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What group of single-celled organisms lacking a nucleus comprises the most numerous organisms on earth? | fungi | eukaryotes | carbohydrates | prokaryotes | No doubt you’ve had a sore throat before, and you’ve probably eaten cheese or yogurt. If so, then you’ve encountered the fascinating world of prokaryotes. Prokaryotes are single-celled organisms that lack a nucleus. They also lack other membrane-bound organelles. Prokaryotes are tiny and sometimes bothersome, but they are the most numerous organisms on Earth. Without them, the world would be a very different place. Prokaryotes are the simplest organisms. The first cells and organisms to evolve would be classified as prokaryotic. |
Diamond, graphite and fullerene are examples of what form of carbon? | magnesium | zirconia | faceted | crystalline | Pure carbon can form different types of crystals. Crystalline forms of carbon include diamond, graphite, and fullerenes. |
A hot-water heating system uses what type of energy to heat water? | atmospheric energy | negative energy | potential energy | thermal energy | A hot-water heating system uses thermal energy to heat water and then pumps the hot water throughout the building in a system of pipes and radiators. You can see a diagram of this type of heating system in Figure below . Typically, the water is heated in a boiler that burns natural gas or heating oil. There is usually a radiator in each room that gets warm when the hot water flows through it. The radiator transfers thermal energy to the air around it by conduction and radiation. The warm air then circulates throughout the room in convection currents. The hot water cools as it flows through the system and transfers its thermal energy. When it finally returns to the boiler, it is heated again and the cycle repeats. |
What captures carbon dioxide as it is emitted by a power plant before it enters the atmosphere? | nitrogen sequestration | chemical sequestration | oxide sequestration | carbon sequestration | Carbon sequestration captures carbon dioxide as it is emitted by a power plant before it enters the atmosphere. The carbon dioxide is then stored in another form. Carbon is sequestered naturally by forests. Trees take in carbon dioxide for photosynthesis. Artificial methods of sequestering carbon underground are being researched. This is just one of the geoengineering methods that are being researched for reducing carbon dioxide. |
What type of oil is being explored to replace petroleum products in lubricants? | whale oil | essential oil | diesel | vegetable | Vegetable oils are being explored for a variety of uses in which they could replace petroleum products. One such application is in the field of lubricants. Every moving part in machinery (such as engine pistons) needs lubrication to decrease friction and prolong the life of the equipment. Petroleum products serve this purpose now, but are not good for the environment. New techniques for making specialized esters from vegetable oil are being explored that will make the compounds more stable and more useful as lubricants. |
What advantage equals the distance of effort divided by the distance the object moves and is also equal to the output force divided by the input force? | constant | potential | atomic | mechanical | Mechanical advantage equals the distance of effort divided by the distance the object moves. It is also equal to the output force divided by the input force. |
What is the outer layer of skin, consisting almost entirely of epithelial cells? | dermis | hypodermis | connective tissue | epidermis | The epidermis is the outer layer of skin, consisting of epithelial cells and little else (see Figure below ). For example, there are no nerve endings or blood vessels in the epidermis. The innermost cells of the epidermis are continuously dividing through mitosis to form new cells. The newly formed cells move up through the epidermis toward the skin surface, while producing a tough, fibrous protein called keratin. The cells become filled with keratin and die by the time they reach the surface, where they form a protective, waterproof layer called the stratum corneum. The dead cells are gradually shed from the surface of the skin and replaced by other cells. |
What is the accumulated total of all the biochemical reactions occurring in a cell or organism called? | circulation | respiration | expansion | metabolism | All living things—even the simplest life forms—have a complex chemistry. Living things consist of large, complex molecules, and they also undergo many complicated chemical changes to stay alive. Thousands (or more) of these chemical reactions occur in each cell at any given moment. Metabolism is the accumulated total of all the biochemical reactions occurring in a cell or organism. Complex chemistry is needed to carry out all the functions of life. |
When fertilizer ends up in bodies of water, the added nutrients cause excessive growth referred to as what, which can render the water unfit for human consumption or recreation? | agricultural bloom | chemical bloom | caustic bloom | algal bloom | When fertilizer ends up in bodies of water, the added nutrients cause excessive growth of algae. This is called an algal bloom. You can see one in Figure below . The algae out-compete other water organisms. They may make the water unfit for human consumption or recreation. |
What part of the cell controls what enters and leaves? | organism | nucleus | protein | membrane | Like all other living cells, prokaryotes have a cell membrane. It controls what enters and leaves the cell. It's also the site of many metabolic reactions. For example, cellular respiration takes place in the cell membrane. |
Where does the development of a fetus take place? | The kidney | The bladder | The vagina | the female reproductive system | Earth has a tremendous amount of water. So why is water sometimes a scarce resource?. |
What is the critical factor for the survival of segmented worms? | sunlight and warmth | sunlight and water | humidity and sunlight | water and humidity | Phylum Annelida Phylum Annelida includes segmented worms. These animals are found in marine, terrestrial, and freshwater habitats, but a presence of water or humidity is a critical factor for their survival, especially in terrestrial habitats. The name of the phylum is derived from the Latin word annellus, which means a small ring. Animals in this phylum show parasitic and commensal symbioses with other species in their habitat. Approximately 16,500 species have been described in phylum Annelida. The phylum includes earthworms, polychaete worms, and leeches. Annelids show protostomic development in embryonic stages and are often called “segmented worms” due to their key characteristic of metamerism, or true segmentation. Morphology Annelids display bilateral symmetry and are worm-like in overall morphology. Annelids have a segmented body plan wherein the internal and external morphological features are repeated in each body segment. Metamerism allows animals to become bigger by adding “compartments” while making their movement more efficient. This metamerism is thought to arise from identical teloblast cells in the embryonic stage, which give rise to identical mesodermal structures. The overall body can be divided into head, body, and pygidium (or tail). The clitellum is a reproductive structure that generates mucus that aids in sperm transfer and gives rise to a cocoon within which fertilization occurs; it appears as a fused band in the anterior third of the animal (Figure 28.28). |
During sexual arousal what does the clitoris, vagina, and labia minora all engorge with? | fluid | urine | bacteria | blood | |
What is another term for joules per second? | parsons | jiffies | jacobs | watts | Electric energy is measured in joules per second, or watts. |
What is extracted from rock by heap leaching, flotation, or smelting? | fuel | methane | copper | ore | Ore is extracted from rock by heap leaching, flotation, or smelting. |
What tool is useful for studying the ocean floor because the environment is remote and underwater? | scale | microscope | telescope | sonar | Studying the ocean floor is difficult because the environment is so hostile. The seafloor can be studied indirectly with tools such as sonar. It can be studied directly using special vehicles. Some vehicles carry scientists and their devices to the ocean floor. Other vehicles are operated remotely. |
What is the functional unit of the kidney which actively filters blood and generates urine? | mecrophron | sechron | epithelial | nephron | 41.2 The Kidneys and Osmoregulatory Organs The kidneys are the main osmoregulatory organs in mammalian systems; they function to filter blood and maintain the osmolarity of body fluids at 300 mOsm. They are surrounded by three layers and are made up internally of three distinct regions—the cortex, medulla, and pelvis. The blood vessels that transport blood into and out of the kidneys arise from and merge with the aorta and inferior vena cava, respectively. The renal arteries branch out from the aorta and enter the kidney where they further divide into segmental, interlobar, arcuate, and cortical radiate arteries. The nephron is the functional unit of the kidney, which actively filters blood and generates urine. The nephron is made up of the renal corpuscle and renal tubule. Cortical nephrons are found in the renal cortex, while juxtamedullary nephrons are found in the renal cortex close to the renal medulla. The nephron filters and exchanges water and solutes with two sets of blood vessels and the tissue fluid in the kidneys. There are three steps in the formation of urine: glomerular filtration, which occurs in the glomerulus; tubular reabsorption, which occurs in the renal tubules; and tubular secretion, which also occurs in the renal tubules. |
Name two candidates for the original sources of viral genomes. | macrophages and transposons | ediacara and transposons | chloroplasts and transposons | plasmids and transposons | |
What do you call a substance that is not an acid or a base? | oxidic | equivalent | toxic | neutral | What is one of the most important characteristics of a referee? A referee must be neutral. He can’t favor one team over the other. In chemistry, being neutral means not being an acid or a base. Pure water is an example of a neutral substance. In some chemical reactions, an acid and a base combine to form neutral products, including water. You’ll see how this happens when you read this article. |
An amide bond joining two amino acid units is called a what? | precipitate bond | carboxyl bond | ammonia bond | peptide bond | An amide bond joining two amino acid units is called a peptide bond. Note that the product molecule still has a reactive amino group on the left and a reactive carboxyl. |
What is the name for spherical groups of old stars held tightly together by gravity? | dark matter | nebula | elliptical clusters | globular clusters | Globular clusters are spherical groups of old stars held tightly together by gravity. |
What type of state do most fungi spend their lives in? | diploid | triploid | meiosis | haploid | Most fungi are multicellular, but some exist as single cells. Fungi spend most of their life cycle in the haploid state. They form diploid cells only during sexual reproduction. Like the cells of protists and plants, the cells of fungi have cell walls. But fungi are unique in having cell walls made of chitin instead of cellulose. Chitin is a tough carbohydrate that also makes up the exoskeleton (outer skeleton) of insects and related organisms. |
What is the white solid that forms on corroded battery terminals? | straight sulfate | ammonia sulfate | copper sulfate | lead sulfate | Pb(s) + 2H+(aq) + SO42−(aq) → PbSO4(s) + H2(g) Lead(II) sulfate is the white solid that forms on corroded battery terminals. Exercise Using the activity series, predict what happens in each situation. If a reaction occurs, write the net ionic equation. |
What does the decomposition of dead organisms and organic waste release into the atmosphere, soil, or ocean? | hydrogen | nitrogen | oxygen | carbon | Decomposition of dead organisms and organic wastes releases carbon back to the atmosphere, soil, or ocean. |
In which process do two light nuclei combine to produce a heavier nucleus and great energy? | certain fusion | general fusion | light fusion | nuclear fusion | Summary Nuclear reactions are accompanied by large changes in energy, which result in detectable changes in mass. The change in mass is related to the change in energy according to Einstein’s equation: ΔE = (Δm)c2. Large changes in energy are usually reported in kiloelectronvolts or megaelectronvolts (thousands or millions of electronvolts). With the exception of 1H, the experimentally determined mass of an atom is always less than the sum of the masses of the component particles (protons, neutrons, and electrons) by an amount called the mass defect of the nucleus. The energy corresponding to the mass defect is the nuclear binding energy, the amount of energy released when a nucleus forms from its component particles. In nuclear fission, nuclei split into lighter nuclei with an accompanying release of multiple neutrons and large amounts of energy. Thecritical mass is the minimum mass required to support a self-sustainingnuclear chain reaction. Nuclear fusion is a process in which two light nuclei combine to produce a heavier nucleus plus a great deal of energy. |
What results from the consumption of pathogenic bacteria, viruses, or parasites that contaminate food? | hidebound diseases | airborne diseases | parabens diseases | foodborne diseases | 22.4 Bacterial Diseases in Humans Devastating diseases and plagues have been among us since early times. There are records about microbial diseases as far back as 3000 B. Infectious diseases remain among the leading causes of death worldwide. Emerging diseases are those rapidly increasing in incidence or geographic range. They can be new or re-emerging diseases (previously under control). Many emerging diseases affecting humans, such as brucellosis, are zoonoses. The WHO has identified a group of diseases whose re-emergence should be monitored: Those caused by bacteria include bubonic plague, diphtheria, and cholera. Biofilms are considered responsible for diseases such as bacterial infections in patients with cystic fibrosis, Legionnaires’ disease, and otitis media. They produce dental plaque; colonize catheters, prostheses, transcutaneous, and orthopedic devices; and infect contact lenses, open wounds, and burned tissue. Biofilms also produce foodborne diseases because they colonize the surfaces of food and food-processing equipment. Biofilms are resistant to most of the methods used to control microbial growth. The excessive use of antibiotics has resulted in a major global problem, since resistant forms of bacteria have been selected over time. A very dangerous strain, methicillin-resistant Staphylococcus aureus (MRSA), has wreaked havoc recently. Foodborne diseases result from the consumption of contaminated food, pathogenic bacteria, viruses, or parasites that contaminate food. |
What type of physical properties of a substance do not depend on amount? | stable | inherent | extensive | intensive | All matter has physical and chemical properties. Physical properties are characteristics that scientists can measure without changing the composition of the sample under study, such as mass, color, and volume (the amount of space occupied by a sample). Chemical properties describe the characteristic ability of a substance to react to form new substances; they include its flammability and susceptibility to corrosion. All samples of a pure substance have the same chemical and physical properties. For example, pure copper is always a reddish-brown solid (a physical property) and always dissolves in dilute nitric acid to produce a blue solution and a brown gas (a chemical property). Physical properties can be extensive or intensive. Extensive properties vary with the amount of the substance and include mass, weight, and volume. Intensive properties, in contrast, do not depend on the amount of the substance; they include color, melting point, boiling point, electrical conductivity, and physical state at a given temperature. For example, elemental sulfur is a yellow crystalline solid that does not conduct electricity and has a melting point of 115.2°C, no matter what amount is examined (Figure 1.12 "The Difference between Extensive and Intensive Properties of Matter"). Scientists commonly measure intensive properties to determine a substance’s identity, whereas extensive properties convey information about the amount of the substance in a sample. Figure 1.12 The Difference between Extensive and Intensive Properties of Matter. |
A wave that consists of vibrating electric and magnetic fields is called what? | propagate wave | mechanical wave | thermal wave | electromagnetic wave | An electromagnetic wave is a wave that consists of vibrating electric and magnetic fields. A familiar example will help you understand the fields that make up an electromagnetic wave. Think about a common bar magnet. It exerts magnetic force in an area surrounding it, called the magnetic field. You can see the magnetic field of a bar magnet in Figure below . Because of this force field, a magnet can exert force on objects without touching them. They just have to be in its magnetic field. An electric field is similar to a magnetic field (see Figure below ). An electric field is an area of electrical force surrounding a charged particle. Like a magnetic field, an electric field can exert force on objects over a distance without actually touching them. |
Both endocytosis and ______ are active transport processes. | cellular respiration | biosynthesis | proteolysis | exocytosis | Both endocytosis and exocytosis are active transport processes. |
What type of roads and parking lots prevent rainwater from soaking into the ground? | dirt | gravel | shaded | paved | Paved roads and parking lots prevent rainwater from soaking into the ground. This increases runoff and the potential for soil erosion. |
What type of acid is often used as a preservative for acidic foods such as fruit juices? | citric acid | hydrochloric acid | sulfuric acid | benzoic acid | Benzoic acid crystals in polarized light are pictured above. Benzoic acid is widely used as a food preservative, either as the carboxylic acid or as the sodium benzoate salt. This compound is most effective when added to acidic foods such as fruit juices and soft drinks. The major industrial source of benzoic acid is the partial oxidation of toluene with oxygen. The process is inexpensive and environmentally benign. |
Vascular plants evolved what basic structures to collect sunlight? | roots | flowers | stems | leaves | Vascular plants evolved leaves to collect sunlight. At first, leaves were tiny and needle-like, which helped reduce water loss. Later, leaves were much larger and broader, so plants could collect more light. |
The entropy is decreasing because a gas is becoming a what? | vapor cloud | swirl | solid | liquid | The entropy is decreasing because a gas is becoming a liquid. |
Sucrose does not undergo reactions that are typical of aldehydes and ketones, therefore it is a nonreducing what? | salt | wheat | juice | sugar | solution. In addition, sucrose does not undergo reactions that are typical of aldehydes and ketones. Therefore, sucrose is a nonreducing sugar. The hydrolysis of sucrose in dilute acid or through the action of the enzyme sucrase(also known as invertase) gives an equimolar mixture of glucose and fructose. This 1:1 mixture is referred to as invert sugar because it rotates plane-polarized light in the opposite direction than sucrose. The hydrolysis reaction has several practical applications. Sucrose readily recrystallizes from a solution, but invert sugar has a much greater tendency to remain in solution. In the manufacture of jelly and candy and in the canning of fruit, the recrystallization of sugar is undesirable. Therefore, conditions leading to the hydrolysis of sucrose are employed in these processes. Moreover, because fructose is sweeter than sucrose, the hydrolysis adds to the sweetening effect. Bees carry out this reaction when they make honey. The average American consumes more than 100 lb of sucrose every year. About twothirds of this amount is ingested in soft drinks, presweetened cereals, and other highly processed foods. The widespread use of sucrose is a contributing factor to obesity and tooth decay. Carbohydrates such as sucrose, are converted to fat when the caloric intake exceeds the body’s requirements, and sucrose causes tooth decay by promoting the formation of plaque that sticks to teeth. |
An electric stove changes electric current to what form of energy? | nuclear | thermodynamic | kinetic | thermal | Electric devices, such as lights and household appliances, change electric current to other forms of energy. For example, an electric stove changes electric current to thermal energy. Other common devices, such as mobile phones and computers, use electric current for another purpose: to encode information. A message encoded this way is called an electronic signal , and the use of electric current for this purpose is called electronics . For an overview of electronics and electronic signals, read the short article at this URL: http://www. bbc. co. uk/scotland/learning/bitesize/standard/physics/electronics/overview_rev1. shtml . |
Mammals are endothermic vertebrates that have four limbs and produce what type of eggs? | epithelial | gymnoic | umbilical | amniotic | Mammals are endothermic vertebrates that have four limbs and produce amniotic eggs. Defining traits of mammals are fur or hair and mammary glands. Mammals are noted for the many different ways they can move and their specialized limbs. |
Which group of metals in the periodic table include elements such as sodium and potassium? | lanthanides | igneous metals | actinides | alkali metals | The first step in the process of inductive reasoning is making specific observations. In the periodic table of elements, which we will discuss later, there is a group of metals with similar properties called the alkali metals. The alkali metals include elements such as sodium and potassium. If I put sodium or potassium in water, I will observe a very violent reaction every time. I draw a general conclusion from these observations: all alkali metals will react violently with water. |
What is the term for force that opposes motion between any touching surfaces? | tension | gravity | stress | friction | All machines make work easier, but they don’t increase the amount of work that is done. You can never get more work out of a machine than you put into it. In fact, a machine always does less work on an object than the user does on the machine. That’s because a machine must use some of the work put into it to overcome friction. Friction is the force that opposes motion between any surfaces that are touching. All machines involve motion, so they all have friction. How much work is needed to overcome friction in a machine depends on the machine’s efficiency. |
Most animals are in which clade? | synapsids | eutheria | metazoa | bilateria | |
What system carries nerve impulses to internal organs, controlling activities that are not under your control, such as sweating and digesting food? | hormonal nervous system | limbic nervous system | circulatory nervous system | autonomic nervous system | The autonomic nervous system carries nerve impulses to internal organs. It controls activities that are not under your control, such as sweating and digesting food. The autonomic nervous system has two parts:. |
What are invertebrate chordates that retain all four defining chordate traits as adults called? | tunicates | vertebrates | sporozoans | lancelets | Lancelets are invertebrate chordates that retain all four defining chordate traits as adults. There are only about 25 species of living lancelets. Lancelets resemble tunicates in several ways. For example:. |
What has traditionally been defined as a force of attraction between two masses? | volume | motion | mass | gravity | Gravity has traditionally been defined as a force of attraction between two masses. According to this conception of gravity, anything that has mass, no matter how small, exerts gravity on other matter. The effect of gravity is that objects exert a pull on other objects. Unlike friction, which acts only between objects that are touching, gravity also acts between objects that are not touching. In fact, gravity can act over very long distances. |
What members of an ecosystem food chain take in food by eating producers or other living things? | insectivores | primary producers | decomposers | consumers | Consumers take in food by eating producers or other living things. |
What are small organelles and are the site of protein synthesis? | chloroplasts | nucleus | vacuoles | ribosomes | Ribosomes are small organelles and are the site of protein synthesis. Ribosomes are found in all cells. |
Lungs, pharynx, larynx, trachea, and bronchi are part of which system? | neural | nervous | digestive | respiratory | The organs of the respiratory system include the lungs, pharynx, larynx, trachea, and bronchi. |
What is necessary for growth and energy? | determination | breeding | warmth | nutrients | |
Bryophyta is the formal taxonomic name for the phylum that consists solely of what? | lichens | trees | grasses | mosses | |
In humans, how many chromosomes does each somatic cell have? | 36 | 51 | 48 | 46 | |
Like mitochondria, plastids contain their own what? | molecule | riboflavin | bacteria | dna | Like mitochondria, plastids contain their own DNA. Therefore, according to endosymbiotic theory, plastids may also have evolved from ancient, free-living prokaryotes that invaded larger prokaryotic cells. If so, they allowed early eukaryotes to make food and produce oxygen. |
Terrestrial and aquatic are the two basic categories of what, on earth? | dendrites | substrates | atmospheres | biomes | 20.3 | Terrestrial Biomes By the end of this section, you will be able to: • Identify the two major abiotic factors that determine the type of terrestrial biome in an area • Recognize distinguishing characteristics of each of the eight major terrestrial biomes Earth’s biomes can be either terrestrial or aquatic. Terrestrial biomes are based on land, while aquatic biomes include both ocean and freshwater biomes. The eight major terrestrial biomes on Earth are each distinguished by characteristic temperatures and amount of precipitation. Annual totals and fluctuations of precipitation affect the kinds of vegetation and animal life that can exist in broad geographical regions. Temperature variation on a daily and seasonal basis is also important for predicting the geographic distribution of a biome. Since a biome is defined by climate, the same biome can occur in geographically distinct areas with similar climates (Figure 20.18). There are also large areas on Antarctica, Greenland, and in mountain ranges that are covered by permanent glaciers and support very little life. Strictly speaking, these are not considered biomes and in addition to extremes of cold, they are also often deserts with very low precipitation. |
When dissolved in water, what do strong acids transfer to the solvent completely? | acidic proteins | acidic neutrons | acidic electrons | acidic protons | Strong acids completely transfer their acidic protons to the solvent when dissolved in water. When a weak acid is dissolved in water, most of the molecules will retain their acidic protons, and only a small percentage will dissociate. |
On the atomic level, the dissolution of an ionic compound occurs when water interacts with the what in the crystal lattice? | particles | atoms | fractals | ions | The last property above requires some additional explanation. We are all familiar with the process of dissolution on a large scale. If you stir a spoonful of salt into a glass of water, the salt crystals are broken down and seem to disappear into the water. On the atomic level, the dissolution of an ionic compound occurs when water interacts with the ions in the crystal lattice, causing the lattice to break apart ( Figure below ):. |
What is one method to observe nebulae? | microscope | mirror | kaleidoscope | telescope | Nebulae can be spotted with the naked eye or simple telescopes. |
When alternating primary current passes through coil p, it does what to the iron core? | heats it | electrilizes it | creates it | magnetizes it | As you can see in Figure above , a transformer consists of two wire coils wrapped around an iron core. When alternating primary current passes through coil P, it magnetizes the iron core. Because the current is alternating, the magnetic field of the iron core keeps reversing. This changing magnetic field induces alternating current in coil S, which is part of another circuit. In Figure above , coil P and coil S have the same number of turns of wire. In this case, the voltages of the primary and secondary currents are the same. However, when the two coils have different numbers of turns, the voltage of the secondary current is different than the voltage of the primary current. Both cases are illustrated in Figure below . |
What state of matter exists if particles do not have enough kinetic energy to overcome the force of attraction between them? | gas | plasma | liquid | solid | If particles do not have enough kinetic energy to overcome the force of attraction between them, matter exists as a solid. The particles are packed closely together and held rigidly in place. All they can do is vibrate. This explains why solids have a fixed volume and a fixed shape. |
What is the“packet” of energy called that the nucleus emits during gamma decay? | ultraviolet particle | transient particle | radioactive particle | gamma particle | Gamma rays are produced during gamma decay of an excited nucleus. During gamma decay, the nucleus emits a “packet” of energy called a gamma particle. |
The movement of molten metal in earth's outer core creates? | earthquakes | the gravitational field | the stellar field | the magnetic field | The magnetic field has north and south poles. The magnetic poles do not exactly match the geographic poles. So the North Magnetic Pole is not the same as the geographic North Pole. The same is true of the South Pole. The magnetic field is created by the movement of molten metal in the outer core. |
Mechanical churning of food in what organ serves to further break it apart and expose more of its surface area to digestive juices, creating an acidic “soup” called chyme? | gall bladder | liver | kidneys | stomach | saliva. Although there may be a tendency to think that mechanical digestion is limited to the first steps of the digestive process, it occurs after the food leaves the mouth, as well. The mechanical churning of food in the stomach serves to further break it apart and expose more of its surface area to digestive juices, creating an acidic “soup” called chyme. Segmentation, which occurs mainly in the small intestine, consists of localized contractions of circular muscle of the muscularis layer of the alimentary canal. These contractions isolate small sections of the intestine, moving their contents back and forth while continuously subdividing, breaking up, and mixing the contents. By moving food back and forth in the intestinal lumen, segmentation mixes food with digestive juices and facilitates absorption. In chemical digestion, starting in the mouth, digestive secretions break down complex food molecules into their chemical building blocks (for example, proteins into separate amino acids). These secretions vary in composition, but typically contain water, various enzymes, acids, and salts. The process is completed in the small intestine. Food that has been broken down is of no value to the body unless it enters the bloodstream and its nutrients are put to work. This occurs through the process of absorption, which takes place primarily within the small intestine. There, most nutrients are absorbed from the lumen of the alimentary canal into the bloodstream through the epithelial cells that make up the mucosa. Lipids are absorbed into lacteals and are transported via the lymphatic vessels to the bloodstream (the subclavian veins near the heart). The details of these processes will be discussed later. In defecation, the final step in digestion, undigested materials are removed from the body as feces. |
A constant and plentiful supply of oxygen is required in order to maintain a high rate of what? | magnesium | digestion | cell division | metabolism | Keeping the rate of metabolism high takes a constant and plentiful supply of oxygen. That’s because cellular respiration, which produces energy, requires oxygen. The lungs and heart of mammals are adapted to meet their oxygen needs. |
Organisms interact with each other and what else? | outside enviroment | thermal environment | atmospheric environment | physical environment | |
What is the center of an earthquake called? | the impact | the magnitude | the core | the epicenter | Where an earthquake takes place is described by its focus and epicenter. |
Calvin cycle reactions can be organized into three basic stages: fixation, reduction, and this? | demarcation | transformation | creation | regeneration | The Calvin cycle reactions (Figure 5.15) can be organized into three basic stages: fixation, reduction, and regeneration. In the stroma, in addition to CO2, two other chemicals are present to initiate the Calvin cycle: an enzyme abbreviated RuBisCO, and the molecule ribulose bisphosphate (RuBP). RuBP has five atoms of carbon and a phosphate group on each end. RuBisCO catalyzes a reaction between CO2 and RuBP, which forms a six-carbon compound that is immediately converted into two three-carbon compounds. This process is called carbon fixation, because CO2 is “fixed” from its inorganic form into organic molecules. ATP and NADPH use their stored energy to convert the three-carbon compound, 3-PGA, into another three-carbon compound called G3P. This type of reaction is called a reduction reaction, because it involves the gain of electrons. A reduction is the gain of an electron by an atom or molecule. The molecules of ADP and NAD+, resulting from the reduction reaction, return to the light-dependent reactions to be re-energized. One of the G3P molecules leaves the Calvin cycle to contribute to the formation of the carbohydrate molecule, which is commonly glucose (C6H12O6). Because the carbohydrate molecule has six carbon atoms, it takes six turns of the Calvin cycle to make one carbohydrate molecule (one for each carbon dioxide molecule fixed). The remaining G3P molecules regenerate RuBP, which enables the system to prepare for the carbon-fixation step. ATP is also used in the regeneration of RuBP. |
What type of cells are arranged into tightly packed sheaths around the veins of the leaf? | cell walls | pattern - sheath cells | cellulose | bundle-sheath cells | |
How are the number of moles of carbon dioxide gas calculated? | phytochemistry | relativistic | casuistry | stoichiometry | The number of moles of carbon dioxide gas is first calculated by stoichiometry. Then the ideal gas law is used to calculate the volume of CO 2 produced. |
What is the name of the blood protein that carries oxygen from the lungs to the body's assorted tissues? | White Blood cells | insulin | plasma | hemoglobin | Anemia is a disease that occurs when there is not enough hemoglobin in the blood to carry oxygen to body cells. Hemoglobin is the blood protein that normally carries oxygen from the lungs to the tissues. Anemia leads to a lack of oxygen in organs. |
The sun and many other light sources produce waves that are randomly this? | colored | obfuscated | amplified | polarized | The Sun and many other light sources produce waves that are randomly polarized (see Figure 27.39). Such light is said to be unpolarized because it is composed of many waves with all possible directions of polarization. Polaroid materials, invented by the founder of Polaroid Corporation, Edwin Land, act as a polarizing slit for light, allowing only polarization in one direction to pass through. Polarizing filters are composed of long molecules aligned in one direction. Thinking of the molecules as many slits, analogous to those for the oscillating ropes, we can understand why only light with a specific polarization can get through. The axis of a polarizing filter is the direction along which the filter passes the electric field of an EM wave (see Figure 27.40). |
Each vertebral vein also flows into which vein? | spiral | trichina | xerophyte | brachiocephalic | The Superior Vena Cava The superior vena cava drains most of the body superior to the diaphragm (Figure 20.36). On both the left and right sides, the subclavian vein forms when the axillary vein passes through the body wall from the axillary region. It fuses with the external and internal jugular veins from the head and neck to form the brachiocephalic vein. Each vertebral vein also flows into the brachiocephalic vein close to this fusion. These veins arise from the base of the brain and the cervical region of the spinal cord, and flow largely through the intervertebral foramina in the cervical vertebrae. They are the counterparts of the vertebral arteries. Each internal thoracic vein, also known as an internal mammary vein, drains the anterior surface of the chest wall and flows into the brachiocephalic vein. The remainder of the blood supply from the thorax drains into the azygos vein. Each intercostal vein drains muscles of the thoracic wall, each esophageal vein delivers blood from the inferior portions of the esophagus, each bronchial vein drains the systemic circulation from the lungs, and several smaller veins drain the mediastinal region. Bronchial veins carry approximately 13 percent of the blood that flows into the bronchial arteries; the remainder intermingles with the pulmonary circulation and returns to the heart via the pulmonary veins. These veins flow into the azygos vein, and with the smaller hemiazygos vein (hemi- = “half”) on the left of the vertebral column, drain blood from the thoracic region. The hemiazygos vein does not drain directly into the superior vena cava but enters the brachiocephalic vein via the superior intercostal vein. The azygos vein passes through the diaphragm from the thoracic cavity on the right side of the vertebral column and begins in the lumbar region of the thoracic cavity. It flows into the superior vena cava at approximately the level of T2, making a significant contribution to the flow of blood. It combines with the two large left and right brachiocephalic veins to form the superior vena cava. Table 20.11 summarizes the veins of the thoracic region that flow into the superior vena cava. |
Almost all plants make food through what process? | hydrolysis | glycolysis | evolution | photosynthesis | Almost all plants make food by photosynthesis. |
What did darwin call the evolutionary concept of change in populations over generations? | metabolism with modifications | formation with modifications | reproduction with modifications | descent with modifications | Wallace and Darwin both observed similar patterns in other organisms and independently conceived a mechanism to explain how and why such changes could take place. Darwin called this mechanism natural selection. Natural selection, Darwin argued, was an inevitable outcome of three principles that operated in nature. First, the characteristics of organisms are inherited, or passed from parent to offspring. Second, more offspring are produced than are able to survive; in other words, resources for survival and reproduction are limited. The capacity for reproduction in all organisms outstrips the availability of resources to support their numbers. Thus, there is a competition for those resources in each generation. Both Darwin and Wallace’s understanding of this principle came from reading an essay by the economist Thomas Malthus, who discussed this principle in relation to human populations. Third, offspring vary among each other in regard to their characteristics and those variations are inherited. Out of these three principles, Darwin and Wallace reasoned that offspring with inherited characteristics that allow them to best compete for limited resources will survive and have more offspring than those individuals with variations that are less able to compete. Because characteristics are inherited, these traits will be better represented in the next generation. This will lead to change in populations over generations in a process that Darwin called “descent with modification. ” Papers by Darwin and Wallace (Figure 11.3) presenting the idea of natural selection were read together in 1858 before the Linnaean Society in London. The following year Darwin’s book, On the Origin of Species, was published, which outlined in considerable detail his arguments for evolution by natural selection. |
Surprisingly, where would you find the earth’s tallest mountains and deepest canyons? | taiga | Tibet | rain forests | ocean floor | Scientists have learned a lot about the ocean floor. For example, they know that Earth’s tallest mountains and deepest canyons are on the ocean floor. The major features on the ocean floor are described below. They are also shown in Figure below . |
The part of the shadow in which light is completely blocked is called what? | corona | penumbra | eclipse | umbra | The umbra is the part of the shadow in which light is completely blocked. |
What is the name of the period of transition between the beginning of puberty and adulthood? | childhood | maturation | aging | adolescence | Adolescence is the period of transition between the beginning of puberty and adulthood. Adolescence is also a time of significant mental, emotional, and social changes. For example:. |
The formula unit of sodium chloride dissociates into one sodium ion and one? | electron | oxygen ion | magnesium ion | chloride ion | The formula unit of sodium chloride dissociates into one sodium ion and one chloride ion. The calcium nitrate formula unit dissociates into one calcium ion and two nitrate ions. This is because of the 2+ charge of the calcium ion. Two nitrate ions, each with a 1− charge are required to make the equation balance electrically. The ammonium phosphate formula unit dissociates into three ammonium ions and one phosphate ion. Note that the polyatomic ions themselves do not dissociate further, but remain intact. |
Fibrous root systems have many small branching roots called what? | tendrils | vines | taproots | fibrous roots | Fibrous root systems have many small branching roots, called fibrous roots , but no large primary root. The huge number of threadlike roots increases the surface area for absorption of water and minerals, but fibrous roots anchor the plant less securely. |
A system of glands secretes what chemical messenger molecules into the blood? | acids | metabolytes | enzymes | hormones | system of glands that secrete chemical messenger molecules called hormones into the blood. |
In eukaryotic cells, molecules such as enzymes are usually compartmentalized into different what? | electrons | organisms | atoms | organelles | Enzyme Compartmentalization In eukaryotic cells, molecules such as enzymes are usually compartmentalized into different organelles. This allows for yet another level of regulation of enzyme activity. Enzymes required only for certain cellular processes can be housed separately along with their substrates, allowing for more efficient chemical reactions. Examples of this sort of enzyme regulation based on location and proximity include the enzymes involved in the latter stages of cellular respiration, which take place exclusively in the mitochondria, and the enzymes involved in the digestion of cellular debris and foreign materials, located within lysosomes. Feedback Inhibition in Metabolic Pathways Molecules can regulate enzyme function in many ways. A major question remains, however: What are these molecules and where do they come from? Some are cofactors and coenzymes, ions, and organic molecules, as you’ve learned. What other molecules in the cell provide enzymatic regulation, such as allosteric modulation, and competitive and noncompetitive inhibition? The answer is that a wide variety of molecules can perform these roles. Some of these molecules include pharmaceutical and non-pharmaceutical drugs, toxins, and poisons from the environment. Perhaps the most relevant sources of enzyme regulatory molecules, with respect to cellular metabolism, are the products of the cellular metabolic reactions themselves. In a most efficient and elegant way, cells have evolved to use the products of their own reactions for feedback inhibition of enzyme activity. Feedback inhibition involves the use of a reaction product to regulate its own further production (Figure 6.21). The cell responds to the abundance of specific products by slowing down production during anabolic or catabolic reactions. Such reaction products may inhibit the enzymes that catalyzed their production through the mechanisms described above. |
What does the stable form of sulfur at room temperature contain? | electron shell | six - membered rings | four - membered rings | eight-membered rings | Larger amounts of sulfur also come from hydrogen sulfide recovered during the purification of natural gas. Sulfur exists in several allotropic forms. The stable form at room temperature contains eight-membered rings, and so the true formula is S8. However, chemists commonly use S to simplify the coefficients in chemical equations; we will follow this practice in this book. |
What term means the amount of a substance required to form a saturated solution in a given amount of solvent at a specified temperature? | turbidity | viscosity | concentration | solubility | The solubility of a substance is the amount of that substance that is required to form a saturated solution in a given amount of solvent at a specified temperature. Solubility is often measured as the grams of solute per 100 g of solvent. The solubility of sodium chloride in water is 36.0 g per 100 g water at 20°C. The temperature must be specified because solubility varies with temperature. For gases, the pressure must also be specified. Solubility is specific for a particular solvent. We will consider solubility of material in water as solvent. |
What bone forms the upper jaw and supports the upper teeth? | tibular bone | subaerial bone | orbital bone | maxillary bone | Figure 7.14 Maxillary Bone The maxillary bone forms the upper jaw and supports the upper teeth. Each maxilla also forms the lateral floor of each orbit and the majority of the hard palate. |
What does increasing a solute's temperature do? | no change | increases its viscosity | decrease its solubility | increases its solubility | If a solute is a solid or liquid, increasing the temperature increases its solubility. For example, more sugar can dissolve in hot water than in cold water. |
What are the pyramid-shaped, paired organs that are connected to the trachea by the right and left bronchi? | ovaries | kidneys | stomachs | lungs | Gross Anatomy of the Lungs The lungs are pyramid-shaped, paired organs that are connected to the trachea by the right and left bronchi; on the inferior surface, the lungs are bordered by the diaphragm. The diaphragm is the flat, dome-shaped muscle located at the base of the lungs and thoracic cavity. The lungs are enclosed by the pleurae, which are attached to the mediastinum. The right lung is shorter and wider than the left lung, and the left lung occupies a smaller volume than the right. The cardiac notch is an indentation on the surface of the left lung, and it allows space for the heart (Figure 22.13). The apex of the lung is the superior region, whereas the base is the opposite region near the diaphragm. The costal surface of the lung borders the ribs. The mediastinal surface faces the midline. |
The global biosphere includes all areas of what? | science | study | geography | life | The global biosphere, which includes all areas that contain life, from the sea to the atmosphere. |
Atomic orbitals from different atoms overlap to form what? | planet orbitals | plasma orbitals | space orbitals | molecular orbitals | Atomic orbitals from different atoms overlap to form molecular orbitals. |
Particulates cause lung diseases. they can also increase the risk of heart disease and the number of what? | shortness of breath | coughing | cancer | asthma attacks | Particulates cause lung diseases. They can also increase the risk of heart disease and the number of asthma attacks. Particulates block sunlight from reaching Earth’s surface. This means there is less energy for photosynthesis. Less photosynthesis means that plants and phytoplankton produce less food. This affects whole ecosystems. |
What reinforces the thin walls of the right ventricle and plays a crucial role in cardiac conduction? | pores valve | pores band | moderator valve | moderator band | The walls of the ventricle are lined with trabeculae carneae, ridges of cardiac muscle covered by endocardium. In addition to these muscular ridges, a band of cardiac muscle, also covered by endocardium, known as the moderator band (see Figure 19.9) reinforces the thin walls of the right ventricle and plays a crucial role in cardiac conduction. It arises from the inferior portion of the interventricular septum and crosses the interior space of the right ventricle to connect with the inferior papillary muscle. When the right ventricle contracts, it ejects blood into the pulmonary trunk, which branches into the left and right pulmonary arteries that carry it to each lung. The superior surface of the right ventricle begins to taper as it approaches the pulmonary trunk. At the base of the pulmonary trunk is the pulmonary semilunar valve that prevents backflow from the pulmonary trunk. |
What kind of radiation is observed in honeycreeper birds? | destructive | spontaneous | symbiotic | adaptive | Figure 18.13 The honeycreeper birds illustrate adaptive radiation. From one original species of bird, multiple others evolved, each with its own distinctive characteristics. |
What do we call the worldwide radio-navigation system formed from a constellation of 24 satellites and their ground stations? | compass | cellular network | radio waves | gps | You must have a GPS receiver to use the system. You can buy many types of these in stores. The GPS receiver detects radio signals from nearby GPS satellites. There are precise clocks on each satellite and in the receiver. The receiver measures the time for radio signals from satellites to reach it. The receiver uses the time and the speed of radio signals to calculate the distance between the receiver and the satellite. The receiver does this with at least four different satellites to locate its position on the Earth’s surface ( Figure above ). GPS receivers are now being built into many items, such as cell phones and cars. |
What substance can be eroded by wind or water? | sand | metal | wood | soil | Soil and water are renewable resources but may be ruined by careless human actions. Soil can be depleted of nutrients. It can also be eroded by wind or water. |
What unit of the nervous system consists of a cell body, dendrites, and axon? | ganglion | Transmitter | mitochondria | neuron | Neurons are the structural and functional units of the nervous system. They consist of a cell body, dendrites, and axon. |
What are small planets in our solar system called? | light planets | scrub planets | Tiny planets | dwarf planets | Eris is the largest known dwarf planet in the solar system. It is 27 percent larger than Pluto ( Figure above ). Like Pluto and Makemake, Eris is in the Kuiper belt. But Eris is about 3 times farther from the Sun than Pluto. Because of its distance, Eris was not discovered until 2005. Early on, it was thought that Eris might be the tenth planet. Its discovery helped astronomers realize that they needed a new definition of “planet. ” Eris has a small moon, Dysnomia. Its moon orbits Eris once about every 16 days. |
What is electrons in the highest occupied principal energy level of an atom called? | gradient electrons | non-valence electrons | shell electrons | valence electrons | In the study of chemical reactivity, we will find that the electrons in the outermost principal energy level are very important and so they are given a special name. Valence electrons are the electrons in the highest occupied principal energy level of an atom. In the second period elements listed above, the two electrons in the 1 s sublevel are called inner-shell electrons and are not involved directly in the element’s reactivity or in the formation of compounds. Lithium has a single electron in the second principal energy level and so we say that lithium has one valence electron. Beryllium has two valence electrons. How many valence electrons does boron have? You must recognize that the second principal energy level consists of both the 2 s and the 2 p sublevels and so the answer is three. In fact, the number of valence electrons goes up by one for each step across a period until the last element is reached. Neon, with its configuration ending in s 2 p 6 , has eight valence electrons. |
Pacemaker cells stimulate the spontaneous contraction of cardiac muscle as a functional unit, called a what? | adipocytes | coenocyte | tapetum | syncytium | 10.7 Cardiac Muscle Tissue Cardiac muscle is striated muscle that is present only in the heart. Cardiac muscle fibers have a single nucleus, are branched, and joined to one another by intercalated discs that contain gap junctions for depolarization between cells and desmosomes to hold the fibers together when the heart contracts. Contraction in each cardiac muscle fiber is triggered by Ca++ ions in a similar manner as skeletal muscle, but here the Ca++ ions come from SR and through voltage-gated calcium channels in the sarcolemma. Pacemaker cells stimulate the spontaneous contraction of cardiac muscle as a functional unit, called a syncytium. |
A mineral’s crystal shape is determined by the way what objects are arranged? | Electrons | molecules | particles | atoms | The patterns of atoms that make a mineral affect its physical properties. A mineral’s crystal shape is determined by the way the atoms are arranged. For example, you can see how atoms are arranged in halite in Figure above . You can see how salt crystals look under a microscope in Figure below . Salt crystals are all cubes whether they're small or large. |
Unlike prokaryotes, eukaryotes have a what? | mitochondria | flagellum | cell wall | cell nucleus | Eukaryotes evolved about 2 billion years ago. Unlike prokaryotes, eukaryotes have a cell nucleus. They have more structures and are better organized. Organelles within a eukaryote can perform certain functions. Some supply energy; some break down wastes. Eukaryotes were better able to live and so became the dominant life form. You can see an example of a eukaryotic cell below ( Figure below ). |
What term is used to describe major changes in the genetic material? | mutational alterations | generational alterations | eukaryotic alterations | chromosomal alterations | Chromosomal Alterations. Chromosomal alterations are major changes in the genetic material. |
What type of rocks form when sediments are compacted and cemented together? | igneous rocks | metamorphic rocks | crystalline rocks | sedimentary rocks | Sedimentary rocks form when sediments are compacted and cemented together. Sediments are pieces of rock. They may be gravel, sand, silt, or clay. Some sedimentary rocks form the solid minerals left behind after a liquid evaporates. |
Processes in which matter changes between liquid and solid states are freezing and? | transpiration | boiling | steaming | melting | Processes in which matter changes between liquid and solid states are freezing and melting. |
Abrasion is a process of what type of weathering? | environmental | geological | molecular | mechanical | Ice wedging and abrasion are two important processes of mechanical weathering. |
Mendel’s observation of pea plants also included many crosses that involved multiple traits, which prompted him to formulate the principle of this? | dependent evolution | independent contain | independent texture | independent assortment | Mendel’s observation of pea plants also included many crosses that involved multiple traits, which prompted him to formulate the principle of independent assortment. The law states that the members of one pair of genes (alleles) from a parent will sort independently from other pairs of genes during the formation of gametes. Applied to pea plants, that means that the alleles associated with the different traits of the plant, such as color, height, or seed type, will sort independently of one another. This holds true except when two alleles happen to be located close to one other on the same chromosome. Independent assortment provides for a great degree of diversity in offspring. Mendelian genetics represent the fundamentals of inheritance, but there are two important qualifiers to consider when applying Mendel’s findings to inheritance studies in humans. First, as we’ve already noted, not all genes are inherited in a dominant–recessive pattern. Although all diploid individuals have two alleles for every gene, allele pairs may interact to create several types of inheritance patterns, including incomplete dominance and codominance. Secondly, Mendel performed his studies using thousands of pea plants. He was able to identify a 3:1 phenotypic ratio in second-generation offspring because his large sample size overcame the influence of variability resulting from chance. In contrast, no human couple has ever had thousands of children. If we know that a man and woman are both heterozygous for a recessive genetic disorder, we would predict that one in every four of their children would be affected by the disease. In real life, however, the influence of chance could change that ratio significantly. For example, if a man and a woman are both heterozygous for cystic fibrosis, a recessive genetic disorder that is expressed only when the individual has two defective alleles, we would expect one in four of their children to have cystic fibrosis. However, it is entirely possible for them to have seven children, none of whom is affected, or for them to have two children, both of whom are affected. For each individual child, the presence or absence of a single gene disorder depends on which alleles that child inherits from his or her parents. |
The skull consists of cranial bones and what other type of bones? | superficial | nasal | subdermal | facial | The bones of the skull support the structures of the face and protect the brain. The skull consists of cranial bones and facial bones. The cranial bones form the cranial cavity, which encloses the brain and serves as an attachment site for muscles of the head and neck. In the adult they are tightly jointed with connective tissue and adjoining bones do not move. The auditory ossicles of the middle ear transmit sounds from the air as vibrations to the fluid-filled cochlea. The auditory ossicles consist of two malleus (hammer) bones, two incus (anvil) bones, and two stapes (stirrups), one on each side. Facial bones provide cavities for the sense organs (eyes, mouth, and nose), and serve as attachment points for facial muscles. The hyoid bone lies below the mandible in the front of the neck. It acts as a movable base for the tongue and is connected to muscles of the jaw, larynx, and tongue. The mandible forms a joint with the base of the skull. The mandible controls the opening to the mouth and hence, the airway and gut. |
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