8 th Grade Science 4th Quarter Final Study Guide ANSWER KEY

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1 Name: Period: Test Date: 8 th Grade Science 4th Quarter Final Study Guide ANSWER KEY Unit 1: Experimental Design 1. 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. 2. What is an independent variable? The independent variable is the factor of the experiment that is tested, or changed on purpose by the investigator. 3. 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 4. 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.) 5. What kind of graph shows change over time? A graph that shows change over time is a line graph. 6. 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. 7. 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. 8. 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. Unit 2: Renewable and Nonrenewable Resources 9. 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) 10. What is a nonrenewable resource? Nonrenewable resources that are used faster than they can be replaced by natural processes. 11. 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.

2 12. How is coal used to make electricity? Coal is burned to make steam, which turns the turbines, which turns an electric generator. 13. Where does hydropower get its energy? Hydropower gets energy from flowing water. 14. Name an advantage of using a hydropower energy resource. An advantage to using hydropower is that it does not release pollution into the air. 15. Name a disadvantage of using a hydropower 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 16. What are the effects of a thunderstorm? Wind damage, flooded streets and streams, eroded land, and hail damage. 17. What kind of hazard might be caused by tectonic plate movement? Tsunamis, earthquakes and / or volcanic eruptions 18. What are seismographs used for? Seismographs are used for detecting and measuring the earthquakes. 19. What causes the Earth s tectonic plates to move? The Earth s tectonic plates move because of convection currents in the mantle. 20. What type of plate boundary causes a rift valley? The plate boundary that causes a rift valley is a divergent boundary. 21. What type of boundary causes a mountain range? The plate boundary that causes a folded mountain range is a convergent boundary. 22. What type of boundary causes a fault zone? The plate boundary that causes a fault zone is a transform boundary. 23. 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 24. What is weather? Weather is happening right now. (Could happen in the near future or past)

3 25. What is climate? Climate is the average temperatures, wind speeds, precipitation for a certain region for a longer period of time. 26. 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. 27. What do greenhouse gases do? Greenhouse gases like CO2 trap thermal heat that is radiated towards space from Earth s surface. 28. 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. 29. 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. 30. 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. Unit 5 Interdependence in Ecosystem 31. What is a biotic factor? All living or once living parts of an ecosystem that directly or indirectly affect the environment. 32. What is an abiotic factor? All of the non living or NEVER living parts of an ecosystem. 33. What is a population? Give an example of a population. A population is a group of individuals of the same species that live together in the same area at the same time. An example of a population would be all of the clams that live and breed in a shallow ocean ecosystem. A population is a biotic factor. 34. What is a community? Give an example of a community. A community is a group of cooperating populations. So basically its all of the living (biotic) parts of an ecosystem. An example of a community would be a pine tree, beavers, hawks, and fish living in a riverside ecosystem. 35. What is an ecosystem? Give an example of an ecosystem. An ecosystem is a community (biotic) and all of its non-living (abiotic) parts of the environment. An example of an

4 ecosystem would be a fish pond with natural sunlight, water, plants to recycle carbon dioxide and water, fish to eat some of the water plants and use the gas emitted. 36. What are some examples of human disruptions to an ecosystem? Pollution, habitat destruction, causing a forest fire, overhunting, over fishing, introducing an invasive species (non-native species) into a new ecosystem, destroying natural habitats. 37. What is parasitism? Give an example. Parasitism is a symbiotic relationship where one organism benefits and the other organism is harmed. An example would be a tick and a deer. The tick drinks blood from the deer which is a benefit and the deer is harmed because it is losing blood. 38. What is mutualism? Give an example. Mutualism is a symbiotic relationship in which both organisms benefit from the relationship a cleaner shrimp and a remoray eel. The eel gets its teeth cleaned and the shrimp gets a free meal. 39. What is commensalism? Give an example. Commensalism is a symbiotic relationship where one organism benefits and the other organism is unaffected. An example of a commensalistic relationship is a remora fish attaching themselves to the body of a shark without hurting the shark, and feed upon the shark s leftover food. 40. What is a characteristic of a stable environment? A characteristic of a stable environment is that it usually contains a great diversity of species. Unit 6 Protein Synthesis and Mutations 41. What is the function of DNA? The function of DNA is for encoding genetic information to make proteins. 42. What is trna and what is its function? trna is a RNA structure that contains an amino acid and an anticodon. Transfer RNA molecules pick up amino acids, which are free in the cytoplasm and carry them to the ribosomes. 43. What is mrna and what is its function? mrna is a single strand of RNA that is complementary to a gene strand of DNA. The function of mrna is to carry the instructions for protein synthesis of a particular protein from DNA in the nucleus of the cell to the ribosomes in the cytoplasm. 44. What organic compound must information be encoded in DNA for green plants to synthesize the other three compounds? proteins

5 45. Using a codon chart identify the amino acid that corresponds with ACA. Threonine 46. Using a codon chart identify the amino acid Glutamine. CAA, and CAG. 47. Describe deletion mutations and what the altered code sequence would look like. A deletion mutation is a mutation where part of the code has been removed from the original sequence. An example would be: a. Normal DNA GTAATCTTG b. Deletion mutation GAATCTTG 48. Describe substitution mutation and what the altered code sequence will look like. A substitution mutation is where a nitrogen base or bases are swapped for another nitrogen base. a. Normal DNA GTAATCTTG b. Substitution mutation CTAATCTTG 49. Describe an insertion mutation and what the altered code sequence would look like. An insertion mutation is where a nitrogen base or bases is added to the original DNA sequence. a. Normal DNA GTAATCTTG b. Insertion mutation - GTACATCTTG 50. Describe how a mutation can be beneficial, harmful, or neutral. a. A mutation can be beneficial if it provides the organism with a trait that will help them survive. b. A mutation can be neutral, or silent, if there is no noticeable change in the organism. c. A mutation can be harmful if it affects the survival of the organism 51. Give an example of a beneficial, neutral and harmful mutations. a. Beneficial - An organism with faster reflexes, camouflaged coloration, or better defense mechanisms. b. Neutral - A horse with the same color fur as his parents. There is a mutation in the genetic code but not in the amino acid sequence for coat color. c. Harmful - An organism that is born with no color pigmentation (albinism) will be extremely noticeable and vulnerable in the wild.

6 Unit 7 Reproduction and Genetics 52. What are nucleic acids? Nucleic acids are the genetic material in living organisms that is composed of organic molecules 53. What is mitosis? The process of cell division in somatic cells, where the products are identical to the parent cell. Mitosis ends in two genetically identical daughter cells. 54. What is meiosis? Meiosis results in four gamete cells which are genetically different from the parent cell. 55. A male sheep has 32 chromosomes in each of its sex cells. How many chromosomes would be present in a normal body cell of a sheep? If somatic cell in a wolf contains 30 chromosomes, how many chromosomes would a wolf egg cell contain? What is one advantage of sexual reproduction? Genetic variety 59. What is one advantage of asexual reproduction? Requires one parent 60. Which of the following statements describes the parental genotypes that would result in this Punnett square? RR Rr RR Rr RR x Rr (heterozygous dominant crossed with homozygous) 61. In mice, the allele for brown coloring (B) is dominant, and the allele for white coloring (b) is recessive. For which parental genotypes are 100% of the offspring expected to be white? bb x bb 62. In Snakes, the allele for patterned scales (P) are dominant. The allele for plain scales (p) is recessive. Two snakes were crossed as shown in the Punnett Square below. Which of these describes the phenotypes of the parent snakes? What is the probability that an offspring from this cross would have plain scales? P p P PP Pp P PP PP 0%