BMST Earth's Geological Cycles 5 — Questions and Answers
Question 1: What is the primary mechanism by which heat from Earth's interior reaches the surface through the mantle?
- Conduction
- Radiation
- Convection (Correct answer)
- Advection
Correct answer: Convection
Convection currents in the mantle transfer heat from Earth's hot interior upward toward the crust, driving plate tectonics.
Question 2: In the phosphorus cycle, where is most of Earth's phosphorus stored?
- The atmosphere
- Ocean water
- Rocks and sediments (Correct answer)
- Living organisms
Correct answer: Rocks and sediments
Unlike carbon and nitrogen, phosphorus has no atmospheric phase — the vast majority is stored in rocks and sediments.
Question 3: Which type of seismic wave travels only along Earth's surface and causes the most damage during an earthquake?
- P-waves (primary waves)
- S-waves (secondary waves)
- Surface waves (Correct answer)
- Body waves
Correct answer: Surface waves
Surface waves travel along the ground surface and have a rolling or shaking motion that causes the greatest structural damage in earthquakes.
Question 4: What geological time scale feature is used to identify boundaries between major periods based on mass extinctions?
- Isotopic ratios
- Fossil assemblages (Correct answer)
- Magnetic reversals
- Rock color changes
Correct answer: Fossil assemblages
Changes in fossil assemblages — particularly mass extinctions — are the primary markers used to define boundaries between geological periods.
Question 5: How does the infiltration of rainwater contribute to the geological cycle?
- It directly causes volcanic eruptions
- It weathers rocks and dissolves minerals, eventually reaching groundwater (Correct answer)
- It forms new igneous rocks underground
- It prevents erosion by stabilizing soil
Correct answer: It weathers rocks and dissolves minerals, eventually reaching groundwater
Infiltrating rainwater chemically weathers rocks, dissolves minerals, and carries them into groundwater systems as part of the hydrological and rock cycles.
Question 6: What term describes the slow, large-scale movement of Earth's lithospheric plates over geological time?
- Isostasy
- Plate tectonics (Correct answer)
- Geomorphology
- Continental weathering
Correct answer: Plate tectonics
Plate tectonics is the theory describing the large-scale movement of Earth's lithospheric plates, explaining earthquakes, volcanoes, and mountain building.
Question 7: Which process returns nitrogen from dead organisms back to the soil in a usable form?
- Nitrogen fixation
- Nitrification
- Denitrification
- Decomposition and ammonification (Correct answer)
Correct answer: Decomposition and ammonification
Decomposers break down dead organisms through ammonification, converting organic nitrogen into ammonia that can be used by plants and other organisms.
BMST Earth's Geological Cycles 5
What is the primary mechanism by which heat from Earth's interior reaches the surface through the mantle?