question stringlengths 14 399 | choices listlengths 4 4 | answer stringclasses 4
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In a chemical reaction, the amounts of reactants and products will be constant when what state is attained? | [
"saturation",
"equilibrium",
"peak",
"homogeneity"
] | B | The amount of reactants and products do not have to be equal. However, after equilibrium is attained, the amounts of reactants and products will be constant.
In chemistry, reactivity is the impulse for which a chemical substance undergoes a chemical reaction, either by itself or with other materials, with an overall re... |
What protects a developing flower while it is still a bud? | [
"shell",
"petals",
"lobes",
"sepals"
] | D | Sepals protect the developing flower while it is still a bud. Sepals are usually green, which camouflages the bud from possible consumers.
Flower development is the process by which angiosperms produce a pattern of gene expression in meristems that leads to the appearance of an organ oriented towards sexual reproductio... |
What is the term for the force of attraction between things that have a mass? | [
"weight",
"motion",
"magnetism",
"gravity"
] | D | Gravity has traditionally been defined as a force of attraction between things that have mass. According to this conception of gravity, anything that has mass, no matter how small, exerts gravity on other matter. Gravity can act between objects that are not even touching. In fact, gravity can act over very long distanc... |
What are the long, thin protein extensions in most prokaryotic cells called? | [
"analyte",
"cingulum",
"neutrons",
"flagellum"
] | D |
The table "60S ribosomal proteins" shows the individual protein folds of the 60S subunit colored by conservation as above. The eukaryote-specific extensions, ranging from a few residues or loops to very long alpha helices and additional domains, are highlighted in red.Historically, different nomenclatures have been us... |
Dialysis is a treatment for failure of what organs? | [
"lungs",
"liver",
"spleen",
"kidneys"
] | D | Kidney failure may be treated with dialysis.
Kidney dialysis (from Greek διάλυσις, dialysis, 'dissolution'; from διά, dia, 'through', and λύσις, lysis, 'loosening or splitting') is the process of removing excess water, solutes, and toxins from the blood in people whose kidneys can no longer perform these functions natu... |
What preventive measure can protect even young children against diseases such as viral meningitis? | [
"nutrition",
"surgical intervention",
"vaccination",
"malnutrition"
] | C | Children as young as 2 years of age can be vaccinated against viral meningitis.
In 2012, the World Health Organization estimated that vaccination prevents 2.5 million deaths each year. With 100% immunization, and 100% efficacy of the vaccines, one out of seven deaths among young children could be prevented, mostly in d... |
Renal plasma flow equals the blood flow per minute times the what? | [
"erythrocytes",
"hematocrit",
"leukocytes",
"hemoglobin"
] | B | Renal plasma flow equals the blood flow per minute times the hematocrit. If a person has a hematocrit of 45, then the renal plasma flow is 55 percent. 1050*0.55 = 578 mL plasma/min.
Para-aminohippurate (PAH) clearance is a method used in renal physiology to measure renal plasma flow, which is a measure of renal functio... |
What does lattice energy of an ionic solid measure the strength of? | [
"metals",
"bonds",
"atoms",
"electrons"
] | B | Lattice energy of an ionic solid is a measure of the strength of bonds in that ionic compound.
The concept of lattice energy was originally applied to the formation of compounds with structures like rocksalt (NaCl) and sphalerite (ZnS) where the ions occupy high-symmetry crystal lattice sites. In the case of NaCl, latt... |
How many different types of taste can be detected by taste buds? | [
"five",
"three",
"two",
"hundreds"
] | A |
Cattle have a well-developed sense of taste and can distinguish the four primary tastes (sweet, salty, bitter and sour). They possess around 20,000 taste buds. The strength of taste perception depends on the individual's current food requirements.
The gustatory system or the sense of taste is the sensory system that i... |
What species do humans belong to? | [
"homo erectus",
"hominids",
"homo sapiens",
"monkeys"
] | C | Homo sapiens is our species. We originated about 200,000 years ago in Africa. Evidence of a spiritual life appears about 32,000 years ago. The evidence includes stone figurines that probably have religious significance ( Figure below ).
Human taxonomy is the classification of the human species (systematic name Homo sap... |
Titration is a method to determine what in acids or bases? | [
"alkalinity",
"concentration",
"maturation",
"glucose"
] | B | The concentration of an acid or base can be determined by titration.
There are many types of titrations with different procedures and goals. The most common types of qualitative titration are acid–base titrations and redox titrations.
Consequently, in the titration of a strong acid with a strong base, the conductance h... |
How many different amino acids make up proteins. | [
"14",
"25",
"30",
"20"
] | D | There are 20 amino acids that make up proteins. With three bases per codon, there are 64 possible codons. This is more than enough to code for the 20 amino acids plus start and stop signals. You can see how to translate the genetic code in Figure below . Start at the center of the chart for the first base of each three... |
What are sores in the lining of the stomach or duodenum that are usually caused by bacterial infections or acidity? | [
"lesions",
"clots",
"ulcers",
"hernia"
] | C | Ulcers are sores in the lining of the stomach or duodenum that are usually caused by bacterial infections. They may also be caused by the acidic environment of the stomach. Stomach acids may damage the lining of the stomach. Symptoms typically include abdominal pain and bleeding. You can see how stomach ulcers develop ... |
In some species, what has led to the evolution of alternative male mating behavior and morphology? | [
"distributive selection",
"similar selection",
"sexual selection",
"sexual process"
] | C |
Several hypotheses have been proposed to explain the phenomenon of assortative mating. Assortative mating has evolved from a combination of different factors, which vary across different species.Assortative mating with respect to body size can arise as a consequence of intrasexual competition. In some species, size is... |
What structure is made from dna and protein molecules coiled together? | [
"bacterium",
"enzymes",
"chromosome",
"atoms"
] | C | As a cell prepares to divide, its DNA first forms one or more structures called chromosomes. A chromosome consists of DNA and protein molecules coiled into a definite shape. Chromosomes are circular in prokaryotes and rodlike in eukaryotes. You can see an example of a human chromosome in Figure below . The rest of the ... |
What renewable energy source converts energy from the sunlight into electricity? | [
"geophysical energy",
"solar energy",
"geothermal energy",
"hydrostatic energy"
] | B | Less energy is needed to get renewable energy sources. Solar energy is a good example. Sunlight is everywhere, so no one needs to go out and find it. We don’t have to drill for it or pump it to the surface. We just need to install solar panels like the ones in Figure below and let sunlight strike them. The energy from ... |
The radial artery and which artery parallel their namesake bones, giving off smaller branches until they reach the wrist, or carpal region? | [
"triceps",
"ulnar",
"humerus",
"biceps"
] | B | Arteries Serving the Upper Limbs As the subclavian artery exits the thorax into the axillary region, it is renamed the axillary artery. Although it does branch and supply blood to the region near the head of the humerus (via the humeral circumflex arteries), the majority of the vessel continues into the upper arm, or b... |
The bones of the skull are connected by what type of joints? | [
"semi-mobile",
"pivoting",
"immovable",
"adjustable"
] | C | Immovable joints allow no movement because the bones at these joints are held securely together by dense collagen. The bones of the skull are connected by immovable joints.
The elements of each pair are triangular in shape, with the broad end articulating with the neural arch of the atlas, and the acute end with the ex... |
What is the lowest layer of the atmosphere? | [
"troposphere",
"ionosphere",
"chromosphere",
"lithosphere"
] | A | The troposphere is the lowest layer of the atmosphere. All of the air you breathe is in the troposphere. All of Earth's weather—wind, rain, snow, heat—is in the troposphere. The troposphere is the lowest and most important layer of the atmosphere!.
The middle layer of the Uranian atmosphere is the stratosphere, where t... |
What is the name of the type of plant tissue consisting of undifferentiated cells that can continue to divide and differentiate? | [
"cuticle",
"guard cell",
"meristem",
"bundle sheth cell"
] | C | The key to continued growth and repair of plant cells is meristem . Meristem is a type of plant tissue consisting of undifferentiated cells that can continue to divide and differentiate. Meristem at the tips of roots and stems allows them to grow in length. This is called primary growth. Meristem within and around vasc... |
Phosphate-containing ocean sediments form primarily from the bodies of ocean organisms and from their what? | [
"ancestors",
"skeletons",
"blood",
"excretions"
] | D | The Phosphorus Cycle Phosphorus is an essential nutrient for living processes; it is a major component of nucleic acids and phospholipids, and, as calcium phosphate, makes up the supportive components of our bones. Phosphorus is often the limiting nutrient (necessary for growth) in aquatic, particularly freshwater, eco... |
What does erosion do to pieces of broken rock? | [
"lead them",
"Smooth them",
"Cancel Them",
"moves them"
] | D | Erosion moves the pieces of broken rock.
After erosion exposed the fractures, they were filled with minerals possibly by acid-sulfate fluids. More erosion removed softer materials and left the more resistant ridges behind. If the impact-caused dike is made of purely melted rock from the heat of the impact, it is called... |
The passing of traits from parents to offspring is done through what? | [
"sperm",
"egg",
"blood",
"dna"
] | D | Genetics is the study of inheritance. Inheritance is the passing of traits from parents to offspring. How are these traits "passed"? Through DNA, which is the genetic material of all organisms. This concept will focus on genetics, inheritance, and DNA.
Another condition that permits the disassociation of genes and envi... |
In a glass of sweet tea the sugar is known as the solute and the water is known as what? | [
"pigment",
"solid",
"solvent",
"calcium"
] | C | If you’re like Tanya in this picture, you prefer your iced tea sweetened with sugar. Sweetened iced tea is a solution in which solid sugar (the solute) is dissolved in cold liquid tea, which is mostly water (the solvent). When you add sugar to tea, particles of water pull apart particles of sugar. The particles of suga... |
A few earthquakes take place away from plate boundaries, these are called what? | [
"outer earthquakes",
"deformation earthquakes",
"intraplate earthquakes",
"distant earthquakes"
] | C | The remaining 5% are scattered around other plate boundaries. A few earthquakes take place away from plate boundaries. These are intraplate earthquakes.
By definition, intraplate earthquakes do not occur near plate boundaries, but along faults in the normally stable interior of plates. These earthquakes often occur at ... |
Red litmus paper turns what color when placed in a basic solution? | [
"white",
"blue",
"orange",
"pink"
] | B | Red litmus paper turns blue when placed in a basic solution.
The main use of litmus is to test whether a solution is acidic or basic, as blue litmus paper turns red under acidic conditions, and red litmus paper turns blue under basic or alkaline conditions, with the color change occurring over the pH range 4.5–8.3 at 2... |
The difference between the theoretical half-reaction reduction potential and the actual voltage required is called what? | [
"overpotential",
"resistance",
"excess",
"overcharge"
] | A | can occur in electrolytic cells by introducing a power supply, which supplies the energy to force the electrons to flow in the nonspontaneous direction. Electrolysis is done in solutions, which contain enough ions so current can flow. If the solution contains only one material, like the electrolysis of molten sodium ch... |
While the egg is developing, other changes are taking place in the uterus. it develops a thick lining that is full of what? | [
"large arteries",
"white blood cells",
"amniotic fluid",
"tiny blood vessels"
] | D | While the egg is developing, other changes are taking place in the uterus. It develops a thick lining that is full of tiny blood vessels. The lining prepares the uterus to receive a fertilized egg if fertilization actually takes place.
It will have divided on its journey to form a blastocyst that will implant itself in... |
The neural plate undergoes a series of cell movements where it rolls up and forms a tube called what? | [
"neural tube",
"cell tube",
"occular tube",
"peripheral tube"
] | A | called growth factors signal some cells at the edge of the ectoderm to become epidermis cells. The remaining cells in the center form the neural plate. If the signaling by growth factors were disrupted, then the entire ectoderm would differentiate into neural tissue. The neural plate undergoes a series of cell movement... |
Due to the __________ nature of the lipids that make up cell membranes, polar molecules (such as water) and ions cannot easily diffuse across the cell membrane. | [
"hydrophobic",
"hydrophylic",
"saturated",
"catalytic"
] | A | Small nonpolar molecules can easily diffuse across the cell membrane. However, due to the hydrophobic nature of the lipids that make up cell membranes, polar molecules (such as water) and ions cannot do so. Instead, they diffuse across the membrane through transport proteins. A transport protein completely spans the me... |
In what way do all vertebrates reproduce? | [
"sexually",
"mitosis",
"asexually",
"biologically"
] | A | Vertebrates reproduce sexually, and almost all have separate male and female sexes. Aquatic species generally have external fertilization, whereas terrestrial species usually have internal fertilization. Vertebrates have one of three reproductive strategies, known as ovipary, ovovivipary, or vivipary.
Bimodal reproduct... |
First, high temperature denatures proteins and does what to cells? | [
"finds them",
"kills them",
"develops them",
"exposes them"
] | B |
As expected, such cells were also highly vulnerable to stress, and ceased to be viable at elevated temperature ranges.Although stress response pathways are mediated in different ways depending on the stressor involved, cell type, etc., a general characteristic of many pathways – especially ones where heat is the princ... |
What term is used to describe a collection of molecules surrounded by a phospholipid bilayer that is capable of reproducing itself? | [
"atom",
"proteins",
"cell",
"organism"
] | C | A cell membrane is essentially a mixture of phospholipids that form a phospholipid bilayer. One definition of a cell is a collection of molecules surrounded by a phospholipid bilayer that is capable of reproducing itself. The simplest cells are bacteria, which consist of only a single compartment surrounded by a single... |
By allowing blood levels of a hormone to be regulated within a narrow range, feedback loops contribute to maintaining what state? | [
"homeostasis",
"hypothesis",
"hibernation",
"consciousness"
] | A | Role of Feedback Loops The contribution of feedback loops to homeostasis will only be briefly reviewed here. Positive feedback loops are characterized by the release of additional hormone in response to an original hormone release. The release of oxytocin during childbirth is a positive feedback loop. The initial relea... |
Collagen fibers, elastic fibers, and reticular fibers comprise what type of tissue? | [
"nucleus tissue",
"connective tissue",
"intestine tissue",
"skin tissue"
] | B | Connective Tissue Fibers and Ground Substance Three main types of fibers are secreted by fibroblasts: collagen fibers, elastic fibers, and reticular fibers. Collagen fiber is made from fibrous protein subunits linked together to form a long and straight fiber. Collagen fibers, while flexible, have great tensile strengt... |
What the name of the disease where some of the alveoli of the lungs fill with fluid so they can no longer exchange gas? | [
"leukemia",
"pneumonia",
"lung cancer",
"emphysema"
] | B | Pneumonia is a disease in which some of the alveoli of the lungs fill with fluid so they can no longer exchange gas. Symptoms of pneumonia typically include coughing, chest pain, difficulty breathing, and fatigue. Pneumonia may be caused by an infection or an injury to the lungs.
The alveoli are the dead end terminals ... |
What occurs when groups from the same species stop mating because of something other than physical or geographic separation? | [
"sympatric speciation",
"extinction",
"complementary speciation",
"invasive speciation"
] | A | Sympatric speciation occurs when groups from the same species stop mating because of something other than physical or geographic separation. The behavior of two groups that live in the same region is an example of such separation. The separation may be caused by different mating seasons, for example. Sympatric speciati... |
What environment do animals with gills live in? | [
"air",
"underground",
"water",
"cold"
] | C |
The gills push the oxygen-poor water out through openings in the sides of the pharynx. Fish from multiple groups can live out of the water for extended time periods. Amphibious fish such as the mudskipper can live and move about on land for up to several days, or live in stagnant or otherwise oxygen depleted water.
Ce... |
What is the boiling and freezing point of water in celcius? | [
"100 degrees c and 32 degrees c",
"100 degrees c and 0 degrees c",
"212 degrees c and 0 degrees c",
"212 degrees c and 32 degrees c"
] | B | Melting and boiling points are somewhat unique identifiers, especially of compounds. In addition to giving some idea as to the identity of the compound, important information can be obtained about the purity of the material.
In the United States, the Fahrenheit scale is the most widely used. On this scale the freezing ... |
What are living things that obtain glucose by eating self feeders called? | [
"producers",
"heterotrophs",
"chimeras",
"viruses"
] | B | Types of organisms that make glucose by photosynthesis are pictured in Figure below . They include plants, plant-like protists such as algae, and some kinds of bacteria. Living things that make glucose are called autotrophs ("self feeders"). All other living things obtain glucose by eating autotrophs (or organisms that... |
Virtually every task performed by living organisms requires this? | [
"solids",
"energy",
"mineral",
"metals"
] | B | Introduction Virtually every task performed by living organisms requires energy. Energy is needed to perform heavy labor and exercise, but humans also use energy while thinking, and even during sleep. In fact, the living cells of every organism constantly use energy. Nutrients and other molecules are imported into the ... |
The binding of what helps eliminate antigens by phagocytosis and complement-mediated lysis | [
"proteins",
"amino acids",
"antibodies",
"fats"
] | C |
The immune system recognizes foreign pathogens and eliminates them. This occurs in several phases. In the early inflammation phase, the pathogens are recognized by antibodies that are already present (innate or acquired through prior infection; see also cross-reactivity). Immune-system components (e.g. complement) are... |
What muscles are used to pump water over the gills? | [
"pharynx and tonsils",
"jaws and pharynx",
"lungs and pharynx",
"muscles and pharynx"
] | B |
Most fish exchange gases using gills on either side of the pharynx (throat), forming the splanchnocranium, the portion of the skeleton where the cartilage of the cranium converges into the cartilage of the pharynx and its associated parts. Gills are tissues which consist of threadlike structures called filaments. Thes... |
Compounds like sodium chloride form structures called what? | [
"ions",
"microorganisms",
"crystals",
"hydrocarbons"
] | C | Compounds like sodium chloride form structures called crystals. A crystal is a rigid framework of many ions locked together in a repeating pattern. Ions are electrically charged forms of atoms. You can see a crystal of sodium chloride in the Figure below . It is made up of many sodium and chloride ions.
This page provi... |
What are made of long chains consisting almost solely of carbon and hydrogen? | [
"lipids",
"nucleic acids",
"enzymes",
"proteins"
] | A | Lipids are made of long chains consisting almost solely of carbon and hydrogen. These long chains are called fatty acids. Fatty acids may be saturated or unsaturated. Figure below shows an example of each type of fatty acid.
Here is a sample molecule with the parent carbons numbered: For simplicity, here is an image of... |
When a series of measurements is precise but not what, the error is usually systematic? | [
"velocity",
"length",
"accurate",
"color"
] | C | 0 .033 g 1 .117 g × 100 = 3 .0% When a series of measurements is precise but not accurate, the error is usually systematic. Systematic errors can be caused by faulty instrumentation or faulty technique. The difference between accuracy and precision is demonstrated in Skill Builder ES7.
When either randomness or uncerta... |
Inserting copies of normal genes into a patient with defective genes is known as? | [
"pattern therapy",
"cloning",
"gene therapy",
"chromosome treatment"
] | C | treat genetic disorders. For example, copies of a normal gene might be inserted into a patient with a defective gene. This is called gene therapy . Ideally, it can cure a genetic disorder.
A person born with one normal copy and one defective copy is called a carrier. They will produce less α-L-iduronidase than an indiv... |
What type of reproduction usually occur during times of environmental stress? | [
"internal reproduction",
"hysterical reproduction",
"sexual reproduction",
"asexual reproduction"
] | C |
At some point, the growing egg or offspring must be expelled. There are several possible modes of reproduction. These are traditionally classified as follows: Oviparity, as in most invertebrates and reptiles, monotremes, dinosaurs and all birds which lay eggs that continue to develop after being laid, and hatch later.... |
All forms of energy can be interconverted. three things can change the energy of an object: the transfer of heat, work performed on or by an object, or some combination of what? | [
"temperature and work",
"heat and work",
"humidity and work",
"cold and energy"
] | B | All forms of energy can be interconverted. Three things can change the energy of an object: the transfer of heat, work performed on or by an object, or some combination of heat and work.
In thermodynamics, heat is energy transferred to or from a thermodynamic system by mechanisms other than thermodynamic work or transf... |
What science includes many fields of science related to our home planet? | [
"meteorology",
"zoology",
"biology",
"earth science"
] | D | Earth science includes many fields of science related to our home planet.
It is also the study of Earth and its neighbors in space. Some Earth scientists use their knowledge of the planet to locate and develop energy and mineral resources. Others study the impact of human activity on Earth's environment, and design met... |
What are alloys that are mostly composed of mercury known as? | [
"amalgams",
"halogens",
"fillings",
"compounds"
] | A | Alloys that are mostly composed of mercury are known as amalgams . Amalgams often have special properties that stem from the fact that mercury exists as a liquid at room temperature. As a result, metal amalgams are used for a variety of purposes, including dentistry and the extraction of other pure metals such as gold.... |
What are made from highly reflective metal that is applied to a curved or flat piece of glass? | [
"lenses",
"kaleidoscopes",
"mirrors",
"prisms"
] | C | Mirrors are made from highly reflective metal that is applied to a curved or flat piece of glass. Converging mirrors can be used to focus light – headlights, telescopes, satellite TV receivers, and solar cookers all rely on this principle.
Today, float glass is the most widely produced form of glass, with a multitude o... |
What do ranchers fear will happen if wolves return? | [
"livestock predation",
"loss of environment",
"human predation",
"vegetation predation"
] | A |
As a result, their numbers have stabilized and are increasing, though they are still hunted legally. According to Alexander Tikhonov, head of the Department of Hunting Resources "the more wolves you have, the more problems there are".
Wolves living in open areas, for example the North American Great Plains, historical... |
How many types of surface waves are there? | [
"two",
"over a hundred",
"three",
"six"
] | A | Surface waves travel along the ground outward from an earthquake’s epicenter. Surface waves are the slowest of all seismic waves. They travel at 2.5 km (1.5 miles) per second. There are two types of surface waves. Love waves move side-to-side, much like a snake. Rayleigh waves produce a rolling motion as they move up a... |
What is the rigid layer that is found outside the cell membrane and surrounds the cell? | [
"cell wall",
"cell barrier",
"cell shield",
"cell root"
] | A | A cell wall is a rigid layer that is found outside the cell membrane and surrounds the cell. The cell wall contains not only cellulose and protein, but other polysaccharides as well. In fact, two other classes of polysaccharides, hemicelluloses and pectic polysaccharides, can comprise 30% of the dry mass of the cell wa... |
Surface tension of alveolar fluid, which is mostly water, creates an inward pull of the tissue of what organ? | [
"spleen",
"brain",
"heart",
"lung"
] | D | Intrapleural pressure is the pressure of the air within the pleural cavity, between the visceral and parietal pleurae. Similar to intra-alveolar pressure, intrapleural pressure also changes during the different phases of breathing. However, due to certain characteristics of the lungs, the intrapleural pressure is alway... |
What type of tumor mostly does not cause serious problems and can be completely removed by surgery? | [
"benign",
"toxic",
"persistent",
"malignant"
] | A |
Some, in whom surgery is unable to remove the entire tumor, have an increased risk of death.About two to three people per million are affected each year. It most commonly affects people who are 20 to 50 years of age.
Malignancy (from Latin male 'badly', and -gnus 'born') is the tendency of a medical condition to becom... |
What supports and protects the soft organs of the body? | [
"Skin",
"skull",
"Muscle",
"skeleton"
] | D | Protection. The skeleton supports and protects the soft organs of the body. For example, the skull surrounds the brain to protect it from injury. The bones of the rib cage help protect the heart and lungs.
This type of tissue can be observed in sweat glands, mammary glands, circumanal glands, and salivary glands. They ... |
What celestial body is the earth’s main source of energy? | [
"sun",
"rivers",
"ocean",
"moon"
] | A | The Sun is Earth’s main source of energy. The Sun gives us both light and heat. The Sun changes hydrogen into helium through nuclear fusion. This releases huge amounts of energy. The energy travels to Earth mostly as visible light. The energy is carried through the empty space by radiation . We can use sunlight as an e... |
What do you call the horizontal stems of a strawberry plant that run over the ground surface? | [
"root volunteers",
"climbing vines",
"sprouts",
"stolons"
] | D | Strawberry plants have horizontal stems called stolons that run over the ground surface. If they take root, they form new plants.
Different forms of underground stems include: Bulb - Short, upright organ leaves modified into thick flesh scales. Tulips, daffodils and Lilies. Corm - Short, upright, hard or fleshy stems c... |
Glaciers are incredibly powerful agents of what? | [
"climate change",
"insulation",
"erosion",
"extinction"
] | C | Glaciers are incredibly powerful agents of erosion.
Ice sheets and glaciers are flowing ice masses that rest on solid land. They are controlled by snow accumulation, surface and basal melt, calving into surrounding oceans or lakes and internal dynamics. The latter results from gravity-driven creep flow ("glacial flow")... |
What type of pressure is the pressure exerted by gas particles in earth’s atmosphere as those particles collide with objects? | [
"vertical pressure",
"atmospheric pressure",
"adjacent pressure",
"adjacent pressure"
] | B | Atmospheric pressure is the pressure exerted by gas particles in Earth’s atmosphere as those particles collide with objects. A barometer is an instrument used to measure atmospheric pressure. A traditional mercury barometer consists of an evacuated tube immersed in a container of mercury. Air molecules push down on the... |
What helps the plasma membrane keep its shape? | [
"molecules of carbohydrates",
"molecules of cholesterol",
"molecules of oxygen",
"cytoplasm"
] | B | The plasma membrane also contains other molecules, primarily other lipids and proteins. The green molecules in Figure above , for example, are the lipid cholesterol. Molecules of cholesterol help the plasma membrane keep its shape. Many of the proteins in the plasma membrane assist other substances in crossing the memb... |
What type of reproduction only involves one parent? | [
"asexual",
"primitive",
"organic",
"binary"
] | A | Asexual reproduction involves just one parent. It produces offspring that are genetically identical to the parent. Methods of asexual reproduction include binary fission, fragmentation, and budding.
At some point, the growing egg or offspring must be expelled. There are several possible modes of reproduction. These are... |
What is defined as a repeating series of events that include growth, dna synthesis, and cell division? | [
"photosynthesis",
"meiosis",
"puberty",
"cell cycle"
] | D | Cell division is just one of several stages that a cell goes through during its lifetime. The cell cycle is a repeating series of events that include growth, DNA synthesis, and cell division. The cell cycle in prokaryotes is quite simple: the cell grows, its DNA replicates, and the cell divides. In eukaryotes, the cell... |
How metalloids behave in chemical interactions with other elements depends mainly on the number of what, in the outer energy level of their atoms? | [
"protons",
"electrons",
"positrons",
"neutrons"
] | B | How metalloids behave in chemical interactions with other elements depends mainly on the number of electrons in the outer energy level of their atoms. Metalloids have from three to six electrons in their outer energy level. Boron, pictured in the Figure below , is the only metalloid with just three electrons in its out... |
What distinguishing characteristic of annelid anatomy shows specialization and adaptation? | [
"segmentation",
"asymmetry",
"beautiful",
"compression"
] | A | Annelids are divided into many repeating segments. The earthworm in Figure below is an annelid. You can clearly see its many segments. Segmentation of annelids is highly adaptive. Each segment has its own nerve and muscle tissues. This allows the animal to move very efficiently. Some segments can also be specialized to... |
The spermatids are transported from the testes to where? | [
"abdominis",
"epididymis",
"Duodenum",
"vas"
] | B | The spermatids are transported from the testes to the epididymis. Involuntary muscular contraction moves the spermatids along.
The spermatids begin to grow a living thread, develop a thickened mid-piece where the mitochondria become localised, and form an acrosome. Spermatid DNA also undergoes packaging, becoming highl... |
How does water from roots reach the leaves? | [
"water - combining cells",
"water-conducting cells",
"water - raising cells",
"water-phobic cells"
] | B |
In plants, the transpiration stream is the uninterrupted stream of water and solutes which is taken up by the roots and transported via the xylem to the leaves where it evaporates into the air/apoplast-interface of the substomatal cavity. It is driven by capillary action and in some plants by root pressure. The main d... |
As a polycrystalline material solidifies, grains with irregular shapes form. the interfaces between grains constitute grain what? | [
"waves",
"boundaries",
"patterns",
"obstacles"
] | B | Grain boundaries. As a polycrystalline material solidifies, grains with irregular shapes form. The interfaces between grains constitute grain boundaries. (Squares represent unit cells within grains.
Recently, grain growth behaviors including normal, abnormal and stagnant behaviors can be interpreted by a general theory... |
Motors are the most common application of magnetic force on current-carrying wires. motors have loops of wire in this? | [
"electrical circuit",
"magnetic field",
"capacitors",
"spark plugs"
] | B | 22.8 Torque on a Current Loop: Motors and Meters Motors are the most common application of magnetic force on current-carrying wires. Motors have loops of wire in a magnetic field. When current is passed through the loops, the magnetic field exerts torque on the loops, which rotates a shaft. Electrical energy is convert... |
What makes and stores pigments that give petals and fruit their orange and yellow colors? | [
"sporozoans",
"protozoa",
"chromoplasts",
"pores"
] | C | Chromoplasts make and store pigments that give petals and fruit their orange and yellow colors.
The flowers are produced from late summer until late autumn, individually small, in 3-to-5 cm-diameter (1.2-to-2.0 in) umbels, greenish-yellow, and very rich in nectar, an important late autumn food source for bees and other... |
What term is used to describe when a liquid is the temperature at which its equilibrium vapor pressure is equal to the pressure exerted on the liquid by its gaseous surroundings? | [
"freezing point",
"burning point",
"boiling point",
"evaporating point"
] | C | Boiling Points When the vapor pressure increases enough to equal the external atmospheric pressure, the liquid reaches its boiling point. The boiling point of a liquid is the temperature at which its equilibrium vapor pressure is equal to the pressure exerted on the liquid by its gaseous surroundings. For liquids in op... |
When electrons return to a lower energy level, they emit the excess energy in the form of what? | [
"weight",
"electricity",
"light",
"energy"
] | C | When electrons return to a lower energy level, they emit energy in the form of light.
When an electron is excited from a lower to a higher energy level, it is unlikely for it to stay that way forever. An electron in an excited state may decay to a lower energy state which is not occupied, according to a particular time... |
What is another term for nearsightedness? | [
"hypoxia",
"myopia",
"glaucoma",
"anemia"
] | B | Nearsightedness, or myopia, is the condition in which nearby objects are seen clearly, but distant objects are blurry. It occurs when the eyeball is longer than normal. This causes images to be focused in front of the retina. Myopia can be corrected with concave lenses. The lenses focus images farther back in the eye, ... |
What are the areas located at fixed distances from the nucleus of the atom? | [
"molar levels",
"atomic regions",
"energy levels",
"orbit points"
] | C | Basic to Bohr’s model is the idea of energy levels. Energy levels are areas located at fixed distances from the nucleus of the atom. They are the only places where electrons can be found. Energy levels are a little like rungs on a ladder. You can stand on one rung or another but not between the rungs. The same goes for... |
In which state of matter do particles take the shape of their container, but cannot expand to fill it? | [
"liquid",
"gas",
"mixture",
"chemical"
] | A | A liquid is a state of matter in which particles can slip past one another and take the shape of their container. However, the particles cannot pull apart and spread out to take the volume of their container.
As heat is added to this substance it melts into a liquid at its melting point, boils into a gas at its boiling... |
Runoff is likely to cause more what if the land is bare? | [
"abrasion",
"sediment",
"weathering",
"erosion"
] | D | Runoff is likely to cause more erosion if the land is bare. Plants help hold the soil in place. The runoff water in Figure below is brown because it eroded soil from a bare, sloping field. Can you find evidence of erosion by runoff where you live? What should you look for?.
Due to the larger area consumed by sprawling ... |
Cations have what type of charge? | [
"positive",
"negative",
"neutral",
"constant"
] | A | Cations have positive charges, and anions have negative charges.
In the process of cation attachment, cations (typically H+ or Na+) attach themselves to analyte molecules; the desorption of the cation attachment (e.g., MNa+) can then be realized through the emitter heating and high field. The ionization of more polar o... |
What organ is subdivided into ascending, descending, transverse and sigmoid parts? | [
"heart",
"uterus",
"colon",
"lungs"
] | C | Colon The cecum blends seamlessly with the colon. Upon entering the colon, the food residue first travels up the ascending colon on the right side of the abdomen. At the inferior surface of the liver, the colon bends to form the right colic flexure (hepatic flexure) and becomes the transverse colon. The region defined ... |
Ammonia, urea, and uric acid are examples of what kind of waste? | [
"nitrogenous",
"carbonous",
"sulphurous",
"oxygenous"
] | A |
The ammonia stems from the urea in urine. Urea is rapidly hydrolyzed and therefore not usually found in raw sewage.
Amino acid catabolism results in waste ammonia. All animals need a way to excrete this product. Most aquatic organisms, or ammonotelic organisms, excrete ammonia without converting it. Organisms that can... |
What are variants of genes called? | [
"antigens",
"mutations",
"alleles",
"allergens"
] | C | Recall that our DNA is wound into chromosomes . Each of our chromosomes contains a long chain of DNA that encodes hundreds, if not thousands, of genes. Each of these genes can have slightly different versions from individual to individual. These variants of genes are called alleles . Each parent only donates one allele... |
Mushrooms are an example of what type of organism, which includes beneficial and toxic specimens? | [
"spores",
"bacteria",
"fungi",
"seeds"
] | C | Some of the best known types of fungi are mushrooms, which can be edible or poisonous ( Figure below ). Many species are grown commercially, but others are harvested from the wild. When you order a pizza with mushrooms or add them to your salad, you are most likely eating Agaricus bisporus , known as white or button mu... |
Comparing what sequences provides clues to evolution and development? | [
"DNA",
"genes",
"genome",
"organisms"
] | C | 21.6 Comparing genome sequences provides clues to evolution and development.
This proposal, that population bottlenecks are possibly the primary generators of the variation that fuels evolution, predicts that evolution will usually occur in intermittent, relatively large scale morphological steps, interspersed with pro... |
What is a measure of the average amount of energy of motion, or kinetic energy, a system contains called? | [
"temperature",
"size",
"variation",
"precipitation"
] | A | There are other units in chemistry that are important, and we will cover others in the course of the entire book. One of the fundamental quantities in science is temperature. Temperature is a measure of the average amount of energy of motion, or kinetic energy, a system contains. Temperatures are expressed using scales... |
What is the minimum mass capable of supporting sustained fission called? | [
"concentrated mass",
"critical mass",
"baseline mass",
"particular mass"
] | B | U92235 + n01® B56141a + K3692r + 3n01 This hypothesis was confirmed by detecting the krypton-92 fission product. As discussed in Section 20.2 "Nuclear Reactions", the nucleus usually divides asymmetrically rather than into two equal parts, and the fission of a given nuclide does not give the same products every time. I... |
Many hydrocarbons are cyclic and adopt specific three-dimensional structures that influence their physical and what properties? | [
"liquid",
"electrical",
"radiation",
"chemical"
] | D | Many hydrocarbons are cyclic and adopt specific three-dimensional structures that influence their physical and chemical properties.
It is a very common and useful process. Hydrocarbons with the same molecular formula but different structural formulae are called structural isomers. : 625 As given in the example of 3-met... |
The secondary wall contains _________ , a secondary cell component in plant cells that have completed cell growth/expansion. | [
"cytoplasm",
"lignin",
"glucogen",
"cellulose"
] | B | Microtubules guide the formation of the plant cell wall. Cellulose is laid down by enzymes to form the primary cell wall. Some plants also have a secondary cell wall. The secondary wall contains a lignin, a secondary cell component in plant cells that have completed cell growth/expansion.
Some eukaryotic cells (plant c... |
What does the cell cycle do? | [
"only divide cells",
"divide and reproduce cells",
"create new cells",
"only reproduce cells"
] | B | The cell cycle is a repeating series of events, characterizing the life of a eukaryotic cell.
The cell cycle is driven by proteins called cyclin dependent kinases that associate with cyclin regulatory proteins at different checkpoints of the cell cycle. Different phases of the cell cycle experience activation and/or de... |
Inside the nasal area of the skull, the nasal cavity is divided into halves by the what? | [
"cerebral cortex",
"nasal septum",
"cytoplasm",
"cell wall"
] | B | Inside the nasal area of the skull, the nasal cavity is divided into halves by the nasal septum. The upper portion of the nasal septum is formed by the perpendicular plate of the ethmoid bone and the lower portion is the vomer bone. Each side of the nasal cavity is triangular in shape, with a broad inferior space that ... |
Bacteria can be chemotrophs, which obtain what by breaking down chemical compounds in their environment? | [
"waste",
"chemials",
"food",
"energy"
] | D | Bacteria can also be chemotrophs. Chemosynthetic bacteria, or chemotrophs , obtain energy by breaking down chemical compounds in their environment. An example of one of these chemicals broken down by bacteria is nitrogen-containing ammonia. These bacteria are important because they help cycle nitrogen through the envir... |
Habitat loss, introduced species, overharvesting, and global change are major threats to what? | [
"the earth's gravity",
"the sun",
"transportation",
"biodiversity"
] | D |
Habitat destruction is currently considered the primary cause of species extinction worldwide. Environmental factors can contribute to habitat destruction more indirectly. Geological processes, climate change, introduction of invasive species, ecosystem nutrient depletion, water and noise pollution are some examples.
... |
What "plumbing" structures inside the veins maintain a unidirectional flow of blood despite the low blood pressure? | [
"funnels",
"tubes",
"valves",
"pumps"
] | C |
When all of the sphincters are closed blood can flow from a metarteriole into a thoroughfare channel and into a collecting venule bypassing the capillary bed. OtherA communicating vein directly connects two parts of the same system such as the Giacomini vein that connects the (superficial) small saphenous vein with th... |
What do we call the cartilaginous structure that surrounds the notochrod? | [
"osteocytes",
"arcualia",
"clavicle",
"membrane"
] | B | distinctly differ from the adult form, spending 3 to 15 years as suspension feeders. Once they attain sexual maturity, the adults reproduce and die within days. Lampreys possess a notochord as adults; however, this notochord is surrounded by a cartilaginous structure called an arcualia, which may resemble an evolutiona... |
What is the process of the transfer of pollen from an anther to a stigma in angiosperms called? | [
"grabation",
"evolution",
"wind",
"pollination"
] | D |
In gymnosperms (e.g., conifers), the pollen is drawn into the ovule on a drop of fluid that exudes out of the micropyle, the so-called pollination drop mechanism. Subsequently, the micropyle closes.
The transfer of pollen (the male gametophytes) to the female stigmas occurs is called pollination. After pollination occ... |
Despite its small size, an erythrocyte contains about 250 million molecules of what? | [
"calcium",
"plasma",
"hemoglobin",
"potassium"
] | C |
a.^ B: B cell. E: erythrocyte. Endo: endothelial cell.
Some of the largest molecules are macromolecules or supermolecules. The smallest molecule is the diatomic hydrogen (H2), with a bond length of 0.74 Å.Effective molecular radius is the size a molecule displays in solution. The table of permselectivity for different... |
How many variables are used to describe the condition of a gas? | [
"five",
"four",
"one",
"three"
] | B | Recall from the kinetic-molecular theory that gas particles move randomly and in straight lines until they elastically collide with either other gas particles or with one of the walls of the container. It is these collisions with the walls of the container that defines the pressure of the gas. Four variables are used t... |
What is a suggested explanation for a phenomenon or a suggested explanation for a relationship between many phenomena called? | [
"query",
"system",
"hypothesis",
"process"
] | C | In order to explain the observed phenomenon, scientists develop a number of possible explanations, or hypotheses. A hypothesis is a suggested explanation for a phenomenon or a suggested explanation for a relationship between many phenomena. Hypotheses are always based on evidence that can be tested by observation or ex... |
Land plants are classified into two major groups according to the absence or presence of what tissue? | [
"disease",
"vascular",
"root",
"bacterial"
] | B | The Major Divisions of Land Plants Land plants are classified into two major groups according to the absence or presence of vascular tissue, as detailed in Figure 14.8. Plants that lack vascular tissue formed of specialized cells for the transport of water and nutrients are referred to as nonvascular plants. The bryoph... |
What type of treatment is necessary for anaphylaxis? | [
"emergency",
"outpatient",
"allergy shot",
"intensive care"
] | A | In some people, a food allergy can trigger a severe allergic reaction called anaphylaxis. Emergency treatment is critical for anaphylaxis. Untreated, anaphylaxis can cause a coma or death. Anaphylaxis is vary rare. The vast majority of people will never have an anaphylactic reaction. The life-threatening symptoms of an... |
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