1 Name: Period: Test Date: 8 th Grade Science 2 nd Quarter Final Study Guide ANSWER KEY Unit 1: Experimental Design 1. What is a scientific problem? A scientific problem is an observation made in the form of a question to be solved or tested. 2. What is a hypothesis? A hypothesis is a possible explanation of a solution to a scientific problem that can be tested. It is written in an if / then format. 3. What is an independent variable? The independent variable is the factor of the experiment that is tested, or changed on purpose by the investigator. 4. How many independent variables should be in a controlled experiment? There should only be one independent variable used for each experiment. Usually expressed as the effect of 5. What is a dependent variable? The dependent variable is the factor of the experiment that is measured or observed. Usually expressed in a statement that says The effect of (independent variable) on the (dependent variable.) 6. What is a control? The control in the experiment is the factor in the experiment that is not being tested and is used as a comparison to determine change. 7. What is a constant? The constants in an experiment are the factors that stay the same within the experiment. 8. What is data? Data in the experiment are the observations and measurements that are recorded during the experiment. Use the following lab experiment to answer questions 9 13 A student was performing an experiment to answer the problem, will Fishgrow brand fish food cause the fish to grow larger? He predicted that Fishgrow brand fish food would cause the fish to grow larger than fish that were fed with regular fish food. He had two fish aquariums with the same type of goldfish; one with goldfish that were fed with Fishgrow fish food and the other tank was filled with goldfish that were fed with regular fish food. He fed the fish the same amounts of food, at the same time every day for a month. He then measured the length of the fish to determine if there was any growth. 9. Identify the hypothesis in the lab. The hypothesis in the lab is If Fishgrow is fed to the goldfish everyday for a month, then the goldfish will grow larger than fish fed with regular fish food.
2 10. Identify the independent variable in the lab. The independent variable in the lab is the Fishgrow fish food. 11. Identify the dependent variable in the lab. The dependent variable in the lab is the growth or length of the fish. 12. Identify the control in the lab. The control in the lab is the goldfish that were fed regular fish food. 13. Identify the constants in the lab. The constants in the lab were same: Kind of goldfish Aquarium size Amount of food Amount of time Same time of day 14. What kind of graph shows change over time? A graph that shows change over time is a line graph. 15. What kind of graph shows categories? A graph that shows categories is a bar graph. 16. What kind of graph has no spaces and a range of values on the x-axis? A graph that has no spaces and a range of values on the x axis is a histogram. 17. Which piece of equipment could be used to determine the volume of gasoline? The piece of science equipment that would best used to determine the volume of gasoline would be a graduated cylinder. 18. Which piece of equipment would be used to measure the mass of a turtle? The piece of science equipment that would be best used to measure the mass of a turtle would be a triple beam balance scale. 19. Which piece of science equipment could be used to measure the length of a snail? The piece of science equipment that could be used to measure the length of a snail would be a ruler. 20. Which piece of science equipment could be used to measure the temperature of a boiling pot? The piece of science equipment that could be used to measure the temperature of a boiling pot would be a thermometer. 21. Which would be more accurate to measure a volume of water, a beaker or a graduated cylinder? A graduated cylinder would be more accurate in measuring a volume of water.
3 Unit 2: Renewable and Nonrenewable Resources 22. What is a renewable resource? Renewable resources are resources that can be replaced by natural processes in a short period of time. (In our lifetime) 23. Name five renewable resources. a. Biomass b. Wind c. Solar d. Geothermal e. Hydropower 24. What is a nonrenewable resource? Nonrenewable resources that are used faster than they can be replaced by natural processes. 25. Name three nonrenewable resources. f. Oil (petroleum) and natural Gas g. Coal h. Uranium 26. How would using renewable energy affect nonrenewable resources? Using renewable resources would reduce the demand for nonrenewable energy resources. If we use a renewable resource we would be so dependent on oil, coal, natural gas, or uranium. 27. How is coal used to make electricity? Coal is burned to make steam, which turns the turbines, which turns an electric generator. 28. Name an advantage of using this nonrenewable energy resource. Coal is cost efficient and it can be transported very easily. 29. Name a disadvantage of using this nonrenewable energy resource. Coal is in limited supply and it releases pollutants into the air. 30. Where does hydropower get its energy? Hydropower gets energy from flowing water. 31. How does hydropower make electricity? Hydropower makes electricity by water flowing down a penstock, turning a turbine, which turns a generator. 32. Name an advantage of using this renewable energy resource. An advantage to using hydropower is that it does not release pollution into the air.
4 33. Name a disadvantage of using this renewable energy resource. A disadvantage of using hydropower is that it will destroy the habitat of wildlife that live in the river. Unit 3: Natural Hazards and Tectonic Plates 34. What are the effects of a thunderstorm? Wind damage, flooded streets and streams, eroded land, and hail damage. 35. What kind of hazard might be caused by tectonic plate movement? Tsunamis, earthquakes and / or volcanic eruptions 36. What are seismographs used for? Seismographs are used for detecting and measuring the earthquakes. 37. What causes the Earth s tectonic plates to move? The Earth s tectonic plates move because of convection currents in the mantle. 38. What type of plate boundary causes a rift valley? The plate boundary that causes a rift valley is a divergent boundary. 39. What type of boundary causes a mountain range? The plate boundary that causes a folded mountain range is a convergent boundary. 40. What type of boundary causes a fault zone? The plate boundary that causes a fault zone is a transform boundary. 41. What plate boundary exists between the North American Plate and the Pacific Plate? The plate boundary that exists between the North American Plate and the Pacific plate is transform boundary. Unit 4 Weather & Climate 42. What is weather? Weather is happening right now. (can happen in the near future or past) 43. What is an example of weather? 25 C in Bowling Green today. 44. What is climate? Climate is the average temperatures, wind speeds, precipitation for a certain region for a longer period of time. 45. What is an example of climate? An of average high and low monthly temperatures for 20 years
5 46. What would happen if the temperature of Earth rose over time? The increasing temperatures would cause the glaciers to melt, which in turn would increase in the amount of flooding because of rising sea levels. 47. What do greenhouse gases do? Greenhouse gases like CO2 trap thermal heat that is radiated towards space from Earth s surface. 48. How do plants reduce greenhouse gases? If the number of living plants significantly increased, global warming might be reduced because of the decrease in carbon dioxide caused by photosynthesis. 49. What would happen to the atmosphere if humans planted more trees? Planting more trees would decrease the amount of carbon dioxide reaching the atmosphere, reducing global warming. 50. Why is it important to use renewable energy resources? It is important to use renewable energy resources because, renewable energy sources produce fewer greenhouse gases than fossil fuels.