questions stringlengths 37 1.22k | reasoning stringlengths 0 3.56k ⌀ | answers stringlengths 4 138 |
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What methods allow scientists to add to scientific knowledge and gain a better understanding of the world?
Here are the choices:
A. through investigations
B. close investigations
C. slow investigations
D. early investigations | Investigations are at the heart of science. They are how scientists add to scientific knowledge and gain a better understanding of the world. Scientific investigations produce evidence that helps answer questions. Even if the evidence cannot provide answers, it may still be useful. It may lead to new questions for investigation. As more knowledge is discovered, science advances. | A: through investigations. |
What is the largest level of organization?
Here are the choices:
A. organism
B. genome
C. protein
D. organelle | Levels of organization, from the atom (smallest) to the organism (largest). Notice that organelles are inside a cell, and organs are inside an organism. | A: organism. |
Living species of chordates are classified into three major subphyla: vertebrata, urochordata, and what?
Here are the choices:
A. xerophyte
B. cephalochordata
C. spirogyra
D. invertebrates | Living species of chordates are classified into three major subphyla: Vertebrata, Urochordata, and Cephalochordata. Vertebrates are all chordates that have a backbone. The other two subphyla are invertebrate chordates that lack a backbone. | B: cephalochordata. |
What force explains why a tennis ball bounces differently on different surfaces, and shoes slip on some surfaces but stick on others?
Here are the choices:
A. kinetics
B. temperature
C. vibration
D. friction | Tennis is played on a variety of court surfaces: grass, clay, hardcourt, and even carpet. Players know that matches on different surfaces are distinctly different games. The ball bounces differently, and shoes slip on some surfaces but stick on others. These differences are a result of friction. | D: friction. |
The term ion applies to entire molecules that are?
Here are the choices:
A. positively charged protons
B. electrically charged
C. neutrally charged
D. magnetic | B: electrically charged. | |
Silicon and germanium react with nitrogen at high temperature to form what?
Here are the choices:
A. nitrides
B. carbonates
C. isotopes
D. oxides | The cavities normally contain hydrated cations that are loosely bound to the oxygen atoms of the negatively charged framework by electrostatic interactions. The sizes and arrangements of the channels and cavities differ in different types of zeolites. For example, in zeolite A the aluminosilicate cages are arranged in a cubic fashion, and the channels connecting the cavities intersect at right angles. In contrast, the cavities in faujasite are much larger, and the channels intersect at 120° angles. In these idealized models, the oxygen atoms that connect each pair of silicon atoms have been omitted. Silicon and germanium react with nitrogen at high temperature to form nitrides(M3N4): Equation 22.26. | A: nitrides. |
What bond is the force of attraction that holds together oppositely charged ions?
Here are the choices:
A. iconic
B. ionic
C. harmonic
D. magnetic | An ionic bond is the force of attraction that holds together oppositely charged ions. It forms when atoms of a metal transfer electrons to atoms of a nonmetal. When this happens, the atoms become oppositely charged ions. | B: ionic. |
What is the pairing of an adult male to an adult female to produce young?
Here are the choices:
A. evolution
B. binary fission
C. mating
D. asexual reproduction | Some of the most important animal behaviors involve mating. Mating is the pairing of an adult male and female to produce young. Adults that are most successful at attracting a mate are most likely to have offspring. Traits that help animals attract a mate and have offspring increase their fitness. As the genes that encode these traits are passed to the next generation, the traits will become more common in the population. | C: mating. |
The cell expels waste and other particles through a process called what?
Here are the choices:
A. exocytosis
B. endocytosis
C. metamorphisis
D. biosynthesis | 3.6 Active Transport The combined gradient that affects an ion includes its concentration gradient and its electrical gradient. Living cells need certain substances in concentrations greater than they exist in the extracellular space. Moving substances up their electrochemical gradients requires energy from the cell. Active transport uses energy stored in ATP to fuel the transport. Active transport of small molecular-size material uses integral proteins in the cell membrane to move the material—these proteins are analogous to pumps. Some pumps, which carry out primary active transport, couple directly with ATP to drive their action. In secondary transport, energy from primary transport can be used to move another substance into the cell and up its concentration gradient. Endocytosis methods require the direct use of ATP to fuel the transport of large particles such as macromolecules; parts of cells or whole cells can be engulfed by other cells in a process called phagocytosis. In phagocytosis, a portion of the membrane invaginates and flows around the particle, eventually pinching off and leaving the particle wholly enclosed by an envelope of plasma membrane. Vacuoles are broken down by the cell, with the particles used as food or dispatched in some other way. Pinocytosis is a similar process on a smaller scale. The cell expels waste and other particles through the reverse process, exocytosis. Wastes are moved outside the cell, pushing a membranous vesicle to the plasma membrane, allowing the vesicle to fuse with the membrane and incorporating itself into the membrane structure, releasing its contents to the exterior of the cell. | A: exocytosis. |
What are diodes, transistors, and integrated circuits examples of?
Here are the choices:
A. electronic components
B. computer parts
C. machine parts
D. radio parts | Electronic components are the parts used in electronic devices. They are made of p-type and n-type semiconductors. Examples of electronic components include diodes, transistors, and integrated circuits (microchips). | A: electronic components. |
Shedding of dead cells ensures constant renewal of what outer layer of the skin?
Here are the choices:
A. dermis
B. scale
C. cuticle
D. epidermis | The skin consists of two distinct layers, an outer layer called the epidermis and an inner layer called the dermis. The epidermis is constantly being renewed as dead cells on the surface are shed. This layer contains melanin-producing melanocytes. The dermis contains blood vessels, nerve endings, hair follicles, and sebaceous and sweat glands. | D: epidermis. |
What causes cumulus clouds to grow upward?
Here are the choices:
A. mantle currents
B. convection currents
C. gas currents
D. moisture currents | Cumulus clouds are white and puffy. Convection currents make them grow upward and they may grow very tall. When they produce rain, they are called cumulonimbus. | B: convection currents. |
What term is used to describe a region getting significantly less precipitation than normal for an extended period of time?
Here are the choices:
A. drought
B. dog days
C. flood
D. doldrums | Droughts also depend on what is normal for a region. A region that gets significantly less precipitation than normal for an extended period of time is in drought. The Southern United States is experiencing an ongoing and prolonged drought. | A: drought. |
What is the name for compounds that contain only carbon and hydrogen?
Here are the choices:
A. particles
B. hydrocarbons
C. carbides
D. carbohydrates | The fuel that burns in a combustion reaction contains compounds called hydrocarbons. Hydrocarbons are compounds that contain only carbon (C) and hydrogen (H). The charcoal pictured in the Figure above consists of hydrocarbons. So do fossil fuels such as natural gas. Natural gas is a fuel that is commonly used in home furnaces and gas stoves. The main component of natural gas is the hydrocarbon called methane (CH 4 ). You can see a methane flame in the Figure below . The combustion of methane is represented by the equation:. | B: hydrocarbons. |
What human disease is caused by a defective enzyme that is unable to produce melanin, the pigment responsible for the color of skin and hair?
Here are the choices:
A. hemophilia
B. mutations
C. albinism
D. anemia | untreated, it produces severe brain damage and mental retardation. Albinism is caused by a defective enzyme that is unable to produce melanin, the pigment responsible for the color of skin and hair. Cystic fibrosis, the most common inherited disease in the United States, blocks pancreatic function and causes thick mucus secretions that make breathing difficult. An area of intense research in combating cancer involves the synthesis of drugs that stop uncontrolled cell growth by interfering with DNA replication. | C: albinism. |
Individuals with sickle cell anemia have crescent-shaped what?
Here are the choices:
A. glial cells
B. red blood cells
C. nerve cells
D. white blood cells | Figure 39.21 Individuals with sickle cell anemia have crescent-shaped red blood cells. (credit: modification of work by Ed Uthman; scale-bar data from Matt Russell). | B: red blood cells. |
Nearly all weather occurs in the lower part of what?
Here are the choices:
A. the lithosphere
B. the atmosphere
C. the ionosphere
D. the mesosphere | All weather takes place in the atmosphere. Nearly all of it in the lower atmosphere. Weather refers to the conditions of the atmosphere at a given time and place. Climate is the average of weather over a long time. | B: the atmosphere. |
For skeletal development, the most common template is what?
Here are the choices:
A. cartilage
B. collagen
C. calcium
D. membrane | Cartilage Templates Bone is a replacement tissue; that is, it uses a model tissue on which to lay down its mineral matrix. For skeletal development, the most common template is cartilage. During fetal development, a framework is laid down that determines where bones will form. This framework is a flexible, semi-solid matrix produced by chondroblasts and consists of hyaluronic acid, chondroitin sulfate, collagen fibers, and water. As the matrix surrounds and isolates chondroblasts, they are called chondrocytes. Unlike most connective tissues, cartilage is avascular, meaning that it has no blood vessels supplying nutrients and removing metabolic wastes. All of these functions are carried on by diffusion through the matrix. This is why damaged cartilage does not repair itself as readily as most tissues do. Throughout fetal development and into childhood growth and development, bone forms on the cartilaginous matrix. By the time a fetus is born, most of the cartilage has been replaced with bone. Some additional cartilage will be replaced throughout childhood, and some cartilage remains in the adult skeleton. | A: cartilage. |
The body's second line of defense against pathogens includes which response?
Here are the choices:
A. reaction
B. inflammatory
C. anxiety
D. blood | The body's second line of defense against pathogens includes the inflammatory response. If bacteria enter the skin through a scrape, the area may become red, warm, and painful. These are signs of inflammation. Inflammation is one way the body reacts to infections or injuries. Inflammation is caused by chemicals that are released when skin or other tissues are damaged. The chemicals cause nearby blood vessels to dilate, or expand. This increases blood flow to the damaged area, which makes the area red and slightly warm. The chemicals also attract white blood cells called neutrophils to the wound and cause them to leak out of blood vessels into the damaged tissue. | B: inflammatory. |
Hiv is a retrovirus, which means it reverse transcribes its rna genome into what?
Here are the choices:
A. ribosomes
B. dna
C. atp
D. amino acid chains | Figure 17.5 Viruses can be complex in shape or relatively simple. This figure shows three relatively complex virions: the bacteriophage T4, with its DNA-containing head group and tail fibers that attach to host cells; adenovirus, which uses spikes from its capsid to bind to the host cells; and HIV, which uses glycoproteins embedded in its envelope to do so. Notice that HIV has proteins called matrix proteins, internal to the envelope, which help stabilize virion shape. HIV is a retrovirus, which means it reverse transcribes its RNA genome into DNA, which is then spliced into the host’s DNA. (credit “bacteriophage, adenovirus”: modification of work by NCBI, NIH; credit “HIV retrovirus”: modification of work by NIAID, NIH). | B: dna. |
Plants can tell the time of day and time of year by sensing and using various wavelengths of what
Here are the choices:
A. precipitation
B. moisture
C. lunar cycles
D. sunlight | Plant Responses to Light Plants have a number of sophisticated uses for light that go far beyond their ability to photosynthesize low-molecularweight sugars using only carbon dioxide, light, and water. Photomorphogenesis is the growth and development of plants in response to light. It allows plants to optimize their use of light and space. Photoperiodism is the ability to use light to track time. Plants can tell the time of day and time of year by sensing and using various wavelengths of sunlight. Phototropism is a directional response that allows plants to grow towards, or even away from, light. The sensing of light in the environment is important to plants; it can be crucial for competition and survival. The response of plants to light is mediated by different photoreceptors, which are comprised of a protein covalently bonded to a lightabsorbing pigment called a chromophore. Together, the two are called a chromoprotein. | D: sunlight. |
In eukaryotes, the major mechanism for shuffling genes is what?
Here are the choices:
A. sexual reproduction
B. asexual reproduction
C. suggesting reproduction
D. subject reproduction | Sexual reproduction In eukaryotes, the major mechanism for shuffling genes is sexual reproduction. Because sex (usually) requires that organisms cooperate sex represents an example of social evolution. So what are the benefits of sexual reproduction? 342 Sexual reproduction involves the alternation of diploid (two copies of each chromosome) and haploid (one copy of each chromosome) cell types. In a diploid cell, the two copies of a particular gene can be different, the the organisms is said to be heterozygous for that gene. Different alleles can (but do not necessarily do) encode functionally distinct gene products and can be associated with different phenotypes (discussed in greater detail in the future two-semester version). We can then characterize different alleles with respect to one one another. Assume that allele-1 is associated with phenotype-1 342. | A: sexual reproduction. |
The vas deferens and ejaculatory ducts transport sperm from the epididymes to the urethra in what system?
Here are the choices:
A. cardiovascular system
B. digestive system
C. male reproductive system
D. famous reproductive system | In addition to these organs, the male reproductive system consists of a series of ducts and glands. Ducts include the vas deferens and ejaculatory ducts. They transport sperm from the epididymes to the urethra in the penis. Glands include the seminal vesicles and prostate gland. They secrete substances that become part of semen. | C: male reproductive system. |
What do nearly all animals have in common with regards to digestion?
Here are the choices:
A. external digestion of food
B. problematic digestion of food
C. complete digestion of food
D. internal digestion of food | Virtually all animals have internal digestion of food. Animals consume other organisms and may use special tissues and organs to digest them. (Many other organisms absorb nutrients directly from the environment. ). | D: internal digestion of food. |
What are the secretions released by the endocrine glands called?
Here are the choices:
A. acids
B. hormones
C. fluids
D. enzymes | Endocrine Glands The secretions of endocrine glands are called hormones. Hormones are released into the interstitial fluid, diffused into the bloodstream, and delivered to targets, in other words, cells that have receptors to bind the hormones. The endocrine system is part of a major regulatory system coordinating the regulation and integration of body responses. A few examples of endocrine glands include the anterior pituitary, thymus, adrenal cortex, and gonads. | B: hormones. |
What are chromosomes in the same pair called?
Here are the choices:
A. reversible chromosomes
B. regulated chromosomes
C. homogeneous chromosomes
D. homologous chromosomes | In sexually reproducing species, chromosomes are present in cells in pairs. Chromosomes in the same pair are called homologous chromosomes. They have the same genes at the same loci. These may be the same or different alleles. During meiosis, when gametes are produced, homologous chromosomes separate. They go to different gametes. Thus, the alleles for each gene also go to different gametes. | D: homologous chromosomes. |
What do you call plastids that contain the green pigment chlorophyll?
Here are the choices:
A. Chromoplasts
B. Gerontoplasts
C. chloroplasts
D. Leucoplasts | Chloroplasts are plastids that contain the green pigment chlorophyll. They capture light energy from the sun and use it to make food. A chloroplast is shown in Figure above . | C: chloroplasts. |
What important and unusual physical property (for birds) do ostriches and penguins share?
Here are the choices:
A. flightlessness
B. waterproofness
C. webbed feet
D. bonelessness | There are about 10,000 living species of birds. Almost all of them can fly. Flying birds are classified in 29 orders. Most species belong to the order of perching birds. A few birds are flightless, such as the ostrich and penguin, but they evolved from a flying ancestor. | A: flightlessness. |
What are changes in membrane potential that vary continuously with the strength of a stimulus are known as?
Here are the choices:
A. variable potentials
B. graded potentials
C. reverse potentials
D. kinetic energy | B: graded potentials. | |
The moon has a crust, mantle, and a?
Here are the choices:
A. ice cap
B. mountain range
C. core
D. magnetic field | The Moon has a crust, mantle, and core. | C: core. |
What type of coal is formed at lower temperatures?
Here are the choices:
A. limestones
B. bituminous
C. clean
D. calcareous | Coal has different grades. Bituminous coal forms at lower temperatures. It contains a lot of sulfur. When it is burned, it causes a lot of pollution. Anthracite coal forms under higher temperatures. This drives off the sulfur, and the coal burns more cleanly. | B: bituminous. |
What can sodium ions not pass through?
Here are the choices:
A. narrowness lipid bilayer
B. benthic lipid bilayer
C. nonpolar lipid bilayer
D. Lipid Control | As an example, even though sodium ions (Na+) are highly concentrated outside of cells, these electrolytes are charged and cannot pass through the nonpolar lipid bilayer of the membrane. Their diffusion is facilitated by membrane proteins that form sodium channels (or “pores”), so that Na+ ions can move down their concentration gradient from outside the cells to inside the cells. There are many other solutes that must undergo facilitated diffusion to move into a cell, such as amino acids, or to move out of a cell, such as wastes. Because facilitated diffusion is a passive process, it does not require energy expenditure by the cell. Water also can move freely across the cell membrane of all cells, either through protein channels or by slipping between the lipid tails of the membrane itself. Osmosis is the diffusion of water through a semipermeable membrane (Figure 3.7). | C: nonpolar lipid bilayer. |
What happens when the kidneys cannot remove wastes from the blood?
Here are the choices:
A. kidney failure
B. tissue failure
C. intestinal failure
D. choanocyte failure | Kidney failure happens when the kidneys cannot remove wastes from the blood. If the kidneys are unable to filter wastes from the blood, the wastes build up in the body. Kidney failure can be caused by an accident that injures the kidneys, the loss of a lot of blood, or by some drugs and poisons. Kidney failure may lead to permanent loss of kidney function. But if the kidneys are not seriously damaged, they may recover. | A: kidney failure. |
What is another name for nearsightedness?
Here are the choices:
A. astigmatism
B. hyperopia
C. myopia
D. presbyopia | Myopia is also called nearsightedness. It affects about one third of people. People with myopia can see nearby objects clearly, but distant objects appear blurry. The picture below shows how a person with myopia might see two boys that are a few meters away ( Figure below ). | C: myopia. |
What is the innermost layer of the sun called?
Here are the choices:
A. the core
B. Chromosphere
C. Photosphere
D. Convection Zone | Because the Sun is not solid, it does not have a defined outer boundary. It does, however, have a definite internal structure with identifiable layers ( Figure below ). Since the layers are not solid, the boundaries are fuzzy and indistinct. From inward to outward, the layers are: the core, the radiative zone, and the convection zone. | A: the core. |
What device is used to study charge?
Here are the choices:
A. nannostomus
B. microtome
C. microscope
D. electroscope | An electroscope is a device used to study charge. When a positively charged object (the rod) nears the upper post, electrons flow to the top of the jar leaving the two gold leaves postivley charged. The leaves repel each other since both hold postive, like charges. The VSEPR theory says that electron pairs, also a set of like charges, will repel each other such that the shape of the molecule will adjust so that the valence electron-pairs stay as far apart from each other as possible. | D: electroscope. |
What term is used to describe large numbers of species that go extinct in a short amount of time?
Here are the choices:
A. formation extinction
B. mass extinction
C. organic extinction
D. species extinction | Sometimes large numbers of species go extinct in a short amount of time. This is a mass extinction . The causes of different mass extinctions are different: collisions with comets or asteroids, massive volcanic eruptions, or rapidly changing climate are all possible causes of some of these disasters ( Figure below ). | B: mass extinction. |
What is the tiny male gametophyte enclosed in a tough capsule?
Here are the choices:
A. calcium
B. nitrogen
C. Cell Capsule
D. pollen | Pollen is a tiny male gametophyte enclosed in a tough capsule. Pollen carries sperm to an ovule while preventing the sperm from drying out. Pollen grains can't swim, but they are very light, so the wind can carry them. Therefore, they can travel through air instead of water. | D: pollen. |
When zinc reacts with hydrochloric acid, the reaction bubbles vigorously as which type of gas is produced?
Here are the choices:
A. oxygen
B. hydrogren
C. nitrogen
D. chlorine | When zinc reacts with hydrochloric acid, the reaction bubbles vigorously as hydrogen gas is produced ( Figure below ). The production of a gas is also an indication that a chemical reaction may be occurring. | B: hydrogren. |
Structural adaptations in flying animals often contribute to reduced what?
Here are the choices:
A. eyesight
B. blood flow
C. respiration
D. body mass | D: body mass. | |
What diagram is used to reflect evolutionary relationships among organisms or groups of organisms?
Here are the choices:
A. biodiversity tree
B. phylogenetic tree
C. relationships tree
D. conceptual tree | Classification and Phylogeny Scientists use a tool called a phylogenetic tree to show the evolutionary pathways and relationships between organisms. A phylogenetic tree is a diagram used to reflect evolutionary relationships among organisms or groups of organisms. The hierarchical classification of groups nested within more inclusive groups is reflected in diagrams. Scientists consider phylogenetic trees to be a hypothesis of the evolutionary past because one cannot go back through time to confirm the proposed relationships. Unlike with a taxonomic classification, a phylogenetic tree can be read like a map of evolutionary history, as shown in Figure 12.4. Shared characteristics are used to construct phylogenetic trees. The point where a split occurs in a tree, called a branch point, represents where a single lineage evolved into distinct new ones. Many phylogenetic trees have a single branch point at the base representing a common ancestor of all the branches in the tree. Scientists call such trees rooted, which means there is a single ancestral taxon at the base of a phylogenetic tree to which all organisms represented in the diagram descend from. When two lineages stem from the same branch point, they are called sister taxa, for example the two species of orangutans. A branch point with more than two groups illustrates a situation for which scientists have not definitively determined relationships. An example is illustrated by the three branches leading to the gorilla subspecies; their exact relationships are not yet understood. It is important to note that sister taxa share an ancestor, which does not mean that one taxon evolved from the other. The branch point, or split, represents a common ancestor that existed in the past, but that no longer exists. Humans did not evolve from chimpanzees (nor did chimpanzees evolve from humans) although they are our closest living relatives. Both humans and chimpanzees evolved from a common ancestor that lived, scientists believe, six million years ago and looked different from both modern chimpanzees and modern humans. | B: phylogenetic tree. |
What is the energy called that is stored in matter?
Here are the choices:
A. possible
B. potential
C. stored energy
D. mechanical | Potential energy is energy stored in matter. | B: potential. |
What is the term for traits that show wide variation, such as height, skin color, and eye color?
Here are the choices:
A. inherited traits
B. maladaptive traits
C. recessive traits
D. polygenic traits | Usually, traits are polygenic when there is wide variation in the trait. For example, humans can be many different sizes. Height is a polygenic trait, controlled by at least three genes with six alleles. If you are dominant for all of the alleles for height, then you will be very tall. There is also a wide range of skin color across people. Skin color is also a polygenic trait, as are hair and eye color. | D: polygenic traits. |
Which system in the human body consists of the heart, a network of blood vessels, and blood?
Here are the choices:
A. circulatory system
B. cardiac system
C. nervous system
D. cardiovascular system | The cardiovascular system consists of the heart, a network of blood vessels, and blood. Blood is a liquid tissue. The heart is a pump that keeps blood flowing through the vessels of the system. | D: cardiovascular system. |
Volume is another way of measuring what?
Here are the choices:
A. height
B. weight
C. material
D. length | Volume is another way of measuring material. Gases cannot be easily weighed, but their volume can be determined quickly and accurately. Liquid chemicals as well as foods and beverages are also sold by volume. Gasoline for our cars and trucks is sold by the gallon. At the grocery store, we can buy a gallon of milk or a two-liter bottle of soda pop. | C: material. |
What do you call a science that aims to find solutions to practical problems?
Here are the choices:
A. applied science
B. experimental science
C. evolved science
D. applied experience | Life science may be basic or applied science. The aim of basic science is to gain new knowledge and a better understanding of the natural world. The aim of applied science is to find solutions to practical problems. | A: applied science. |
What term describes weathering that occurs as water expands when it freezes, wedging apart rock?
Here are the choices:
A. mechanical weathering
B. cleavage
C. chemical weathering
D. erosion | form of mechanical weathering that occurs as water expands when it freezes, wedging apart rock. | A: mechanical weathering. |
How many pairs of chromosomes are found in human cells?
Here are the choices:
A. 24
B. 23
C. 13
D. 25 | Human cells have 23 pairs of chromosomes, and each chromosome within a pair is called a homologous chromosome . For each of the 23 chromosome pairs, you received one chromosome from your father and one chromosome from your mother. Alleles are alternate forms of genes found on chromosomes. Homologous chromosomes have the same genes, though they may have different alleles. So, though homologous chromosomes are very similar, they are not identical. The homologous chromosomes are separated when gametes are formed. Therefore, gametes have only 23 chromosomes, not 23 pairs. | B: 23. |
An aqueous solution is a homogeneous mixture in which the most abundant component is what?
Here are the choices:
A. blood
B. air
C. oxygen
D. water | An aqueous solution is a homogeneous mixture in which the most abundant component is water. The other substance(s) are typically introduced in a solid or liquid form and mixed into the water until they are evenly distributed. For example, if we placed a sample of ethanol in water and mixed it homogeneously, we would have a solution. Table salt mixed with water is another example of a solution. More generally, a solution is a homogeneous mixture. The solution component that is present in the largest amount is called the solvent , and all other substances are referred to as solutes . In aqueous solutions, water is always the solvent. | D: water. |
What happens to light when it reflects from a rough surface?
Here are the choices:
A. becomes concentrated
B. becomes isolated
C. gets diffused
D. reflects | Figure 25.5 Light is diffused when it reflects from a rough surface. Here many parallel rays are incident, but they are reflected at many different angles since the surface is rough. | C: gets diffused. |
Isothermal expansion is a process occurring without a change in?
Here are the choices:
A. weight
B. variation
C. temperature
D. precipitation | isothermal expansion is a process occurring without a change in temperature. | C: temperature. |
Nearly all fish reproduce sexually and have what?
Here are the choices:
A. flexible sexes
B. modified sexes
C. separate sexes
D. single sexes | Nearly all fish reproduce sexually and have separate sexes. | C: separate sexes. |
Cilia and flagella are generally associated with what function in organisms, whether the function is internal or external?
Here are the choices:
A. movement
B. digestion
C. sight
D. reproduction | Cilia ( cilium , singular) are made up of microtubule containing extensions of the cell membrane. Although both cilia and flagella are used for movement, cilia are much shorter than flagella. Cilia cover the surface of some single-celled organisms, such as paramecium. Their cilia beat together to move the little animal-like protists through the water. In multicellular animals, including humans, cilia are usually found in large numbers on a single surface of cells. Multicellular animals' cilia usually move materials inside the body. For example, the mucociliary escalator of the respiratory system is made up of mucus-secreting ciliated cells that line the trachea and bronchi. These ciliated cells, shown in Figure below , move mucus away from the lungs. This mucus catches spores, bacteria, and debris and moves to the esophagus, where it is swallowed. | A: movement. |
Do particles collide more in two reactants when they are both in fluid forms or solid forms?
Here are the choices:
A. fluid
B. neither
C. plasma
D. solid | Phase and Surface Area Effects When two reactants are in the same fluid phase, their particles collide more frequently than when one or both reactants are solids (or when they are in different fluids that do not mix). If the reactants are uniformly dispersed in a single homogeneous solution, then the number of collisions per unit time depends on concentration and temperature, as we have just seen. If the reaction is heterogeneous, however, the reactants are in two different phases, and collisions between the reactants can occur only at interfaces between phases. The number of collisions between reactants per unit time is substantially reduced relative to the homogeneous case, and, hence, so is the reaction rate. The reaction rate of a heterogeneous reaction depends on the surface area of the more condensed phase. Automobile engines use surface area effects to increase reaction rates. Gasoline is injected into each cylinder, where it combusts on ignition by a spark from the spark plug. The gasoline is injected in the form of microscopic droplets because in that form it has a much larger surface area and can burn much more rapidly than if it were fed into the cylinder as a stream. Similarly, a pile of finely divided flour burns slowly (or not at all), but spraying finely divided flour into a flame produces a vigorous reaction (Figure 14.3 "The Effect of Surface Area on Reaction Rates"). Similar phenomena are partially responsible for dust explosions that occasionally destroy grain elevators or coal mines. | A: fluid. |
The process of moving from areas of high amounts to areas of low amounts is called what?
Here are the choices:
A. filtration
B. diffusion
C. transfer
D. deposition | They will all blend together. The dyes will move through the water until an even distribution is achieved. The process of moving from areas of high amounts to areas of low amounts is called diffusion. | B: diffusion. |
Vascular tissue allowed these plants to do what?
Here are the choices:
A. grow smaller
B. have more flowers
C. live shorter
D. grow taller | Seedless vascular plants evolved to have vascular tissue after the nonvascular plants but do not have seeds. Examples include the ferns, whisk ferns, club mosses, and horsetails. Vascular tissue allowed these plants to grow taller. | D: grow taller. |
What were the first forms of life on earth?
Here are the choices:
A. protists
B. prokaryotes
C. eukaryotes
D. aniryotes | Prokaryotes, the First Inhabitants of Earth When and where did life begin? What were the conditions on Earth when life began? Prokaryotes were the first forms of life on Earth, and they existed for billions of years before plants and animals appeared. The Earth and its moon are thought to be about 4.54 billion years old. This estimate is based on evidence from radiometric dating of meteorite material together with other substrate material from Earth and the moon. Early Earth had a very different atmosphere (contained less molecular oxygen) than it does today and was subjected to strong radiation; thus, the first organisms would have flourished where they were more protected, such as in ocean depths or beneath the surface of the Earth. At this time too, strong volcanic activity was common on Earth, so it is likely that these first organisms—the first prokaryotes—were adapted to very high temperatures. Early Earth was prone to geological upheaval and volcanic eruption, and was subject to bombardment by mutagenic radiation from the sun. The first organisms were prokaryotes that could withstand these harsh conditions. Microbial Mats Microbial mats or large biofilms may represent the earliest forms of life on Earth; there is fossil evidence of their presence starting about 3.5 billion years ago. A microbial mat is a multi-layered sheet of prokaryotes (Figure 22.2) that includes mostly bacteria, but also archaea. Microbial mats are a few centimeters thick, and they typically grow where different types of materials interface, mostly on moist surfaces. The various types of prokaryotes that comprise them carry out different metabolic pathways, and that is the reason for their various colors. Prokaryotes in a microbial mat are held together by a glue-like sticky substance that they secrete called extracellular matrix. The first microbial mats likely obtained their energy from chemicals found near hydrothermal vents. A hydrothermal vent is a breakage or fissure in the Earth’s surface that releases geothermally heated water. With the evolution of photosynthesis about 3 billion years ago, some prokaryotes in microbial mats came to use a more widely available energy source—sunlight—whereas others were still dependent on chemicals from hydrothermal vents for energy and food. | B: prokaryotes. |
What warms the base of the mantle creating convection currents there?
Here are the choices:
A. molten lava
B. mantle soil
C. the hot regenerate
D. the hot core | The hot core warms the base of the mantle, which creates convection currents in the mantle. | D: the hot core. |
What do we call an incorrect test result that should have been positive?
Here are the choices:
A. external positive
B. false negative
C. false positive
D. personal negative | Cancer Proteomics Genomes and proteomes of patients suffering from specific diseases are being studied to understand the genetic basis of the disease. The most prominent disease being studied with proteomic approaches is cancer. Proteomic approaches are being used to improve screening and early detection of cancer; this is achieved by identifying proteins whose expression is affected by the disease process. An individual protein is called a biomarker, whereas a set of proteins with altered expression levels is called a protein signature. For a biomarker or protein signature to be useful as a candidate for early screening and detection of a cancer, it must be secreted in body fluids, such as sweat, blood, or urine, such that largescale screenings can be performed in a non-invasive fashion. The current problem with using biomarkers for the early detection of cancer is the high rate of false-negative results. A false negative is an incorrect test result that should have been positive. In other words, many cases of cancer go undetected, which makes biomarkers unreliable. Some examples of protein biomarkers used in cancer detection are CA-125 for ovarian cancer and PSA for prostate cancer. Protein signatures may be more reliable than biomarkers to detect cancer cells. Proteomics is also being used to develop individualized treatment plans, which involves the prediction of whether or not an individual will respond to specific drugs and the side effects that the individual may experience. Proteomics is also being used to predict the possibility of disease recurrence. The National Cancer Institute has developed programs to improve the detection and treatment of cancer. The Clinical Proteomic Technologies for Cancer and the Early Detection Research Network are efforts to identify protein signatures specific to different types of cancers. The Biomedical Proteomics Program is designed to identify protein signatures and design effective therapies for cancer patients. | B: false negative. |
The conversion factor between solubility and molar solubility of a compound is known as what?
Here are the choices:
A. molar mass
B. mass effect
C. stochastic mass
D. molar value | Solubility is normally expressed in g/L of saturated solution. However, solubility can also be expressed as the moles per liter. Molar solubility is the number of moles of solute in one liter of saturated solution. In other words, the molar solubility of a given compound represents the highest molarity solution that is possible for that compound. The molar mass of a compound is the conversion factor between solubility and molar solubility. Given that the solubility of Zn(OH) 2 is 4.2 × 10 -4 g/L, the molar solubility can be calculated as shown below:. | A: molar mass. |
What describes the process of vesicles fusing with the plasma membrane and releasing their contents to the outside of the cell?
Here are the choices:
A. exocytosis
B. expulsion
C. autolysis
D. endocytosis | Exocytosis describes the process of vesicles fusing with the plasma membrane and releasing their contents to the outside of the cell, as shown in Figure below . Exocytosis occurs when a cell produces substances for export, such as a protein, or when the cell is getting rid of a waste product or a toxin. Newly made membrane proteins and membrane lipids are moved to the plasma membrane by exocytosis. | A: exocytosis. |
Out of the four ways that allele frequencies of a population can be changed, which way is caused by individuals leaving or joining the population?
Here are the choices:
A. Allopatric speciation
B. gene flow
C. spontaneous mutation
D. mass extinction | 11.2 Mechanisms of Evolution There are four factors that can change the allele frequencies of a population. Natural selection works by selecting for alleles that confer beneficial traits or behaviors, while selecting against those for deleterious qualities. Mutations introduce new alleles into a population. Genetic drift stems from the chance occurrence that some individuals have more offspring than others and results in changes in allele frequencies that are random in direction. When individuals leave or join the population, allele frequencies can change as a result of gene flow. | B: gene flow. |
What kind of bond doesn't form molecules, but instead forms crystals?
Here are the choices:
A. electron bonds
B. magnetic bonds
C. ionic bonds
D. covalent bonds | Ionic compounds contain ions of metals and nonmetals held together by ionic bonds. Ionic compounds do not form molecules. Instead, many positive and negative ions bond together to form a structure called a crystal. You can see an example of a crystal in Figure below . It shows the ionic compound sodium chloride. Positive sodium ions (Na + ) alternate with negative chloride ions (Cl - ). The oppositely charged ions are strongly attracted to each other. | C: ionic bonds. |
Where does the natural synthesis of lactose occur?
Here are the choices:
A. liver tissue
B. nervous tissue
C. mammary tissue
D. ovarian tissue | Lactose Lactose is known as milk sugar because it occurs in the milk of humans, cows, and other mammals. In fact, the natural synthesis of lactose occurs only in mammary tissue, whereas most other carbohydrates are plant products. Human milk contains about 7.5% lactose, and cow’s milk contains about 4.5%. This sugar is one of the lowest ranking in terms of sweetness, being about one-sixth as sweet as sucrose (seeTable 16.1 "The Relative Sweetness of Some Compounds (Sucrose = 100)" in Section 16.3 "Important Hexoses"). Lactose is produced commercially from whey, a by-product in the manufacture of cheese. It is important as an infant food and in the production of penicillin. Lactose is a reducing sugar composed of one molecule of D-galactose and one molecule of D-glucose joined by a β-1,4-glycosidic bond (the bond from the anomeric carbon of the first monosaccharide unit being directed upward). The two monosaccharides are obtained from lactose by acid hydrolysis or the catalytic action of the enzyme lactase:. | C: mammary tissue. |
The ratio between the radii of a wheel and axle determines what?
Here are the choices:
A. fundamental mechanical advantage
B. ideal mechanical advantage
C. introduced mechanical advantage
D. theoretical mechanical advantage | Just like it sounds, a wheel and axle is composed of two connected cylinders of different diameters. Since the wheel has a larger radius (distance) than the axle, the axle will always have a larger force than the wheel. The ideal mechanical advantage of a wheel and axle is dependent on the ratio between the radii:. | B: ideal mechanical advantage. |
What is the first stage of cellular respiration called?
Here are the choices:
A. glycolysis
B. reproduction
C. appetite
D. photosynthesis | When was the last time you enjoyed yogurt on your breakfast cereal, or had a tetanus shot? These experiences may appear unconnected, but both relate to bacteria which do not use oxygen to make ATP. In fact, tetanus bacteria cannot survive if oxygen is present. However, Lactobacillus acidophilus (bacteria which make yogurt) and Clostridium tetani (bacteria which cause tetanus or lockjaw) share with nearly all organisms the first stage of cellular respiration, glycolysis ( Figure below ). Because glycolysis is universal, whereas aerobic (oxygen-requiring) cellular respiration is not, most biologists consider it to be the most fundamental and primitive pathway for making ATP. | A: glycolysis. |
Many species use their body shape and coloration to avoid being detected by what?
Here are the choices:
A. biology
B. males
C. predators
D. viruses | Many species use their body shape and coloration to avoid being detected by predators. The tropical walking stick is an insect with the coloration and body shape of a twig, which makes it very hard to see when it is stationary against a background of real twigs (Figure 19.15a). In another example, the chameleon can change its color to match its surroundings (Figure 19.15b). | C: predators. |
A reference point is used in measurement to make what?
Here are the choices:
A. estimation
B. deviation
C. regression
D. focal point | Estimation, as used in measurement, is the process of referencing a physical quantity in terms of a calibration or reference point. All measurement devices have reference marks of some kind. | A: estimation. |
Why do adult herbivores in a herd surround their young?
Here are the choices:
A. to keep them warm on long cold nights
B. to protect them as they are vulnerable to predators
C. to protect them from other adult herbivores
D. to show them love | Herbivores such as zebras and elephants live in herds . Adults in the herd surround and protect the young, who are most vulnerable to predators. | B: to protect them as they are vulnerable to predators. |
When orders are sent from your brain to your legs, these signals pass through what type of cells?
Here are the choices:
A. mobility cells
B. molecules
C. nerve cells
D. skin cells | Cells, like these nerve cells, do not work in isolation. To send orders from your brain to your legs, for example, signals pass through many nerve cells. These cells work together to perform a similar function. Just as muscle cells work together, bone cells and many other cells do as well. A group of similar cells that work together is known as a tissue. | C: nerve cells. |
What is the leading cause of soil erosion?
Here are the choices:
A. glacier movement
B. volcanic explosions
C. running water
D. tidal winds | The same agents that erode landscapes also erode soil. They are water, wind, ice, or gravity. Running water is the leading cause of soil erosion. Water is abundant and has a lot of power. Wind is also a leading cause of soil erosion. Wind can pick up soil and blow it far away. | C: running water. |
What class of organisms help decompose matter to release nutrients and make nutritious food for other organisms ?
Here are the choices:
A. yeast
B. coral
C. bacteria
D. fungi | If so, then you have encountered fungi . Fungi are organisms that belong to the Kingdom Fungi ( Figure below ). Our environment needs fungi. Fungi help decompose matter to release nutrients and make nutritious food for other organisms. Fungi are all around us and are useful in many ways. | D: fungi. |
A pedigree is a chart which shows the inheritance of a trait over several what?
Here are the choices:
A. organisms
B. generations
C. centuries
D. events | A pedigree is a chart which shows the inheritance of a trait over several generations. A pedigree is commonly created for families, as it can be used to outlines the inheritance patterns of familial traits or genetic disorders. It can be used to demonstrate autosomal dominant or recessive inheritance, or sex-linked inheritance. Figure below shows a pedigree depicting recessive inheritance of a disorder through three generations. The trait is thought to be recessive as for the two individuals with the trait, neither has a parent who also has the trait. Geneticists may also be able to determine whether individuals with the trait in question are heterozygous or homozygous for the allele associated with the trait. When alleles are added to the pedigree shown ( A or a ), recessive inheritance in conformed. | B: generations. |
The release of calcium ions initiates what?
Here are the choices:
A. muscle contractions
B. exhalation
C. cramps
D. spasms | The release of calcium ions initiates muscle contractions. Watch this video (http://openstaxcollege. org/l/calciumrole) to learn more about the role of calcium. (a) What are “T-tubules” and what is their role? (b) Please describe how actinbinding sites are made available for cross-bridging with myosin heads during contraction. | A: muscle contractions. |
The electron released during beta decay is not an orbital electron but an electron whose origin was where?
Here are the choices:
A. connected to the nucleus
B. outside the nucleus
C. orbiting the nucleus
D. in the nucleus | The symbol represents an electron whose charge corresponds to and since it has no nucleons, . It must be carefully noted that the electron released during beta decay is NOT an orbital electron but an electron whose origin was in the nucleus. The process has one neutron becoming one proton and one electron and the electron being emitted as a beta particle. Since a neutron has been lost AND a proton has been gained, the mass number does not change. The atomic number, however, has increased one due to the gain of a proton. Therefore, as a result of beta decay, the daughter product will have the same mass number as the parent and an atomic number one greater than the parent. | D: in the nucleus. |
What is created by the polymerization of glucose?
Here are the choices:
A. cellulose
B. methane
C. glucose
D. carbonate | Zachary Wilson. Cellulose is created by the polymerization of glucose . CC BY-NC 3.0. | A: cellulose. |
Fungi reproduce asexually by fragmentation and either sexually or asexually via what lightweight, windblown structures?
Here are the choices:
A. ions
B. lesions
C. spores
D. seeds | 23.25 Fungal Reproduction Fungi can reproduce in two ways. Firstly, they make asexually produce through fragmentation. This occurs when pieces of hyphae are broken off, which then grow into new mycelia. The second method is by spores. Spores are lightweight structures and windblown designed to be transported over long distances and by many mediums, such as on the bodies of insects and birds. They are additionally light enough to be blown away for hundreds of kilometers. Spores may be asexual and sexual. Their sexual properties can be analysed to classify the four phylla of fungi. | C: spores. |
The desire to understand how and why things happen is shared by all branches of what?
Here are the choices:
A. population
B. society
C. government
D. science | Scientists may focus on very different aspects of the natural world. For example, some scientists focus on the world of tiny objects, such as atoms and molecules. Other scientists devote their attention to huge objects, such as the sun and other stars. But all scientists have at least one thing in common. They want to understand how and why things happen. Achieving this understanding is the goal of science. | D: science. |
The scientific revolution took place where starting in the 1500s?
Here are the choices:
A. north america
B. south america
C. africa
D. europe | People have probably wondered about the natural world for as long as there have been people. So it’s no surprise that science has roots that go back thousands of years. Some of the earliest contributions to science were made by Greek philosophers more than two thousand years ago. It wasn’t until many centuries later, however, that the scientific method and experimentation were introduced. The dawn of modern science occurred even more recently. It is generally traced back to the scientific revolution, which took place in Europe starting in the 1500s. | D: europe. |
Ionic bonds are electrostatic attractions between two oppositely charged what?
Here are the choices:
A. compounds
B. gasses
C. molecules
D. ions | Ionic bonds are electrostatic attractions between two oppositely charged ions. Ions can be formed and then bonded when metal atoms donate their valence electrons to nonmetal atoms. | D: ions. |
What is the theoretical event that began the universe often called?
Here are the choices:
A. string theory
B. big bang
C. dark matter
D. Coreolis effect | The generation of an isolated but open system, which we might call a protocell, was a critical step in the origin of life. Such an isolated system has important properties that are likely to have facilitated the further development of life. For example, because of the membrane boundary, changes that occur within one such structure will not be shared with neighboring systems. Rather, they accumulated in, and favor the survival of, one system over its neighbors. Such systems can also reproduce in a crude way by fragmentation. If changes within one such system improved its stability, its ability to accumulate resources, or its ability to survive and reproduce, that system, and its progeny, would be likely to become more common. As these changes accumulate and are passed from parent to offspring, the organisms will inevitably evolve, as we will see in detail in the next chapter. As in living systems today, the earliest steps in the formation of the first organisms required a source of energy to maintain the non-equilibrium living system. There are really two choices for the source of this energy, either light (electromagnetic radiation from the sun) or thermodynamically unstable chemicals present in the environment. There have been a number of plausible scenarios, based on various observations, for the steps leading to life. For example, a recent study based on the analysis of the genes (and the proteins that they encode) found in modern organisms, suggests that the last universal common ancestor (LUCA) arose in association with hydrothermal vents.60 But whether this reflects LUCA or an ancestor of LUCA that became adapted to living is association with hydrothermal vents is difficult (and perhaps impossible) to resolve unambiguously, particularly since LUCA lived ~3.4-3.8 billion years ago and cannot be studied directly. Mapping the history of life on earth Assuming, as seems likely, that life arose spontaneously, we can now look at what we know about the fossil record to better understand the diversification of life and life’s impact on the Earth. This is probably best done by starting with what we know about where the Universe and Earth came from. The current scientific model for the origin of the universe is known as the “Big Bang” (also known as the “primeval atom” or the “cosmic egg”), an idea originally proposed by the priest, physicist and astronomer Georges Lemaître (1894-1966).61 The Big Bang model arose from efforts to answer the question of whether the fuzzy nebulae identified by astronomers were located within or outside of our galaxy. This required some way to determine how far these nebulae were from Earth. Edwin Hubble (1889-1953) and his co-workers were the first to realize that nebulae were in fact galaxies in their own right, each very much like our own Milky Way and each is composed of many billions of stars. This was a surprising result. It made Earth, sitting on the edge of one (the Milky Way) among many, many galaxies seem less important – a change in cosmological perspective similar to that associated with the idea that the Sun, rather than Earth, was the center of the solar system (and the Universe). To measure the movement of galaxies with respect to Earth, Hubble and colleagues combined to types of observations. The first of these allowed them to estimate the distance from the Earth to. | B: big bang. |
In the cardiovascular system, net filtration pressure represents the interaction of osmotic pressures and what other pressures?
Here are the choices:
A. uptake
B. hydrophilic
C. homeostatic
D. hydrostatic | Interaction of Hydrostatic and Osmotic Pressures The normal unit used to express pressures within the cardiovascular system is millimeters of mercury (mm Hg). When blood leaving an arteriole first enters a capillary bed, the CHP is quite high—about 35 mm Hg. Gradually, this initial CHP declines as the blood moves through the capillary so that by the time the blood has reached the venous end, the CHP has dropped to approximately 18 mm Hg. In comparison, the plasma proteins remain suspended in the blood, so the BCOP remains fairly constant at about 25 mm Hg throughout the length of the capillary and considerably below the osmotic pressure in the interstitial fluid. The net filtration pressure (NFP) represents the interaction of the hydrostatic and osmotic pressures, driving fluid out of the capillary. It is equal to the difference between the CHP and the BCOP. Since filtration is, by definition, the movement of fluid out of the capillary, when reabsorption is occurring, the NFP is a negative number. NFP changes at different points in a capillary bed (Figure 20.16). Close to the arterial end of the capillary, it is approximately 10 mm Hg, because the CHP of 35 mm Hg minus the BCOP of 25 mm Hg equals 10 mm Hg. Recall that the hydrostatic and osmotic pressures of the interstitial fluid are essentially negligible. Thus, the NFP of 10 mm Hg drives a net movement of fluid out of the capillary at the arterial end. At approximately the middle of the capillary, the CHP is about the same as the BCOP of 25 mm Hg, so the NFP drops to zero. At this point, there is no net change of volume: Fluid moves out of the capillary at the same rate as it moves into the capillary. Near the venous end of the capillary, the CHP has dwindled to about 18 mm Hg due to loss of fluid. Because the BCOP remains steady at 25 mm Hg, water is drawn into the capillary, that is, reabsorption occurs. Another way of expressing this is to say that at the venous end of the capillary, there is an NFP of −7 mm Hg. | D: hydrostatic. |
What attracts the earth to the sun?
Here are the choices:
A. the moon
B. light
C. gravity
D. weight | The earth is attracted to the sun by the force of gravity. Why doesn’t the earth fall into the sun?. | C: gravity. |
Fermat’s principle states that light will always take the path of least amount of?
Here are the choices:
A. momentum
B. time
C. resistance
D. energy | Fermat’s Principle states that light will always take the path of least amount of time (not distance). This principle governs the paths light will take and explains the familiar phenomena of reflection, refraction, lenses and diffraction. Light rarely travels in a straight-line path. When photons interact with electrons in matter the time it takes for this interaction determines the path. For example, higher frequency blue light is refracted more than red because blue wavelengths interacts more frequently with electrons than red wavelengths and the path of least time is for blue to bend more then red in order to get out of this ‘slow’ area faster. The rainbows we see are a result of this. Fermat’s Principle explains the many fascinating phenomena of light from rainbows to sunsets to the haloes around the moon. | B: time. |
Many enzymes require nonprotein helpers for what activity?
Here are the choices:
A. functional
B. catalytic
C. kinetic
D. hydrogen | B: catalytic. | |
What is often a result of untreated atherosclerosis?
Here are the choices:
A. a heart attack or stroke
B. seizures
C. heart disease
D. cancer | A: a heart attack or stroke. | |
The hormones epinephrine and norepinephrine are released by what?
Here are the choices:
A. uptake medulla
B. nutrients medulla
C. adrenal medulla
D. external medulla | Short-term Stress Response When presented with a stressful situation, the body responds by calling for the release of hormones that provide a burst of energy. The hormones epinephrine (also known as adrenaline) and norepinephrine (also known as noradrenaline) are released by the adrenal medulla. How do these hormones provide a burst of energy? Epinephrine and norepinephrine increase blood glucose levels by stimulating the liver and skeletal muscles to break down glycogen and by stimulating glucose release by liver cells. Additionally, these hormones increase oxygen availability to cells by increasing the heart rate and dilating the bronchioles. The hormones also prioritize body function by increasing blood supply to essential organs such as the heart, brain, and skeletal muscles, while restricting blood flow to organs not in immediate need, such as the skin, digestive system, and kidneys. Epinephrine and norepinephrine are collectively called catecholamines. | C: adrenal medulla. |
How many possible alleles do the majority of human genes have?
Here are the choices:
A. three or more
B. two or more
C. less than four
D. two or less | The majority of human genes have two or more possible alleles. Differences in alleles account for the considerable genetic variation among people. In fact, most human genetic variation is the result of differences in individual DNA bases within alleles. | B: two or more. |
What occurs during the new moon and full moon, due to gravitational pull?
Here are the choices:
A. spring waves
B. spring storms
C. spring tides
D. spring floods | Spring tides occur during the new moon and full moon. The Sun and Moon must either be in a straight line on the same side of Earth, or they must be on opposite sides of Earth. Their gravitational pull combines to cause very high and very low tides. Spring tides have the greatest tidal range. | C: spring tides. |
Alleles that carry deadly diseases are usually which type?
Here are the choices:
A. dominant
B. inherited
C. predominant
D. recessive | D: recessive. | |
What releases fatty acids and other components from fats and phospholipids?
Here are the choices:
A. enzymatic hydrolysis
B. enzyme respiration
C. metabolism
D. peristaltic hydrolysis | A: enzymatic hydrolysis. | |
What kind of energy comes from the position of a charged particle in an electric field?
Here are the choices:
A. solar energy
B. mechanical energy
C. thermal energy
D. potential energy | Electric potential energy comes from the position of a charged particle in an electric field. For example, when two negative charges are close together, they have potential energy because they repel each other and have the potential to push apart. If the charges actually move apart, their potential energy decreases. Electric charges always move spontaneously from a position where they have higher potential energy to a position where they have lower potential energy. This is like water falling over a dam from an area of higher to lower potential energy due to gravity. | D: potential energy. |
What does interstellar medium consist of?
Here are the choices:
A. the strong force
B. gravitational waves
C. dark matter
D. thinly spread gas and dust | Space may seem empty, but actually it contains thinly spread gas and dust, called interstellar medium, that gradually collapses over immense stretches of time and collects into denser clouds of gas and dust. The atoms of gas are mostly hydrogen and are typically about a centimeter apart. The dust is mostly carbon and silicon. In some places, this interstellar medium is collected into particularly dense clouds of gas and dust known as a nebula . A nebula is the birthplace of stars. Our sun was probably born in a nebula around 5 billion years ago. | D: thinly spread gas and dust. |
Sickle-cell disease significantly impairs the function of what?
Here are the choices:
A. circulatory system
B. metabolism system
C. limbic system
D. nervous system | A: circulatory system. | |
What is the enlarged tip of the penis called?
Here are the choices:
A. testicular point
B. glans penis
C. angles penis
D. outer penis | The penis is an external genital organ with a long shaft and enlarged tip called the glans penis. The shaft of the penis contains erectile tissues that can fill with blood and cause an erection. When this occurs, the penis gets bigger and stiffer. The urethra passes through the penis. Sperm pass out of the body through the urethra. (During urination, the urethra carries urine from the bladder. ). | B: glans penis. |
What do you call the point at which the entire weight of a body may be considered to be concentrated?
Here are the choices:
A. center of gravity
B. complex of gravity
C. center of earth
D. direction of gravity | Every object has a center of gravity . The center of gravity is the point at which the entire weight of a body may be considered to be concentrated; if supported at this point, the body would remain in equilibrium in any position. For example, if we were discussing a 12-inch ruler, the center of gravity for the ruler would be at the center of the 6-inch line. You could put your finger directly under the 6-inch line to hold the ruler and it would not fall either left or right. If you placed your finger underneath any other place on the ruler, it would fall off to one side or the other. | A: center of gravity. |
At how many places does points source pollution enter water?
Here are the choices:
A. four
B. three
C. one
D. two | Point source pollution enters water at just one place. For example, it might enter a stream through a pipe. Non-point source pollution enters water everywhere. It is carried by runoff. | C: one. |
What do monarch butterfly larvae depend on for their food?
Here are the choices:
A. seaweed
B. honey
C. milkweeds
D. pollen | Another concern about biotechnology is how it may affect the environment. Negative effects on the environment have already occurred because of some GMOs. For example, corn has been created that has a gene for a pesticide. The corn plants have accidentally cross-pollinated nearby milkweeds. Monarch butterfly larvae depend on milkweeds for food. When they eat milkweeds with the pesticide gene, they are poisoned. This may threaten the survival of the monarch species as well as other species that eat monarchs. Do the benefits of the genetically modified corn outweigh the risks? What do you think?. | C: milkweeds. |
As lava cools, tiny iron-rich crystals line up with earth’s what?
Here are the choices:
A. molecular field
B. magnetic field
C. oceans
D. gravitational field | Some rocks contain little compasses too! As lava cools, tiny iron-rich crystals line up with Earth’s magnetic field. Anywhere lavas have cooled, these magnetite crystals point to the magnetic poles. The little magnets point to where the north pole was when the lava cooled. Scientists can use this to figure out where the continents were at that time. This evidence clearly shows that the continents have moved. | B: magnetic field. |
What do we call the amount of time a substance is stored in a reservoir?
Here are the choices:
A. storage time
B. presence time
C. residence time
D. latency | A substance is stored in a reservoir. The amount of time it stays in that reservoir is its residence time. | C: residence time. |
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