questions stringlengths 37 1.22k | reasoning stringlengths 0 3.56k ⌀ | answers stringlengths 4 138 |
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Which organ is the control center of the nervous system?
Here are the choices:
A. the spine
B. the heart
C. the brain
D. the lungs | What weighs about three pounds and contains up to 100 billion cells? The answer is the human brain. The brain is the control center of the nervous system. It’s like the pilot of a plane. It tells other parts of the nervous system what to do. | C: the brain. |
Continental climates are generally found in what areas of landmasses?
Here are the choices:
A. wetlands
B. inland
C. northerly
D. buttes | Farther inland, the climate is influenced by cold or hot air from the land. This air may be dry, because it comes from over land. An inland climate is usually more extreme. Winters may be very cold, and summers may be very hot. Precipitation can be low. This is a continental climate . | B: inland. |
What mainly gives the body energy?
Here are the choices:
A. fuel
B. food
C. water
D. sunlight | Food gives the body energy. You need energy for everything you do. The energy in food is measured in a unit called the Calorie. | B: food. |
A mineral can be made of an element or a?
Here are the choices:
A. component
B. compound
C. cell
D. Sediment | A mineral is a solid material that forms by a natural process. A mineral can be made of an element or a compound. It has a specific chemical composition that is different from other minerals. One mineral's physical properties differ from others'. These properties include crystal structure, hardness, density and color. Each is made of different elements. Each has different physical properties. For example, silver is a soft, shiny metal. Salt is a white, cube-shaped crystal. Diamond is an extremely hard, translucent crystal. | B: compound. |
Herbivores are heterotrophs that eat only or mainly what?
Here are the choices:
A. plants
B. fish
C. decayed matter
D. animals | Many mammals are herbivores. Herbivores are heterotrophs that eat only or mainly plant foods (or algae). Depending on the species of mammals, they may eat leaves, shoots, stems, roots, seeds, nuts, fruits, flowers, and/or grasses. Some mammals even eat conifer needles or tree bark. Mammals that are herbivores include rabbits, mice, sheep, zebras, deer, kangaroos, and monkeys. The manatee in Figure below is also a herbivorous mammal. It eats mainly kelp (seaweed). | A: plants. |
The heart is an organ in which system?
Here are the choices:
A. respiratory system
B. immune system
C. nervous system
D. circulatory system | Human organs are organized into organ systems. An organ system is a group of organs that work together to carry out a complex function. Each organ of the system does part of the overall job. For example, the heart is an organ in the circulatory system. The circulatory system also includes the blood vessels and blood. There are many different human organ systems. Figure below shows six of them and gives their functions. | D: circulatory system. |
What are the subatomic particles of the nucleus called?
Here are the choices:
A. eukaryotes
B. cores
C. protons
D. nucleons | Summary Subatomic particles of the nucleus (protons and neutrons) are called nucleons. Anuclide is an atom with a particular number of protons and neutrons. An unstable nucleus that decays spontaneously is radioactive, and its emissions are collectively called radioactivity. Isotopes that emit radiation are Saylor URL: http://www. saylor. org/books. | D: nucleons. |
Who wrote the book, on the origin of species?
Here are the choices:
A. darwin
B. Sagan
C. shaw
D. Scopes | In his book On the Origin of Species , Darwin included a lot of evidence for evolution. Since then, much more evidence has accumulated. The evidence includes millions of fossils, like the one in Figure below . It also includes detailed knowledge of living organisms. | A: darwin. |
Tar sands are rocky materials mixed with what?
Here are the choices:
A. coal
B. very thick oil
C. shale
D. magma | Tar sands are rocky materials mixed with very thick oil. The tar is too thick to pump, and so tar sands are strip-mined. Hot water and caustic soda are used to separate the oil from the rock. This creates a slurry, which is shaken. The oil floats to the top and is skimmed off. | B: very thick oil. |
A current in a circuit needs a complete what?
Here are the choices:
A. path
B. stream
C. speed
D. cause | Electromagnetic waves generally propagate out from a source in all directions, sometimes forming a complex radiation pattern. A linear antenna like this one will not radiate parallel to its length, for example. The wave is shown in one direction from the antenna in Figure 24.7 to illustrate its basic characteristics. Instead of the AC generator, the antenna can also be driven by an AC circuit. In fact, charges radiate whenever they are accelerated. But while a current in a circuit needs a complete path, an antenna has a varying charge distribution forming a standing wave, driven by the AC. The dimensions of the antenna are critical for determining the frequency of the radiated electromagnetic waves. This is a resonant phenomenon and when we tune radios or TV, we vary electrical properties to achieve appropriate resonant conditions in the antenna. | A: path. |
How do glucose, ions, and other larger molecules leave the blood?
Here are the choices:
A. through veinous fissures
B. through cell membranes
C. through capillary tips
D. through intercellular clefts | 20.3 | Capillary Exchange By the end of this section, you will be able to: • Identify the primary mechanisms of capillary exchange • Distinguish between capillary hydrostatic pressure and blood colloid osmotic pressure, explaining the contribution of each to net filtration pressure • Compare filtration and reabsorption • Explain the fate of fluid that is not reabsorbed from the tissues into the vascular capillaries The primary purpose of the cardiovascular system is to circulate gases, nutrients, wastes, and other substances to and from the cells of the body. Small molecules, such as gases, lipids, and lipid-soluble molecules, can diffuse directly through the membranes of the endothelial cells of the capillary wall. Glucose, amino acids, and ions—including sodium, potassium, calcium, and chloride—use transporters to move through specific channels in the membrane by facilitated diffusion. Glucose, ions, and larger molecules may also leave the blood through intercellular clefts. Larger molecules can pass through the pores of fenestrated capillaries, and even large plasma proteins can pass through the great gaps in the sinusoids. Some large proteins in blood plasma can move into and out of the endothelial cells packaged within vesicles by endocytosis and exocytosis. Water moves by osmosis. | D: through intercellular clefts. |
The basal forebrain contains what that are important in learning and memory?
Here are the choices:
A. nuclei
B. ribosomes
C. atoms
D. oxygen | Many of the higher neurological functions, such as memory, emotion, and consciousness, are the result of cerebral function. The complexity of the cerebrum is different across vertebrate species. The cerebrum of the most primitive vertebrates is not much more than the connection for the sense of smell. In mammals, the cerebrum comprises the outer gray matter that is the cortex (from the Latin word meaning “bark of a tree”) and several deep nuclei that belong to three important functional groups. The basal nuclei are responsible for cognitive processing, the most important function being that associated with planning movements. The basal forebrain contains nuclei that are important in learning and memory. The limbic cortex is the region of the cerebral cortex that is part of the limbic system, a collection of structures involved in emotion, memory, and behavior. | A: nuclei. |
What thin layer of air acts as a barrier to prevent cool air from mixing with warm air in the stratosphere?
Here are the choices:
A. tropopause
B. liposphere
C. endosphere
D. methosphere | At the top of the troposphere is a thin layer of air called the tropopause. You can see it in Figure above . This layer acts as a barrier. It prevents cool air in the troposphere from mixing with warm air in the stratosphere. | A: tropopause. |
What is the name for the male gamete?
Here are the choices:
A. egg
B. sperm
C. ova
D. chromatid | B: sperm. | |
The strength of acids is measured on what scale?
Here are the choices:
A. ph
B. μg
C. qcd
D. Killalot | The strength of acids is measured on the pH scale. A pH value less than 7 indicates an acid, and the lower the number is, the stronger the acid. | A: ph. |
What term is also known as the contact activation pathway?
Here are the choices:
A. identical pathway
B. internal pathway
C. intrinsic pathway
D. central pathway | Intrinsic Pathway The intrinsic pathway (also known as the contact activation pathway) is longer and more complex. In this case, the factors involved are intrinsic to (present within) the bloodstream. The pathway can be prompted by damage to the tissues, resulting from internal factors such as arterial disease; however, it is most often initiated when factor XII (Hageman factor) comes into contact with foreign materials, such as when a blood sample is put into a glass test tube. Within the body, factor XII is typically activated when it encounters negatively charged molecules, such as inorganic polymers and phosphate produced earlier in the series of intrinsic pathway reactions. Factor XII sets off a series of reactions that in turn activates factor XI (antihemolytic factor C or plasma thromboplastin antecedent) then factor IX (antihemolytic factor B or plasma thromboplasmin). In the meantime, chemicals released by the platelets increase the rate of these activation reactions. Finally, factor VIII (antihemolytic factor A) from the platelets and endothelial cells combines with factor IX (antihemolytic factor B or plasma thromboplasmin) to form an enzyme complex that activates factor X (Stuart–Prower factor or thrombokinase), leading to the common pathway. The events in the intrinsic pathway are completed in a few minutes. | C: intrinsic pathway. |
What comprises the contents of a cell between the plasma membrane and the nuclear envelope?
Here are the choices:
A. cerebellum
B. protoplasm
C. cytoskeleton
D. cytoplasm | The Cytoplasm The cytoplasm comprises the contents of a cell between the plasma membrane and the nuclear envelope (a structure to be discussed shortly). It is made up of organelles suspended in the gel-like cytosol, the cytoskeleton, and various chemicals (Figure 3.7). Even though the cytoplasm consists of 70 to 80 percent water, it has a semi-solid consistency, which comes from the proteins within it. However, proteins are not the only organic molecules found in the cytoplasm. Glucose and other simple sugars, polysaccharides, amino acids, nucleic acids, fatty acids, and derivatives of glycerol are found there too. Ions of sodium, potassium, calcium, and many other elements are also dissolved in the cytoplasm. Many metabolic reactions, including protein synthesis, take place in the cytoplasm. | D: cytoplasm. |
What is used to convert concentrations to collisions per second?
Here are the choices:
A. collision meter
B. frequency factor
C. speeds factor
D. particles factor | The frequency factor is used to convert concentrations to collisions per second. Equation 14.39 is known as the Arrhenius equation and summarizes the collision model of chemical kinetics, where T is the absolute temperature (in K) and R is the ideal gas constant [8.314 J/(K·mol)]. Ea indicates the sensitivity of the reaction to changes in temperature. The reaction rate with a large Ea increases rapidly with increasing temperature, whereas the reaction rate with a smaller Ea increases much more slowly with increasing temperature. If we know the reaction rate at various temperatures, we can use the Arrhenius equation to calculate the activation energy. Taking the natural logarithm of both sides ofEquation 14.39, Equation 14.40. | B: frequency factor. |
The ovules, which are the female gametophytes, are held in what organ?
Here are the choices:
A. uterus
B. testes
C. abdomen
D. ovary | The ovary holds the ovules , the female gametophytes. When the ovules are fertilized, the ovule becomes the seed and the ovary becomes the fruit. | D: ovary. |
Snippet 2: one of the reasons the periodic table is so useful is because its structure allows us to qualitatively determine how some properties of the elements vary versus their position on the periodic table. the variation of properties versus position on the periodic table is called what?
Here are the choices:
A. gravity trends
B. chemical trends
C. periodic trends
D. acoustic trends | One of the reasons the periodic table is so useful is because its structure allows us to qualitatively determine how some properties of the elements vary versus their position on the periodic table. The variation of properties versus position on the periodic table is called periodic trends. There is no other tool in science that allows us to judge relative properties of a class of objects like this, which makes the periodic table a very useful tool. Many periodic trends are general. There may be a few points where an opposite trend is seen, but there is an overall trend when considered across a whole row or down a whole column of the periodic table. The first periodic trend we will consider atomic radius. The atomic radius is an indication of the size of an atom. Although the concept of a definite radius of an atom is a bit fuzzy, atoms behave as if they have a certain radius. Such radii can be estimated from various experimental techniques, such as the x-ray crystallography of crystals. As you go down a column of the periodic table, the atomic radii increase. This is because the valence electron shell is getting a larger and there is a larger principal quantum number, so the valence shell lies physically farther away from the nucleus. This trend can be summarized as follows:. | C: periodic trends. |
Equilibriums are affected by changes in concentration, total pressure or volume, and this?
Here are the choices:
A. temperature
B. time
C. rate
D. oxygen | Equilibriums are affected by changes in concentration, total pressure or volume, and temperature. | A: temperature. |
What type of seed-bearing structure of a flowering plant usually develop into?
Here are the choices:
A. Stem
B. food
C. Apple
D. fruit | Development of Fruit and Fruit Types After fertilization, the ovary of the flower usually develops into the fruit. Fruits are usually associated with having a sweet taste; however, not all fruits are sweet. Botanically, the term “fruit” is used for a ripened ovary. In most cases, flowers in which fertilization has taken place will develop into fruits, and flowers in which fertilization has not taken place will not. Some fruits develop from the ovary and are known as true fruits, whereas others develop from other parts of the female gametophyte and are known as accessory fruits. The fruit encloses the seeds and the developing embryo, thereby providing it with protection. Fruits are of many types, depending on their origin and texture. The sweet tissue of the blackberry, the red flesh of the tomato, the shell of the peanut, and the hull of corn (the tough, thin part that gets stuck in your teeth when you eat popcorn) are all fruits. As the fruit matures, the seeds also mature. | D: fruit. |
What are ionic substances completely held together by?
Here are the choices:
A. magnetic bonds
B. ionic bonds
C. thermal bonds
D. localized bonds | Ionic substances are completely held together by ionic bonds. The full charges of the ions (for example, Na + and Cl - in sodium chloride) cause electrostatic interactions that result in a stable crystal lattice. We saw in the previous chapter that most ionic compounds have high melting points, are brittle, are often soluble in water, and conduct electricity when melted or dissolved in water. Ionic compounds exist as extended, orderly arrangements of ions. As we will see, this is quite different from the structure of molecular substances, which take the form of collections of individual molecules. The atoms within a molecule are held very strongly together, but the interactions between different molecules are significantly weaker. | B: ionic bonds. |
What word do get from the arabic al-qili, meaning “ashes of the saltwort plant from salt marshes”?
Here are the choices:
A. metals
B. water
C. crystals
D. alkali | The elements of group 1 are called the alkali metals. Alkali (from the Arabic al-qili, meaning “ashes of the saltwort plant from salt marshes”) was a general term for substances derived from wood ashes, all of which possessed a bitter taste and were able to neutralize acids. Although oxides of both group 1 and group 2 elements were obtained from wood ashes, the alkali metals had lower melting points. Potassium and sodium were first isolated in 1807 by the British chemist Sir Humphry Davy (1778–1829) by passing an electrical current through molten samples of potash (K2CO3) and soda ash (Na2CO3). The potassium burst into flames as soon as it was produced because it reacts readily with oxygen at the higher temperature. However, the group 1 elements, like the group 2 elements, become less reactive with air or water as their atomic number decreases. The heaviest element (francium) was not discovered until 1939. It is so radioactive that studying its chemistry is very difficult. The alkali metals have ns1 valence electron configurations and the lowest electronegativity of any group; hence they are often referred to as being electropositiveelements. As a result, they have a strong tendency to lose their single valence electron to form compounds in the +1 oxidation state, producing the EX monohalides and the E 2O oxides. Because they are so reactive, pure group 1 elements are powerful reducing agents that are used in lithium batteries and cardiac pacemakers. Sodium salts such as common table salt (NaCl), baking soda (NaHCO3), soda ash (Na2CO3),. | D: alkali. |
Metals are elements that can conduct what?
Here are the choices:
A. orchestras
B. electricity
C. cycle
D. pollution | Metals are elements that can conduct electricity. Most elements are metals. | B: electricity. |
The earth is like organisms in that it maintains a stable state, which is also known as what?
Here are the choices:
A. dormancy
B. homeostasis
C. hibernation
D. ketosis | Most scientists agree that the Earth itself is not a living thing. However, the Earth does have some aspects of life. Some scientists argue that the Earth maintains homeostasis, a stable state, just like a living organisms. | B: homeostasis. |
The purpose of any cooling system is to transfer what type of energy in order to keep things cool?
Here are the choices:
A. radiation
B. thermal
C. atmospheric
D. physical | A refrigerator is an example of a cooling system. Another example is an air conditioner. The purpose of any cooling system is to transfer thermal energy in order to keep things cool. A refrigerator, for example, transfers thermal energy from the cool air inside the refrigerator to the warm air in the kitchen. If you’ve ever noticed how warm the back of a running refrigerator gets, then you know that it releases a lot of thermal energy into the room. | B: thermal. |
What is the heart's main task?
Here are the choices:
A. clean blood
B. split blood cells
C. make blood
D. pump blood | Tissues may be organized into organs. An organ is a structure composed of two or more types of tissue that work together to do a specific task. For example, the heart is an organ. It consists of muscle, nerve, and other types of tissues. Its task is to pump blood. | D: pump blood. |
Which antibacterial protein is found in tears and saliva?
Here are the choices:
A. human lysozyme
B. amino acid
C. dopamine
D. human growth hormone | A: human lysozyme. | |
What elements tend to conduct well?
Here are the choices:
A. organics
B. gases
C. metals
D. oils | While many elements differ dramatically in their chemical and physical properties, some elements have similar properties. We can identify sets of elements that exhibit common behaviors. For example, many elements conduct heat and electricity well, whereas others are poor conductors. These properties can be used to sort the elements into three classes: metals (elements that conduct well), nonmetals (elements that conduct poorly), and metalloids (elements that have properties of both metals and nonmetals). The periodic table is a table of elements that places elements with similar properties close together (Figure 1.22). You will learn more about the periodic table as you continue your study of chemistry. | C: metals. |
What type of masses are structureless particles that cannot spin?
Here are the choices:
A. inertial mass
B. turning masses
C. weightless masses
D. point masses | • Point masses are structureless particles that cannot spin. | D: point masses. |
What do scientists use to search other planets suitable for living?
Here are the choices:
A. telescopes
B. microscopes
C. optics
D. lasers | Scientists are using telescopes to search for other planets that may have conditions favorable for life. The places they can look are near our solar system in our galaxy. | A: telescopes. |
All species of crocodilians have similar body structures, including an elongated snout, powerful jaws, muscular tail, large protective scales, streamlined body, and eyes and nostrils that are positioned on what?
Here are the choices:
A. below the neck
B. top of head
C. side of head
D. back of head | The basic crocodilian body plan ( Figure below ) is a very successful one and has changed little over time. Modern species actually look very similar to their Cretaceous ancestors of 84 million years ago. All species of crocodilians have similar body structures, including an elongated snout, powerful jaws, muscular tail, large protective scales, streamlined body, and eyes and nostrils that are positioned on top of the head. | B: top of head. |
During adulthood, what is needed for the production of sperm?
Here are the choices:
A. testosterone
B. androgen
C. estrogen
D. steroids | During adulthood, testosterone is needed for the production of sperm. | A: testosterone. |
What are solid lipids that animals use to store energy called?
Here are the choices:
A. fats
B. steroids
C. hydrocortisol
D. cholesterol | Fats are solid lipids that animals use to store energy. | A: fats. |
What in science are very important so that we can compare experimental data from one lab to another and make sure we all are talking about the same thing?
Here are the choices:
A. available measurements
B. standard measurements
C. Conventional measurements
D. uses measurements | Standardized measurements make it possible for people everywhere to get the same amount of something. Note the red and white labels on the gas pump above. These labels certify that the gas pump has been checked and is pumping an accurate gallon of gas. Standard measurements in science are very important so that we can compare experimental data from one lab to another and make sure we all are talking about the same thing. | B: standard measurements. |
What substances in a car battery can be melted and recycled?
Here are the choices:
A. lead and steel
B. steel and sodium
C. lead and sodium
D. lead and plastic | Lead is still widely used in car batteries. In recent years, battery recycling is becoming very common - about 98% of car batteries a recycled today. The used batteries go to a processing plant where they are crushed and placed in a tank. The lead sinks to the bottom and can be separated, melted and used again. Plastic materials float to the top, are separated, and melted. The plastic can then be used in a number of applications. The battery acids are treated with chemicals to neutralize them before they are disposed of. | D: lead and plastic. |
Unlike a crystalline solid, an amorphous solid is a solid that lacks a what?
Here are the choices:
A. color
B. atoms
C. weight
D. ordered internal structure | Unlike a crystalline solid, an amorphous solid is a solid that lacks an ordered internal structure. Some examples of amorphous solids include rubber, plastic, and gels. Glass is a very important amorphous solid that is made by cooling a mixture of materials in such a way that it does not crystallize. Glass is sometimes referred to as a supercooled liquid rather than a solid. If you have ever watched a glassblower in action, you have noticed that he takes advantage of the fact that amorphous solids do not have a distinct melting point like crystalline solids do. Instead, as glass is heated, it slowly softens and can be shaped into all sorts of interesting forms. When a glass object shatters, it does so in a very irregular way, unlike crystalline solids, which always break into fragments that have the same shape as dictated by its crystal system. | D: ordered internal structure. |
Many carbohydrates can enter glycolysis, most often after conversion to what?
Here are the choices:
A. sucrose
B. glucose
C. insulin
D. fructose | B: glucose. | |
If a quantity of a reactant remains unconsumed after complete reaction has occurred, it is?
Here are the choices:
A. static
B. missing
C. in excess
D. reduced | The stoichiometry of a reaction describes the relative amounts of reactants and products in a balanced chemical equation. A stoichiometric quantity of a reactant is the amount necessary to react completely with the other reactant(s). If a quantity of a reactant remains unconsumed after complete reaction has occurred, it is in excess. The reactant that is consumed first and limits the amount of product(s) that can be obtained is the limiting reactant. To identify the limiting reactant, calculate the number of moles of each reactant present and compare this ratio to the mole ratio of the reactants in the balanced chemical equation. The maximum amount of product(s) that can be obtained in a reaction from a given amount of reactant(s) is the theoretical yield of the reaction. The actual yieldis the amount of product(s) actually obtained in the reaction; it cannot exceed the theoretical yield. The percent yield of a reaction is the ratio of the actual yield to the theoretical yield, expressed as a percentage. | C: in excess. |
Name the one metal that melts below room temperature?
Here are the choices:
A. bronze
B. aluminum
C. mercury
D. gold | Metals have a wide range of melting points, but most are quite high. Only one metal (mercury) melts below room temperature. Others (such as gallium) are solid at room temperature but would melt at body temperature, so they can be melted simply by holding them in your hand. On the other end of the spectrum, tungsten has a melting point of 3422°C. Figure below shows the melting points of various elements in their most common pure form. | C: mercury. |
The way a mineral cleaves or fractures depends on what part of the mineral?
Here are the choices:
A. the crystal structure
B. the core
C. the crust
D. the fault structure | The way a mineral cleaves or fractures depends on the crystal structure of the mineral. | A: the crystal structure. |
Ultimately, most life forms get their energy from this?
Here are the choices:
A. food
B. heat
C. sun
D. earth | Figure 4.2 Ultimately, most life forms get their energy from the sun. Plants use photosynthesis to capture sunlight, and herbivores eat the plants to obtain energy. Carnivores eat the herbivores, and eventual decomposition of plant and animal material contributes to the nutrient pool. | C: sun. |
What was diorite commonly used for in ancient civilizations?
Here are the choices:
A. currency
B. medicine
C. school
D. art | An example of a physical model is a drawing of the layers of Earth ( Figure below ). A drawing helps us to understand the structure of the planet. Yet there are many differences between a drawing and the real thing. The size of a model is much smaller, for example. A drawing also doesn’t give good idea of how substances move. Arrows showing the direction the material moves can help. A physical model is very useful but it can’t explain the real Earth perfectly. | D: art. |
Aquatic biomes in the ocean are called what?
Here are the choices:
A. arid biomes
B. artificial biomes
C. marine biomes
D. jungle biomes | Aquatic biomes in the ocean are called marine biomes. Organisms that live in marine biomes must be adapted to the salt in the water. For example, many have organs for excreting excess salt. Marine biomes include the oceans, coral reefs, and estuaries ( Figure below ). The oceans are the largest of all the ecosystems. They can be divided into four separate zones based on the amount of sunlight. Ocean zones are also divided based on their depth and their distance from land. Each zone has a great diversity of species. Within a coral reef , the dominant organisms are corals. Corals consist partially of algae, which provide nutrients via photosynthesis. Corals also extend tentacles to obtain plankton from the water. Coral reefs include several species of microorganisms, invertebrates, fishes, sea urchins, octopuses, and sea stars. Estuaries are areas where freshwater streams or rivers merge with the ocean. | C: marine biomes. |
When an ionic compound dissociates in water, water molecules surround each ion and separate it from the rest of the what?
Here are the choices:
A. mixture
B. gas
C. electron shell
D. solid | When an ionic compound dissociates in water, water molecules surround each ion and separate it from the rest of the solid. Each ion goes its own way in solution. Saylor URL: http://www. saylor. org/books. | D: solid. |
What device is used to measure temperature?
Here are the choices:
A. compass
B. thermometer
C. barometer
D. anemometer | A thermometer is a device used to measure temperature. It is placed in contact with an object and allowed to reach thermal equilibrium with the object (they will have the same temperature). The operation of a thermometer is based on some property, such as volume, that varies with temperature. The most common thermometers contain liquid mercury, or some other liquid, inside a sealed glass tube. The liquid expands and contracts faster than the glass tube. Therefore, when the temperature of the thermometer increases, the liquid volume expands faster than the glass volume, allowing the liquid to rise in the tube. The positions of the liquid in the tube can then be calibrated for accurate temperature readings. Other properties that change with temperature can also be used to make thermometers; liquid crystal colors and electrical conductivity change with temperature, and are also relatively common thermometers. | B: thermometer. |
What has the smallest, lightest atoms of all the elements and is colorless, odorless, tasteless and nontoxic, but highly flammable in its pure state?
Here are the choices:
A. hydrogen
B. magnesium
C. barium
D. helium | Hydrogen has the smallest, lightest atoms of all elements. Pure hydrogen is a colorless, odorless, tasteless gas that is nontoxic but highly flammable. Hydrogen gas exists mainly as diatomic (“two-atom”) molecules (H 2 ), as shown in the diagram on the right. Hydrogen is the most abundant element in the universe and the third most abundant element on Earth, occurring mainly in compounds such as water. | A: hydrogen. |
If two populations do not mate and produce fertile offspring, what results?
Here are the choices:
A. same species
B. small species
C. separate species
D. large species | How do you think scientists test whether two populations are separate species? They bring species from two populations back together again. If the two populations do not mate and produce fertile offspring, they are separate species. | C: separate species. |
What system includes the brain and the spinal cord?
Here are the choices:
A. lymbic
B. central nervous
C. muscular
D. digestive | 31.2 Central nervous system Central nervous system includes the brain and the spinal cord. Brain There are four lobes of the brain. • • • •. | B: central nervous. |
Light is produced when charged particles do what, frequently in the form of oscillating?
Here are the choices:
A. accelerate
B. decelerate
C. offset
D. increase | Light is produced when charged particles accelerate . As a result changing electric and magnetic fields radiate outward. The traveling electric and magnetic fields of an accelerating (often oscillating) charged particle are known as electromagnetic radiation or light. | A: accelerate. |
Respiration rate correlates with what?
Here are the choices:
A. pressure
B. size
C. energy use
D. heat | There must be more to this story than just gas exchange with the environment. To begin to appreciate the role of oxygen inside your body, think about when your breathing rate increases: climbing a steep slope, running a race, or skating a shift in a hockey game. Respiration rate correlates with energy use, and that correlation reflects the link between oxygen and energy metabolism. For this reason, the chemical process inside your cells that consume oxygen to produce usable energy is known as cellular respiration . During this process, energy is converted from glucose , in the presence of oxygen, into numerous ATP molecules. The glucose, of course, comes from the food you eat. In biological terms, you do not eat because you are hungry, you eat to get energy. Other heterotrophic organisms also acquire glucose from other organisms, whereas autotrophic organisms make their own glucose, mostly through photosynthesis. | C: energy use. |
What is the only commercial way of reproducing plants such as orchids?
Here are the choices:
A. cloning
B. sexual reproduction
C. cross-breeding
D. grafting | A: cloning. | |
Birds adapted wings and weathers for flight during what process?
Here are the choices:
A. emergence
B. migration
C. variation
D. evolution | Wings and feathers are two adaptations for flight that evolved in birds. Both are clearly displayed in the flying gull in Figure below . Wings evolved from the front limbs of a four-legged ancestor. The wings are controlled by large flight muscles in the chest. Feathers also help birds fly. They provide air resistance and lift. In addition, they provide insulation and serve other roles. | D: evolution. |
Which factor ruins renewable resources like soil and water?
Here are the choices:
A. resentful human action
B. melancholic human action
C. careless human action
D. hateful human action | Theoretically, soil and water are renewable resources. However, they may be ruined by careless human actions. | C: careless human action. |
How does the solubility of gases in liquids change with increasing temperature?
Here are the choices:
A. it stabilizes
B. no change
C. it increases
D. it decreases | Effect of Temperature on the Solubility of Gases The solubility of gases in liquids decreases with increasing temperature, as shown inFigure 13.10 "Solubilities of Several Common Gases in Water as a Function of Temperature at Partial Pressure of 1 atm". Attractive intermolecular interactions in the gas phase are essentially zero for most substances. When a gas dissolves, it does so because its molecules interact with solvent molecules. Because heat is released when these new attractive interactions form, dissolving most gases in liquids is an exothermic. | D: it decreases. |
What are all living things made of?
Here are the choices:
A. proteins
B. water
C. cells
D. muscles | Cells are the tiny building blocks of living things. They couldn’t be discovered until the microscope was invented. The discovery of cells led to the cell theory. This is one of the most important theories in life science. | C: cells. |
Where does the nucleus store chromatin ?
Here are the choices:
A. ribosome
B. chloroplasts
C. nucleoplasm
D. xerophyte | Figure 4.11 The nucleus stores chromatin (DNA plus proteins) in a gel-like substance called the nucleoplasm. The nucleolus is a condensed region of chromatin where ribosome synthesis occurs. The boundary of the nucleus is called the nuclear envelope. It consists of two phospholipid bilayers: an outer membrane and an inner membrane. The nuclear membrane is continuous with the endoplasmic reticulum. Nuclear pores allow substances to enter and exit the nucleus. | C: nucleoplasm. |
What do the liver, gallbladder, and pancreas contribute that aid in digestion?
Here are the choices:
A. chemicals
B. plasma
C. crystals
D. contaminants | The liver, gallbladder, and pancreas contribute chemicals that aid in digestion. | A: chemicals. |
What are all tissues external to the vascular cambium called?
Here are the choices:
A. nucleus
B. membranes
C. larvae
D. bark | D: bark. | |
Spirals, spheres, and rods are examples of what distinguishing property of bacteria?
Here are the choices:
A. function
B. color
C. shape
D. organ | Bacteria come in many different shapes. Some of the most common shapes are bacilli (rods), cocci (spheres), and spirilli (spirals). Bacteria can be identified and classified by their shape. | C: shape. |
The goal of homeostasis is the maintenance of what, around a point or value called a set point?
Here are the choices:
A. agitation
B. imbalance
C. steadiness
D. equilibrium | Homeostatic Process The goal of homeostasis is the maintenance of equilibrium around a point or value called a set point. While there are normal fluctuations from the set point, the body’s systems will usually attempt to go back to this point. A change in the internal or external environment is called a stimulus and is detected by a receptor; the response of the system is to adjust the deviation parameter toward the set point. For instance, if the body becomes too warm, adjustments are made to cool the animal. If the blood’s glucose rises after a meal, adjustments are made to lower the blood glucose level by getting the nutrient into tissues that need it or to store it for later use. | D: equilibrium. |
What type of energy of a system is the sum of the kinetic and potential energies of its atoms and molecules?
Here are the choices:
A. internal energy u
B. primary energy u
C. deep energy u
D. external energy u | Internal Energy U We can think about the internal energy of a system in two different but consistent ways. The first is the atomic and molecular view, which examines the system on the atomic and molecular scale. The internal energy U of a system is the sum of the kinetic and potential energies of its atoms and molecules. Recall that kinetic plus potential energy is called mechanical energy. Thus internal energy is the sum of atomic and molecular mechanical energy. Because it is impossible to keep track of all individual atoms and molecules, we must deal with averages and distributions. A second way to view the internal energy of a system is in terms of its macroscopic characteristics, which are very similar to atomic and molecular average values. Macroscopically, we define the change in internal energy. | A: internal energy u. |
Primary batteries are single-use batteries because they cannot be what?
Here are the choices:
A. plugged
B. recharged
C. refreshed
D. UP ticked. | Primary Batteries Primary batteries are single-use batteries because they cannot be recharged. A common primary battery is the dry cell (Figure 17.10). The dry cell is a zinc-carbon battery. The zinc can serves as both a container and the negative electrode. The positive electrode is a rod made of carbon that is surrounded by a paste of manganese(IV) oxide, zinc chloride, ammonium chloride, carbon powder, and a small amount of water. The reaction at the anode can be represented as the ordinary oxidation of zinc: Zn(s) ⟶ Zn 2+(aq) + 2e −. | B: recharged. |
Layers of fat are formed by what type of tissue?
Here are the choices:
A. areolar tissue
B. adipose tissue
C. trypanosome tissue
D. colchis tissue | B: adipose tissue. | |
Basidiomycetes do what to wood and other plant material?
Here are the choices:
A. revive
B. decompose
C. evolve
D. evaporate | B: decompose. | |
Pathogens infect many animals and are agents of what?
Here are the choices:
A. disease
B. drought
C. mutation
D. change | A: disease. | |
Sediments in oligotrophic lakes contain large amounts of what?
Here are the choices:
A. fertilizer
B. algae
C. igneous rocks
D. decomposable organic matter | D: decomposable organic matter. | |
What tides occur during the new moon and full moon?
Here are the choices:
A. bottom
B. spring
C. autumn
D. high | Spring tides occur during the new moon and full moon. The Sun and Moon are in a straight line either on the same side of Earth or on opposite sides. Their gravitational pull combines to cause very high and very low tides. Spring tides have the greatest tidal range. | B: spring. |
In passive transport, small molecules or ions move across the cell membrane without requiring input of what?
Here are the choices:
A. heating
B. energy
C. water
D. pressure | Passive transport is a way that small molecules or ions move across the cell membrane without input of energy by the cell. The three main kinds of passive transport are diffusion, osmosis, and facilitated diffusion. | B: energy. |
Some bacteria also have tail-like structures called what?
Here are the choices:
A. sporangia
B. nuclei
C. plasmids
D. flagella | Some bacteria also have tail-like structures called flagella ( Figure below ). Flagella help bacteria move. As the flagella rotate, they spin the bacteria and propel them forward. Though some eukaryotic cells do have a flagella, a flagella in eukaryotes is rare. | D: flagella. |
People with which skin type run a greater risk of vitamin d deficiency?
Here are the choices:
A. weaker skin
B. brighter skin
C. darker skin
D. lighter skin | The epidermis also contains melanocytes , which are cells that produce melanin. Melanin is the brownish pigment that gives skin much of its color. Everyone has about the same number of melanocytes, but the melanocytes of people with darker skin produce more melanin. The amount of melanin produced is determined by heredity and exposure to UV light, which increases melanin output. Exposure to UV light also stimulates the skin to produce vitamin D . Because melanin blocks UV light from penetrating the skin, people with darker skin may be at greater risk of vitamin D deficiency. | C: darker skin. |
What happens to temperature in the troposphere as the altitude increases?
Here are the choices:
A. it increases
B. it decreases
C. it disappears
D. it stays the same | In the troposphere, temperature decreases with altitude. The troposphere gets some of its heat directly from the Sun. Most, however, comes from Earth's surface. The surface is heated by the Sun. Some of that heat radiates back into the air. This makes the temperature higher near the surface than at higher altitudes. | B: it decreases. |
The kidneys help control acid-base balance by excreting _____ and generating bicarbonate that helps maintain blood plasma ph within a normal range?
Here are the choices:
A. magnesium ions
B. lithium ions
C. hydrogen ions
D. sodium ions | Buffer Systems in the Body The buffer systems in the human body are extremely efficient, and different systems work at different rates. It takes only seconds for the chemical buffers in the blood to make adjustments to pH. The respiratory tract can adjust the blood pH upward in minutes by exhaling CO2 from the body. The renal system can also adjust blood pH through the excretion of hydrogen ions (H+) and the conservation of bicarbonate, but this process takes hours to days to have an effect. The buffer systems functioning in blood plasma include plasma proteins, phosphate, and bicarbonate and carbonic acid buffers. The kidneys help control acid-base balance by excreting hydrogen ions and generating bicarbonate that helps maintain blood plasma pH within a normal range. Protein buffer systems work predominantly inside cells. | C: hydrogen ions. |
What does the geiger counter detect?
Here are the choices:
A. convection
B. moisture
C. vibration
D. radiation | You generally can’t see, smell, taste, hear, or feel radiation. Fortunately, there are devices such as Geiger counters that can detect radiation. A Geiger counter, like the one pictured in the Figure below , contains atoms of a gas that is ionized if it encounters radiation. When this happens, the gas atoms change to ions that can carry an electric current. The current causes the Geiger counter to click. The faster the clicks occur, the higher the level of radiation. You can see a video about the Geiger counter and how it was invented at the URL below. | D: radiation. |
Mollusks such as squid and octopi, which must hunt to survive, possess what complex organs containing millions of neurons?
Here are the choices:
A. brains
B. gills
C. tentacles
D. hearts | Figure 35.2 Nervous systems vary in structure and complexity. In (a) cnidarians, nerve cells form a decentralized nerve net. In (b) echinoderms, nerve cells are bundled into fibers called nerves. In animals exhibiting bilateral symmetry such as (c) planarians, neurons cluster into an anterior brain that processes information. In addition to a brain, (d) arthropods have clusters of nerve cell bodies, called peripheral ganglia, located along the ventral nerve cord. Mollusks such as squid and (e) octopi, which must hunt to survive, have complex brains containing millions of neurons. In (f) vertebrates, the brain and spinal cord comprise the central nervous system, while neurons extending into the rest of the body comprise the peripheral nervous system. (credit e: modification of work by Michael Vecchione, Clyde F. Roper, and Michael J. Sweeney, NOAA; credit f: modification of work by NIH). | A: brains. |
Which direction from the source do pollutants in an aquifer spread?
Here are the choices:
A. forward
B. southward
C. outward
D. inward | Pollutants that enter an aquifer spread outward from the source. They spread in the direction the water is moving. | C: outward. |
What type of activity in the brain causes epilepsy?
Here are the choices:
A. hormone imbalance
B. bleeding
C. abnormal electrical activity
D. toxic overload | Epilepsy is a disease that causes seizures. A seizure is a period of lost consciousness that may include violent muscle contractions. It is caused by abnormal electrical activity in the brain. The cause of epilepsy may be an infection, a brain injury, or a tumor. The seizures of epilepsy can often be controlled with medicine. There is no known cure for the disease, but children with epilepsy may outgrow it by adulthood. | C: abnormal electrical activity. |
What does a healthy immune system fight off?
Here are the choices:
A. respiratory and other dieases
B. microorganisms and other dieases
C. infections and other dieases
D. bacteria and viruses | Eat well, get enough sleep, and be active every day. These healthy lifestyle choices will help keep your immune system healthy so it can fight off respiratory infections and other diseases. | C: infections and other dieases. |
Groundwater dissolves minerals and rocks into what?
Here are the choices:
A. sand
B. ions
C. grit
D. gravel | Groundwater dissolves minerals and rocks into ions. Groundwater deposits those ions into different types of structures. Limestone caves are the best place to see these structures. Water erodes the cave and it has deposits structures like stalactites and stalagmites. The cave pictured here is Carlsbad Caverns in New Mexico. | B: ions. |
What is the term for a certain form of matter that has the same physical properties throughout?
Here are the choices:
A. phase
B. balance
C. wave
D. structure | 8.5 End-of-Chapter Material Chapter Summary To ensure that you understand the material in this chapter, you should review the meanings of the following bold terms in the following summary and ask yourself how they relate to the topics in the chapter. A phase is a certain form of matter that has the same physical properties throughout. Three phases are common: the solid, the liquid, and the gas phase. What determines the phase of a substance? Generally, the strength of the intermolecular interactions determines whether a substance is a solid, liquid, or gas under any particular conditions. Covalent network bonding is a very strong form of intermolecular interaction. Diamond is one example of a substance that has this intermolecular interaction. Ionic interactions, the forces of attraction due to oppositely charged ions, are also relatively strong. Covalent bonds are another type of interaction within molecules, but if the bonds are polar covalent bonds, then the unequal sharing of electrons can cause charge imbalances within molecules that cause interactions between molecules. These molecules are described as polar, and these interactions are called dipole-dipole interactions. A certain rather strong type of dipole-dipole interaction, involving a hydrogen atom, is called hydrogen bonding. On the other hand, equal sharing of electrons forms nonpolar covalent bonds, and the interactions between different molecules is less because the molecules are nonpolar. All substances have very weak dispersion forces (also called London forces) caused by the movement of electrons within the bonds themselves. In the solid phase, intermolecular interactions are so strong that they hold the individual atoms or molecules in place. In many solids, the regular three-dimensional arrangement of particles makes a crystal. In other solids, the irregular arrangement of particles makes an amorphous solid. In liquids, the intermolecular interactions are Saylor URL: http://www. saylor. org/books. | A: phase. |
Bacteria are responsible for many types of what in humans?
Here are the choices:
A. diseases
B. food
C. colors
D. smells | Bacteria are responsible for many types of diseases in humans. | A: diseases. |
Humans and other animals can suffer from diets lacking in what essential "ingredients"?
Here are the choices:
A. fiber
B. liquids
C. nutrients
D. steroids | C: nutrients. | |
The size and symmetry of a beetle’s or an elk’s antlers or a grasshopper’s song communicate rather clearly their state of what?
Here are the choices:
A. society
B. problem
C. need
D. health | transient males. Since these loyal males already bond and cooperate with females, it may well be a simple matter for them to bond and cooperate with each other. In a semi-counter intuitive manner, the ability to bond with males could be selected for based on its effect on reproductive success with females. On the other hand, a male that commits himself to a cooperative (loyal and exclusive) arrangement with a female necessarily limits his interactions One of the most robust and reliable findings in with other females. This implies that he will attempt to insure the scientific literature on interpersonal that the offspring he is raising are genetically related to him. attraction is the overwhelming role played by physical attractiveness in defining the ideal Of course, another possibility is that a loyal male may be romantic partner (Hatfield & Sprecher, 1986; attractive to multiple females, who in turn compete for his Jackson, 1992). Both men and women express attention and loyalty. Clearly the outcome of such interactions marked preference for an attractive partner in a is influenced by how many females can the male effectively non- committed short-term (casual, one night stand) relationship (Buss & Schmitt, 1993). protect (that is, improve their reproductive success). The situation quickly gets complex and many competing strategies are possible. Different species make different choices depending upon their evolutionary history and environmental constraints. As we noted above, secondary sexual characteristics, that is, traits that vary dramatically between the two sexes, serve to advertise various traits, including heath, loyalty, robustness, and fertility. The size and symmetry of a beetle’s or an elk’s antlers or a grasshopper’s song communicate rather clearly their state of health.192 The tail of the male peacock is a common example, a male either has large, colorful and symmetrical tail, all signs of a health or it does not – there is little room for ambiguity. These predictions have been confirmed experimentally in a number of systems; the robustness of offspring does correlate with the robustness of the male, a win for evolutionary logic.193 It is critical that both females and males correctly read and/or respond to various traits, and this ability is likely to be selected for. For example, males that can read the traits of other males can determine whether they are likely to win a fight with another male; not being able to make such an accurate determination could result in crippling injuries. A trickier question is how does a female or a male determine whether a possible mate will be loyal? As with advertisements of overall robustness, we might expect that traits that are difficult or expensive to generate will play a key role. So how. | D: health. |
How is blood supplied from the mother to the fetus?
Here are the choices:
A. brain stem
B. vagina
C. spinal cord
D. umbilical cord | Hemoglobin of the Fetus The fetus has its own circulation with its own erythrocytes; however, it is dependent on the mother for oxygen. Blood is supplied to the fetus by way of the umbilical cord, which is connected to the placenta and separated from maternal blood by the chorion. The mechanism of gas exchange at the chorion is similar to gas exchange at the respiratory membrane. However, the partial pressure of oxygen is lower in the maternal blood in the placenta, at about 35 to 50 mm Hg, than it is in maternal arterial blood. The difference in partial pressures between maternal and fetal blood is not large, as the partial pressure of oxygen in fetal blood at the placenta is about 20 mm Hg. Therefore, there is not as much diffusion of oxygen into the fetal blood supply. The fetus’ hemoglobin overcomes this problem by having a greater affinity for oxygen than maternal hemoglobin (Figure 22.27). Both fetal and adult hemoglobin have four subunits, but two of the subunits of fetal hemoglobin have a different structure that causes fetal hemoglobin to have a greater affinity for oxygen than does adult hemoglobin. | D: umbilical cord. |
How long does membrane depoloriazation typically last for?
Here are the choices:
A. 1 hour
B. 3 seconds
C. 5 minutes
D. one minute | D: one minute. | |
What are the three types of mixtures?
Here are the choices:
A. solutions, suspensions, colloids
B. Powders, Gels, Smooth
C. absorbing , suspensions , colloids
D. cosmic , suspensions , colloids | Mixtures have different properties depending on the size of their particles. Three types of mixtures based on particle size are solutions, suspensions, and colloids, all of which are described in Table below . You can watch videos about the three types of mixtures at these URLs:. | A: solutions, suspensions, colloids. |
Double strands of what wrap around histone proteins to form nucleosomes, which are coiled into a chromatin fiber?
Here are the choices:
A. dna
B. ribosomes
C. chromatids
D. bacteria | Figure 10.4 Double-stranded DNA wraps around histone proteins to form nucleosomes that have the appearance of “beads on a string. ” The nucleosomes are coiled into a 30-nm chromatin fiber. When a cell undergoes mitosis, the chromosomes condense even further. | A: dna. |
What is the process when animals maintain an internal temperature?
Here are the choices:
A. osmoregulation
B. thermoregulation
C. bioaccumulation
D. homeostasis | B: thermoregulation. | |
Both androgen secretion and spermatogenesis occur continuously starting with what?
Here are the choices:
A. walking
B. puberty
C. birth
D. mutation | B: puberty. | |
Where does the process of digestion start?
Here are the choices:
A. esophagus
B. stomach
C. mouth
D. small intestine | Digestion starts in the mouth. When food is swallowed, it travels through the esophagus to the stomach. In the stomach, digestion continues and a small amount of absorption of nutrients takes place. | C: mouth. |
As distance from the source increases, the area covered by the sound waves increases, lessening what?
Here are the choices:
A. duration
B. intensity
C. velocity
D. density | The energy of sound waves spreads out over a greater area as the waves travel farther from the sound source. This diagram represents just a small section of the total area of sound waves spreading out from the source. Sound waves actually travel away from the source in all directions. As distance from the source increases, the area covered by the sound waves increases, lessening their intensity. | B: intensity. |
Mountain ranges, plateaus, and plains are features of what large landforms?
Here are the choices:
A. Countries
B. planets
C. continents
D. States | Features of continents include mountain ranges, plateaus, and plains. | C: continents. |
How many pathogens can each droplet contain?
Here are the choices:
A. thousands
B. tens
C. hundreds
D. billions | Many pathogens that cause respiratory diseases spread by droplets in the air. Droplets are released when a person sneezes or coughs. Thousands of tiny droplets are released when a person sneezes ( Figure below ). Each droplet can contain thousands of pathogens. Viruses that cause colds and the flu can spread in this way. You may get sick if you breathe in the pathogens. | A: thousands. |
The ability to change color, separately mobile and stereoscopic eyes, and rapidly extrudable tongues are distinguishing features of what lizards?
Here are the choices:
A. crocodiles
B. snakes
C. geckos
D. chameleons | Chameleons are a distinctive and highly specialized type of lizard. They are distinguished partly by their parrot-like feet, their separately mobile and stereoscopic eyes, their very long, highly modified, and rapidly extrudable tongues, crests or horns on their distinctively shaped heads, and the ability of some to change color. But there are approximately 160 species of chameleons. So how are they classified?. | D: chameleons. |
What is the other name of newton’s first law?
Here are the choices:
A. law of matter
B. law of momentum
C. law of inertia
D. mass and matter | Mass The property of a body to remain at rest or to remain in motion with constant velocity is called inertia. Newton’s first law is often called the law of inertia. As we know from experience, some objects have more inertia than others. It is obviously more difficult to change the motion of a large boulder than that of a basketball, for example. The inertia of an object is measured by its mass. Roughly speaking, mass is a measure of the amount of “stuff” (or matter) in something. The quantity or amount of matter in an object is determined by the numbers of atoms and molecules of various types it contains. Unlike weight, mass does not vary with location. The mass of an object is the same on Earth, in orbit, or on the surface of the Moon. In practice, it is very difficult to count and identify all of the atoms and molecules in an object, so masses are not often determined in this manner. Operationally, the masses of objects are determined by comparison with the standard kilogram. | C: law of inertia. |
The velocity at the beginning of the time interval is called what?
Here are the choices:
A. previous velocity
B. initial velocity
C. growing velocity
D. internal velocity | Acceleration that does not change in time is called uniform or constant acceleration. The velocity at the beginning of the time interval is called initial velocity, , and the velocity at the end of the time interval is called final velocity, . In a velocity versus time graph for uniform acceleration, the slope of the line is the acceleration. The equation that describes the curve is . | B: initial velocity. |
In which sphere of the atmosphere do the northern and southern lights occur?
Here are the choices:
A. stratosphere
B. thermosphere
C. ionosphere
D. lithosphere | The thermosphere is the layer above the mesosphere. Temperature increases with altitude in this layer. The northern and southern lights occur here. | B: thermosphere. |
What carbohydrate from fruit juices is a gel-forming substance important in jelly making?
Here are the choices:
A. pectin
B. potassium
C. gelatin
D. cellulose | Pectin, a carbohydrate from fruit juices, is a gel-forming substance important in jelly making. Silica gel, a colloidal dispersion of hydrated silicon dioxide, is formed when dilute hydrochloric acid is added to a dilute solution of sodium silicate. Canned Heat is a gel made by mixing alcohol and a saturated aqueous solution of calcium acetate. | A: pectin. |
Warm water from the equator mixes with cold water from where?
Here are the choices:
A. the poles
B. the continents
C. the oceans
D. the tropics | Water flows through all the world’s oceans. Warm water from the equator mixes with cold water from the poles. The mixing of warm and cold water makes the water temperature moderate. | A: the poles. |
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