everything from fertilizers to cans for food. Plastics are made with the aid of transition metal catalysts, along with detergents, fertilizers, paints, and more (see Figure 19.26). Very complicated pharmaceuticals are manufactured with catalysts that are selective, reacting with one specific bond out of a large number of possibilities. Catalysts allow processes to be more economical and more environmentally friendly. Developing new catalysts and better understanding of existing systems are important areas of current research.
What type of mammals are humans?	respiratory mammals	somatic mammals	marsupial mammals	placental mammals	Human beings are mammals. Like other mammals, we have hair and mammary glands. The subclass in which the human species is classified is the placental mammals.
The shape of the path of an object undergoing projectile motion in two dimensions is a what?	radius	orbit	circle	parabola	The shape of the path of an object undergoing projectile motion in two dimensions is a parabola.
The earliest cells were called what?	microcytes	eukaryotes	carbohydrates	prokaryotes	The first organisms were made of only one cell ( Figure below ). The earliest cells were prokaryotes . Prokaryotic cells are surrounded by a cell membrane, but they do not have a nucleus. The cells got their nutrients directly from the water. The cells needed to use these nutrients to live and grow.
Protists are the simplest of what?	fungi	prokaryotes	plants	eukaryotes	Protists are the simplest eukaryotes. They are easiest to define by what they are not. Protists are not animals, plants, or fungi.
The measure of magnetic fields is named after a serbian physicist. what is his name?	Niels Bohr	Carl Sagan	Albert Einstein	nikola tesla	For static electric charges, the electromagnetic force is manifested by the Coulomb electric force alone. If charges are moving, an additional force emerges, called magnetism. The century realization that electricity and magnetism are dual aspects of the same force completely changed our understanding of the world we live in. Insights due to Ampere, Gauss, and Maxwell led to the understanding that moving charges – electric currents – create magnetic fields. Varying magnetic fields create electric fields. Thus a loop of wire in a changing magnetic field will have current induced in it. This is called electromagnetic induction. Magnetic fields are usually denoted by the letter and are measured in Teslas, in honor of the Serbian physicist Nikola Tesla.
Radon (rn) is a radioactive gas formed by the decay of naturally occurring uranium in rocks such as granite. it tends to collect in the basements of houses and poses a significant health risk if present in indoor air. many states now require that houses be tested for radon before they are what?	built	modified	seen	sold	M = dRTP Exercise Radon (Rn) is a radioactive gas formed by the decay of naturally occurring uranium in rocks such as granite. It tends to collect in the basements of houses and poses a significant health risk if present in indoor air. Many states now require that houses be tested for radon before they are sold. Calculate the density of radon at 1.00 atm pressure and 20°C and compare it with the density of nitrogen gas, which constitutes 80% of the atmosphere, under the same conditions to see why radon is found in basements rather than in attics. Answer: radon, 9.23 g/L; N2, 1.17 g/L A common use of Equation 10.23 is to determine the molar mass of an unknown gas by measuring its density at a known temperature and pressure. This method is particularly useful in identifying a gas that has been produced in a reaction, and it is not difficult to carry out. A flask or glass bulb of known volume is carefully dried, evacuated, sealed, and weighed empty. It is then filled with a sample of a gas at a known temperature and pressure and reweighed. The difference in mass between the two readings is the mass of the gas. The volume of the flask is usually determined by weighing the flask when empty and when filled with a liquid of known density such as water. The use of density measurements to calculate molar masses is illustrated in Example 10.
What state of matter takes neither the shape nor the volume of its container?	liquid	hot	gas	solid	All three containers contain a substance with the same mass, but the substances are in different states. In the left-hand container, the substance is a gas, which has spread to fill its container. It takes both the shape and volume of the container. In the middle container, the substance is a liquid, which has spread to take the shape of its container but not the volume. In the right-hand container, the substance is a solid, which takes neither the shape nor the volume of its container.
Force times distance is the equation for what?	gravity	power	speed	work	Work is directly related to both the force applied to an object and the distance the object moves. It can be represented by the equation: Work = Force × Distance.
What is the name for a series of changes in the reproductive system of mature females that repeats every month on average?	puberty	periodic table	urinary cycle	menstrual cycle	Egg production in the ovary is part of the menstrual cycle. The menstrual cycle is a series of changes in the reproductive system of mature females that repeats every month on average. These changes include the development of an egg and follicle in the ovary.
What is the name of the iron-containing oxygen-transport protein in the red blood cells of all vertebrates?	ferric acid	plasma	platelet	hemoglobin	Hemoglobin is the iron-containing oxygen-transport protein in the red blood cells of all vertebrates. The hemoglobin molecule is an assembly of four globular protein subunits, each tightly associated with a non-protein heme group. The heme group binds to the iron ion. The most common hemoglobin is hemoglobin A, a tetramer consisting of two alpha and two beta subunits, denoted as α2β2.
What is the active ingredient in household bleach?	iodine	magnesium	oxygen	chlorine	Chlorine is the active ingredient in household bleach. It removes stains from clothes. It can also be used to disinfect countertops and other surfaces.
What are the membrane-bound organelles that are usually larger than vesicles and can have secretory, excretory, and storage functions?	nucleolus	ribosomes	tubules	vacuoles	Vacuoles are membrane-bound organelles that can have secretory, excretory, and storage functions. They are usually larger than vesicles.
What broad category of animals is primarily ectothermic and covered with scales that facilitate swimming?	deer	armadillo	turtles	fish	Fish show great diversity in body size. They range in length from about 8 millimeters (0.3 inches) to 16 meters (about 53 feet). Most are ectothermic and covered with scales. Scales protect fish from predators and parasites and reduce friction with the water. Multiple, overlapping scales provide a flexible covering that allows fish to move easily while swimming.
What has two chains of nucleotides, one more than rna?	mna	gna	fna	dna	RNA consists of just one chain of nucleotides. DNA consists of two chains. Nitrogen bases on the two chains of DNA form hydrogen bonds with each other. Hydrogen bonds are relatively weak bonds that form between a positively charged hydrogen atom in one molecule and a negatively charged atom in another molecule. Hydrogen bonds form only between adenine and thymine, and between guanine and cytosine. These bonds hold the two chains together and give DNA is characteristic double helix, or spiral, shape.
The axon terminates on muscle fibers at the neuromuscular junction. acetylcholine is released at this specialized synapse, which causes the muscle action potential to begin, following a large potential known as an end plate potential. when the lower motor neuron excites the muscle fiber, it contracts. all of this occurs in a fraction of a second, but this story is the basis of how this functions?	muscular system	cardiovascular system	respiratory system	nervous system	described in the chapter on muscle tissue, an action potential travels along the motor neuron axon into the periphery. The axon terminates on muscle fibers at the neuromuscular junction. Acetylcholine is released at this specialized synapse, which causes the muscle action potential to begin, following a large potential known as an end plate potential. When the lower motor neuron excites the muscle fiber, it contracts. All of this occurs in a fraction of a second, but this story is the basis of how the nervous system functions.
Misconceptions about what theory contribute to the controversy that still surrounds this fundamental principle of biology?	cycle of evolution	darwin on evolution	brain of evolution	theory of evolution	Today, evolution is still questioned by some people. Often, people who disagree with the theory of evolution do not really understand it. For example, some people think that the theory of evolution explains how life on Earth first began. In fact, the theory explains only how life changed after it first appeared. Some people think the theory of evolution means that humans evolved from modern apes. In fact, the theory suggests humans and modern apes have a common ancestor that lived several million years ago. These and other misconceptions about evolution contribute to the controversy that still surrounds this fundamental principle of biology.
What device is used to stop a current in a circuit?	a mirror	a signal	a valve	a switch	Understand current as it passes through a series circuit.
What oily substance prevents the hair and skin of living things from drying out?	pancreatic enzymes	pus	progesterone	sebum	Sebaceous glands are commonly called oil glands. They produce an oily substance called sebum. Sebum is secreted into hair follicles. Then it makes its way along the hair shaft to the surface of the skin. Sebum waterproofs the hair and skin and helps prevent them from drying out.
What two types of communication do both humans and birds use primarily?	interaction and auditory	sensual and auditory	material and auditory	visual and auditory
Eggs are produced in what organs and, upon fertilization, develop in what other organ?	uterus, vagina	fallopian tubes, ovaries	cervix, ovaries	ovaries, uterus
The first line of defense includes mechanical, chemical, and which other barrier?	surgical	independent	physical	biological	The first line of defense includes mechanical, chemical, and biological barriers.
What is another term for nearsightedness?	anemia	hypoxia	astigmatism	myopia	Nearsightedness, or myopia, is the condition in which nearby objects are seen clearly, but distant objects appear blurry. The Figure below shows how it occurs. The eyeball is longer (from front to back) than normal. This causes images to be focused in front of the retina instead of on the retina. Myopia can be corrected with concave lenses. The lenses focus images farther back in the eye, so they fall on the retina instead of in front of it.
Because all animals require an external source of what, they are called heterotrophic?	water	fuel	energy	food	27.1 \| Features of the Animal Kingdom By the end of this section, you will be able to: • List the features that distinguish the kingdom Animalia from other kingdoms • Explain the processes of animal reproduction and embryonic development • Describe the roles that Hox genes play in development Even though members of the animal kingdom are incredibly diverse, most animals share certain features that distinguish them from organisms in other kingdoms. All animals are eukaryotic, multicellular organisms, and almost all animals have a complex tissue structure with differentiated and specialized tissues. Most animals are motile, at least during certain life stages. All animals require a source of food and are therefore heterotrophic, ingesting other living or dead organisms; this feature distinguishes them from autotrophic organisms, such as most plants, which synthesize their own nutrients through photosynthesis. As heterotrophs, animals may be carnivores, herbivores, omnivores, or parasites (Figure 27.2ab). Most animals reproduce sexually, and the offspring pass through a series of developmental stages that establish a determined and fixed body plan. The body plan refers to the morphology of an animal, determined by developmental cues.
What causes blue litmus to turn red?	carbon	oxygen	base	acid	Acids change the color of certain acid-base indicators. Two common indicators are litmus and phenolphthalein. Blue litmus turns red in the presence of an acid, while phenolphthalein turns colorless.
When fossil fuel is burned the chemical energy is converted into what?	natural energy	kinetic energy	atmospheric energy	thermal energy	Watching movies, eating hot popcorn, and many other activities depend on electrical energy. Most electrical energy comes from the burning of fossil fuels, which contain stored chemical energy. When fossil fuels are burned, the chemical energy changes to thermal energy and the thermal energy is then used to generate electrical energy. These are all examples of energy conversion. Energy conversion is the process in which one kind of energy changes into another kind. When energy changes in this way, the energy isn’t used up or lost. The same amount of energy exists after the conversion as before. Energy conversion obeys the law of conservation of energy, which states that energy cannot be created or destroyed.
What two activities are especially important when a number of local populations are linked, forming a metapopulation?	immigration and family reunions	family reunions and emigration	flow and emigration	immigration and emigration
What is the physical environment in which a species lives and to which it has adapted?	farmland	ecosystem	land mass	habitat	Another important aspect of a species’ niche is its habitat. Habitat is the physical environment in which a species lives and to which it has adapted. Features of a habitat depend mainly on abiotic factors, such as temperature and rainfall. These factors influence the traits of the organisms that live there.
What kind of tests may detect substances associated with particular disorders?	genetic	hormonal	electrical	biochemical
Scientists think the solar system formed from a big cloud of gas and dust called what?	Oort cloud	comet	supernova	nebula	Scientists think the solar system formed from a big cloud of gas and dust, called a nebula . This is the solar nebula hypothesis. The nebula was made mostly of hydrogen and helium. There were heavier elements too. Gravity caused the nebula to contract ( Figure below ).
What are the largest phylum of the animal kingdom?	Pycnogonida	Crustacea	Chelicerata	arthropods	Two chemical species combine to produce a new compound. The general expression for this reaction is A + B → C.
What is the name for a material that prevents the transfer of heat energy?	thermal condenser	physical insulator	structure insulator	thermal insulator	Another example of a thermal insulator is pictured in the Figure below . The picture shows fluffy pink insulation inside the attic of a home. Like the down filling in a snowsuit, the insulation traps a lot of air. The insulation helps to prevent the transfer of thermal energy into the house on hot days and out of the house on cold days. Other materials that are thermal insulators include plastic and wood. That’s why pot handles and cooking utensils are often made of these materials. Notice that the outside of the toaster pictured in the opening image is made of plastic. The plastic casing helps prevent the transfer of thermal energy from the heating element inside to the outer surface of the toaster where it could cause burns. You can learn more about thermal insulators at this URL: http://www. school-for-champions. com/science/thermal_insulation. htm .
What is a rock exposed to if it's undergoing metamorphism?	time and energy	humidity and pressure	gravity and precipitation	heat and pressure	Metamorphism. This long word means “to change form. “ A rock undergoes metamorphism if it is exposed to extreme heat and pressure within the crust. With metamorphism, the rock does not melt all the way. The rock changes due to heat and pressure. A metamorphic rock may have a new mineral composition and/or texture.
Water infiltrates the ground because soil and rock may have air spaces between the grains. these pores, or tiny holes, result in the rock's what?	shine	sheen	energy	porosity	Identify features caused by groundwater erosion and deposition.
Work is done only if a force is exerted in the direction of what?	gravity	wind	north	motion	Work is done only if a force is exerted in the direction of motion. If the motion is perpendicular to the force, no work has been done. If the force is at an angle to the motion, then the component of the force in the direction of the motion is used to determine the work done.
What is the smallest independently functioning unit of a living organism?	atom	proteins	molecule	cell	A cell is the smallest independently functioning unit of a living organism. Even bacteria, which are extremely small, independently-living organisms, have a cellular structure. Each bacterium is a single cell. All living structures of human anatomy contain cells, and almost all functions of human physiology are performed in cells or are initiated by cells. A human cell typically consists of flexible membranes that enclose cytoplasm, a water-based cellular fluid together with a variety of tiny functioning units called organelles. In humans, as in all organisms, cells perform all functions of life. A tissue is a group of many similar cells (though sometimes composed of a few related types) that work together to perform a specific function. An organ is an anatomically distinct structure of the body composed of two or more tissue types. Each organ performs one or more specific physiological functions. An organ system is a group of organs that work together to perform major functions or meet physiological needs of the body. This book covers eleven distinct organ systems in the human body (Figure 1.4 and Figure 1.5). Assigning organs to organ systems can be imprecise since organs that “belong” to one system can also have functions integral to another system. In fact, most organs contribute to more than one system.
All animals have specialized types of what basic structures, which can then do different jobs?	atoms	proteins	muscles	cells	Animals are multicellular eukaryotes in the Animal Kingdom. All animals are heterotrophs. They eat other living things because they can’t make their own food. All animals also have specialized cells that can do different jobs. Most animals have higher levels of organization as well. They may have specialized tissues, organs, and even organ systems. Having higher levels of organization allows animals to perform many complex functions. For a visual introduction to what makes a living thing an animal, watch this short video: https://www. youtube. com/watch?v=DXPhJUHooP8 .
What term describes the number of items in a given area or volume?	density	alkalinity	fraction	concentration	In its most general form, concentration describes the number of items in a given area or volume. The units generally depend on the types of items being counted. For example, if we were to calculate the concentration of people that live in a city, we would divide the total number of people by the area. If we measured the area in square miles, the units of concentration for this measurement would be people per square mile. Or, we could determine the concentration of fish in a lake by dividing the total number of fish by the volume of the lake. If we measure the volume in cubic meters, the concentration would have units of fish per cubic meter.
Birds are known for flying south in the winter to avoid what?	hurricanes	solar radiation	rain	cold weather
The root system is usually anchored by one main root developed from what?	organisms radicle	sperm radicle	nuclei radicle	embryonic radicle	Eudicots Eudicots, or true dicots, are characterized by the presence of two cotyledons. Veins form a network in leaves. Flower parts come in four, five, or many whorls. Vascular tissue forms a ring in the stem. (In monocots, vascular tissue is scattered in the stem. ) Eudicots can be herbaceous (like dandelions or violets), or produce woody tissues. Most eudicots produce pollen that is trisulcate or triporate, with three furrows or pores. The root system is usually anchored by one main root developed from the embryonic radicle. Eudicots comprise two-thirds of all flowering plants. Many species seem to exhibit characteristics that belong to either group; therefore, the classification of a plant as a monocot or a eudicot is not always clearly evident (Table 14.1).
What type of learning is done from past experiences and reasoning?	rational learning	consequence learning	transformation learning	insight learning	Insight learning is learning from past experiences and reasoning. It usually involves coming up with new ways to solve problems. Insight learning generally happens quickly. An animal has a sudden flash of insight. Insight learning requires relatively great intelligence. Human beings use insight learning more than any other species. They have used their intelligence to solve problems ranging from inventing the wheel to flying rockets into space.
Where is the pituitary gland?	lung	thyroid	heart	brain	The regulation of Leydig cell production of testosterone begins outside of the testes. The hypothalamus and the pituitary gland in the brain integrate external and internal signals to control testosterone synthesis and secretion. The regulation begins in the hypothalamus. Pulsatile release of a hormone called gonadotropin-releasing hormone (GnRH) from the hypothalamus stimulates the endocrine release of hormones from the pituitary gland. Binding of GnRH to its receptors on the anterior pituitary gland stimulates release of the two gonadotropins: luteinizing hormone (LH) and follicle-stimulating hormone (FSH). These two hormones are critical for reproductive function in both men and women. In men, FSH binds predominantly to the Sertoli cells within the seminiferous tubules to promote spermatogenesis. FSH also stimulates the Sertoli cells to produce hormones called inhibins, which function to inhibit FSH release from the pituitary, thus reducing testosterone secretion. These polypeptide hormones correlate directly with Sertoli cell function and sperm number; inhibin B can be used as a marker of spermatogenic activity. In men, LH binds to receptors on Leydig cells in the testes and upregulates the production of testosterone. A negative feedback loop predominantly controls the synthesis and secretion of both FSH and LH. Low blood concentrations of testosterone stimulate the hypothalamic release of GnRH. GnRH then stimulates the anterior pituitary to secrete LH into the bloodstream. In the testis, LH binds to LH receptors on Leydig cells and stimulates the release of testosterone. When concentrations of testosterone in the blood reach a critical threshold, testosterone itself will bind to androgen receptors on both the hypothalamus and the anterior pituitary, inhibiting the synthesis and secretion of GnRH and LH, respectively. When the blood concentrations of testosterone once again decline, testosterone no longer interacts with the receptors to the same degree and GnRH and LH are once again secreted, stimulating more testosterone production. This same process occurs with FSH and inhibin to control spermatogenesis.
Which fungi eaten by people all over the world?	algae	fruits	legumes	mushrooms	Mushrooms are fungi that are eaten by people all over the globe.
The outermost layer of the leaf is the epidermis; it is present on both sides of the leaf and is called the upper and lower epidermis, respectively. botanists call the upper side the adaxial surface (or adaxis) and the lower side this?	anterior surface	dorsal surface	posterior surface	abaxial surface (or abaxis)	Leaf Structure and Function The outermost layer of the leaf is the epidermis; it is present on both sides of the leaf and is called the upper and lower epidermis, respectively. Botanists call the upper side the adaxial surface (or adaxis) and the lower side the abaxial surface (or abaxis). The epidermis helps in the regulation of gas exchange. It contains stomata (Figure 30.24): openings through which the exchange of gases takes place. Two guard cells surround each stoma, regulating its opening and closing.
A small quake preceding a large quake is called what?	preshock	aftershock	warning shock	foreshock	There are sometimes signs that a large earthquake is coming. There may be small quakes, called foreshocks . These can occur a few seconds to a few weeks before a major quake. Unfortunately, foreshocks are not very useful for predicting large earthquakes. Many quakes do not have foreshocks. Also, small earthquakes are not necessarily followed by a large earthquake.
What do winter storms develop from at higher latitudes?	temperatures	humidity	clouds	cyclones	Winter storms develop from cyclones at higher latitudes. They include blizzards and lake-effect snow storms.
What is the only substance on earth that is present in all three states of matter?	carbon	mercury	air	water	Water is the only substance on Earth that is present in all three states of matter. This means that water is present as a solid, liquid, and gas. Earth is the only planet where water is present in all three states. All three phases may be present in a single location or in a region. The three phases are solid (ice or snow), liquid (water), and gas ( water vapor ). See ice, water, and clouds pictured below ( Figure below ).
What is essential for forming new genes?	chromosome deversity	enough mutations	enough chromosomes	large mutations	It is believed that large mutations form new genes. Mutations that duplicate large sections of DNA are a major source of genetic material for new genes. It is thought that tens to hundreds of genes are duplicated in animal genomes every million years. Most genes belong to larger families of genes of shared ancestry. These gene families have domains within the protein with a particular and independent function. These domains have corresponding conserved regions within their genes. It is through duplication mutations that such gene families formed. Genetic recombination after duplication of different domains forms new combinations of domains with new functions. For example, the human eye uses four genes to make structures that sense light: three for color vision and one for night vision; all four arose from a single ancestral gene.
What is fluid friction with air called?	gravity	buoyancy	wind resistance	air resistance	Types of friction include static friction, sliding friction, rolling friction, and fluid friction. Fluid friction with air is called air resistance.
Plants produce their own sugars and other food molecules through what process?	glycolysis	hydrogenesis	spermatogenesis	photosynthesis
What do fission reactors use to slow down the neutrons?	control	inertia	brake	moderator	U-235 nuclei can capture neutrons and disintegrate more efficiently if the neutrons are moving slower than the speed at which they are released. Fission reactors use a moderator surrounding the fuel rods to slow down the neutrons. Water is not only a good coolant but also a good moderator, so a common type of fission reactor has the fuel core submerged in a huge pool of water. This type of reactor is called a light water reactor or LWR. All public electricity generating fission reactors in the United States are LWRs.
What term is used to describe an unusual sound coming from the heart that is caused by the turbulent flow of blood?	whisper	garble	music	murmur	The term murmur is used to describe an unusual sound coming from the heart that is caused by the turbulent flow of blood. Murmurs are graded on a scale of 1 to 6, with 1 being the most common, the most difficult sound to detect, and the least serious. The most severe is a 6. Phonocardiograms or auscultograms can be used to record both normal and abnormal sounds using specialized electronic stethoscopes. During auscultation, it is common practice for the clinician to ask the patient to breathe deeply. This procedure not only allows for listening to airflow, but it may also amplify heart murmurs. Inhalation increases blood flow into the right side of the heart and may increase the amplitude of right-sided heart murmurs. Expiration partially restricts blood flow into the left side of the heart and may amplify left-sided heart murmurs. Figure 19.30 indicates proper placement of the bell of the stethoscope to facilitate auscultation.
Carbon atoms are bonded to as many hydrogen atoms as possible in what type of fatty acids?	oily	super	unsaturated	saturated	Saturated fatty acids have only single bonds between carbon atoms. As a result, the carbon atoms are bonded to as many hydrogen atoms as possible. In other words, the carbon atoms are saturated with hydrogens. Saturated fatty acids are found in fats.
What kind of mouthparts do aphids have?	siphoning mouthparts	chewing mouthparts	sponging mouthparts	piercing-sucking mouthparts	Some insects, such as aphids, have piercing-sucking mouthparts. Other insects, like grasshoppers, have chewing mouthparts.
Sounds, chemicals, and visual cues are examples of what between animals?	procreation	migration	circulation	communication	For individuals to cooperate, they need to communicate . Animals can communicate with sounds, chemicals, or visual cues. For example, to communicate with sounds, birds sing and frogs croak. Both may be communicating that they are good mates. Ants communicate with chemicals called pheromones . For example, they use the chemicals to mark trails to food sources so other ants can find them. Male dogs use pheromones in urine to mark their territory. They are “telling” other dogs to stay out of their yard. You can see several examples of visual communication in Figure below .
What is pressure times area equal to?	density	volume	mass	force	There is a pressure difference when the channel narrows. This pressure difference results in a net force on the fluid: recall that pressure times area equals force. The net work done increases the fluid’s kinetic energy. As a result, the pressure will drop in a rapidly-moving fluid, whether or not the fluid is confined to a tube. There are a number of common examples of pressure dropping in rapidly-moving fluids. Shower curtains have a disagreeable habit of bulging into the shower stall when the shower is on. The high-velocity stream of water and air creates a region of lower pressure inside the shower, and standard atmospheric pressure on the other side. The pressure difference results in a net force inward pushing the curtain in. You may also have noticed that when passing a truck on the highway, your car tends to veer toward it. The reason is the same—the high velocity of the air between the car and the truck creates a region of lower pressure, and the vehicles are pushed together by greater pressure on the outside. (See Figure 12.4. ) This effect was observed as far back as the mid-1800s, when it was found that trains passing in opposite directions tipped precariously toward one another.
What part of the kangaroo helps it balance when it leaps as well as when it sits?	the spine	large feet	the pouch	the tail
What is the evolutionary history of a group of related organisms called?	ancestry	lineage	superfamily	phylogeny	Linnaeus classified organisms based on obvious physical traits. Basically, organisms were grouped together if they looked alike. After Darwin published his theory of evolution in the 1800s, scientists looked for a way to classify organisms that showed phylogeny. Phylogeny is the evolutionary history of a group of related organisms. It is represented by a phylogenetic tree , like the one in Figure below .
What are specialized cells in the brain that monitor the concentration of solutes in the blood called?	ionconcentrate	staurikosaurus	sporozoans	osmoreceptors	Many marine invertebrates have internal salt levels matched to their environments, making them isotonic with the water in which they live. Fish, however, must spend approximately five percent of their metabolic energy maintaining osmotic homeostasis. Freshwater fish live in an environment that is hypotonic to their cells. These fish actively take in salt through their gills and excrete diluted urine to rid themselves of excess water. Saltwater fish live in the reverse environment, which is hypertonic to their cells, and they secrete salt through their gills and excrete highly concentrated urine. In vertebrates, the kidneys regulate the amount of water in the body. Osmoreceptors are specialized cells in the brain that monitor the concentration of solutes in the blood. If the levels of solutes increase beyond a certain range, a hormone is released that retards water loss through the kidney and dilutes the blood to safer levels. Animals also have high concentrations of albumin, which is produced by the liver, in their blood. This protein is too large to pass easily through plasma membranes and is a major factor in controlling the osmotic pressures applied to tissues.
Bones consist of four types of tissue, compact bone, spongy bone, bone marrow, and what?	plasma	collagen	epithelium	periosteum	Bones consist of four different types of tissue: periosteum, compact bone, spongy bone, and bone marrow. Ossification gradually changes the cartilage skeleton of the fetus to the bony skeleton of the adult.

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