Semester Exam Review 8Th Grade Science

Semester Exam Review – 8th Grade Science Spring 2010

1. How do you calculate Density? Density = Mass/ volume (mass divided by volume) 2. What would be the density of an object that is 25 g and 10 cm3 25/10 = 2.5 gm/cm3 3. What tools do you need to calculate density? A triple beam balance and a graduated cylinder 4. What is the effect of weathering and erosion on landforms, such as mountains? Weathering breaks down rock into sediment, and erosion carries the sediment away. This process gradually wears down landforms making them smaller and smaller 5. What evidence did Alfred Wegener have to support the theory of Continental Drift? 1. Puzzle piece shape of continents fit together 2. Fossils found on multiple continents that couldn’t have gotten there unless the land was connected. 3. Landforms continue from one continent to the next when they are placed together – example mountain range from S. America to Africa 6. What are the 3 types of plate boundaries? 1. Divergent – Moving apart 2. Convergent – Moving together (crashing into each other) 3. Transform – Sliding past each other (California – San Andreas Fault) 7. What landforms are created at each of these? 1. Divergent: Sea Floor Spreading creates underwater volcanic mountains, on land divergent creates rift valleys 2. Convergent: Continent to Continent producesFolded mountains – like two cars having a head on crash & crumpling up at the front. Ocean to Continent creates subduction zones. Subducted ocean crust sinks back into the mantle and gets recycled. Volcanic mountains form on land because of the friction of the subducting plate 3. Transform: Faults and earthquakes 8. What is subduction? Subduction is where the ocean crust sinks below the continental crust and gets melted back into the mantle 9. What happens to ocean crust in subduction zones? Subducted ocean crust sinks back into the mantle and gets recycled. 10. What is sea floor spreading? Magma from the mantle rises at the mid ocean ridge because it is less dense than the surrounding cooler material. This rising magma pushes the ocean plates away and forms underwater volcanic mountains. 11. What landform results from sea floor spreading? Mid Ocean Ridge – Underwater volcanic mountain range 12. What forms of energy travel as mechanical waves? Seismic waves, Sound waves and Water waves 13. What forms of energy travel as electromagnetic waves? The EM Spectrum: Microwaves, Radio waves, Light Waves, Ultraviolet Waves, X rays, Gamma Rays 14. What is the difference between potential energy and kinetic energy? Potential is stored energy and is based on the position of the object (the higher it is the more potential), Kinetic is the energy of movement – the more movement the more kinetic energy 15. Where on a rollercoaster would the train have the most potential energy? (draw a sketch if needed). At the top of the highest hill 16. Where would the rollercoaster have the most kinetic energy? (sketch if needed) Where it is traveling the fastest – usually at the bottom of the highest hill 17. Explain Newton’s 2nd law in words. Give an example to illustrate it. Force = mass x acceleration. The more mass an object has, the more force it takes to move it. 18. How does specific heat influence climate? Remember our example of being barefoot on the beach vs. barefoot in the water) Water has a HIGHER SPECIFIC HEAT than land – so it can absorb more energy without changing temperature. Because of this, places near the ocean have a milder, more even climate with less difference between summer and winter temperatures. The ocean absorbs the energy that would otherwise cause the temperature to go higher on land. 19. What has more impact on climate – elevation or proximity (how close) to the ocean? Closer to the ocean = milder climate 20. How does the burning of fossil fuels affect the Earth’s atmosphere? Contributes to global warming (rise in average temperature of Earth) by adding more CO2 into the atmosphere 21. What is homeostasis? Homeostatis is when all the systems within an organism are in balance and functioning within normal ranges. When things are NOT in balance your body will do things like sweat or shiver to maintain body temperature, or make you feel thirsty to get more water into your system etc 22. What is the main function of each of these body systems: a. Circulatory – Transport nutrients and oxygen throughout your body b. Respiratory – exchanges gases – brings in 02 and gets rid of CO2 c. Immune – battles infection and foreign viruses etc in your body d. Digestive – breaks down food to a form which is usable by your cells for energy e. Excretory – Rids your body of wastes not needed for function – gases, liquids and solid wastes 23. What is the difference between an inherited trait and an environmental (acquired trait)? Give examples of each? Inherited traits are passed on through genes in the DNA. Environmental traits are acquired during an organisms lifetime and are NOT passed on to offspring. Inherited = eye color, hair color Acquired: A scar from an accident, a tattoo or pierce ears. 24. What is the genotype of an organism? The actual PAIR OF GENES that determine a trait – for example GG, Gg, BB, bb 25. What is the phenotype? The physical expression of the genotype – for example curly hair, blue eyes, left handed 26. Know how to work a punnett Square and determine ratios and probability

R=red r=white Give genotype and phenotype ratios

27. What is a producer? Give examples? A producer makes its own food using photosynthesis – examples are grasses, algae, trees, flowers – basically any plant 28. What is a consumer? What are some different types of consumers? Give examples Consumers have to eat other organisms to get their energy. They can’t make their own food. Carnivores are consumers that eat meat, herbivores are consumers that eat only plants, omnivores are consumers that eat both meat and plants, and scavengers eat animals that are already dead 29. What is a decomposer and why are they important to the food web? Give examples Decomposers are fungi (mold and mushrooms) and bacteria. Without them, dead organic material couldn’t be broken down. Then the nutrients wouldn’t be returned to the soil to be put back into the food web 30. What is the difference between biotic and abiotic factors in an ecosystem? Give examples of each. Biotic means living factors, abiotic means non-living factors. Biotic = bacteria, plants, animals, grass, bugs etc. Abiotic = sun, temperature, soil, light 31. Explain how the sun’s energy is actually responsible for supporting organisms at all levels of the food chain. ALL organisms get their energy from the sun – sometimes it just has to pass through other organisms first. A mouse eats a seed, then the energy in that sun is transferred to the mouse. When an owl eats the mouse, the sun’s energy is transferred from the mouse to the owl. Consumers can’t get energy directly from the sun, but it does provide the energy found in all the food the consumer eats 32. Put these components of the Universe in order from largest to smallest AND from Smallest to largest: Galaxy, Solar System, Universe, Planet a. Universe, Galaxy, Solar System, Planet b. Planet, Solar System, Galaxy, Universe 33. How are distances measured in space? Why do we have to use a different method for measuring them? Distances in space are measured in Light Years – this is the distance light can travel in 1 year. We use light years because the distances between objects in space is so huge. One light year is about 9,500,000,000,000 kilometers 34. What is a Hertzsprung Russell Diagram? An HR Diagram is used to classify stars based on brightness and temperature. Temperature is on the X axis with Brightness on the Y axis see example below

35. What two characteristics of stars are graphed on a Hertzsprung Russell Diagram? Brightness (Luminosity) and Temperature 36. How does the brightness and size of our Sun compare to other stars? Our sun is an average star in size, brightness and temperature. It is a Main Sequence Star 37. What is a galaxy? A galaxy is a group of stars, dust and gases that is held together by gravity 38. What are the 3 types of galaxies? Draw a sketch of each

Spiral Elliptical Irregular 39. What causes the moon to have phases? The sun’s light reflects off the surface of the moon – from earth we can see various fractions of that lit surface at different times in the month 40. What percentage of the moon’s lit side can we see at a full moon? 100 % 41. What percentage of the moon’s lit side can we see at a new moon? 0%