MAP General Science (Grades 6-8) 2 — Questions and Answers
Question 1: What type of rock is formed when magma cools and solidifies?
- Sedimentary
- Metamorphic
- Igneous (Correct answer)
- Limestone
Correct answer: Igneous
Igneous rock forms when magma (underground) or lava (on Earth's surface) cools and solidifies. The word 'igneous' comes from Latin for 'fire.'
The three rock types and their formation: Igneous = formed from cooled magma or lava (granite, basalt, obsidian). Sedimentary = formed from compressed layers of sediment (sandstone, limestone, shale). Metamorphic = formed when existing rock is transformed by heat and/or pressure (marble, quartzite, slate). Limestone is a type of sedimentary rock, not a rock category. MAP Growth Earth Science tests the rock cycle and rock type classification.
Question 2: What is the difference between weather and climate?
- They mean exactly the same thing
- Weather is long-term; climate is short-term
- Weather is day-to-day atmospheric conditions; climate is the long-term pattern (Correct answer)
- Climate is what it is like outside; weather is a scientific theory
Correct answer: Weather is day-to-day atmospheric conditions; climate is the long-term pattern
Weather describes short-term atmospheric conditions (today's temperature, rain). Climate describes the long-term average weather patterns of a region over 30 or more years.
Weather = the current or short-term state of the atmosphere (today's temperature, precipitation, wind). Climate = the long-term average pattern of weather in a region over 30 or more years. A desert has a dry climate, but may occasionally have rain (weather). MAP Growth Earth Science tests this key distinction between weather and climate, as well as climate change concepts.
Question 3: Which of the following best describes the process of natural selection?
- Humans choose which animals survive in nature
- Organisms with traits better suited to their environment are more likely to survive and reproduce (Correct answer)
- All members of a species evolve at the same rate
- Stronger animals always live longer than weaker ones
Correct answer: Organisms with traits better suited to their environment are more likely to survive and reproduce
Natural selection is the process by which organisms with favorable traits for their environment are more likely to survive, reproduce, and pass those traits to offspring.
Charles Darwin's theory of natural selection states: (1) Variation exists among individuals. (2) Some variations are heritable (passed to offspring). (3) More offspring are produced than can survive (competition). (4) Individuals with favorable traits are more likely to survive and reproduce. Over time, favorable traits become more common in the population. This is the mechanism of evolution. MAP Growth Life Science tests natural selection and evolution at grades 6-8.
Question 4: A wave has a frequency of 5 Hz and a wavelength of 4 meters. What is its wave speed?
- 1.25 m/s
- 9 m/s
- 20 m/s (Correct answer)
- 0.8 m/s
Correct answer: 20 m/s
Wave speed = frequency times wavelength = 5 Hz times 4 m = 20 m/s.
The wave speed formula: v = f times lambda, where v = wave speed, f = frequency (Hz), lambda = wavelength (meters). Substituting: v = 5 Hz times 4 m = 20 m/s. Frequency = number of waves per second; Wavelength = distance between consecutive crests or troughs. This formula applies to all wave types (sound, light, water waves). MAP Growth Physical Science tests wave properties and calculations.
Question 5: What happens to the density of water when it freezes into ice?
- Density increases because the molecules pack more tightly
- Density stays the same
- Density decreases because ice forms an open crystalline structure (Correct answer)
- Density varies depending on temperature
Correct answer: Density decreases because ice forms an open crystalline structure
When water freezes, hydrogen bonds arrange water molecules into an open hexagonal lattice (ice crystal structure) that is less dense than liquid water — which is why ice floats.
Water is unusual because its solid form (ice) is less dense than its liquid form. When water freezes, hydrogen bonds form a hexagonal crystalline lattice that spaces molecules farther apart than in liquid water. This means ice has lower density (0.917 g/cm3) than liquid water (1.00 g/cm3). As a result, ice floats. This property is crucial for aquatic life — frozen lakes insulate liquid water beneath the ice. MAP Growth Physical and Earth Science tests properties of water.
Question 6: Which of the following is an example of a renewable energy source?
- Coal
- Natural gas
- Nuclear energy
- Solar energy (Correct answer)
Correct answer: Solar energy
Solar energy is renewable because it comes from the sun, which is an essentially inexhaustible natural resource. Coal and natural gas are fossil fuels (non-renewable).
Renewable energy sources are replenished naturally on human timescales: Solar (sunlight), Wind, Hydroelectric (flowing water), Geothermal (Earth's heat), Biomass (plant/organic material). Non-renewable sources are finite and take millions of years to form: Coal, Oil, Natural gas (fossil fuels), Nuclear (uranium is finite). MAP Growth Earth Science tests energy sources and environmental science concepts.
MAP General Science (Grades 6-8) 2
What type of rock is formed when magma cools and solidifies?