Physical
What is the smallest particle of an element that still retains the properties of that element?
Atom.
What type of rock is formed from the compaction and cementation of sediments? (One-word answer.)
Sedimentary.
Which of these is smaller and nonliving: bacteria or virus? (Answer with the correct choice and one short reason.)
Virus — it is nonliving and much smaller, requiring a host cell to replicate.
Classify the following as a physical change or a chemical change: melting ice, rust forming on iron, and dissolving sugar in water. Provide one sentence justification for each.
Melting ice: physical change (state change, no new substance). Rust forming: chemical change (new substance Fe2O3, color change). Dissolving sugar: physical (sugar molecules disperse; no new chemical bonds broken/formed).
Describe how index fossils are used to determine the relative age of rock layers. (Two to three sentences.)
Index fossils are remains of species that lived for a relatively short, well-known time and are widespread; finding an index fossil in a layer lets geologists correlate and order layers by relative age.
Define the difference between an epidemic and a pandemic. Give one historical example of each (name and brief context).
Epidemic: disease outbreak in a specific region (e.g., 2014–2016 Ebola outbreak in West Africa). Pandemic: global spread across multiple countries/continents (e.g., 2009 H1N1 influenza pandemic; 2020 COVID-19 pandemic).
Use the periodic table idea: Which atomic subparticle determines the chemical reactivity of an element and why? (One-sentence answer referencing subparticle and its role.)
Electrons (especially valence electrons) determine chemical reactivity because they participate in bond formation and chemical reactions.
Explain two ways that ocean currents influence Earth's climate. Give one specific example (e.g., a named current or regional climate effect).
Currents redistribute heat (e.g., Gulf Stream warms Western Europe) and affect precipitation patterns/nutrient distribution (upwelling brings nutrients to surface, supporting marine life).
Describe one example of a biotic and one example of an abiotic factor in an ecosystem, and explain how each can affect population size.
Biotic: predator presence — can reduce prey population. Abiotic: drought (water shortage) — can reduce plant growth and thus food availability, lowering populations.
Explain how the Law of Conservation of Mass applies to a sealed chemical reaction. Include what would happen to total mass before and after the reaction.
In a sealed system, total mass of reactants equals total mass of products; atoms are rearranged but not created/destroyed, so measured mass stays the same
Given data showing increasing global average temperature since industrialization, name two human activities that contribute to this trend and briefly explain one mechanism by which they increase global temperature.
Examples: burning fossil fuels (releases CO2, enhances greenhouse effect), deforestation (reduces CO2 uptake). Mechanism: increased atmospheric greenhouse gases trap more outgoing infrared radiation, raising temperatures.
Using natural selection, explain how a trait that provides an advantage in an environment becomes more common in a population over generations. Include the roles of variation and reproductive success.
Individuals with advantageous heritable traits survive and reproduce more successfully; these traits become more common as offspring inherit them. Variation provides differences; selection increases frequency of beneficial traits over generations.
Balance this chemical equation and state whether mass is conserved: C3H8 + O2 yields CO2 + H2O (Show the balanced equation.)
Balanced: C3H8 + 5O2 yields 3CO2 + 4H2O Mass is conserved.
Describe how temperature and salinity together drive major ocean currents. Include how changes in these factors affect water density and movement.
Higher salinity and lower temperature increase water density, causing it to sink; lower salinity and higher temperature reduce density and cause rising — combined with wind and Earth rotation, these density differences drive thermohaline circulation.
Explain how energy flows through a simple food web of three trophic levels (producer → primary consumer → secondary consumer) and describe how matter (carbon or water) cycles through the same system.
Energy flows: producers capture solar energy and make biomass; primary consumers eat producers and gain energy; secondary consumers eat primary consumers. Matter cycles: carbon moves from atmosphere into producers (photosynthesis), into consumers (feeding), and back to the atmosphere via respiration and decomposition; water cycles via transpiration, evaporation, precipitation.