questions stringlengths 37 1.22k | reasoning stringlengths 0 3.56k ⌀ | answers stringlengths 4 138 |
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Human population is growing exponentially and humans have increased what normally limiting factor through technology, urbanization, and harnessing the energy of fossil fuels?
Here are the choices:
A. mass extinction
B. habitat loss
C. carrying capacity
D. zero population growth | 19.3 The Human Population Earth’s human population is growing exponentially. Humans have increased their carrying capacity through technology, urbanization, and harnessing the energy of fossil fuels. The age structure of a population allows us to predict population growth. Unchecked human population growth could have dire long-term effects on human welfare and Earth’s ecosystems. | C: carrying capacity. |
Amides are carbonyls attached to one nitrogen atom and one carbon or which other atom?
Here are the choices:
A. hydrogen
B. calcium
C. nitrogen
D. helium | Amides are carbonyls attached to one nitrogen atom and one carbon or hydrogen atom. Amides are used in materials such as crayons and inks, as well as in paper rubber products. | A: hydrogen. |
The epidermis of the leaf consists of a single layer of which cells?
Here are the choices:
A. chloroplasm
B. dermal cells
C. insular cells
D. endothermic cells | The epidermis of the leaf consists of a single layer of tightly-packed dermal cells. They secrete waxy cuticle to prevent evaporation of water from the leaf. The epidermis has tiny pores called stomata (singular, stoma) that control transpiration and gas exchange with the air. Figure below explains how stomata carry out this vital function. | B: dermal cells. |
What is beneath the cerebrum and includes the thalamus and hypothalamus?
Here are the choices:
A. diencephalon
B. rendalen
C. subvocalization
D. brain stem | Diencephalon The diencephalon is beneath the cerebrum and includes the thalamus and hypothalamus. In the somatic nervous system, the thalamus is an important relay for communication between the cerebrum and the rest of the nervous system. The hypothalamus has both somatic and autonomic functions. In addition, the hypothalamus communicates with the limbic system, which controls emotions and memory functions. Sensory input to the thalamus comes from most of the special senses and ascending somatosensory tracts. Each sensory system is relayed through a particular nucleus in the thalamus. The thalamus is a required transfer point for most sensory tracts that reach the cerebral cortex, where conscious sensory perception begins. The one exception to this rule is the olfactory system. The olfactory tract axons from the olfactory bulb project directly to the cerebral cortex, along with the limbic system and hypothalamus. The thalamus is a collection of several nuclei that can be categorized into three anatomical groups. White matter running through the thalamus defines the three major regions of the thalamus, which are an anterior nucleus, a medial nucleus, and a lateral group of nuclei. The anterior nucleus serves as a relay between the hypothalamus and the emotion and memoryproducing limbic system. The medial nuclei serve as a relay for information from the limbic system and basal ganglia to the cerebral cortex. This allows memory creation during learning, but also determines alertness. The special and somatic senses connect to the lateral nuclei, where their information is relayed to the appropriate sensory cortex of the cerebrum. | A: diencephalon. |
What is the raw material for evolution by natural selection called?
Here are the choices:
A. genetic variation
B. comparable variation
C. pattern variation
D. mutation | A: genetic variation. | |
The changing of a light ray’s direction (loosely called bending) when it passes through variations in matter is called this?
Here are the choices:
A. vibration
B. wavelength
C. resonance
D. refraction | Refraction The changing of a light ray’s direction (loosely called bending) when it passes through variations in matter is called refraction. Speed of Light The speed of light c not only affects refraction, it is one of the central concepts of Einstein’s theory of relativity. As the accuracy of the measurements of the speed of light were improved, c was found not to depend on the velocity of the source or the observer. However, the speed of light does vary in a precise manner with the material it traverses. These facts have far-reaching implications, as we will see in Special Relativity. It makes connections between space and time and alters our expectations that all observers measure the same time for the same event, for example. The speed of light is so important that its value in a vacuum is one of the most fundamental constants in nature as well as being one of the four fundamental SI units. | D: refraction. |
What decreases with the loss of subsequent protons?
Here are the choices:
A. acid strength
B. Movement strength
C. seawater strength
D. example strength | Polyprotic Acids and Bases As you learned in Chapter 4 "Reactions in Aqueous Solution", polyprotic acids such as H2SO4, H3PO4, and H2CO3 contain more than one ionizable proton, and the protons are lost in a stepwise manner. The fully protonated species is always the strongest acid because it is easier to remove a proton from a neutral molecule than from a negatively charged ion. Thus acid strength decreases with the loss of subsequent protons, and, correspondingly, the pKa increases. Consider H2SO4, for example: Figure 16.5. | A: acid strength. |
What is defined as a loss of hydrogen atoms?
Here are the choices:
A. oxidation
B. evaporation
C. Reduction
D. conduction | Oxidation is also defined as a loss of hydrogen atoms. In the following equation, ethanol is oxidized to acetaldehyde by the loss of two hydrogen atoms:. | A: oxidation. |
Natural gas is often found along with what other fossil fuels in underground deposits?
Here are the choices:
A. coal and methane
B. methane and oil
C. coal and oil
D. repository and oil | Natural gas is often found along with coal or oil in underground deposits. This is because natural gas forms with these other fossil fuels. One difference between natural gas and oil is that natural gas forms at higher temperatures. | C: coal and oil. |
What term is used to describe cells without a nucleus?
Here are the choices:
A. Simple
B. prokaryotic
C. unicellular
D. monophyletic | Prokaryotic cells are cells without a nucleus. | B: prokaryotic. |
What is used to carry out metric unit conversions?
Here are the choices:
A. calculation analysis
B. metric analysis
C. dimensional analysis
D. mechanical analysis | Dimensional analysis can be used to carry out metric unit conversions. | C: dimensional analysis. |
If solutions of differing osmolarities are present on opposite sides of a semipermeable membrane, solvent will transfer from what to what, in terms of osmolarity of the solution?
Here are the choices:
A. low to low
B. high to low
C. low to high
D. high to high | osmol = M × i If more than one solute is present in a solution, the individual osmolarities are additive to get the total osmolarity of the solution. Solutions that have the same osmolarity have the same osmotic pressure. If solutions of differing osmolarities are present on opposite sides of a semipermeable membrane, solvent will transfer from the lower-osmolarity solution to the higher-osmolarity solution. Counterpressure exerted on the highosmolarity solution will reduce or halt the solvent transfer. An even higher pressure can be exerted to force solvent from the high-osmolarity solution to the low-osmolarity solution, a process called reverse osmosis. Reverse osmosis is used to make potable water from saltwater where sources of fresh water are scarce. | C: low to high. |
What do populations gain through births and immigration?
Here are the choices:
A. Over Crowding
B. humans
C. individuals
D. Over Population | Populations gain individuals through births and immigration. They lose individuals through deaths and emigration. These factors together determine how fast a population grows. | C: individuals. |
What is it called when plants release water vapor through their leaves?
Here are the choices:
A. evaporation
B. respiration
C. transpiration
D. propagation | Transpiration is like evaporation because it changes liquid water to water vapor. In transpiration, plants release water vapor through their leaves. This water vapor rises into the atmosphere. | C: transpiration. |
What do you call the atomic "ingredients" that go into a chemical reaction?
Here are the choices:
A. Starters
B. complexes
C. reactants
D. propellants | Like equations in math, equations in chemistry must balance. There must be the same number of each type of atom in the products as there is in the reactants. In equation 1, count the number of hydrogen and oxygen atoms on each side of the arrow. There are two hydrogen atoms in both reactants and products. There are two oxygen atoms in the reactants but only one in the product. Therefore, equation 1 is not balanced. | C: reactants. |
What is stacked in layers in "layer cake geology"?
Here are the choices:
A. soil
B. horizontal stata
C. rock stata
D. sediment | Geologists say that the Grand Canyon ( Figure above ) has "layer cake geology. " This is because the rock strata are in layers. They are extremely easy to see. Sedimentary rocks are like a book that tells the story of the environment in which they formed. Rock units can be traced across large expanses. Looking down into the Grand Canyon, you get a sense of the vastness of space and of time. | C: rock stata. |
A spontaneous change process called neutrino oscillations can occur only if neutrinos have what property?
Here are the choices:
A. mass
B. color
C. temperature
D. velocity | that the weak interaction could change quark flavor. It should also change neutrino flavor—that is, any type of neutrino could change spontaneously into any other, a process called neutrino oscillations. However, this can occur only if neutrinos have a mass. Why? Crudely, because if neutrinos are massless, they must travel at the speed of light and time will not pass for them, so that they cannot change without an interaction. In 1999, results began to be published containing convincing evidence that neutrino oscillations do occur. Using the Super-Kamiokande detector in Japan, the oscillations have been observed and are being verified and further explored at present at the same facility and others. Neutrino oscillations may also explain the low number of observed solar neutrinos. Detectors for observing solar neutrinos are specifically designed to detect electron neutrinos ν e produced in huge numbers by fusion in the Sun. A large fraction of electron neutrinos. | A: mass. |
What type of plate is an island arc found on?
Here are the choices:
A. continental
B. coastal
C. oceanic
D. shear | An island arc is a line of volcanoes on an oceanic plate. A continental arc is a line of volcanoes on a continental plate. | C: oceanic. |
How do you calculate the atomic mass of an element?
Here are the choices:
A. add the protons and neutrons together
B. count the electrons
C. multiply protons by neutrons
D. add neutrons and electrons | In this lesson, you learned about chemical bonds in a water molecule. The bonds form between atoms of hydrogen and oxygen when they share electrons. This type of bond is an example of a covalent bond. | A: add the protons and neutrons together. |
The cytoskeleton is a cellular "scaffolding" or "skeleton" that crisscrosses what?
Here are the choices:
A. cytoplasm
B. cell membrane
C. golgi apparatus
D. cerebellum | The cytoskeleton is a cellular "scaffolding" or "skeleton" that crisscrosses the cytoplasm. All eukaryotic cells have a cytoskeleton, and recent research has shown that prokaryotic cells also have a cytoskeleton. The eukaryotic cytoskeleton is made up of a network of long, thin protein fibers and has many functions. It helps to maintain cell shape, holds organelles in place, and for some cells, it enables cell movement. The cytoskeleton plays important roles in both the intracellular movement of substances and in cell division. Certain proteins act like a path that vesicles and organelles move along within the cell. The threadlike proteins that make up the cytoskeleton continually rebuild to adapt to the cell's constantly changing needs. Three main kinds of cytoskeleton fibers are microtubules, intermediate filaments, and microfilaments. | A: cytoplasm. |
In animal cells, what arises from the centrosomes and includes spindle microtubules and asters?
Here are the choices:
A. the spindle
B. DNA helix
C. ribosomes
D. Golgi apparatus | A: the spindle. | |
What's the term for a relationship between two organisms where at least one benefits?
Here are the choices:
A. meiosis
B. morphogenesis
C. dermatitis
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, or it may be unaffected or 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. |
Drip iirigation requires less water and reduces what?
Here are the choices:
A. bacteria
B. moisture
C. salinization
D. sediment | C: salinization. | |
What term refers to a wall or partition that divides the heart into chambers?
Here are the choices:
A. cartilage
B. septum
C. valve
D. cysts | Septa of the Heart The word septum is derived from the Latin for “something that encloses;” in this case, a septum (plural = septa) refers to a wall or partition that divides the heart into chambers. The septa are physical extensions of the myocardium lined with endocardium. Located between the two atria is the interatrial septum. Normally in an adult heart, the interatrial septum bears an oval-shaped depression known as the fossa ovalis, a remnant of an opening in the fetal heart known as the foramen ovale. The foramen ovale allowed blood in the fetal heart to pass directly from the right atrium to the left atrium, allowing some blood to bypass the pulmonary circuit. Within seconds after birth, a flap of tissue known as the septum primum that previously acted as a valve closes the foramen ovale and establishes the typical cardiac circulation pattern. Between the two ventricles is a second septum known as the interventricular septum. Unlike the interatrial septum, the interventricular septum is normally intact after its formation during fetal development. It is substantially thicker than the interatrial septum, since the ventricles generate far greater pressure when they contract. The septum between the atria and ventricles is known as the atrioventricular septum. It is marked by the presence of four openings that allow blood to move from the atria into the ventricles and from the ventricles into the pulmonary trunk and aorta. Located in each of these openings between the atria and ventricles is a valve, a specialized structure that ensures one-way flow of blood. The valves between the atria and ventricles are known generically as atrioventricular valves. The valves at the openings that lead to the pulmonary trunk and aorta are known generically as semilunar valves. The interventricular septum is visible in Figure 19.9. In this figure, the atrioventricular septum has been removed to better show the bicupid and tricuspid valves; the interatrial septum is not visible, since its location is covered by the aorta and pulmonary trunk. Since these openings and valves structurally weaken the atrioventricular septum, the remaining tissue is heavily reinforced with dense connective tissue called the cardiac skeleton, or skeleton of the heart. It includes four rings that surround the openings between the atria and ventricles, and the openings to the pulmonary trunk and aorta, and serve as the point of attachment for the heart valves. The cardiac skeleton also provides an important boundary in the heart electrical conduction system. | B: septum. |
What mammal is the most intelligent?
Here are the choices:
A. monkey
B. humans
C. dog
D. lion | In this lesson, you learned some of the ways that humans differ from other mammals. For example, humans have a larger and more complex brain than other mammals. That’s why they are also the most intelligent mammals. The next chapter introduces the biology of the human animal. | B: humans. |
What is the primary force driving fluid transport between the capillaries and tissues?
Here are the choices:
A. constructs pressure
B. temperature pressure
C. hydrostatic pressure
D. isolate pressure | Hydrostatic Pressure The primary force driving fluid transport between the capillaries and tissues is hydrostatic pressure, which can be defined as the pressure of any fluid enclosed in a space. Blood hydrostatic pressure is the force exerted by the blood confined within blood vessels or heart chambers. Even more specifically, the pressure exerted by blood against the wall of a capillary is called capillary hydrostatic pressure (CHP), and is the same as capillary blood pressure. CHP is the force that drives fluid out of capillaries and into the tissues. As fluid exits a capillary and moves into tissues, the hydrostatic pressure in the interstitial fluid correspondingly rises. This opposing hydrostatic pressure is called the interstitial fluid hydrostatic pressure (IFHP). Generally, the CHP originating from the arterial pathways is considerably higher than the IFHP, because lymphatic vessels are continually absorbing excess fluid from the tissues. Thus, fluid generally moves out of the capillary and into the interstitial fluid. This process is called filtration. | C: hydrostatic pressure. |
Mercury is small, rocky and covered with what objects?
Here are the choices:
A. craters
B. diamonds
C. volcanoes
D. rivers | 6. Mercury is small, rocky and covered with craters. Why?. | A: craters. |
Heat expansion is a result of the increase of what type of energy, exhibited by molecules bumping together?
Here are the choices:
A. harmonic energy
B. light energy
C. radioactivity
D. kinetic energy | Heat expansion is a result of the increase of kinetic energy of the molecules. As their movement increases, they bump into each other more and the material slightly expands as a result. Most materials expand with heat. Water is a particularly interesting substance in that it contracts as its temperature increases from to (and then expands from to ). | D: kinetic energy. |
What is the molecular formula of carbon dioxide?
Here are the choices:
A. h2o
B. c2o
C. cl2
D. co 2 | The molecular formula of carbon dioxide is CO 2 . One molecule of carbon dioxide consists of 1 atom of carbon and 2 atoms of oxygen. We can calculate the molar mass of carbon dioxide by adding together the molar masses of each atom present in the compound. | D: co 2. |
What organism constitutes frothy green "pond scum"?
Here are the choices:
A. sponges
B. protozoa
C. algae
D. bacteria | Polluted water can form a frothy green scum on the surface. This "pond scum" is actually a living organism, algae. The algae are plant-like protists. Usually the algae are too small to notice, but sometimes algae grow in excess because of the excess nutrients in polluted water. | C: algae. |
Spontaneous reactions release what type of energy, meaning it is available to do work?
Here are the choices:
A. kinetic energy
B. potential energy
C. radioactive energy
D. free energy | Many chemical reactions and physical processes release energy that can be used to do other things. When the fuel in a car is burned, some of the released energy is used to power the vehicle. Free energy is energy that is available to do work. Spontaneous reactions release free energy as they proceed. Recall that the determining factors for spontaneity of a reaction are the enthalpy and entropy changes that occur for the system. The free energy change of a reaction is a mathematical combination of the enthalpy change and the entropy change. | D: free energy. |
Why do butterfly fish have fake eyespots?
Here are the choices:
A. confuse predators
B. mating purposes
C. random evolution
D. aerodynamic purposes | Butterfly fish like this one have “fake” eyespots. The eyespots may confuse larger predators long enough for the butterfly fish to escape. | A: confuse predators. |
Is urea or salt reabsorbed faster?
Here are the choices:
A. salt
B. neither is reabsorbed
C. urea
D. same speed | A: salt. | |
Glucose is an example of what simple carboyhydrates with relatively few carbon atoms?
Here are the choices:
A. mixtures
B. acids
C. solvents
D. sugars | Sugars are simple carbohydrates. Molecules of sugars have relatively few carbon atoms. Glucose (C 6 H 12 O 6 ) is one of the smallest sugar molecules. Plants and some other organisms make glucose in the process of photosynthesis. Living things that cannot make glucose obtain it by consuming plants or these other organisms. | D: sugars. |
Chemical energy results from the particular arrangement of atoms in a chemical compound; the heat and light produced in this reaction are due to energy released during the breaking and reforming of what?
Here are the choices:
A. carbon bonds
B. chemical bonds
C. atom bonds
D. acid bonds | energy is released when particles in the nucleus of the atom are rearranged. (e) Chemical energy results from the particular arrangement of atoms in a chemical compound; the heat and light produced in this reaction are due to energy released during the breaking and reforming of chemical bonds. Electrical energy, nuclear energy, and chemical energy are different forms ofpotential energy (PE), which is energy stored in an object because of the relative positions or orientations of its components. A brick lying on the windowsill of a 10th-floor office has a great deal of potential energy, but until its position changes by falling, the energy is contained. In contrast, kinetic energy (KE) is energy due to the motionof an object. When the brick falls, its potential energy is transformed to kinetic energy, which is then transferred to the object on the ground that it strikes. | B: chemical bonds. |
The visible surface of the sun is called what?
Here are the choices:
A. photosphere
B. Radiative Zone
C. Chromosphere
D. Corona | The photosphere is the visible surface of the Sun ( Figure below ). It's the part that we see shining. Surprisingly, the photosphere is also one of the coolest layers of the Sun. It is only about 6000 degrees C. | A: photosphere. |
Which system is capable of responding quickly to changing situations?
Here are the choices:
A. circulatory system
B. nervous system
C. reproductive system
D. endocrine system | In addition, endocrine signaling is typically less specific than neural signaling. The same hormone may play a role in a variety of different physiological processes depending on the target cells involved. For example, the hormone oxytocin promotes uterine contractions in women in labor. It is also important in breastfeeding, and may be involved in the sexual response and in feelings of emotional attachment in both males and females. In general, the nervous system involves quick responses to rapid changes in the external environment, and the endocrine system is usually slower acting—taking care of the internal environment of the body, maintaining homeostasis, and controlling reproduction (Table 17.1). So how does the fight-or-flight response that was mentioned earlier happen so quickly if hormones are usually slower acting? It is because the two systems are connected. It is the fast action of the nervous system in response to the danger in the environment that stimulates the adrenal glands to secrete their hormones. As a result, the nervous system can cause rapid endocrine responses to keep up with sudden changes in both the external and internal environments when necessary. | B: nervous system. |
What two substances do plants give off when they make food?
Here are the choices:
A. carbon dioxide and oxygen
B. chlorophyll and nitrogen
C. water and oil
D. oxygen and water | D: oxygen and water. | |
What kind of energy positions do electrons occupy during ground state?
Here are the choices:
A. highest energy positions
B. lowest energy positions
C. relative energy positions
D. closest energy positions | Oxygen has 6 valence electrons in its ground state. Remember that ground state refers to the neutral atom in which the electrons occupy the lowest possible energy positions. Oxygen is two electrons away from being isoelectronic with the nearest noble gas. Oxygen will therefore form ions by gaining two electrons to become isoelectronic with neon, as shown below:. | B: lowest energy positions. |
What are metals and good electrical conductors that tend to lose their valence electrons in chemical reactions called?
Here are the choices:
A. reductants
B. conservants
C. precious metals
D. stable metals | Electronegativity Differences between Metals and Nonmetals An element’s electronegativity provides us with a single value that we can use to characterize the chemistry of an element. Elements with a high electronegativity (χ ≥ 2.2 in Figure 7.15 "Pauling Electronegativity Values of the ") have very negative affinities and large ionization potentials, so they are generally nonmetals and electrical insulators that tend to gain electrons in chemical reactions (i. , they are oxidants). In contrast, elements with a low electronegativity (χ ≤ 1.8) have electron affinities that have either positive or small negative values and small ionization potentials, so they are generally metals and good electrical conductors that tend to lose their valence electrons in chemical reactions (i. , they are reductants). In between the metals and nonmetals, along the heavy diagonal line running from B to At in Figure 1.24 "The Periodic Table Showing the Elements in Order of Increasing ", is a group of elements with intermediate electronegativities (χ ~ 2.0). These are the semimetals, elements that have some of the chemical properties of both nonmetals and metals. The distinction between metals and nonmetals is. | A: reductants. |
What is the term for liquid water falling from the sky?
Here are the choices:
A. mud
B. rain
C. wind
D. fire | B: rain. | |
What term did schrödinger use for regions around the nucleus where electrons are most likely to be?
Here are the choices:
A. ellipses
B. orbitals
C. arrays
D. isotopes | Schrödinger developed an equation that could be used to calculate the chances of an electron being in any given place around the nucleus. Based on his calculations, he identified regions around the nucleus where electrons are most likely to be. He called these regions orbitals . As you can see in the Figure below , orbitals may be shaped like spheres, dumbbells, or rings. In each case, the nucleus of the atom is at the center of the orbital. You can see animated models of orbitals this URL: http://www. chemistry. wustl. edu/~edudev/Orbitals/movie. html . | B: orbitals. |
What exactly happens during rna translation?
Here are the choices:
A. membrane is synthesized
B. protein is synthesized
C. chromosome is synthesized
D. carbohydrate is synthesized | Translation is the RNA → protein part of the central dogma. It occurs at a ribosome. During translation, a protein is synthesized using the codons in mRNA as a guide. All three types of RNA play a role in translation. | B: protein is synthesized. |
How long are microfilaments?
Here are the choices:
A. 7 nm
B. 9 nm
C. 7 m
D. 4 nm | A: 7 nm. | |
What is the area around the nucleus of an atom where electrons are likely to be, called?
Here are the choices:
A. electron pocket
B. electron cloud
C. electron wave
D. electron membrane | Today, these ideas about electrons are represented by the electron cloud model. The electron cloud is an area around the nucleus where electrons are likely to be. Figure below shows an electron cloud model for a helium atom. | B: electron cloud. |
What type of matter in the spinal cord has the appearance of an ink-blot test and is subdivided into regions that are referred to as horns?
Here are the choices:
A. wet matter
B. dark matter
C. gray matter
D. bright matter | Gray Horns In cross-section, the gray matter of the spinal cord has the appearance of an ink-blot test, with the spread of the gray matter on one side replicated on the other—a shape reminiscent of a bulbous capital “H. ” As shown in Figure 13.14, the gray matter is subdivided into regions that are referred to as horns. The posterior horn is responsible for sensory processing. The anterior horn sends out motor signals to the skeletal muscles. The lateral horn, which is only found in the thoracic, upper lumbar, and sacral regions, is the central component of the sympathetic division of the autonomic nervous system. Some of the largest neurons of the spinal cord are the multipolar motor neurons in the anterior horn. The fibers that cause contraction of skeletal muscles are the axons of these neurons. The motor neuron that causes contraction of the big toe, for example, is located in the sacral spinal cord. The axon that has to reach all the way to the belly of that muscle may be a meter in length. The neuronal cell body that maintains that long fiber must be quite large, possibly several hundred micrometers in diameter, making it one of the largest cells in the body. | C: gray matter. |
What type of sedimentary rocks are made of minerals that precipitate from saline water?
Here are the choices:
A. sandstone
B. limestone
C. chemical sedimentary rocks
D. shale | The main types of sedimentary rocks are clastic or chemical. Some sedimentary rocks are a third type, organic. Clastic sedimentary rocks are made of sediments. The sediments differ in size. Chemical sedimentary rocks are made of minerals that precipitate from saline water. Organic sedimentary rocks are made from the bodies of organisms. | C: chemical sedimentary rocks. |
Sexual reproduction involves the production of haploid gametes by what?
Here are the choices:
A. meiosis
B. lesions
C. mutations
D. mitosis | Cycle of Sexual Reproduction. Sexual reproduction involves the production of haploid gametes by meiosis. This is followed by fertilization and the formation of a diploid zygote. The number of chromosomes in a gamete is represented by the letter n. Why does the zygote have 2n, or twice as many, chromosomes?. | A: meiosis. |
What is emitted by nuclei in alpha, beta, and gamma decay?
Here are the choices:
A. convection
B. solar energy
C. radiation
D. magnetic field | There are several types of radioactive decay, including alpha, beta, and gamma decay. In all three types, nuclei emit radiation, but the nature of the radiation differs. The Table below shows the radiation emitted in each type of decay. You can watch a video about the three types at this URL: http://www. youtube. com/watch?v=3koOwozY4oc . | C: radiation. |
What do we call the recycling of inorganic matter between living organisms and their environment?
Here are the choices:
A. nutrient cycle
B. biogeochemical cycle
C. phosphorus cycle
D. water cycle | 46.3 | Biogeochemical Cycles By the end of this section, you will be able to: • Discuss the biogeochemical cycles of water, carbon, nitrogen, phosphorus, and sulfur • Explain how human activities have impacted these cycles and the potential consequences for Earth Energy flows directionally through ecosystems, entering as sunlight (or inorganic molecules for chemoautotrophs) and leaving as heat during the many transfers between trophic levels. However, the matter that makes up living organisms is conserved and recycled. The six most common elements associated with organic molecules—carbon, nitrogen, hydrogen, oxygen, phosphorus, and sulfur—take a variety of chemical forms and may exist for long periods in the atmosphere, on land, in water, or beneath the Earth’s surface. Geologic processes, such as weathering, erosion, water drainage, and the subduction of the continental plates, all play a role in this recycling of materials. Because geology and chemistry have major roles in the study of this process, the recycling of inorganic matter between living organisms and their environment is called a biogeochemical cycle. Water contains hydrogen and oxygen, which is essential to all living processes. The hydrosphere is the area of the Earth where water movement and storage occurs: as liquid water on the surface and beneath the surface or frozen (rivers, lakes, oceans, groundwater, polar ice caps, and glaciers), and as water vapor in the atmosphere. Carbon is found in all organic macromolecules and is an important constituent of fossil fuels. Nitrogen is a major component of our nucleic acids and proteins and is critical to human agriculture. Phosphorus, a major component of nucleic acid (along with nitrogen), is one of the main ingredients in artificial fertilizers used in agriculture and their associated environmental impacts on our surface. | B: biogeochemical cycle. |
The tensor fascia latae acts as what, in relation to the gluteus medius and iliopsoas, for the purpose of flexing and abducting the thigh?
Here are the choices:
A. synergist
B. antagonist
C. spicule
D. symbiotic | The tensor fascia latae is a thick, squarish muscle in the superior aspect of the lateral thigh. It acts as a synergist of the gluteus medius and iliopsoas in flexing and abducting the thigh. It also helps stabilize the lateral aspect of the knee by pulling on the iliotibial tract (band), making it taut. Deep to the gluteus maximus, the piriformis, obturator internus, obturator externus, superior gemellus, inferior gemellus, and quadratus femoris laterally rotate the femur at the hip. The adductor longus, adductor brevis, and adductor magnus can both medially and laterally rotate the thigh depending on the placement of the foot. The adductor longus flexes the thigh, whereas the adductor magnus extends it. The pectineus adducts and flexes the femur at the hip as well. The pectineus is located in the femoral triangle, which is formed at the junction between the hip and the leg and also includes the femoral nerve, the femoral artery, the femoral vein, and the deep inguinal lymph nodes. | A: synergist. |
What cellular process is controlled by allosteric enzymes at key points in glycolysis and the citric acid cycle?
Here are the choices:
A. cellular respiration
B. photosynthesis
C. mitosis
D. Metabolism | A: cellular respiration. | |
What is the main function of the cardiovascular system?
Here are the choices:
A. coordinate bones and muscles
B. excretion of food waste
C. transporting substances around the body
D. respiration of air | The main function of the cardiovascular system is transporting substances around the body. Figure above shows some of the substances that are transported in the blood. They include hormones, oxygen, nutrients from digested food, and cellular wastes. Transport of all these materials is necessary to maintain homeostasis of the body and life itself. | C: transporting substances around the body. |
What happens to water when it is heated in the broiler?
Here are the choices:
A. it expands
B. it introduces
C. it evolves
D. it contracts | When water is heated in the boiler, it expands. It might burst the pipes of the system if it weren’t for the expansion tank. This tank holds excess water after it expands. | A: it expands. |
What atoms make up a water molecule?
Here are the choices:
A. One Hydrogen
B. Sodium and Oxygen
C. alumhg and oxygen
D. hydrogen and oxygen | Water is a compound that forms molecules. Each water molecule consists of two atoms of hydrogen (white) and one atom of oxygen (red). | D: hydrogen and oxygen. |
What leads to the buildup of electric charges on objects?
Here are the choices:
A. movement
B. rotation
C. polarization
D. gravity | Polarization leads to the buildup of electric charges on objects. This buildup of charges is known as static electricity . Once an object becomes charged, it is likely to remain charged until another object touches it or at least comes very close to it. That’s because electric charge cannot travel easily through air, especially if the air is dry. | C: polarization. |
What is it called when body’s internal environment is stable?
Here are the choices:
A. homeostasis
B. hypothesis
C. ketosis
D. synchronicity | The tennis player in Figure below has really worked up a sweat. Do you know why we sweat? Sweating helps to keep us cool. When sweat evaporates from the skin, it uses up some of the body’s heat energy. Sweating is one of the ways that the body maintains a stable internal environment. It helps keep the body’s internal temperature constant. When the body’s internal environment is stable, the condition is called homeostasis . | A: homeostasis. |
Precipitation, evaporation, transpiration, and condensation are part of what cycle?
Here are the choices:
A. air cycle
B. cold cycle
C. life cycle
D. water cycle | The water cycle includes the ocean, atmosphere, ground, and living things. During the water cycle, water keeps changing state by processes such as evaporation, transpiration, condensation, and precipitation. | D: water cycle. |
Life span is distinct from what, which means the sequence of stages a plant goes through from seed germination to seed production of the mature plant?
Here are the choices:
A. spin cycle
B. society cycle
C. life cycle
D. feeding cycle | Plant Life Spans The length of time from the beginning of development to the death of a plant is called its life span. The life cycle, on the other hand, is the sequence of stages a plant goes through from seed germination to seed production of the mature plant. Some plants, such as annuals, only need a few weeks to grow, produce seeds and die. Other plants, such as the bristlecone pine, live for thousands of years. Some bristlecone pines have a documented age of 4,500 years Figure 32.29. Even as some parts of a plant, such as regions containing meristematic tissue—the area of active plant growth consisting of undifferentiated cells capable of cell division—continue to grow, some parts undergo programmed cell death (apoptosis). The cork found on stems, and the water-conducting tissue of the xylem, for example, are composed of dead cells. | C: life cycle. |
What is it called when the soils of the arctic tundra remain in a perennially frozen state?
Here are the choices:
A. permafreeze
B. permafrost
C. concentrated freeze
D. glacial domination | Arctic Tundra The Arctic tundra lies north of the subarctic boreal forest and is located throughout the Arctic regions of the northern hemisphere (Figure 44.12). The average winter temperature is -34 °C (-34 °F) and the average summer temperature is from 3 °C to 12 °C (37 °F–52 °F). Plants in the arctic tundra have a very short growing season of approximately 10–12 weeks. However, during this time, there are almost 24 hours of daylight and plant growth is rapid. The annual precipitation of the Arctic tundra is very low with little annual variation in precipitation. And, as in the boreal forests, there is little evaporation due to the cold temperatures. Plants in the Arctic tundra are generally low to the ground (Figure 44.20). There is little species diversity, low net primary productivity, and low aboveground biomass. The soils of the Arctic tundra may remain in a perennially frozen state referred to as permafrost. The permafrost makes it impossible for roots to penetrate deep into the soil and slows the decay of organic matter, which inhibits the release of nutrients from organic matter. During the growing season, the ground of the Arctic tundra can be completely covered with plants or lichens. | B: permafrost. |
The three classes of elements are metals, nonmetals, and what?
Here are the choices:
A. molecules
B. metalloids
C. atoms
D. ionic compounds | Metals are elements that can conduct electricity. They are one of three classes of elements (the other two classes are nonmetals and metalloids). Metals are by far the largest of the three classes. In fact, most elements are metals. All of the elements on the left side and in the middle of the periodic table, except for hydrogen, are metals. There are several different types of metals, including alkali metals in group 1 of the periodic table, alkaline Earth metals in group 2, and transition metals in groups 3–12. The majority of metals are transition metals. | B: metalloids. |
What do you call the fixed point of a lever?
Here are the choices:
A. base
B. caliper
C. apex
D. fulcrum | A lever is a simple machine consisting of a bar that rotates around a fixed point. The fixed point of a lever is called the fulcrum. Like other machines, a lever makes work easier by changing the force applied to the machine or the distance over which the force is applied. For a video introduction to levers using skateboards as examples, go to this URL:. | D: fulcrum. |
What process tends to be external in aquatic species and internal in terrestrial species?
Here are the choices:
A. fertilization
B. infection
C. pollination
D. migration | Aquatic species generally have external fertilization, whereas terrestrial species usually have internal fertilization. | A: fertilization. |
Which electromagnetic radiation is used to kill cancer cells?
Here are the choices:
A. X-rays
B. ultraviolet rays
C. plasma rays
D. gamma rays | X rays and gamma rays are the electromagnetic waves with the shortest wavelengths and highest frequencies. X rays are used in medicine and dentistry and to screen luggage at airports. Gamma rays are used to kill cancer cells. | D: gamma rays. |
What is the term for going into a dormant state during the winter?
Here are the choices:
A. homeostasis
B. hibernation
C. gestation
D. fermentation | B: hibernation. | |
Shrimp are an example of what group within the arthropods?
Here are the choices:
A. myriapods
B. insect
C. crustaceans
D. scorpion | Shrimp are an example of crustaceans, one group within the arthropods. Shrimp live on the ocean floor in many parts of the world. Shrimp are not only food for humans; they are also an important food source for larger marine animals. | C: crustaceans. |
Many enzymes are simple proteins consisting entirely of one or more of these?
Here are the choices:
A. interaction acid chains
B. proteins acid chains
C. alkali acid chains
D. amino acid chains | Many enzymes are simple proteins consisting entirely of one or more amino acid chains. Other enzymes contain a nonprotein component called a cofactor that is necessary for the enzyme’s proper functioning. There are two types of cofactors: inorganic ions [e. , zinc or Cu(I) ions] and organic molecules known as coenzymes. Most coenzymes are vitamins or are derived from vitamins. | D: amino acid chains. |
What property of carbon and other elements can be used to date fossils and rocks, among other things?
Here are the choices:
A. full-life
B. half-life
C. mass
D. magnetic force | Carbon-14 has a relatively short half-life. It decays quickly compared to some other unstable isotopes. So carbon-14 dating is useful for specimens younger than 50,000 years old. That’s a blink of an eye in geologic time. But radiocarbon dating is very useful for more recent events. One important use of radiocarbon is early human sites. Carbon-14 dating is also limited to the remains of once-living things. To date rocks, scientists use other radioactive isotopes. | B: half-life. |
A solution is what type of mixture, where the dissolved particles are spread evenly through the mixture?
Here are the choices:
A. gaseous
B. homogeneous
C. saline
D. heterogeneous | A solution is a mixture of two or more substances, but it’s not just any mixture. A solution is a homogeneous mixture. In a homogeneous mixture, the dissolved particles are spread evenly through the mixture. The particles of the solution are also too small to be seen or to settle out of the mixture. To put solutions in context as a type of mixture, watch the video at this URL: http://www. youtube. com/watch?v=z2vM-G5I92U . | B: homogeneous. |
The base in an antacid reacts to do what to excess stomach acid?
Here are the choices:
A. expel it
B. repel it
C. neutralize it
D. oxidize it | Perhaps you have eaten too much pizza and felt very uncomfortable hours later. This feeling is due to excess stomach acid being produced. The discomfort can be dealt with by taking an antacid. The base in the antacid will react with the HCl in the stomach and neutralize it, taking care of that unpleasant feeling. | C: neutralize it. |
In single-celled organisms, what does the plasma membrane extensions help the organisms to do?
Here are the choices:
A. inspect
B. prevent
C. move
D. increase | The plasma membrane may have extensions, such as whip-like flagella or brush-like cilia . In single-celled organisms, like those shown in Figure below , the membrane extensions may help the organisms move. In multicellular organisms, the extensions have other functions. For example, the cilia on human lung cells sweep foreign particles and mucus toward the mouth and nose. | C: move. |
Red-green color blindness is an example of a sex-linked condition caused by what?
Here are the choices:
A. dominant gene
B. phenotype
C. genetic disorder
D. recessive allele | D: recessive allele. | |
What can be switched off by a protein called the trp repressor?
Here are the choices:
A. the cytokine
B. the operon
C. the genetic precursor
D. the chaperone protein | B: the operon. | |
What is the name of vesicles that are formed by the golgi apparatus?
Here are the choices:
A. lysosomes
B. capillaries
C. lymphocytes
D. vessels | Lysosomes are vesicles that are formed by the Golgi apparatus. They contain powerful enzymes that could break down (digest) the cell. Lysosomes break down harmful cell products, waste materials, and cellular debris and then force them out of the cell. They also digest invading organisms such as bacteria. Lysosomes also break down cells that are ready to die, a process called autolysis. | A: lysosomes. |
What is the term for the arrangement of veins in a leaf?
Here are the choices:
A. venation pattern
B. dorsal pattern
C. vein pattern
D. cerebellum pattern | Within each leaf, the vascular tissue forms veins. The arrangement of veins in a leaf is called the venation pattern. Monocots and dicots differ in their patterns of venation (Figure 30.22). Monocots have parallel venation; the veins run in straight lines across the length of the leaf without converging at a point. In dicots, however, the veins of the leaf have a net-like appearance, forming a pattern known as reticulate venation. One extant plant, the Ginkgo biloba, has dichotomous venation where the veins fork. | A: venation pattern. |
Anabolic reactions require energy, so they are considered what type of reaction?
Here are the choices:
A. autotrophic
B. hydrostatic
C. exothermic
D. endothermic | Anabolic reactions involve forming bonds. Smaller molecules are combined to form larger ones. For example, simple sugars are combined to form complex carbohydrates. Anabolic reactions require energy, so they are endothermic. | D: endothermic. |
Lack of which attachment makes ester molecules incapable of intermolecular hydrogen bonding?
Here are the choices:
A. carbon fluorine atom
B. carbon sulfur atom
C. carbon oxygen atom
D. hydrogen-oxygen atom | Ester molecules are polar but have no hydrogen atom attached directly to an oxygen atom. They are therefore incapable of engaging in intermolecular hydrogen bonding with one another and thus have considerably lower boiling points than their isomeric carboxylic acids counterparts. Because ester molecules can engage in hydrogen bonding with water molecules, however, esters of low molar mass are somewhat soluble in water. Borderline solubility occurs in those molecules that have three to five carbon atoms. http://catalog. flatworldknowledge. com/bookhub/reader/2547 - gob-ch15_s07_t01lists the physical properties of some common esters. | D: hydrogen-oxygen atom. |
Viruses need what kind of cell in order to help themselves reproduce?
Here are the choices:
A. round
B. side
C. double
D. host | 22.3 Viral Genome The genome of a virus consists of DNA or RNA, whose size and configuration vary. The entire genome can exist as a single nucleic acid molecule or several nucleic acid segments. Also, the DNA or RNA may be single-stranded or double-stranded, and either linear or circular. Not all viruses can reproduce in a host cell by themselves. Since viruses are so small, the size of their genome is limiting. For example, some viruses have coded instructions for only making a few different proteins for the viruses' capsid. On the other hand, the human genome codes for over 30,000 different proteins. Therefore, the lack of coded instructions cause some viruses to need the presence of other viruses to help them reproduce themselves. Such viruses are called replication defective. Lastly, it is worthy to note that 70% of all viruses are RNA viruses. As the process of RNA replication (with enzymes and other organelles of the host cell) is more prone to errors, RNA viruses have much higher mutation rates than do DNA viruses. | D: host. |
Although vitamins and minerals do not provide what, they are still essential for good health?
Here are the choices:
A. energy
B. enzymes
C. antioxidants
D. flavor | Vitamins and minerals do not provide energy, but they are still essential for good health. The needed amounts generally can be met with balanced eating. However, people who do not eat enough of the right foods may need vitamin or mineral supplements. | A: energy. |
What is the science of how living things interact with each other and their environment?
Here are the choices:
A. biology
B. compatibility
C. zoology
D. ecology | The science of how living things interact with each other and their environment is called ecology. Ecology is a major branch of life science, but it overlaps with many other fields. For example, it shares data and theories with geography, biology, climatology, and other sciences. In this lesson, you’ll learn some of the basic concepts of ecology. | D: ecology. |
What function does a vacuole do for a cell?
Here are the choices:
A. division
B. reproduction
C. storage
D. transfer | Most mature plant cells have a central vacuole that occupies more than 30% of the cell's volume. The central vacuole can occupy as much as 90% of the volume of certain cells. The central vacuole is surrounded by a membrane called the tonoplast . The central vacuole has many functions. Aside from storage, the main role of the vacuole is to maintain turgor pressure against the cell wall. Proteins found in the tonoplast control the flow of water into and out of the vacuole. The central vacuole also stores the pigments that color flowers. | C: storage. |
Sight, hearing, balance, taste, smell, and touch are types of what?
Here are the choices:
A. memories
B. temperaments
C. senses
D. sensation types | Human senses include sight, hearing, balance, taste, smell, and touch. | C: senses. |
During grafting, the part of the plant that is grafted is called?
Here are the choices:
A. roots
B. stock
C. stem
D. scion | Artificial Methods of Asexual Reproduction These methods are frequently employed to give rise to new, and sometimes novel, plants. They include grafting, cutting, layering, and micropropagation. Grafting Grafting has long been used to produce novel varieties of roses, citrus species, and other plants. In grafting, two plant species are used; part of the stem of the desirable plant is grafted onto a rooted plant called the stock. The part that is grafted or attached is called the scion. Both are cut at an oblique angle (any angle other than a right angle), placed in close contact with each other, and are then held together Figure 32.26. Matching up these two surfaces as closely as possible is extremely important because these will be holding the plant together. The vascular systems of the two plants grow and fuse, forming a graft. After a period of time, the scion starts producing shoots, and eventually starts bearing flowers and fruits. Grafting is widely used in viticulture (grape growing) and the citrus industry. Scions capable of producing a particular fruit variety are grated onto root stock with specific resistance to disease. | D: scion. |
What is a winding ridge of sand deposited by a stream of meltwater called?
Here are the choices:
A. esker
B. desert
C. sand dune
D. oasis | An esker is a winding ridge of sand deposited by a stream of meltwater. Such streams flow underneath a retreating glacier. | A: esker. |
What is a measure of the change in velocity of a moving object?
Here are the choices:
A. inclination
B. vibration
C. acceleration
D. kinetic energy | Acceleration is a measure of the change in velocity of a moving object. It shows how quickly velocity changes and whether the change is positive or negative. It may reflect a change in speed, a change in direction, or both. | C: acceleration. |
Sympatric type of what occurs when a single population of organisms splits into two reproductively isolated communities within the same physical region?
Here are the choices:
A. accumulation
B. speciation
C. extraction
D. biodiversity | Sympatric speciation While the logic and mechanisms of allopatric speciation are relatively easy to grasp (we hope), there is a second type of speciation, known as sympatric speciation, which was originally more controversial. It occurs when a single population of organisms splits into two reproductively isolated communities within the same physical region. How could this possibly occur? What stop (or inhibits) the distinct sub-populations from inbreeding and reversing the effects of selection and nascent speciation? Recently a number of plausible mechanisms have been identified. One involves host selection.143 In host selection, animals (such as insects) that feed off specific hosts may find themselves reproducing in distinct zones associated with their hosts. For example, organisms that prefer blueberries will mate in a different place, time of day, or time of year than those that prefer raspberries. There are blueberry- and raspberry-specific niches. Through a process of disruptive selection (see above), organisms that live primarily on a particular plant (or part of a plant) can be subject to different selective pressures, and reproductive isolation will enable the populations to more rapidly adapt. Mutations that reinforce an initial, perhaps weak, mating preference can lead reproductive isolation - this is a simple form of sexual selection (which we will discuss soon).144 One population has become two distinct, reproductively independent populations, one species has become two. | B: speciation. |
Each atom has a required number of what?
Here are the choices:
A. acceleration bonds
B. covalent bonds
C. matrix bonds
D. accretion bonds | B: covalent bonds. | |
When the volume of a gas is decreased, what happens to its pressure?
Here are the choices:
A. increases
B. LOWERS
C. STAYS THE SAME
D. drops | When the volume of a gas is decreased, its pressure is increased. | A: increases. |
Exposure to what causes skin color to darken?
Here are the choices:
A. sunlight
B. hormones
C. pressure
D. heat | Skin color darkens when exposed to the sun. | A: sunlight. |
What colorful phenomenon occurs in the northern sky when particles from the sun energize ions in the thermosphere?
Here are the choices:
A. Coriolis effect
B. meteor shower
C. northern lights
D. aurora nervosa | Particles from the Sun energize ions in the thermosphere. This creates the northern and southern lights. | C: northern lights. |
By what processes does the ocean modify landforms?
Here are the choices:
A. shape and deposition
B. sweeping and deposition
C. splash and deposition
D. erosion and deposition | The power of the ocean modifies landforms by erosion and deposition. Landforms modified by both erosion and deposition are seen in this photo. The cliff is being eroded by incoming waves. The beach is being created as sand is being deposited. | D: erosion and deposition. |
The term “vapor” refers to the gas phase when it exists at a temperature below what?
Here are the choices:
A. freezing temperature
B. boiling temperature
C. liquid temperature
D. contaminated temperature | for low temperatures, where the phase can change from a gas to a liquid. The term “vapor” refers to the gas phase when it exists at a temperature below the boiling temperature. | B: boiling temperature. |
Hypertension, or high blood pressure, can increase the risk of what?
Here are the choices:
A. abnormal disease
B. bone disease
C. cardiovascular disease
D. physiological disease | Hypertension, or high blood pressure, can increase the risk of cardiovascular disease. | C: cardiovascular disease. |
The carbon atoms are bonded together, with each carbon also being bonded to two of what kind of atoms?
Here are the choices:
A. hydrogen
B. helium
C. calcium
D. ions | Some molecules are not able to satisfy the octet rule by making only single covalent bonds between the atoms. Consider the compound ethene, which has a molecular formula of C 2 H 4 . The carbon atoms are bonded together, with each carbon also being bonded to two hydrogen atoms. | A: hydrogen. |
What is the final stage of cell division in eukaryotes as well as prokaryotes?
Here are the choices:
A. electrolysis
B. anaphase
C. cytokinesis
D. mitosis | Cytokinesis is the final stage of cell division in eukaryotes as well as prokaryotes. During cytokinesis, the cytoplasm splits in two and the cell divides. Cytokinesis occurs somewhat differently in plant and animal cells, as shown in Figure below . In animal cells, the plasma membrane of the parent cell pinches inward along the cell’s equator until two daughter cells form. In plant cells, a cell plate forms along the equator of the parent cell. Then, a new plasma membrane and cell wall form along each side of the cell plate. | C: cytokinesis. |
The metacarpophalangeal joints in the finger are examples of what kind of joints?
Here are the choices:
A. saddle
B. fibrous
C. condyloid
D. hinge | Figure 38.30 The metacarpophalangeal joints in the finger are examples of condyloid joints. (credit: modification of work by Gray's Anatomy). | C: condyloid. |
What is idefined as the mass of a substance divided by its volume?
Here are the choices:
A. height
B. weight
C. density
D. length | The ideal gas law can also be used to determine the densities of gases. Density, recall, is defined as the mass of a substance divided by its volume:. | C: density. |
What does the kyoto protocol focus on controlling?
Here are the choices:
A. Helium emissions
B. Ozone emissions
C. carbonate gas emissions
D. greenhouse gas emissions | The Kyoto Protocol is another worldwide agreement on air pollution. It was passed in 1997. The Protocol focuses on controlling greenhouse gas emissions. Its aim is to control global warming. | D: greenhouse gas emissions. |
A van de graff generator produces what type of charge on its dome, causing the tendency to give up electrons?
Here are the choices:
A. no charge
B. positive charge
C. similar charge
D. negative charge | The transfer of electrons from the van de Graaff generator to the man is an example of conduction. Conduction occurs when there is direct contact between materials that differ in their ability to give up or accept electrons. A van de Graff generator produces a negative charge on its dome, so it tends to give up electrons. Human hands are positively charged, so they tend to accept electrons. Therefore, electrons flow from the dome to the man’s hand when they are in contact. | D: negative charge. |
What forms the small holes found in bread?
Here are the choices:
A. oxygen
B. carbon dioxide gas
C. carbon monoxide gas
D. yeast | The small holes in bread are formed by bubbles of carbon dioxide gas. The gas was produced by alcoholic fermentation carried out by yeast. | B: carbon dioxide gas. |
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