science praxis form 3

Which of the following is true about the formation of a covalent bond? A.A covalent bond forms when electrons are shared between two atoms. B.A covalent bond forms when one atom donates protons to another atom. C.A covalent bond forms when two negatively charged atoms become attached to each other. D.A covalent bond forms when the neutrons of one atom fuse with the neutrons of another atom.

Option (A) is correct. A covalent bond involves the sharing of one or more pairs of electrons between two atoms.

During a total solar eclipse, the Moon is in which of the following phases? A.New Moon B.First quarter Moon C.Full Moon D.Third quarter Moon

Option (A) is correct. A total solar eclipse occurs when the Moon is between Earth and the Sun. The new Moon phase of the lunar cycle is when 0% of the sunlit portion of the Moon is visible from Earth, which also occurs when the Moon is between Earth and the Sun.

Which of the following molecules is a product of cellular respiration and is used for energy transfer in cells? A.ATPA T P B.Carbon dioxide C.Oxygen D.Water

Option (A) is correct. ATPA T P is a small molecule that stores and transports chemical energy in cells. Cellular respiration is a multistep process in cells that uses chemical energy stored in glucose and other organic molecules to produce ATP.

Which of the following conditions is required for the rapid replenishment of an aquifer? A.Permeable soil B.Steeply sloped land C.Direct sunlight D.High atmospheric pressure

Option (A) is correct. Aquifers are underground layers of porous rock that hold groundwater. Water removed from an aquifer can be replenished naturally by the infiltration of precipitation into the ground, a process that occurs rapidly when the subsurface soil is permeable.

The process by which a gas becomes a liquid is called A.condensation B.freezing C.melting D.reduction

Option (A) is correct. Condensation is the process by which a gas becomes a liquid.

Which of the following processes in a plant's life cycle involves the emergence of leaves and roots from a seed? A.Germination B.Fertilization C.Pollination D.Flowering

Option (A) is correct. Germination is the development of the first roots and shoots from a seed after a period of dormancy. The process of germination results in a seedling.

As a rock begins tumbling down a hillside, most of its gravitational potential energy is converted into A.kinetic energy B.thermal energy C.chemical energy D.nuclear energy

Option (A) is correct. Kinetic energy is the energy of motion. As the rock begins moving down the hillside under the influence of gravity, most of the rock's gravitational potential energy is converted into kinetic energy.

In which of the following layers of Earth's atmosphere does most weather occur? A.The troposphere, the layer closest to Earth's surface B.The stratosphere, the layer just above the troposphere C.The mesosphere, the layer just above the stratosphere D.The exosphere, the layer farthest from Earth's surface

Option (A) is correct. Most weather in Earth's atmosphere occurs in the troposphere. The troposphere is the lowest layer of the atmosphere and contains approximately 75% of the mass of the atmosphere.

A neutral atom becomes a positive ion when it loses one or more A.electrons B.neutrons C.protons D.nuclei

Option (A) is correct. Protons are positively charged, and electrons are negatively charged. A neutral atom has the same number of protons and electrons. A neutral atom becomes a positive ion when it loses one or more electrons, resulting in the ion having more positive charges than negative charges.

An animal is found to have the following characteristics. It has a backbone. It has soft, moist skin covered by a slippery layer of mucus. It goes through complete metamorphosis in its life cycle. It lives part of its life in water and part of its life on land. To which of the following groups does the animal most likely belong? A.Amphibians B.Insects C.Mammals D.Reptiles

Option (A) is correct. The characteristics presented are typical of frogs. Frogs belong to the class Amphibia, which also includes toads and salamanders.

Which of the following elements are most abundant in the Sun? A.Hydrogen and helium B.Oxygen and carbon C.Nitrogen and phosphorus D.Uranium and plutonium

Option (A) is correct. The composition of the Sun is approximately 99.9% hydrogen and helium.

Which of the following is an important function of the digestive system? A.Absorbing nutrients into the body B.Transporting signals to and from different parts of the body C.Providing structural support for the body D.Protecting the body from ultraviolet radiation

Option (A) is correct. The digestive system includes organs that break down food into small molecules, which are then absorbed into the body. The primary location of absorption is the small intestine.

In which of the following types of power plants would the normal generation of electricity most likely produce the least amount of carbon dioxide gas? A.Nuclear-fueled B.Coal-fueled C.Natural gas-fueled D.Oil-fueled

Option (A) is correct. Under normal operation, nuclear power plants release only water vapor from cooling towers. In contrast, the other types of power plants rely on the combustion of fossil fuels to generate electricity, which results in the release of significant amounts of carbon dioxide gas.

In a demonstration of the Doppler effect, an observer who is standing still will most likely hear a sound's pitch increase when the source of the sound does which of the following? A.Remains motionless B.Moves toward the observer C.Moves away from the observer D.Revolves in a circle around the observer

Option (B) is correct. An observer who is standing still will most likely hear a sound's pitch increase when the source of the sound moves toward the observer. As the source of the sound moves toward the observer, each successive sound wave starts at a point closer to the observer, resulting in the sound waves reaching the observer with increasing frequency. Because the frequency of the sound waves increases, the observer perceives an increase in the sound's pitch.

Which of the following is a primary function of plant roots? A.Transporting seeds away from a plant B.Anchoring the plant body to the ground C.Transferring pollen between flowers D.Absorbing sunlight for photosynthesis

Option (B) is correct. Anchoring the plant to the ground is an important function of plant roots. Other important functions of plant roots include absorbing water, storing nutrients, and forming new plants via vegetative reproduction.

Two black mice have a litter that contains some black offspring and some brown offspring. In mice, black fur is dominant to brown fur. Which of the following best explains the presence of the brown offspring? A.One parent was homozygous for black fur (BBuppercase B, uppercase B), and one was heterozygous for black fur (Bbuppercase B, lowercase b). B.Both parents were heterozygous for black fur (Bbuppercase B, lowercase b). C.Both parents were homozygous for brown fur (bblowercase b, lowercase b). D.Both parents were homozygous for black fur (BBuppercase B, uppercase B)

Option (B) is correct. Both parents must have been heterozygous for black fur (Bbuppercase B, lowercase b) because the brown offspring (bblowercase b, lowercase b) must have inherited a recessive allele (b) from each parent.

The balanced chemical equation shown above represents a reaction between methane ( CH4 Based on the balanced chemical equation, how many molecules of oxygen react with each molecule of methane? A.One B.Two C.Three D.Four

Option (B) is correct. In a chemical reaction between two substances, the atoms of the substances are rearranged to form other substances. In the chemical reaction represented by the equation, atoms in molecules of methane and oxygen are rearranged to form molecules of carbon dioxide and water. Because atoms are neither created nor destroyed in a chemical reaction, the equation has been balanced so that the same number of carbon, hydrogen, and oxygen atoms appear on both sides of the reaction arrow. Based on the balanced chemical equation, one molecule of methane reacts with two molecules of oxygen to produce one molecule of carbon dioxide and two molecules of water.

The scientific name for a domestic cat is Felis catus. Which of the following classification levels is indicated by the first part of the scientific name? A.Order B.Genus C.Family D.Kingdom

Option (B) is correct. In binomial nomenclature, the first term refers to the genus, and the genus and specific epithet together define the species. Felis is the name of the genus that includes some small and medium cat species, including the domestic cat, Felis catus.

Which of the following scientists did pioneering research on the properties of radioactive elements? A.Isaac Newton B.Marie Curie C.Nicolaus Copernicus D.Charles Darwin

Option (B) is correct. Marie and Pierre Curie are credited with the discovery of the radioactive elements polonium and radium. Marie Curie also investigated the properties of radioactive elements and their compounds.

Which of the following best describes the approximate length of time it takes Earth to rotate once about its axis? A.One hour B.One day C.One month D.One year

Option (B) is correct. On average, it takes 24 hours, or one day, for Earth to rotate once about its axis. The rotation of Earth about its axis leads to the cycle of day and night.

Which of the following processes most directly involves the movement of water from the atmosphere to Earth's surface? A.Infiltration B.Precipitation C.Transpiration D.Sublimation

Option (B) is correct. Precipitation is the process by which atmospheric water falls to Earth's surface in the form of rain, hail, sleet, or snow. Because atmospheric water returns to Earth's surface primarily through the process of precipitation, it is an important part of the water cycle. Infiltration is the process by which water on Earth's surface enters the subsurface soil and rock. Transpiration is the process by which water evaporates from plant leaves and enters the atmosphere. Sublimation is the process by which a substance transitions directly from the solid phase to the gas phase without going through the liquid phase.

Which of the following factors best accounts for the seasonal changes in weather conditions that occur at a particular location on Earth? A.The Moon's gravitational pull B.Tilt of Earth's rotational axis C.Proximity to large bodies of water D.Distortion of Earth's magnetic field

Option (B) is correct. Seasonal changes in weather conditions are largely due to the tilt of Earth's rotational axis. As Earth revolves around the Sun, the tilt of Earth's axis results in the Northern Hemisphere being tilted toward the Sun for one part of the year and away from the Sun for another part of the year. When tilted toward the Sun, the Northern Hemisphere receives more direct sunlight, leading to generally warmer weather conditions. When tilted away from the Sun, the Northern Hemisphere receives less direct sunlight, leading to generally cooler weather conditions. Because the Southern Hemisphere is tilted away from the Sun when the Northern Hemisphere is tilted toward the Sun, the Southern Hemisphere experiences generally cooler weather during the same part of the year that the Northern Hemisphere experiences generally warmer weather.

Based on the information presented in the table, sedimentary rock made up mostly of angular fragments that have an average size of 3,000 micrometers should be classified as which of the following? A.Conglomerate B.Breccia C.Sandstone D.Mudstone

Option (B) is correct. Sedimentary rocks are composed of particles of various sizes and types. Based on the data in the table, sedimentary rocks made up mostly of angular particles that have an average size of 3,000 micrometers are classified as breccia.

Which of the following demonstrations provides the best opportunity for students to gain an understanding of why the Sun appears larger than other stars, even though many stars are actually larger than the Sun? A.Positioning two lit bulbs of the same size on opposite sides of an observer but at the same distance from the observer B.Positioning two lit bulbs of the same size at different distances from an observer C.Positioning a large lit bulb and a small lit bulb at the same distance from an observer D.Positioning a large lit bulb close to an observer and a small lit bulb far from the same observer

Option (B) is correct. The bulb positioned closer to the observer will appear larger than the bulb positioned farther away, even though the two bulbs are the same size. Similarly, of two stars that have approximately the same size and temperature, the star that is closer to Earth will appear to be the larger star.

Which of the following systems is responsible for the production of hormones? A.Immune B.Endocrine C.Digestive D.Skeletal

Option (B) is correct. The endocrine system includes glands that produce, store, and secrete hormones, which are carried by the circulatory system to their target tissues.

Which of the following statements best describes how the individual molecules in water vapor are different from those in liquid water? A.They weigh less. B.They are farther apart. C.They are composed of different elements. D.They interact more strongly with one another

Option (B) is correct. Water vapor is the gaseous phase of water. The average distance between water molecules is greater when water is in the gaseous phase than when it is in the liquid phase. Because water molecules are always composed of two hydrogen atoms and an oxygen atom, the average mass of a water molecule does not change as a result of a phase change. The attractive forces between water molecules are weaker in the gaseous phase than they are in the liquid phase.

Which of the following is the best example of an interaction between different biotic factors in an ecosystem? A.A caterpillar undergoing metamorphosis B.A plant absorbing sunlight C.A grazing animal eating plants D.An icicle melting on a warm day

Option (C) is correct. A grazing animal eating plants is an example of an interaction between two different biotic factors (an animal and the plants it eats) in an ecosystem. The metamorphosis of a caterpillar into a butterfly is an example of a type of insect life cycle. A plant absorbing sunlight is an example of an interaction between a biotic factor (a plant) and an abiotic factor (sunlight). An icicle melting on a warm day is an example of an interaction between two abiotic factors (water and temperature).

In an activity, students filled two identical containers with equal volumes of either freshwater or salt water. The students then placed different objects, one at a time, in the containers and observed whether the objects sank or floated. Which of the following statements best accounts for an observation that the same object sank in the freshwater but floated in the salt water? A.The freshwater was colder than the salt water. B.The freshwater weighed more than the salt water. C.The salt water was denser than the freshwater. D.The salt water was more transparent than the freshwater.

Option (C) is correct. An object will sink in a liquid if its density is greater than that of the liquid, and it will float if its density is less than or equal to that of the liquid. The observation that the same object sank in the freshwater but floated in the salt water is best accounted for by concluding that the salt water is denser than both the object and the freshwater.

On the periodic table, the elements lithium, sodium, and potassium are grouped together in the first column. Based on their locations on the periodic table, which of the following is most likely true about the elements lithium, sodium, and potassium? A.They have the same atomic number. B.They have the same atomic mass. C.They have similar chemical properties. D.They have similar melting points.

Option (C) is correct. Atoms of lithium, sodium, and potassium have one valence electron. As a result of the similarity in their electron configurations, which is reflected in their locations on the periodic table, the three different elements have similar chemical properties. In contrast, they have different atomic numbers, different atomic masses, and different melting points.

Based on the graph shown, a decrease in the string length of a simple pendulum will most likely result in which of the following? A.No change in the pendulum's frequency B.A decrease in the pendulum's frequency C.An increase in the pendulum's frequency D.An unpredictable change in the pendulum's frequency

Option (C) is correct. Based on the graph shown, a decrease in the string length of a simple pendulum will result in an increase in the pendulum's frequency. For example, reducing a simple pendulum's string length from 11 centimeters to 2 centimeters will cause the pendulum's frequency to increase from 1.5 oscillations per second to 3.5 oscillations per second, approximately.

which of the following identifies the ultimate source of genetic variation in a population of organisms? A.Nonfatal injuries to some members of the population B.Predators that catch and eat some members of the population C.Changes in the DNAD N A of some members of the population D.Seasonal weather changes in the area where the population is found

Option (C) is correct. Genetic variation results from random changes in genetic information. The genetic information of an organism is encoded in its DNAD N A, and heritable changes in the base pair sequences of DNAD N A are called mutations. Organisms in a population pass some mutations on to their offspring, and over multiple generations the accumulation of different mutations leads to greater genetic variation in the population.

In an activity, students create models of landscapes by cutting two-liter plastic bottles in half lengthwise and filling them with different combinations of soil, sand, pebbles, and small plants. After positioning the models at an angle, the students pour equal amounts of water onto each model's raised end and collect the runoff in beakers placed under each model's lower end. The students then determine the dry mass of the sediment contained in the runoff from each model. Which of the following scientific questions can the students investigate most directly in the activity described? A.How can growing plants break apart rocks? B.Do earthworms improve soil fertility? C.What are some factors that affect erosion? D.Does temperature affect weathering rates?

Option (C) is correct. In the activity, the students are simulating the flow of water down a hillside. Erosion is the movement of soil and rock particles by water, wind, or other natural agents. The sediment contained in the runoff from each model is the result of erosion. By determining the dry mass of the sediment collected in the runoff from each model and then comparing their results, the students can investigate how the different combinations of soil, sand, pebbles, and small plants affect erosion by water.

Which of the following best describes the type of chemical reaction that occurs when the acid HClH C l is mixed with the base NaOHN a O H in a solution? A.Combustion B.Decomposition C.Neutralization D.Dehydration

Option (C) is correct. Mixing the acid HClH C l with the base NaOHN a O H results in a neutralization reaction that produces water and the salt NaClN a C l.

The graph represents the motion of an object traveling along a straight path. Based on the graph, the object's average speed between the 4-second and 7-second time points was most nearly A. 1.9 m/smeters per second B. 3.0 m/smeters per second C. 4.3 m/smeters per second D.12.8 m/s

Option (C) is correct. Speed is distance divided by time. The average speed of an object traveling along a straight path can be calculated by dividing the distance the object traveled by the amount of time it took to travel that distance. Based on the graph, the object traveled approximately 13 meters between the 4-second and 7-second time points: 13 meters divided by 3 seconds is approximately equal to 4.3 meters per second.

Which of the following most likely accounts for structural and functional differences between the skin cells, smooth muscle cells, and liver cells of the same person? A.Differences in the genetic code B.Differences in chromosome number C.Differences in gene expression D.Differences in mutation rates

Option (C) is correct. Structural and functional differences between the body cells of a person are best accounted for by differences in gene expression. Because they originated from a single fertilized egg, the body cells of a person contain the same genetic information. However, some genes are expressed only in certain types of cells, such as skin cells, but not in other types of cells, such as smooth muscle cells or liver cells. The expression of different sets of genes results in the production of different sets of proteins in different cells, leading to structural and functional differences between the cells.

As part of a unit on plate tectonics, students use various materials to construct physical models of Earth's layered structure. The students will use the models to explore how the separate plates of the lithosphere, Earth's solid outer layer, move over the asthenosphere, the partially molten upper portion of Earth's mantle, over geologic time. Based on the description provided, which of the following materials would best represent the asthenosphere? A.Paper that is thin, delicate, and easily punctured B.A solid wood block that has a rough and uneven surface C.Soft wax that can bend or stretch without breaking D.A piece of stainless steel that is rigid and impermeable

Option (C) is correct. The asthenosphere is a hot, malleable layer of rock immediately beneath the lithosphere. Compared with the lithosphere, the asthenosphere has a weaker mechanical strength that allows the rigid crustal plates above it to move across Earth's surface over long periods of time. Of the materials described, the soft wax would best represent the asthenosphere because of its malleability.

A teacher rubs an inflated balloon with a wool cloth and then holds the balloon over bits of paper that are lying on a table. The students in the class watch as the bits of paper rise from the table toward the balloon. Which of the following hypotheses is best supported by the observed interaction between the balloon and the bits of paper? A.The balloon contains helium. B.The balloon is unaffected by gravity. C.The balloon has an electrostatic charge. D.The balloon weighs more than the bits of paper do

Option (C) is correct. The attraction of the bits of paper to the balloon is best explained by the hypothesis that the balloon has an electrostatic charge. Rubbing the balloon with a wool cloth transferred electrons from the wool to the balloon, resulting in an electrostatic charge on the balloon's surface. Holding the charged balloon over the bits of paper induced a rearrangement of charges within the paper, resulting in positively charged areas in the bits of paper that caused them to be attracted to the negatively charged balloon.

In an investigation of the rusting process, students soaked a sample of steel wool in vinegar for approximately 1 minute. After removing the steel wool from the vinegar, the students squeezed it and blotted it with a paper towel. The students then wrapped the steel wool around the bulb of a thermometer and placed the steel wool and thermometer together in a covered beaker to allow the rusting process to occur. The students observed that the temperature reading of the thermometer gradually increased. Which of the following conclusions is best supported by the students' observation? A.A reaction occurred in which energy was created. B.A reaction occurred in which energy was destroyed. C.A reaction occurred in which energy was released. D.No reaction occurred

Option (C) is correct. The observed temperature increase best supports the conclusion that energy was released into the surroundings. Soaking the steel wool in vinegar removed a protective coating on the steel wool, resulting in the exposure of iron in the steel wool to oxygen in the air. The reaction of iron with oxygen in the presence of water produces rust, which is a process that releases energy in the form of heat.

An object is moving in a straight line at a constant speed. What will happen if a constant force is then applied to the object in the same direction in which the object is moving? A.The object will stop moving. B.The object will continue moving in the same direction but will slow down. C.The object will continue moving in the same direction but will speed up. D.The object will move in the opposite direction but at the same speed as before

Option (C) is correct. When a constant force is applied to the object in the same direction in which the object is moving, the object will accelerate in that direction.

Which of the following best describes a galaxy? A.A small celestial body composed of ice B.A giant planet orbited by ten or more moons C.A collection of planets revolving around a star D.A large cluster of stars, dust, and gas

Option (D) is correct. A galaxy is a system composed of many stars, dust, and gas, which is held together by gravitational attraction.

Which of the following is a method of heat transfer? A.Nuclear decay B.Insulation C.Transpiration D.Convection

Option (D) is correct. Convection is the transfer of heat from one area to another by the bulk movement of a liquid or gas. An example of convection is the upward movement of air that has been warmed over a hot surface. Warm air expands, becoming less dense than cold air. As a result, the warm air above a hot surface rises and is replaced by colder air. The upward movement of the warm air transfers heat away from the hot surface.

Which of the following human organs is responsible for the formation of sperm cells? A.Pancreas B.Thyroid C.Ovary D.Testis

Option (D) is correct. In human males, the testis is the organ in which the formation of sperm cells occurs.

Which of the following phenomena best accounts for an observation that an object underwater appears to be closer to the water's surface than it really is? A.The bouncing of light off a smooth, shiny surface B.The warming of water by the absorption of energy from light C.The casting of a shadow by an object through which light cannot pass D.The bending of light as it passes from one substance to another

Option (D) is correct. Light waves travel through different substances at different speeds. When light waves pass from one substance to another, their path changes (or bends) as a result of a change in speed. When light waves that have bounced off an object underwater pass from water to air, the change in the path of the light waves makes the object appear closer to the water's surface than it really is.

Researchers found fossils of marine organisms in rock layers that are located high above sea level. Which of the following conclusions is best supported by the researchers' observations? A.The fossils were transported to the research site by wind currents. B.The rock layer in which the fossils were found is igneous rock. C.The organisms from which the fossils were formed lived less than a hundred years ago. D.The area containing the rock layers was previously submerged under water

Option (D) is correct. Marine fossils are the preserved remains or traces of organisms that lived in shallow seas or other marine environments. The fossils were formed after the marine organisms died and became buried in sediment on the seafloor. The sediment containing the fossils hardened into rock over many millions of years and became exposed above sea level as a result of geological processes, such as the uplifting of land due to plate tectonic activity.

Which of the following best describes where most earthquakes occur? A.In the middle of continents B.Where streams merge with rivers C.In Earth's inner core D.At tectonic plate boundaries

Option (D) is correct. Most earthquakes occur at tectonic plate boundaries. Tectonic plates are pieces of Earth's solid outer layer (the lithosphere). The tectonic plates are resting atop a layer of hot, partially molten rock (the asthenosphere), which allows the plates to move over Earth's surface over geologic time. The movement of the plates causes the plates to collide with or slide past one another. The sudden release of energy near the edges of two tectonic plates results in an earthquake.

Which of the following biomes has the greatest diversity of species? A.Cold desert B.Temperate grassland C.Alpine tundra D.Tropical rain forest

Option (D) is correct. Of the four biomes listed, tropical rain forests have the greatest diversity of species.

Which of the following typically increases with increasing depth in the open ocean? A.Biomass B.Sunlight C.Temperature D.Pressure

Option (D) is correct. Pressure increases with ocean depth. As ocean depth increases, the weight of water above that is pushing down on the water below increases. Biomass, sunlight, and temperature typically decrease as ocean depth increases.

Researchers are measuring surface salinity in different areas of an ocean. In which of the following areas will the researchers most likely find the highest surface salinity? A.An area in which cooler temperatures are causing heavy rainfall B.An area in which warmer temperatures are causing icebergs to melt C.An area in which river flow is causing a mixing of freshwater with seawater D.An area in which warm, dry winds are causing a high rate of evaporation

Option (D) is correct. Salinity is a measure of the amount of dissolved salts in water. Processes that increase the concentration of dissolved salts in water lead to increased salinity. Evaporation is the process by which a liquid changes to a gas. Water evaporating from an ocean surface enters the atmosphere but leaves behind dissolved salts, resulting in an increase in the surface salinity in that area of the ocean. Heavy rainfall, the melting of icebergs, and inflow from a river are processes that add freshwater to the ocean, causing the surface salinity in those areas of the ocean to decrease.

Bread molds belong to which of the following groups of organisms? A.Bacteria B.Animalia C.Plantae D.Fung

Option (D) is correct. The molds that grow on bread belong to the kingdom Fungi.

In which of the following ways can a tree-fall gap result in increased species diversity in a mature forest community? A.By reducing the amount of carbon dioxide gas in the atmosphere B.By increasing competition between birds for limited resources C.By creating a barrier to the dispersal of seeds produced by mature trees D.By providing a habitat in which shade-intolerant plants can grow

Option (D) is correct. When a tree falls in a forest, a gap in the forest canopy is created, allowing more sunlight to reach the forest floor. Plant species that prefer sunny spots can colonize the area until trees regrow and create a full canopy.

Which THREE of the following types of household waste are most likely to be accepted by a curbside recycling program? A.Dry newspaper B.Clean aluminum cans C.Rinsed glass jars D.Food-soiled waxed paper

Options (A), (B), and (C) are correct. Dry newspaper, clean aluminum cans, and rinsed glass jars are typically accepted by curbside recycling programs. In contrast, waxed paper contaminated with food is not accepted by many curbside recycling programs.

Which THREE of the following are generally acceptable rules for laboratory activities? A.Students should wash their hands after mixing chemicals in the laboratory. B.Students should inform the teacher immediately of any accidents or spills in the laboratory. C.Students should use cracked glassware only when the teacher is in the laboratory. D.Students should read instructions thoroughly before performing laboratory procedures

Options (A), (B), and (D) are correct. To prevent accidental ingestion or absorption of potentially harmful substances, students should wash their hands after working with chemicals. To help maintain a safe environment, accidents and spills in the laboratory should be reported to the teacher immediately so that a correct response can be implemented. To safely and effectively complete laboratory procedures, students should read instructions thoroughly before starting the procedures. Cracked glassware is a safety hazard and should never be used.

Which TWO of the following examples illustrate the application of genetic engineering in agriculture? A.Scientists compared the cadmium concentrations of the grain produced by durum wheat grown in one of two different types of soil. B.Scientists found that expression of a certain basil-plant gene in ripening tomatoes changes the flavor and aroma of the tomatoes. C.Scientists investigated the amount of provitamin A that is produced and stored by certain naturally occurring strains of sweet potatoes. D.Scientists developed a strain of corn with increased resistance to certain insects by inserting a bacterial gene into the corn's genome

Options (B) and (D) are correct. Genetic engineering is the targeted modification of an organism's genetic information. Modifying the genetic information of tomato plants by inserting a basil-plant gene and modifying the genetic information of corn by inserting a bacterial gene are examples of genetic engineering.

Which THREE of the following statements about DNAD N A are true? A.DNAD N A is a major source of cellular energy. B.DNAD N A stores and transmits genetic information. C.DNAD N A molecules have a double helix structure. D.DNAD N A is found in animal cells but not bacterial cells. E.DNAD N A is packaged into structures called chromosomes

Options (B), (C), and (E) are correct. Genetic information is stored in DNAD N A in the form of different base pair sequences, and transmission of genetic information occurs when DNAD N A is replicated and transferred from one cell or organism to another. DNAD N A molecules have two complementary strands of nucleotides that form a double helix. In eukaryotic cells, long DNAD N A molecules are coiled around histone proteins into structures called chromosomes, which at certain times during the cell cycle become condensed into more compact structures that in some cases can be observed under a light microscope. DNAD N A is not typically used by cells as a source of energy. All organisms, including animals and bacteria, store genetic information as DNAD N A inside their cells.