March 2013 Science Mock STAAR Test 8th Grade
1. How many different elements are involved in the reaction shown above? All element symbols start with a capital letter. The elements in this reaction are carbon, hydrogen, and oxygen. There are the same exact 3 elements on the products side as there are on the reactants side. 3
2. Which of these best describes one of the subatomic particles that could be found at location X in the model of an atom shown above? F. It has mass but no charge. G. It has no mass and a positive charge. H. It has a large mass and a negative charge. J. It has no mass and an equal number of positive and negative charges. Location X is the nucleus. In the nucleus are two particles. One is the proton. It has mass and is positively charged. The other is a neutron. It has mass and has no charge. The electrons, which are negatively charged are NOT found in the nucleus.
3. An element has a metallic-gray appearance. It also has the properties of both a metal and a nonmetal. In which section of the periodic table indicated above would the element most likely be found? A. 1B. 2C. 3D. 4 Elements having properties of both a metal and a nonmetal are metalloids. Metalloids are found on the “staircase” between the metals and the nonmetals.
4. A student observes some sugar as it is heated and burns. The student concludes that a chemical reaction has occurred. Which of the following observations about the burning sugar provides evidence of a chemical reaction? F. Heat is added to the sugar crystals. G. The sugar melts and becomes a liquid. H. The temperature of the sugar increases.J. Gas is produced as the sugar turns black. • Indicators of a chemical change/reaction include: • temperature change (but not due to external heating) • color change • light production • gas production • precipitate formation • Change in state of matter is NOT an indicator of a chemical change.
5. In the diagram above, a wind turbine is transforming energy from the wind. Between which two steps in the diagram is mechanical energy being converted into electrical energy? • A. 1 and 2 • B. 2 and 3 • C. 3 and 4 • D. 4 and 5 Mechanical energy is a form of energy that moves objects. Electrical energy is the presence and flow of an electric charge, usually through wires.
6. In a series of controlled experiments, a student measures the force acting on a wheeled cart and the cart’s acceleration. The student’s data are shown below. Based on the recorded observations, what is the mass of the cart in kilograms? Force = mass * acceleration F m a 2 0 Choose any force with its acceleration. If F=ma, then m=F/a m=? F=20 a=1.0 m=20/1=20
7. A toy train engine rests motionless on a track. One student begins pushing the engine to the right with a force of 2 newtons. At the same time, another student begins pushing the engine to the left with a force of 5 newtons. Which of the following best describes the resulting motion of the engine? • A. It travels left at a constant speed. • B. It travels left at an increasing speed. • C. It travels right at a constant speed. • D. It travels right at an increasing speed. Newton’s 2nd Law of Motion states that unbalanced forces cause objects to accelerate in the direction of the greater force.
8. The diagram above shows the orbit of the moon around Earth. At which point in the moon’s orbit will a person standing on Earth see a waxing crescent moon? F. 1 G. 2 H. 3 J. 4 When the moon is between the Earth and Sun, it is a new moon. As it revolves counterclockwise, it begins to wax (or more of the lit portion is visible. When it is on the other side of the Earth, it is a full moon and then begins to wane (or less of the lit portion is visible.) Halfway between each of these stages is a quarter moon.
9. Earth’s land areas, oceans, and atmosphere maintain fairly constant average temperatures. What is the best explanation for these constant average temperatures? A. Earth’s Northern Hemisphere and Southern Hemisphere have opposite seasons.B. Earth is tilted and rotates daily on its axis.C. The continuous motion of air and water distributes the sun’s energy.D. Global weather systems generally move from west to east. The sun provides energy that drives convection within the atmosphere and oceans, producing winds and ocean currents.
10. The high winds of hurricanes and typhoons often destroy mangrove forests. The destruction of these forests most likely affects ecosystems by — F. reducing beach erosion in sea-turtle nesting areasG. reducing the amount of saltwater flowing into lakesH. causing pollution in inland rivers and streamsJ. forcing migratory birds to find other places to rest If the mangrove trees were destroyed, there would be more beach erosion and less area for wildlife to be.
11. A diagram of a plant cell is shown below. The function of the plant cell structure shown in the enlargement is to — • A. provide support for the cell • B. direct all the cell’s activities • C. use energy from sunlight to make sugar • D. regulate substances that enter and exit the cell • Cell support is provided by the cell wall and it surrounds the entire cell. • The nucleus directs the cell’s activities and there is only one per cell. • The chloroplasts use energy from sunlight to make sugar and there are several of those in plant cells. • Substances entering and exiting the cell are regulated by the cell membrane which surrounds the cell.
12. Eukaryotes are classified into four kingdoms according to certain characteristics. The diagram below shows some characteristics of the four kingdoms. Which of these is the plant kingdom? F. Kingdom 1G. Kingdom 2H. Kingdom 3J. Kingdom 4 Plants are organisms that have many cells and make their own food. Multi- means many and Uni-means single or one. Autotrophic means makes own food. Heterotrophic means gets food by consuming other organisms.
13. A drain cleaner consists of sodium hydroxide and aluminum. When the drain cleaner is added to water, bubbles of hydrogen are produced, and the solution becomes very hot. Which of these best describes what happens to form the bubbles when the cleaner is added to water? • A. A chemical reaction • B. Condensation • C. A physical change • D. Evaporation Bubbles can indicate gas production which can indicate a chemical change. Condensation is the change from a gas to a liquid. Evaporation is the change from a liquid to a gas. A physical change is a change in a physical property that does not create new substances.
14. In the picture above, a boy is trying to pull a dog on a leash, but the dog and the boy are moving in the same direction. Which of the following best describes the forces in this situation? F. The forces are balanced, and the net force is zero.G. The forces are unbalanced, and the boy’s force is greater.H. The forces are unbalanced, and the dog’s force is greater. J. The forces are balanced, and the dog is stronger than the boy. Newton’s 2nd Law of Motion states that unbalanced forces cause objects to accelerate in the direction of the greater force.
15. Nicholas and Zach were playing darts, as seen above in the picture. If the dartboard represents an atom, which dart would indicate a positively charged region? • A. dart W • B. dart X • C. dart Y • D. dart Z The nucleus contains protons (+) and neutrons (Ø) and is located in the center of the atom. The electrons (-) are located in the electron cloud outside of the nucleus.
16. A gasoline-powered vehicle goes up a hill from point X to point Y. What energy transformation must occur in the car’s engine? F. Chemical energy into mechanical energy G. Electrical energy into chemical energy H. Heat energy into chemical energy J. Mechanical energy into nuclear energy • Chemical energy is a form of potential energy in foods and fuel. It is released through chemical reactions such as digestion and combustion. • Mechanical energy is a form of energy that moves objects. • Electrical energy is a form of energy that is present and flows through electrical charge. • Heat energy is caused by the increase of speed in molecules. • Nuclear energy is energy associated with atomic reactions.
17. The table above shows where some birds in a Texas ecosystem are located within the layers of plants in their environment. These layers begin at the ground and end in the area above the treetops. Which of these would most likely occur if a wildfire destroyed all the plants in the lowest level of this ecosystem? • A. Vireos would begin to nest on the ground. • B. Doves would have to move to a different area to find food. • C. Hawks would begin to hunt for animals in the middle level. • D. Cardinals would move to above tree level and begin competing with hawks. Animals’ habitat affected by the wildfire would have to adapt what they did to get food and shelter, but would not make an extreme change. Animals not directly affected by it would not make much, if any, change in their food and shelter.
18. Which process below uses carbon dioxide and the sun’s radiant energy to produce chemical energy? F. Evaporation G. Photosynthesis H. Respiration J. Decomposition • Evaporation-changing from liquid to gas • Photosynthesis-carbon dioxide + water and light yields oxygen and glucose (food for the organism) • Respiration-ridding the organism of waste materials • Decomposition-breaking down of molecules into simpler substances
19. The series of pictures shows a view of the moon from the same position on Earth on different days of one month. The pictures show that on certain nights the moon — • A. moves away from Earth • B. receives less light from Earth • C. is unlit as viewed from Earth • D. makes half a turn around Earth Phases of the moon occur because the moon revolves around the Earth, taking approximately one month. As it moves around the Earth, we can different amounts of the lit portion including times where we see all of the lit portion and other times where we seen none of the lit portion.
Measures 5.5 & 8.2 cm 20. The scale drawings above show two catfish collected from a river. What is the difference in the actual body lengths of these catfish? 1 0 8 • Find scale measurement, subtract, then multiply difference by scale value. • Scale is 1 cm = 4 cm • 8.2-5.5= 2.7 cm • 2.7 cm * 4= 10.8 cm
21. Water, H2O, is classified as a(n) – A. colloid B. compound C. element D. mixture A compound is a molecule made up of more than one element. Water is made up of hydrogen and oxygen.
22. Sally was trying to calculate the speed of the hummingbirds feeding outside her window. Sally measured the distance from one feeder to the next, 24 meters. Then she sat and timed how long it took a hummingbird to fly from one feeder to the next. She timed 10 trials and calculated the average time, 3 seconds. What was the average speed of the hummingbird flying from one feeder to the other? F. 6 m/s G. 8 m/s H. 24 m/s J. 72 m/s Speed = distance/time S = ? d = 24 m t = 3 s S = d/t S = 24 m/3s S = ___ m/s
23. Which of these best explains why the oceans have a great impact on the weather over the continents? • A. Ocean waves move more easily than continental rock. • B. The oceans contain a wider variety of organisms than the continents. • C. The oceans store and transfer more heat than the continents. • D. Ocean water contains more salt than most continental lake water. Oceans impact the weather over continents greatly because they have a high specific heat which means they store radiant energy and through convection transfer it throughout the globe.
24. Which of the following traits is most influenced by the environment? • F. Body weight • G. Eye color • H. Blood type • J. Color blindness Environment doesn’t just mean trees, animals, and the Sun. It also refers to influences that are not genetic in nature, such as food intake, amount of exercise, etc.
25. How many elements are in the compound Mg(OH)2? • A. 2 • B. 3 • C. 4 • D. 5 All element symbols start with a capital letter. The elements in this compound are magnesium, oxygen, and hydrogen.
26. According to the periodic table, all of the following are metals except — F. sodium G. zinc H. fluorine J. calcium All elements found on the left of the staircase (metalloids) are metals, except for hydrogen. All the elements found to the right of the staircase are nonmetals.
27. Three students use their bodies to show how the sun, the moon, and Earth are aligned during the phases of the moon. What is one limitation of this model? • A. It cannot show the relative motion of the three objects. • B. It cannot be safely used to show gaseous objects such as the sun. • C. It cannot show how the sun’s light affects the moon’s appearance. • D. It cannot be used to show the direction of Earth’s revolution. A limitation is a weakness of the model or something the model cannot show.
28. A field geologist collected data for two nuggets of copper and determined their density. Which two pieces of equipment did the geologist most likely use to determine the density of the copper nuggets? F. balance and graduated cylinder G. metric ruler and beaker H. thermometer and Erlyenmeyer flask J. specimen bottle and tweezers • balance measures mass • graduated cylinder measures precise liquid volume • metric ruler measures small distances/lengths • thermometer measures temperature • Erlynmeyer flask is used to heat and store chemicals • specimen bottle is used to hold objects for observation • tweezers are used to pick up small objects
29. The petals of flowers often are brightly colored. These petals provide a benefit for the plant because they — • A. prevent insects from taking pollen to other flowers • B. hide the plant from predators that would eat its flowers • C. protect the leaves from injury by birds and insects • D. attract insects that can carry the pollen needed for plant reproduction Brightly colored flowers attract insects and birds to the plant. The animal picks up pollen on itself. When the animal flies to another flower, it can spread the pollen. Pollen is used in reproduction of many plants.
30. Which of the following examples is a chemical reaction? F. a pot of water boiling G. an iron nail rusting H. corn being ground J. sugar dissolving in tea Chemical reactions produce new substances different from what you start and have indications of chemical changes (see question 4.) Most chemical changes are not reversible.
31. The model of the atom above best represents which element? A. Boron B. Neon C. Sodium D. Carbon Atoms are identified by their atomic number which is the number of protons. Protons are positive (+).
32. Which of the following shows how the plant above would grow if the pot were knocked on its side and left for several weeks? • Geotropism-a plant’s roots will grow toward gravity and the leaves will grow away from gravity • Phototropism-a plant’s leaves will grow toward light
33. According to the periodic table, which of the following models best represents a carbon atom? A carbon atom has 6 protons, as indicated by its atomic number.
34. Some data about the atmosphere of Mars are shown above. What conclusion can be made about the ability of humans to breathe Martian air? F. Life support will be needed because the percentage of oxygen is too low. G. It will be impossible to breathe because the percentage of nitrogen is too low. H. Oxygen and nitrogen will make it possible for photosynthesis to produce food. J. Humans will be able to breathe the air because oxygen is present. Though Earth’s atmosphere is primarily nitrogen (78%), about 20% is oxygen and essential for life. Humans expel carbon dioxide as a waste product.
35. Which of the following is the most reasonable topographic map of the area shown in the picture? The closer together the lines are, the steeper the rise.
36. The table above shows the number of protons in an atom of four different elements. According to the periodic table, which of these elements is a metal? F. T G. Q H. X J. Z • The atomic number indicates the number of protons. • Look up the elements on the periodic table. • Elements to the left of the staircase are metals (except Hydrogen)
37. Which energy transformation occurs when a match is lit? A. Chemical energy to heat energy B. Heat energy to potential energy C. Electrical energy to heat energy D. Kinetic energy to potential energy • Chemical energy is a form of potential energy in foods and fuel. It is released through chemical reactions such as digestion and combustion. • Electrical energy is a form of energy that is present and flows through electrical charge. • Heat energy is a form of energy that is caused by the increase of speed in molecules. • Kinetic energy is a type of energy that occurs when a object is in motion. • Potential energy is a type of energy that is stored energy due to position or mass.
38. As the air became polluted and darker, ______________ was demonstrated in the darkening of the population of the peppered moth in Europe over a relatively short period of time. F. Natural selection G. Natural integration H. Kettlewell adaptation J. Industrial modification • Natural selection-Living things that have traits that are best-suited, or adapted, to their environment survive and multiply • Natural integration-no definition • Kettlewell adaptation-no definition; Kettlewell did study the peppered moth, though. • Industrial modification-a company in Gardena, CA, specializing in Refurbishment Of Material Handling Equipment
39. A tsunami can lead to massive devastation on Earth, resulting in loss of life and property as well as the destruction of the natural habitats where it occurs. A tsunami is caused by • A. a tornado over the ocean • B. drilling for oil off the coast • C. an earthquake on the ocean floor • D. a strong hurricane developing over the ocean • A tsunami is a giant wave. • Tsunami can be caused by earthquakes on the ocean floor or underwater landslides.
40. Which player would have the GREATEST kinetic energy? F. lineman G. half back H. tight end J. full back • Kinetic energy is the energy of motion. • The greater the speed, the greater the kinetic energy. • The greater the mass, the greater the kinetic energy
41. Based on the food web above, what would happen if the wheat plants were wiped out by a disease? • A. The field mice would thrive. • B. The flies would start eating flowers. • C. The field mice would start eating frogs. • D. The field mice would die off, and the wolf, hawk and snake • populations would suffer. Organisms connected directly or indirectly to the ones that are wiped out (or reduced) will be negatively affected. The greater variety of organisms consumed reduces the effect.
42. Wetlands support a large number of animal species. Chemical weed killers are dumped into this wetland and the aquatic plants are killed. We should expect _______________ to be affected by the death of the plants. F. the insect and insect larva G. the migratory bird populations H. the animals that breed and nest here J. all the animals in and near the wetlands Organisms connected directly or indirectly to the ones that are wiped out (or reduced) will be negatively affected. The greater variety of organisms consumed reduces the effect.
43. At the county fair, Carrie and Sam climbed up on the carousel horses. Around and around they went; the horses also bobbed up and down. When they got off of the carousel, Carrie told Sam they had been accelerating during their ride. Sam disagreed; they had been moving at a constant speed. Who is correct and why? • A. Carrie is, because the carousel changed speed when it started and stopped. • B. Sam is, because the horses never moved from their position on the carousel. • C. Carrie is, because velocity includes speed and direction, and both changed. • D. Sam is, they did not accelerate since their speed remained constant for the ride. Acceleration is a change in velocity. Velocity is speed and direction of an object. Acceleration occurs when an object speeds up, slows down, or changes direction.
44. It is theorized that Virginia’s Blue Ridge Mountains were pushed up when tectonic plates converged. Which of the following best depicts this process? • continental plates sliding past each other are transform boundaries and create faults and earthquakes • a continental plate and ocean plate coming together form a convergent boundary with subduction and can form volcanoes. • continental plates that come toward each other form convergent boundaries and form mountains.
45. Describe the structure of an atom. A. The nucleus is the dense center of the atom composed of protons and neutrons. Surrounding the nucleus is an electron cloud composed of electrons. B. The nucleus is the dense center of the atom composed of electrons and neutrons. Surrounding the nucleus is an electron cloud composed of protons. C. The electron cloud is the dense center of the atom composed of electrons. Surrounding the electron cloud is a nucleus composed of protons and neutrons. D. The electron cloud is the dense center of the atom composed of protons and neutrons. Surrounding the electron cloud is a nucleus composed of electrons.
46. Finch species living on the islands exhibit a variety of beak types that favor different foods. Finches that eat seeds and plant parts have beaks of the shorter, thicker variety while finches that eat insects and other small organisms have thin, pointed beaks. Drought has hit the Galapagos Islands. Plant species are dying out; seeds and nuts have all but vanished. Of these four finch species, which is MOST LIKELY to survive under these conditions? F. Finch 1 G. Finch 2 H. Finch 3 J. Finch 4
47. Jenny accidentally drops her ring into a graduated cylinder. If the ring has a mass of 5 grams and the water level in the cylinder rises from 5 ml to 7 ml, determine the density of the ring. • Density = mass/volume • volume can be found using a graduated cylinder; the amount of water displaced in the cylinder is equal to the volume of the object. (subtract volumes) 2 5 D = m/v D = ? m = 5 g v = 2 mL (7 mL – 5 mL= 2mL) D = 5g/2mL D = 2.5 g/mL
48. What is an ADVANTAGE of sexual reproduction? F. two parents are required G. only one parent is required H. it leads to genetically diverse offspring J. It leads to genetically identical offspring • Sexual reproduction-requires two parent organisms, but will create a variety in the offspring. • asexual reproduction-requires only one parent organism, but all offspring are genetically the same including flaws in the genes
49. If the forces acting upon an object are balanced, then an object MUST A. be moving B. be accelerating C. be sitting still D. have a constant velocity Newton’s 1st law of motion states that objects will remain at a constant velocity (speed and direction) unless unbalanced forces act upon the object. The 2nd law indicates that unbalanced forces cause objects to accelerate.