8th Grade Science Study Guides

Strand 1: Science and Engineering Practices Consider the graph to the right, and answer the questions below: 1. List the following:  Independent variable: depth (m)  Dependent variable: bubbles/min  Problem Question: W.I.T.E.O. water depth on the number Of bubbles produced by plant X  Hypothesis: If the depth of water plant X is in Is moderate, then it will produce more Oxygen bubbles, because it will get enough light for photosynthesis, but not be too warm.  Control variables: type/size of plant, timer, and number of leaves counting bubbles…… 2. Analyzing the data, list the following:  Highs/lows/range: High: 45 bubbles/min at 10 meters deep Low: approximately 8 bubbles per minute at around 37 m deep Range: 37 bubbles per minute (45 – 8)  Trends/patterns: The is a postitive realationship from 1-10 meters; as depth increases, so does the number of bubbles/minute; then there is a negative relationship at depths greater than 10 meters, as number of bubbles decreases as depth increases  Relationships (you can list 2): See above  Inference (something you can assume from the data, but is not directly in the graph): Temperature probably plays a role in oxygen production; fewer than 8 bubbles/min would be produced at 40 meters deep or more 3. How many bubbles did the plant produce at 25 meters deep? 20 bubbles/min 4. What instrument(s) would be needed to measure data in this experiment? Meter stick, timer 5. What metric base units are used to measure:   Length: meter Width: meter  Volume: cubic cm (cm3) or mL  Temperature: °C 6. What other observations about the water plants could scientists make?  Qualitative: green color, thick stem, small bubbles  Quantitative: depth, number of bubbles, number of leaves… 7. Why is a line graph used? When would you used a bar graph? Continuous data (depth – x axis); Bar graph would be for discreet (NOT quantifiable) 8. What is the most accurate measurement of the liquid volume in the graduated cylinder? (in metric liquid units) 21.2 mL Strand 2: History and Nature of Science 9. List scientific fields of the following people, AND their major accomplishments:  Charles Darwin: sailed around the world, studying species adaptations; BIG IDEAS: natural selection, variation, evolution, fossils, diversity, overproduction….  Gregor Mendel: Austrian monk who studied traits in pea plants; theorized dominant vs. recessive; “Father of Modern Genetics”  Schwann, Schleiden, Virchow: studied different aspects of cells through microscopes; CELL THEORY: All living things are made of cells; Cells are the basic units of structure and function in living things; Living cells come only from other living cells  Rosalind Franklin, James Watson, Francis Crick: All three were working on figuring out the structure of DNA; Watson and Crick saw a picture of Rosalind’s X-ray crystallography and instantly knew their model, with the base pairs on the outside was wrong; DNA was a double-helix (twisted ladder) with the base pairs (ATCG) on the inside, and the sugar-phosphate backbone on the outside Strand 3: Personal and Social Perspectives 10. Which population is invasive in this study? Gray Squirrels 11. Explain THREE possible impacts to the ecosystem where the invasive was introduced (include at least one NOT on the graph – infer) -Red squirrel population dropped drastically; -Coyote population decreased; -Coyotes may eat red squirrels, but not gray; -Red squirrels may become extinct and coyotes endangered/threatened -The carrying capacity of the gray squirrel, after the exponential growth, is slightly higher than the red… maybe they eat more of a variety of different foods 12. Propose at least one way ecologists might help minimize the impact of the invasive species They could study/trap grays to get more information; Game and Fish department could allow hunting/harvesting of grays; a predator that eats gray squirrels could be introduced; red squirrels could be bred in captivity and released…. Strand 4: Energy (also embedded in Chemistry/Life Science) 13. If the girl on the bike eats a nutritious lunch, hops on her bike, and starts pedaling, describe the energy transfer that starts the process in the picture. Chemical (Food) energy is transferred to mechanical (pedaling And both wheels turning); mechanical is transferred to electrical (wires), then heat and light in the bulb. 14. Where is heat/thermal energy leaving the system? Is that energy “gone”? Anywhere there is friction (the pulley cable and the wheels), some heat/thermal energy escapes the system. Also, heat/thermal energy is being emitted by the light bulb. This energy left the system, but is not “gone”. It is transferred to the environment outside the system 15. State the Law of Conservation of Energy AND Matter: Neither energy NOR matter can be created or destroyed – only transferred or changed forms Strand 5: Structure and Properties of Matter 16. 17. 18. 19. 20. Draw a complete model of a Lithium atom. Label PROTONS, NEUTRONS, and ELECTRONS. Define, in as many details as you can, the 3 terms above: Protons: have positive (+) charge, mass of 1 AMU; in nucleus Neutrons: have no charge (neutral), mass of 1 AMU; in nucleus Electrons: have negative (-) charge, relatively no mass (1/1800 of an AMU); Orbits in energy levels outside the nucleus 21. What elements would readily bond with Lithium? Explain why. Elements in GROUP 17 would because lithium has 1 valence e- and fluorine, chlorine… have 7 7 + 1 makes a “happy” full outer shell of 8 (stable like noble gases) 22. If it made an ionic bond, what kind of ion would Lithium make? Why? Lithium would lose an electron, giving it an overall positive charge of +1 (Li+1 – a cation), because it has one more proton (+) than it has electrons (-) 23. What PERIOD is Lithium in? What does this mean? Lithium is in PERIOD (horizontal row) 2, which means it has 2 energy levels for its electrons to orbit in 24. What GROUP is Lithium in? What does this mean? Lithium is in GROUP (vertical column) 1, because it has one valence (bonding) electron in its outer shell; this means it is HIGHLY reactive, and would tend to lose one electron 25. How many neutrons does Lithium have? How did you find the answer? Atomic mass (6.94 averages to 7) – Atomic number (number of protons: 3) = 4 neutrons 26. Draw a Bohr AND Lewis Dot Structure of Lithium below. 27. Are melting gold and toasting bread the same kind of change? Explain why or why not. - melting is a PHYSICAL state change – the molecules are staying the same, but moving faster and farther apart - toasting is a CHEMICAL change; the bread molecules are burning, and changing into carbon and other substances 28. What number balances the equation for photosynthesis? __6__ 29. List signs of a chemical reaction: unexpected temperature/color change, formation of a gas/precipitate, permanent change in physical properties (cannot be reversed by physical means like cooling/heating) 30. Describe what is happening in the diagram, including phase changes and particle/molecular energy.     1) freezing: molecules slowing and getting closer (liquid to solid) 2) melting: molecules speeding up and getting farther apart (solid to liquid) 3) condensing: molecules slowing and getting closer (gas to liquid) 4) vaporizing: molecules speeding up and getting farther apart (liquid to gas) 31. What is the formula for density? What volume would a block of wood have if it had a density of .9 g/cm3 and a mass of 27 g (use/show the formula triangle)? 27 g ÷ .9 g/cm3 = 30 cm3 32. Draw particle diagrams for an ELEMENT, COMPOUND and MIXTURE: Element (one type of atom) Compound (2 or more types of atoms, chemically bonded in a set ratio) Mixture (two or more different types of molecules) 33. Give examples of substances that are:  ELEMENT: gold, silver, helium….. anything on the periodic table  COMPOUND: carbon dioxide (CO2), water (H2O), Table Salt (NaCl)…. Anything with a set ratio (chemical formula)  HOMOGENEOUS MIXTURE: mayonnaise, butter, clay…. Anything that “looks” the same, but has different ingredients, not chemically bonded  HETEROGENEOUS MIXTURE: dirt, Italian salad dressing, marble…. Anything where different components are visible to the naked eye. 34. Make a pH scale below, and label ACIDS and BASES. 35. Explain what happens when an acid and a base react. Use hydrochloric acid and Sodium Hydroxide (HCl + NaOH) as an example. any acid + base = water + salt Strand 4: Life Science / Biology 36. Explain the difference between BIOTIC and ABIOTIC factors: BIOTIC factors: anything living in an environment (algae, plants, animals, fungi….) ABIOTIC factors: any NON-living thing in an environment (dirt, terrain, altitude, weather…) 37. Define an ecosystem, using the terms above: 1. ECOSYSTEM: a biological community of interacting organisms (biotic factors) and their physical environment (abiotic factors). 38. Label the type of growth shown in the graphs below. What does the dotted line represent?  Carrying Capacity Exponential growth   Logistic Growth 39. What 4 factors influence population size? Birth rate, death rate, immigration, emigration 40. Draw a Punnett Square for possible offspring if the mother has green eyes (genotype Gb) and the father has blue eyes. List the percentages for each possible genotype of eye color. Which is dominant and which is recessive? Green – dominant; Blue - recessive b b Probability: G Gb Gb Green phenotype: 50% b bb bb blue phenotype: 50% 41. Explain how Mountain Mice was an example of Darwin’s Natural Selection Organisms with contrasting fur color have less likelihood of survival, because they are easily seen/eaten by predators (a genetic disadvantage in survival) 42. What is the difference between a behavioral and a physical adaptation? Give an example of each. BEHAVIORAL: something an organism DOES that influences survival (migration, hibernation, mating dances….) PHYSICAL: something an organism HAS on/in its body/structure that influences survival (wings, camouflage, claws, xylem/phloem, anther….) 43. List the parts/purpose of:  ROOTS: xylem/phloem… helps absorb water/minerals and anchor plant  STEMS: xylem/phloem… transport food from leaves and water/minerals from roots; support plant  LEAVES: vascular tissue, stoma, chloroplasts…. Absorbs energy from sun (photosynthesis) and respires through stoma  FLOWERS: anther/stigma (stamen - male), pistil (stigma, ovary, seeds.. female); reproductive organs of plant 44. Explain/sketch how photosynthesis are related *Mitochondria’s produces ATP 45. Draw a pedigree chart for sickle cell disease, where mom is NOT a carrier (CC) and dad has a mild form of sickle cell disease (Cc) and their 4 possible offspring (do a Punnett).