questions stringlengths 37 1.22k | reasoning stringlengths 0 3.56k ⌀ | answers stringlengths 4 138 |
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Ions that contain fewer electrons than protons have a net positive charge and are called what?
Here are the choices:
A. oxides
B. particles
C. cations
D. anions | Ionic Compounds The substances described in the preceding discussion are composed of molecules that are electrically neutral; that is, the number of positively charged protons in the nucleus is equal to the number of negatively charged electrons. In contrast, ions are atoms or assemblies of atoms that have a net electrical charge. Ions that contain fewer electrons than protons have a net positive charge and are called cations. Conversely, ions that contain more electrons than protons have a net negative charge and are called anions. Ionic compounds contain both cations and anions in a ratio that results in no net electrical charge. | C: cations. |
What factors consist of parts of the environment that are or were alive, and their remains?
Here are the choices:
A. xerophytic factors
B. biotic factors
C. abiotic factors
D. decomposition factors | Biotic factors are the parts of the environment that are alive, or were alive and then died, such as plants, animals, and their remains. Biotic factors also include bacteria, fungi and protists. | B: biotic factors. |
What is another name for a reasonable explanation for something that might be formed near the beginning of a scientific inquiry into a problem?
Here are the choices:
A. hypothesis
B. theory
C. conclusion
D. experiment | After doing the research, the farmer will try to answer the question. She might think, “If I don’t plow my fields, I will lose less soil than if I do plow the fields. Plowing disrupts the soil and breaks up roots that help hold soil in place. ” This answer to her question is a hypothesis . A hypothesis is a reasonable explanation. A hypothesis can be tested. It may be the right answer, it may be a wrong answer, but it must be testable. Once she has a hypothesis, the next step is to do experiments to test the hypothesis. A hypothesis can be proved or disproved by testing. If a hypothesis is repeatedly tested and shown to be true, then scientists call it a theory . | A: hypothesis. |
What is the logarithmic scale that measures the largest jolt of energy released by an earthquake called?
Here are the choices:
A. tremor scale
B. Geiger counter
C. Shake scale
D. richter scale | The Richter scale is a logarithmic scale that measures the largest jolt of energy released by an earthquake. | D: richter scale. |
Polarization occurs between a charged and what other object?
Here are the choices:
A. obsolete
B. molecular
C. motionless
D. neutral | Polarization occurs between a charged and neutral object. | D: neutral. |
Glucose, fructose, and other sugars that have six carbons are called what?
Here are the choices:
A. fluxes
B. hexoses
C. catalysts
D. alcohols | B: hexoses. | |
What is precipitation that flows over the surface of the land?
Here are the choices:
A. runoff
B. seawater
C. blizzard
D. storm surge | Runoff is precipitation that flows over the surface of the land. This water may travel to a river, lake, or ocean. Runoff may pick up fertilizer and other pollutants and deliver them to the water body where it ends up. In this way, runoff may pollute bodies of water. | A: runoff. |
What is the method that is a plan for asking questions and testing possible answers called?
Here are the choices:
A. scientific investigation
B. independent variable
C. forecasting
D. sample size | At the heart of science is the scientific investigation, which is done by following the scientific method. A scientific investigation is a plan for asking questions and testing possible answers. | A: scientific investigation. |
What branch of physics deals with the smallest units of elements and compounds?
Here are the choices:
A. quantum
B. atomic
C. gravity
D. oxygen | Introduction to Particle Physics Following ideas remarkably similar to those of the ancient Greeks, we continue to look for smaller and smaller structures in nature, hoping ultimately to find and understand the most fundamental building blocks that exist. Atomic physics deals with the smallest units of elements and compounds. In its study, we have found a relatively small number of atoms with systematic properties that explained a tremendous range of phenomena. Nuclear physics is concerned with the nuclei of atoms and their substructures. Here, a smaller number of components—the proton and neutron—make up all nuclei. Exploring the systematic behavior of their interactions has revealed even more about matter, forces, and energy. Particle physics deals with the substructures of atoms and nuclei and is particularly aimed at finding those truly fundamental particles that have no further substructure. Just as in atomic and nuclear physics, we have found a complex array of particles and properties with systematic characteristics analogous to the periodic table and the chart of nuclides. An underlying structure is apparent, and there is some reason to think that we are finding particles that have no substructure. Of course, we have been in similar situations before. For example, atoms were once thought to be the ultimate substructure. Perhaps we will find deeper and deeper structures and never come to an ultimate substructure. We may never really know, as indicated in Figure 33.2. | B: atomic. |
What kinds of acids are proteins made out of?
Here are the choices:
A. protein acids
B. amino acids
C. sequence acids
D. acetic acids | Proteins are organic compounds made up of amino acids. | B: amino acids. |
Whisk ferns have yellow sporangia and no what?
Here are the choices:
A. flowers
B. stems
C. leaves
D. roots | Whisk ferns have yellow sporangia and no leaves. | C: leaves. |
Do tropical regions have very high or very low rates of immigration?
Here are the choices:
A. medium
B. too high
C. low
D. very high | D: very high. | |
What type of experiment involves two identical experiments carried out side-by-side, with and without an independent variable?
Here are the choices:
A. blind test
B. trial run
C. controlled experiment
D. defined experiment | One way to test a cause and effect hypothesis is to perform a controlled experiment. In a controlled experiment, two identical experiments are carried out side-by-side. In one of the experiments, the independent variable being tested is used, and in the other experiment, the control, the independent variable is not used. | C: controlled experiment. |
How does the core of the sun radiate energy?
Here are the choices:
A. carbon radiation
B. electrical radiation
C. nuclear fission
D. nuclear fusion | The extremely hot core of the sun radiates energy from nuclear fusion. | D: nuclear fusion. |
What is the concentration of gas molecules in the mesosphere?
Here are the choices:
A. very low density
B. medium density
C. low density
D. high density | The mesosphere has a very low density of gas molecules. | A: very low density. |
What type of energy causes erosion at the shore?
Here are the choices:
A. kinetic
B. tidal
C. wave
D. potential | Wave energy does the work of erosion at the shore. Waves erode sediments from cliffs and shorelines. The sediment in ocean water acts like sandpaper. Over time, they erode the shore. The bigger the waves are and the more sediment they carry, the more erosion they cause ( Figure below ). | C: wave. |
Long distance runners try to maintain constant velocity with very little acceleration or deceleration to conserve what?
Here are the choices:
A. momentum
B. pressure
C. energy
D. fuel | Long distance runners try to maintain constant velocity with very little acceleration or deceleration to conserve energy. | C: energy. |
What is the smallest particle of an element that still has the element’s properties?
Here are the choices:
A. an ion
B. an atom
C. a nucleus
D. an electron | The smallest particle of an element that still has the element’s properties is an atom . All the atoms of an element are alike, and they are different from the atoms of all other elements. For example, atoms of gold are the same whether they are found in a gold nugget or a gold ring (see Figure below ). All gold atoms have the same structure and properties. | B: an atom. |
A biofilm is a colony of what that is stuck to a surface such as a rock or a host’s tissues?
Here are the choices:
A. insects
B. prokaryotes
C. eukaryotes
D. vacuoles | Many prokaryotes have an extra layer, called a capsule, outside the cell wall. The capsule protects the cell from chemicals and drying out. It also allows the cell to stick to surfaces and to other cells. Because of this, many prokaryotes can form biofilms, like the one shown in Figure below . A biofilm is a colony of prokaryotes that is stuck to a surface such as a rock or a host’s tissues. The sticky plaque that collects on your teeth between brushings is a biofilm. It consists of millions of bacteria. | B: prokaryotes. |
The stem of a horsetail is characterized by the presence of joints, or nodes: hence the name arthrophyta, which means this?
Here are the choices:
A. elongated plant
B. jointed plant
C. molted plant
D. solid plant | The stem of a horsetail is characterized by the presence of joints, or nodes: hence the name Arthrophyta, which means “jointed plant”. Leaves and branches come out as whorls from the evenly spaced rings. The needle-shaped leaves do not contribute greatly to photosynthesis, the majority of which takes place in the green stem (Figure 14.15). | B: jointed plant. |
What do power plants burn to generate electricity?
Here are the choices:
A. fossil fuels
B. biofuel
C. timber
D. nuclear fuel | Power plants and factories account for more than a quarter of fossil fuel use. Power plants burn fossil fuels to generate electricity. Factories burn fossil fuels to power machines. | A: fossil fuels. |
What organ lets us understand what we see, hear, or sense in other ways, and allows us to use language, learn, think, and remember?
Here are the choices:
A. heart
B. brain
C. Kidneys
D. bone | The brain is the organ that lets us understand what we see, hear, or sense in other ways. It also allows us to use language, learn, think, and remember. The brain controls the organs in our body and our movements as well. The brain consists of three main parts, the cerebrum, the cerebellum, and the brain stem ( Figure below ). | B: brain. |
What is the more common term for ethanoic acid, the active substance in vinegar?
Here are the choices:
A. acetic acid
B. polymer acid
C. methyl acid
D. amino acid | Methanoic acid and ethanoic acid are also called formic acid and acetic acid, respectively. Formic acid is the compound that makes certain ant bites sting, while acetic acid is the active substance in vinegar. How acidic are carboxylic acids? It turns out that they are not very acidic. No carboxylic acid is on the list of strong acids (Table 12.2 "Strong Acids and Bases"). (For more information about strong acids, see Chapter 12 "Acids and Bases", Section 12.4 "Strong and Weak Acids and Bases and Their Salts". ) This means that all carboxylic acids are weak acids. A 1 M solution of formic acid is only about 1.3% dissociated into H+ ions and formate ions, while a similar solution of acetic acid is ionized by about only 0.4%. Some carboxylic acids are stronger—for example, trichloroacetic acid is about 45% dissociated in aqueous solution. But no carboxylic acid approaches the 100% dissociation amount required by the definition of a strong acid. As their name suggests, however, carboxylic acids do act like acids in the presence of bases. The H atom in the carboxyl group comes off as the H+ ion, leaving acarboxylate anion:. | A: acetic acid. |
What type of pollution results from the contaminants that enter a waterway or water body through a single site?
Here are the choices:
A. targeted source pollution
B. point source pollution
C. simple source pollution
D. liquid source pollution | Point source pollution results from the contaminants that enter a waterway or water body through a single site. Examples of this include untreated sewage, wastewater from a sewage treatment plant, and leaking underground tanks. | B: point source pollution. |
What are the "chemical messenger" molecules used by the endocrine system?
Here are the choices:
A. axons
B. acids
C. enzymes
D. hormones | If you are a typical teenager, you like to eat. For your body to break down, absorb and spread the nutrients from your food throughout your body, your digestive system and endocrine system need to work together. The endocrine system sends hormones around your body to communicate between cells. Essentially, hormones are chemical messenger molecules. | D: hormones. |
Many innovative farming methods can prevent what type of erosion, which is especially important in agriculture?
Here are the choices:
A. fertilizer erosion
B. plains erosion
C. soil erosion
D. vegetable erosion | There are many farming methods that help prevent soil erosion. | C: soil erosion. |
As the atoms approach one another, their electron clouds gradually begin to do what?
Here are the choices:
A. magnetize
B. overlap
C. disappear
D. shrink | As the atoms approach one another, their electron clouds gradually begin to overlap. Now there are several interactions which begin to occur. One is that the single electrons that each hydrogen atom possesses begin to repel each other. This repulsive force would tend to make the potential energy of the system increase. However, the electron of each atom begins to be attracted to the nucleus of the other atom. This attractive force tends to make the potential energy of the system decrease. | B: overlap. |
What force holds together both types of star clusters?
Here are the choices:
A. inertia
B. magnetism
C. gravity
D. weight | Star clusters are small groups of stars. A star cluster is smaller than a galaxy. There are two main types, open clusters and globular clusters. Both types are held together by gravity. | C: gravity. |
What are the rod-like structures made of short microtubules that play an important part in cellular division?
Here are the choices:
A. centrioles
B. mitochondria
C. fibrils
D. cilia | Centrioles are rod-like structures made of short microtubules. Nine groups of three microtubules make up each centriole. Two perpendicular centrioles make up the centrosome . Centrioles are very important in cellular division, where they arrange the mitotic spindles that pull the chromosome apart during mitosis. | A: centrioles. |
Vertebrates with four limbs are also called what?
Here are the choices:
A. Mammals
B. tetrapods
C. Amphibians
D. Birds | Amphibians are vertebrates that exist in two worlds. They divide their time between freshwater and terrestrial habitats. They share a number of features with air-breathing lungfish, but they also differ from lungfish in many ways. One way they differ is their appendages. Amphibians are the first true tetrapods, or vertebrates with four limbs. Modern amphibians include frogs, salamanders, and caecilians, as shown Figure below . | B: tetrapods. |
What is the name of the disorder of the arteries in which cholesterol and other materials are deposited on the interior of the arterial wall?
Here are the choices:
A. atherosclerosis
B. paralysis
C. anemia
D. arthritis | Cholesterol has been implicated in heart disease for decades. Atherosclerosis is a disorder of the arteries in which cholesterol and other materials are deposited on the interior of the arterial wall. These deposits lead to the formation of plaques that can restrict or even block the flow of blood through these blood vessels (see Figure below ). A decrease in the flow of blood can lead to high blood pressure and a lowered oxygen supply to the heart muscle. A complete blockage of blood flow to parts of the heart (a heart attack) can cause significant damage due to oxygen deprivation, in some cases leading to death. | A: atherosclerosis. |
What is defined as a close relationship between organisms of different species in which at least one of the organisms benefits?
Here are the choices:
A. endosymbiosis
B. co-operative
C. parasitic
D. symbiosis | Symbiosis is a close relationship between organisms of different species in which at least one of the organisms benefits. The other organism may also benefit, it may be unaffected by the relationship, or it may be harmed by the relationship. Figure below shows an example of symbiosis. The birds in the picture are able to pick out food from the fur of the deer. The deer won't eat the birds. In fact, the deer knowingly lets the birds rest on it. What, if anything, do you think the deer gets out of the relationship?. | D: symbiosis. |
What do you call the force identified by a north and south pole?
Here are the choices:
A. normal force
B. gravity
C. buoyancy
D. magnetism | D: magnetism. | |
The voltage of a voltaic cell can be determined by the reduction potentials of what?
Here are the choices:
A. old reactions
B. half reactions
C. full reactions
D. thermal reactions | The voltage of a voltaic cell can be determined by the reduction potentials of the half reactions. | B: half reactions. |
What type of fatty acids have bent chains?
Here are the choices:
A. cholesterol
B. saturated fatty acids
C. unsaturated fatty acids
D. lipids | Fatty Acids. Saturated fatty acids have straight chains, like the three fatty acids shown on the left. Unsaturated fatty acids have bent chains, like all the other fatty acids in the figure. | C: unsaturated fatty acids. |
All seed plants and a few seedless vascular plants are what?
Here are the choices:
A. zygotes
B. heterosporous
C. homosporous
D. protozoans | B: heterosporous. | |
The three segments of arthropods are the head, thorax and what?
Here are the choices:
A. chest
B. abdomen
C. antennae
D. appendages | Most arthropods have three body segments. The segments are the head, thorax, and abdomen. You can see the three segments in a range of arthropods in Figure below . In some arthropods, the head and thorax are joined together. | B: abdomen. |
A notochord has in common with what vertbrate structure?
Here are the choices:
A. trichord
B. spinal cord
C. rip chord
D. rib cage | Some invertebrates evolved a rigid rod along the length of their body. This rod is called a notochord. You can see the notochord in the tunicates in Figure below . The notochord gives the body support and shape. It also provides a place for muscles to attach. It can counterbalance the pull of the muscles when they contract. Animals with a notochord are called chordates. All of them are placed in Phylum Chordata. Some early chordates eventually evolved into vertebrates. | B: spinal cord. |
Most members of what mammalian order possess opposable thumbs?
Here are the choices:
A. marsupials
B. amphibians
C. primates
D. rodents | Most primates have opposable thumbs. An opposable thumb can be brought into opposition with the other fingers of the same hand. This allows the hand to grasp and hold things. | C: primates. |
What refers to a group of individual organisms of the same species that live closely together?
Here are the choices:
A. a flock
B. a colony
C. a enviroment
D. a habitat | Some single-celled organisms such as bacteria can group together and form a colony. A colony refers to a group of individual organisms of the same species that live closely together. This is usually done to benefit the group, such as by providing a stronger defense or the ability to attack bigger prey. A colony can also form from organisms other than bacteria. A bacterial colony often defends from a single organism, producing a colony of genetically identical individuals. | B: a colony. |
The rise in greenhouse gases has what effect on the temperature of earth?
Here are the choices:
A. no effect
B. it increases
C. it drops
D. more moderate | The rise in greenhouse gases due to human actions is too much of a good thing. It increases the greenhouse effect and causes Earth’s average temperature to rise. Rising global temperatures, in turn, are melting polar ice caps and glaciers. Figure below shows how much smaller the Arctic ice cap was in 2012 than it was in 1984. With more liquid water on Earth’s surface, sea levels are rising. | B: it increases. |
What two types of atoms bond to form sulfate minerals?
Here are the choices:
A. oxygen and sulfur
B. oxygen and carbon
C. oxygen and calcium
D. carbon and sulfur | Sulfate minerals contain sulfur atoms bonded to oxygen atoms. Like halides, they can form in places where salt water evaporates. Many minerals belong in the sulfate group, but there are only a few common sulfate minerals. Gypsum is a common sulfate mineral that contains calcium, sulfate, and water. Gypsum is found in various forms. For example, it can be pink and look like it has flower petals. However, it can also grow into very large white crystals. Gypsum crystals that are 11 meters long have been found. That is about as long as a school bus! Gypsum also forms at the Mammoth Hot Springs in Yellowstone National Park, shown in Figure below . | A: oxygen and sulfur. |
Where does groundwater primarily come from?
Here are the choices:
A. sediment
B. precipitation
C. erosion
D. evaporation | Some precipitation that falls on land soaks into the ground. This water becomes groundwater. Groundwater may seep out of the ground at a spring or into a body of water such as the ocean. Some groundwater is taken up by plant roots. Some may flow deeper underground to an aquifer. An aquifer is an underground layer of rock that stores water. Water may be stored in an aquifer for thousands of years. | B: precipitation. |
What determines sex in animals?
Here are the choices:
A. sex chromosomes
B. ribosomes
C. cell density
D. cell structure | Sex chromosomes determine sex in animals and many plants. Other chromosomes are called autosomes. Sex-linked traits are controlled by genes on sex chromosomes. They may be inherited differently than autosomal traits. | A: sex chromosomes. |
The joints of the carpal bones in the wrist are examples of what type of joints?
Here are the choices:
A. planar joints
B. isojoints
C. digit joints
D. filter joints | Figure 38.27 The joints of the carpal bones in the wrist are examples of planar joints. (credit: modification of work by Brian C. Goss). | A: planar joints. |
If a unit is named after a person it needs to be?
Here are the choices:
A. capitalized
B. squandered
C. short
D. forgotten | If a unit is named after a person, it is capitalized. So you write “10 Newtons,” or “10 N,” but “10 meters,” or “10 m. ”. | A: capitalized. |
What is the name for the inner lining of the uterus?
Here are the choices:
A. the endometrium
B. cuticle
C. the epidermis
D. the uterine shell | A: the endometrium. | |
What is it called when currents keep reversing direction?
Here are the choices:
A. alternating current
B. emitting current
C. circle current
D. stream current | When current keeps reversing direction, it is called alternating current (AC) . You can see how it works in the two diagrams below. The current that comes from a power plant and supplies electricity to homes and businesses is alternating current. The current changes direction 60 times per second. It happens so quickly that the light bulb doesn’t have a chance to stop glowing when the reversals occur. | A: alternating current. |
What is the name given to anything that has mass and takes up space?
Here are the choices:
A. vacuum
B. organism
C. molecule
D. matter | D: matter. | |
What is the upper most level of earth's layers called?
Here are the choices:
A. volcanic
B. crust
C. surface
D. mantle | You can't go to the mantle but small pieces of the mantle can come to you. Kimberlite forms deep in the mantle and is erupted violently into the crust. Kimberlite can contain diamonds. Most kimberlites reached the surface much earlier in Earth history. | B: crust. |
What are secreted into the gi tract by organs of the gi tract or from a nearby gland named the pancreas?
Here are the choices:
A. digestive enzymes
B. stomach acid
C. insulin and pepsin
D. bile | Most digestive enzymes are secreted into the GI tract by organs of the GI tract or from a nearby gland named the pancreas. Figure below shows where the pancreas is located. The figure also shows the locations of the liver and gall bladder. These organs produce or store other digestive secretions. | A: digestive enzymes. |
In what organ does pepsin help break down proteins?
Here are the choices:
A. skin
B. liver
C. stomach
D. kidney | Acids and bases are important in living things because most enzymes can do their job only at a certain level of acidity. Cells secrete acids and bases to maintain the proper pH for enzymes to work. For example, every time you digest food, acids and bases are at work in your digestive system. Consider the enzyme pepsin, which helps break down proteins in the stomach. Pepsin needs an acidic environment to do its job, and the stomach secretes a strong acid that allows pepsin to work. However, when stomach contents enter the small intestine, the acid must be neutralized. This is because enzymes in the small intestine need a basic environment in order to work. An organ called the pancreas secretes a strong base into the small intestine, and this base neutralizes the acid. | C: stomach. |
What begins when a neuron receives a chemical stimulus?
Here are the choices:
A. a induce impulse
B. a metabolism impulse
C. a nerve impulse
D. nerve reaction | A nerve impulse begins when a neuron receives a chemical stimulus. The impulse travels down the axon membrane as an electrical action potential to the axon terminal. The axon terminal releases neurotransmitters that carry the nerve impulse to the next cell. | C: a nerve impulse. |
Pink snapdragons are an example of what?
Here are the choices:
A. cloning
B. nh3 hybridization
C. grafting
D. incomplete dominance | Pink snapdragons are an example of incomplete dominance. | D: incomplete dominance. |
Air quality is a measure of what in the air?
Here are the choices:
A. pollutants
B. gases
C. water
D. clouds | Air quality is a measure of the pollutants in the air. More pollutants mean poorer air quality. Poor air quality started to become a serious problem after the Industrial Revolution. Factories burned coal for energy. Gasoline burned by cars and trucks added greatly to air pollution. By the mid-1900s, air quality in many big cities was very bad. Incidents in London and in U. S. cities alerted people to the extent of the problem. It was clear that air quality needed to be protected. | A: pollutants. |
What do solar cells convert the energy in sunlight into?
Here are the choices:
A. free energy
B. electrical energy
C. subsequent energy
D. experimental energy | Solar cells convert the energy in sunlight to electrical energy. They contain a material such as silicon that absorbs light energy and gives off electrons. The electrons flow and create electric current. Figure below and the animation at the URL below show how a solar cell uses light energy to produce electric current and power a light bulb. Many calculators and other devices are also powered by solar cells. | B: electrical energy. |
Both endotherms and ectotherms control what through behavioral responses to changes in the environment?
Here are the choices:
A. hormones
B. sleep cycles
C. gas temperature
D. body temperature | D: body temperature. | |
What occurs when the bronchioles swell and the muscles around the bronchioles contract?
Here are the choices:
A. allergies
B. nausea
C. asthma
D. bronchitis | Courtesy of the U. S. Food and Drug Administration (FDA). Asthma occurs when the bronchioles swell and the muscles around the bronchioles contract . Public Domain. | C: asthma. |
What giant planet is far away from and much less dense than earth?
Here are the choices:
A. jupiter
B. mars
C. uranus
D. venus | Jupiter is truly a giant! The planet has 318 times the mass of Earth, and over 1,300 times Earth’s volume. So Jupiter is much less dense than Earth. Because Jupiter is so large, it reflects a lot of sunlight. When it is visible, it is the brightest object in the night sky besides the Moon and Venus. Jupiter is quite far from the Earth. The planet is more than five times as far from Earth as the Sun. It takes Jupiter about 12 Earth years to orbit once around the Sun. | A: jupiter. |
Bacteria, viruses, fungi, and protozoa are examples of what, the term for a disease-causing microorganism?
Here are the choices:
A. germ
B. pathogen
C. microbe
D. fungus | There are several types of pathogens that cause diseases in human beings. They include bacteria, viruses, fungi, and protozoa. The different types are described in Table below . The table also lists several diseases caused by each type of pathogen. Many infectious diseases caused by these pathogens can be cured with medicines. For example, antibiotic drugs can cure most diseases caused by bacteria. | B: pathogen. |
Newton’s third law of motion describes what property of forces that means balance?
Here are the choices:
A. magnetism
B. acceleration
C. symmetry
D. gravity | 4.4 Newton’s Third Law of Motion: Symmetry in Forces There is a passage in the musical Man of la Mancha that relates to Newton’s third law of motion. Sancho, in describing a fight with his wife to Don Quixote, says, “Of course I hit her back, Your Grace, but she’s a lot harder than me and you know what they say, ‘Whether the stone hits the pitcher or the pitcher hits the stone, it’s going to be bad for the pitcher. ’” This is exactly what happens whenever one body exerts a force on another—the first also experiences a force (equal in magnitude and opposite in direction). Numerous common experiences, such as stubbing a toe or throwing a ball, confirm this. It is precisely stated in Newton’s third law of motion. Newton’s Third Law of Motion Whenever one body exerts a force on a second body, the first body experiences a force that is equal in magnitude and opposite in direction to the force that it exerts. This law represents a certain symmetry in nature: Forces always occur in pairs, and one body cannot exert a force on another without experiencing a force itself. We sometimes refer to this law loosely as “action-reaction,” where the force exerted is the action and the force experienced as a consequence is the reaction. Newton’s third law has practical uses in analyzing the origin of forces and understanding which forces are external to a system. We can readily see Newton’s third law at work by taking a look at how people move about. Consider a swimmer pushing off from the side of a pool, as illustrated in Figure 4.9. She pushes against the pool wall with her feet and accelerates in the direction opposite to that of her push. The wall has exerted an equal and opposite force back on the swimmer. You might think that two equal and opposite forces would cancel, but they do not because they act on different systems. In this case, there are two systems that we could investigate: the swimmer or the wall. If we select the swimmer to be the system of interest, as in the figure, then F wall on feet is an external force on this system and affects its motion. The swimmer moves in the direction of. | C: symmetry. |
Translation is the second part of the central dogma of what?
Here are the choices:
A. relativity
B. string theory
C. molecular gastronomy
D. molecular biology | Translation is the second part of the central dogma of molecular biology: RNA → Protein . It is the process in which the genetic code in mRNA is read, one codon at a time, to make a protein. Figure below shows how this happens. After mRNA leaves the nucleus, it moves to a ribosome , which consists of rRNA and proteins. The ribosome reads the sequence of codons in mRNA. Molecules of tRNA bring amino acids to the ribosome in the correct sequence. | D: molecular biology. |
What helps us see rainbows in the sky?
Here are the choices:
A. prism
B. spectral light
C. myopia
D. visible light | We can see rainbows because they are formed by visible light. Visible light includes all the wavelengths of light that the human eye can detect. It allows us to see objects in the world around us. Without visible light, we would only be able to sense most objects by sound or touch, and we would never see rainbows. Like humans, most other organisms also depend on visible light, either directly or indirectly. Many animals use it to see. All plants use it to make food in the process of photosynthesis. Without the food made by plants, most other organisms could not survive. | D: visible light. |
How the individuals in a population are spread throughout their habitat is referred to as what?
Here are the choices:
A. population spread
B. population distribution
C. habitual distribution
D. population habitation | Population density just represents the average number of individuals per unit of area or volume. Often, individuals in a population are not spread out evenly. Instead, they may live in clumps or some other pattern (see Figure below ). The pattern may reflect characteristics of the species or its environment. Population distribution describes how the individuals are distributed, or spread throughout their habitat. | B: population distribution. |
The passenger pigeon, the dodo bird, and the woolly mammoth represent individual cases of what fate?
Here are the choices:
A. compression
B. isolation
C. accumulation
D. extinction | 47.2 | The Importance of Biodiversity to Human Life By the end of this section, you will be able to: • Identify chemical diversity benefits to humans • Identify biodiversity components that support human agriculture • Describe ecosystem services It may not be clear why biologists are concerned about biodiversity loss. When biodiversity loss is thought of as the extinction of the passenger pigeon, the dodo bird, and even the woolly mammoth, the loss may appear to be an emotional one. But is the loss practically important for the welfare of the human species? From the perspective of evolution and ecology, the loss of a particular individual species is unimportant (however, the loss of a keystone species can lead to ecological disaster). Extinction is a normal part of macroevolution. But the accelerated extinction rate means the loss of tens of thousands of species within our lifetimes, and it is likely to have dramatic effects on human welfare through the collapse of ecosystems and in added costs to maintain food production, clean air and water, and human health. Agriculture began after early hunter-gatherer societies first settled in one place and heavily modified their immediate environment. This cultural transition has made it difficult for humans to recognize their dependence on undomesticated living things on the planet. Biologists recognize the human species is embedded in ecosystems and is dependent on them,. | D: extinction. |
Both fats and oils are made up of long chains of carbon atoms that are bonded together. what are these chains called?
Here are the choices:
A. amino acids
B. nucleic acids
C. fatty acids
D. metabolic acids | Lipids consist only or mainly of carbon, hydrogen, and oxygen. Both fats and oils are made up of long chains of carbon atoms that are bonded together. These chains are called fatty acids. Fatty acids may be saturated or unsaturated. In the Figure below you can see structural formulas for two small fatty acids, one saturated and one unsaturated. | C: fatty acids. |
What adds phosphate groups to receptor proteins at the surface of the cell?
Here are the choices:
A. nitrogen kinases
B. brain kinases
C. receptor kinases
D. protein kinases | Receptor tyrosine kinases epidermal growth factor receptor (EGFR), platelet-derived growth factor receptor (PDGFR), vascular endothelial growth factor receptor (VEGFR), HER2/neu Receptor tyrosine kinases add phosphate groups to other proteins to activate or inactivate them. Receptor kinases add phosphate groups to receptor proteins at the surface of the cell. These receptor proteins receive signals from outside the cell and initiate a signal transduction process inside the cell. Tyrosine kinases add phosphate groups to tyrosine residues in the target protein. They can cause cancer by turning the receptor permanently on (constitutively), even without signals from outside the cell. | C: receptor kinases. |
Cold fronts in winter may bring what type of storm?
Here are the choices:
A. snow storm
B. monsoon
C. typhoon
D. showers | As the fast-moving cold air mass keeps advancing, so does the cold front. Cold fronts often bring sudden changes in the weather. There may be a thin line of storms right at the front that moves as it moves. In the spring and summer, these storms may be thunderstorms and tornadoes. In the late fall and winter, snow storms may occur. After a cold front passes, the cold air mass behind it brings cooler temperatures. The air is likely to be less humid as well. Can you explain why?. | A: snow storm. |
What is added to alcohol and used as an antiseptic?
Here are the choices:
A. chloride
B. arsenic
C. iodine
D. chlorine | Iodine is added to alcohol and used as an antiseptic. It reacts with germs on cuts and wounds. Small amounts of iodine are also needed for good health. In the U. S. , iodine is added to table salt to prevent iodine deficiencies. Does the salt you use contain iodine?. | C: iodine. |
Excretion of ions occurs mainly through what organ?
Here are the choices:
A. tissues
B. lungs
C. kidneys
D. Heart | down to supply the blood and other tissues with these minerals. Phosphate is a normal constituent of nucleic acids; hence, blood levels of phosphate will increase whenever nucleic acids are broken down. Excretion of ions occurs mainly through the kidneys, with lesser amounts lost in sweat and in feces. Excessive sweating may cause a significant loss, especially of sodium and chloride. Severe vomiting or diarrhea will cause a loss of chloride and bicarbonate ions. Adjustments in respiratory and renal functions allow the body to regulate the levels of these ions in the ECF. Table 26.1 lists the reference values for blood plasma, cerebrospinal fluid (CSF), and urine for the six ions addressed in this section. In a clinical setting, sodium, potassium, and chloride are typically analyzed in a routine urine sample. In contrast, calcium and phosphate analysis requires a collection of urine across a 24-hour period, because the output of these ions can vary considerably over the course of a day. Urine values reflect the rates of excretion of these ions. Bicarbonate is the one ion that is not normally excreted in urine; instead, it is conserved by the kidneys for use in the body’s buffering systems. | C: kidneys. |
Acids can also react with metals, and when they do they produce what?
Here are the choices:
A. hydrogen gas
B. potassium gas
C. rust
D. alloys | You already know that a sour taste is one property of acids. ( Warning : Never taste an unknown substance to see whether it is an acid!) Acids have certain other properties as well. For example, acids can conduct electricity when dissolved in water because they consist of charged particles in solution. (Electric current is a flow of charged particles. ) Acids can also react with metals, and when they do they produce hydrogen gas. An example of this type of reaction is hydrochloric acid reacting with the metal zinc (Zn). The reaction is pictured in the Figure below . It can be represented by the chemical equation:. | A: hydrogen gas. |
Convection is the transfer of what type of energy by particles moving through a fluid?
Here are the choices:
A. Chemical
B. Nuclear
C. thermal
D. atmospheric | Convection is the transfer of thermal energy by particles moving through a fluid. The particles transfer energy by moving from warmer to cooler areas. They move in loops called convection currents. | C: thermal. |
Foresters commonly inoculate pine seedlings with a type of what to promote growth?
Here are the choices:
A. proteins
B. soil
C. fungi
D. yeast | C: fungi. | |
What are animal fats and oils such as olive and vegetable oil classified as?
Here are the choices:
A. inorganic compounds
B. lipids
C. proteins
D. amino acids | A: Lipids that are fats include butter and the fats in meats. Lipids that are oils include olive oil and vegetable oil. Examples of both types of lipids are pictured in the Figure below . | B: lipids. |
What type of alloys are used in musical instruments?
Here are the choices:
A. copper
B. plastics
C. bronze
D. brass | Brass alloys have long been employed in musical instruments. | D: brass. |
Osteoclasts and osteoblasts play key roles in repair of what?
Here are the choices:
A. brain
B. heart
C. liver
D. bone | Connective tissue Bone remodeling and repair: bone has mineral structure, and develops tiny fractures, which, under stress, can lead to larger fractures. To combat this, bone is constantly replaced. Osteoclasts channel through existing bone, tear down and leave behind osteoblasts and lacuna, leaving osteocytes. Continually resets mineral structure of bone, and is preventative maintenance. When bone broken, callus forms in open ends, periosteum gives rise to new bone with calcium and new bone matrix, leaves irregular mend. Later, osteoblasts continue fixing over time and slowly removing imperfection. | D: bone. |
What is the general shape of centrioles?
Here are the choices:
A. spherical
B. oval
C. arc
D. rod | Centrioles are rod-like structures made of short microtubules. Though they are found in most eukaryotic cells, centrioles are absent in some plants and most fungi. | D: rod. |
Why does water infiltrate the ground?
Here are the choices:
A. run-off from flooding
B. prolonged drought conditions
C. because soil and rocks are porous
D. gravity | Water infiltrates the ground because soil and rock are porous. Between the grains are pores, or tiny holes. Since water can move through this rock it is permeable. Eventually, the water reaches a layer of rock that is not porous and so is impermeable. Water stops moving downward when it reaches this layer of rock. | C: because soil and rocks are porous. |
What is the upward force exerted by fluids when any object, such as a boat, is placed in it?
Here are the choices:
A. atomic force
B. human force
C. impetuous force
D. bouyant force | Objects such as ships may float in a fluid like water because of buoyant force. This is an upward force that a fluid exerts on any object that is placed in it. Archimedes discovered that the buoyant force acting on an object equals the weight of the fluid displaced by the object. This is known as Archimedes’ law (or Archimedes’ principle). For an entertaining video presentation of Archimedes’ law, go to this URL:. | D: bouyant force. |
What do dendrites receive signals from?
Here are the choices:
A. electrons
B. hormones
C. neurons
D. fibers | C: neurons. | |
What is the term for the exchange of genetic material between non-sister chromatids of homologous chromosomes?
Here are the choices:
A. crossing-over
B. inheritance
C. asexual reproduction
D. meiosis | When homologous chromosomes pair up during meiosis I, crossing-over can occur. Crossing-over is the exchange of genetic material between non-sister chromatids of homologous chromosomes. It results in new combinations of genes on each chromosome. | A: crossing-over. |
What must be overcome to change the motion of an object?
Here are the choices:
A. weight
B. inertia
C. pressure
D. density | To change the motion of an object, inertia must be overcome by an unbalanced force acting on the object. Until the soccer player kicks the ball in Figure below , the ball remains motionless on the ground. However, when the ball is kicked, the force on it is suddenly unbalanced. The ball starts moving across the field because its inertia has been overcome. | B: inertia. |
Which action of the stomach helps chemical digestion by gastric juice?
Here are the choices:
A. chewing
B. contraction
C. peristalsis
D. churning action | D: churning action. | |
What two lenses comprise a compound microscope?
Here are the choices:
A. concave and convex
B. scope and focus
C. objective and eyepiece
D. polarized and focal | Figure 26.16 A compound microscope composed of two lenses, an objective and an eyepiece. The objective forms a case 1 image that is larger than the object. This first image is the object for the eyepiece. The eyepiece forms a case 2 final image that is further magnified. | C: objective and eyepiece. |
Physical and chemical differences help ecologists distinguish between freshwater and marine types of what?
Here are the choices:
A. microbiomes
B. cities
C. habitats
D. biomes | D: biomes. | |
What are the organic compounds that the body needs in small amounts to function properly; humans need 13 different ones?
Here are the choices:
A. minerals
B. vitamins
C. proteins
D. nutrients | Vitamins are organic compounds that the body needs in small amounts to function properly. Humans need 13 different vitamins. Some of them are listed below ( Table below ). The table also shows how much of each vitamin you need every day. Vitamins have many roles in the body. For example, Vitamin A helps maintain good vision. Vitamin B 9 helps form red blood cells. Vitamin K is needed for blood to clot when you have a cut or other wound. | B: vitamins. |
To undo the tarnish on copper pennies, you can place them in what liquid?
Here are the choices:
A. honey
B. vinegar
C. seawater
D. distilled water | Because chemical changes produce new substances, they often cannot be undone. For example, you can’t change a fried egg back to a raw egg. Some chemical changes can be reversed, but only by other chemical changes. For example, to undo the tarnish on copper pennies, you can place them in vinegar. The acid in the vinegar reacts with the tarnish. This is a chemical change that makes the pennies bright and shiny again. You can try this yourself at home to see how well it works. | B: vinegar. |
What kind of bonding between alcohol molecules means that more energy is required to convert the liquid to vapor, and boiling points are therefore high?
Here are the choices:
A. stronger mineral bonding
B. stronger hydrogen bonding
C. weaker carbon bonding
D. stronger diffusion bonding | Only weak London dispersion forces hold molecules of nonpolar alkanes together in the liquid phase. Consequently, less energy is required to break these molecules away from the surface of the liquid and turn them into a vapor. The stronger hydrogen bonding between alcohol molecules means that more energy is required to convert the liquid to vapor, and boiling points are therefore high. | B: stronger hydrogen bonding. |
During summer in the northern hemisphere, the north pole is tilted toward what?
Here are the choices:
A. horizon
B. the north star
C. moon
D. sun | During summer in the Northern Hemisphere, the North Pole is tilted toward the Sun. The Sun's rays strike the Northern Hemisphere more directly ( Figure below ). The region gets a lot of sunlight. Summer solstice is June 21 or 22. At that time, the Sun's rays hit directly at the Tropic of Cancer (23.5°N). This is the farthest north that the Sun will be directly overhead. Summer solstice in the Northern Hemisphere is winter solstice in the Southern Hemisphere. | D: sun. |
Also called lodestone, the mineral magnetite is the most powerful what?
Here are the choices:
A. material on Earth
B. synthetic magnet
C. natural permanent magnet
D. healing magnet | Some materials are natural permanent magnets. The most magnetic material in nature is the mineral magnetite, also called lodestone (see Figure below ). The magnetic domains of magnetite naturally align with Earth’s axis. The picture on the left shows a chunk of magnetite attracting small bits of iron. The magnetite spoon compass shown on the right dates back about 2000 years and comes from China. The handle of the spoon always points north. Clearly, the magnetic properties of magnetite have been recognized for thousands of years. | C: natural permanent magnet. |
How many valves are in the heart?
Here are the choices:
A. six
B. four
C. one
D. two | So how is the blood kept from flowing back on itself? Valves ( Figure below ) in the heart keep the blood flowing in one direction. The valves do this by opening and closing in one direction only. Blood only moves forward through the heart. The valves stop the blood from flowing backward. There are four valves of the heart. | B: four. |
Momentum is directly related to both mass and?
Here are the choices:
A. mass
B. intensity
C. speed
D. velocity | This equation shows that momentum is directly related to both mass and velocity. An object has greater momentum if it has greater mass, greater velocity, or both. For example, a bowling ball has greater momentum than a softball when both are moving at the same velocity because the bowling ball has greater mass. However, a softball moving at a very high velocity — say, 100 miles an hour — would have greater momentum than a slow-rolling bowling ball. If an object isn’t moving at all, it has no momentum. That’s because its velocity is zero, and zero times anything is zero. | D: velocity. |
Bones are made up of different types of what?
Here are the choices:
A. tissue
B. fiber
C. cartilage
D. blood cells | Christopher Auyeung. Bones are made up of different types of tissues . CC BY-NC 3.0. | A: tissue. |
What do metals typically lose to achieve stability?
Here are the choices:
A. molecules
B. electrons
C. ions
D. atoms | Metals will typically lose electrons to achieve stability, while non-metals typically gain electrons to achieve stability. Two atoms or ions with the same number of electrons are referred to as isoelectronic . | B: electrons. |
What happens when a sperm and an egg cell combine?
Here are the choices:
A. fertilization
B. migration
C. manipulation
D. stimulation | Sexual reproduction happens when a sperm and an egg cell combine together. This is called fertilization . Sperm are released into the vagina during sexual intercourse. They “swim” through the uterus and enter a fallopian tube . This is where fertilization normally takes place. | A: fertilization. |
What is the ability to change or move matter?
Here are the choices:
A. temperature
B. density
C. volume
D. energy | Energy is the ability to change or move matter. All living things need energy. They need energy for everything they do, whether it is to move long distances or simply to carry out basic biochemical processes inside cells. Energy enters most ecosystems in the form of sunlight. In a few ecosystems, energy enters in the form of chemical compounds. All ecosystems need a constant input of energy in one of these two forms. | D: energy. |
How many weeks are in the life cycle of ladybugs
Here are the choices:
A. nine to six
B. two to four
C. four to six
D. three to six | Ladybugs, also known as ladybird beetles, have a life cycle of four to six weeks. In one year, as many as six generations of ladybird beetles may hatch. In the spring, each adult female lays up to 300 eggs in small clusters on plants where aphids are present. After a week, the wingless larvae hatch. Both the ladybird beetle larvae and adults are active predators, eating only aphids, scales, mites and other plant-eating insects. The ladybugs live on the vegetation where their prey is found, which includes roses, oleander, milkweed and broccoli. Adult ladybugs don’t taste very good. A bird careless enough to try to eat one will not swallow it. | C: four to six. |
What is the respiratory pigment of almost every vertebrate?
Here are the choices:
A. plasma
B. insulin
C. hemoglobin
D. iron | C: hemoglobin. | |
Objects moving at different speeds, in different directions have different what?
Here are the choices:
A. vibrations
B. protons
C. velocities
D. electrons | Objects have the same velocity only if they are moving at the same speed and in the same direction. Objects moving at different speeds, in different directions, or both have different velocities. | C: velocities. |
What type of compounds make up the cells and tissues of organisms?
Here are the choices:
A. organic compounds
B. hormonal compounds
C. biochemical compounds
D. productive compounds | Biochemical compounds make up the cells and tissues of organisms. They are also involved in life processes, such as making and using food for energy. Given their diversity of functions, it’s not surprising that there are millions of different biochemical compounds. However, they can be grouped into just four main classes: carbohydrates, proteins, lipids, and nucleic acids. The classes are summarized in Table below and described in the rest of this lesson. | C: biochemical compounds. |
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