Subtest II: Science - Physical, Life, and Earth and Space Science plus Investigation
Subtest II Science spans physical science (matter, motion, energy, waves), life science (cells, heredity, evolution, ecosystems, body systems), Earth and space science (rocks, plate tectonics, weather and climate, the solar system), and scientific investigation - variables, measurement, data representation, and evidence-based explanation.
Physical science anchors
- Matter is conserved in changes of state; chemical changes create new substances. Density = mass ÷ volume, and objects denser than the fluid sink.
- Newton's laws: inertia, F = ma, action-reaction. Energy transfers but is conserved; heat flows from warmer to cooler until equilibrium.
- Waves carry energy without transporting matter; frequency × wavelength = speed.
Life science anchors
- Cells are the basic unit; the cell membrane regulates what enters and exits; organelles have specific roles.
- DNA → genes → proteins; inherited traits come from genes plus environment.
- Energy pyramids lose roughly 90% of usable energy at each level, so top predators are fewest. Producers occupy the base; decomposers recycle nutrients.
Earth and space anchors
- Plate tectonics: divergent boundaries create new crust (mid-ocean ridges); convergent boundaries build mountains or subduct; transform boundaries cause faulting.
- Rock cycle: igneous from cooling magma, sedimentary from compaction of deposited material, metamorphic from heat and pressure.
- Seasons result from Earth's 23.5° axial tilt, not distance from the Sun; moon phases arise from orbital geometry, while eclipses require alignment.
Worked example. A block has mass 54 g and volume 20 cm³. Density = 54 ÷ 20 = 2.7 g/cm³ - consistent with aluminum. Because 2.7 > 1.0 g/cm³ (water), the block sinks; in a liquid of density 3.0 g/cm³ it would float, since floating depends on comparison with the fluid, not the solid alone.
Investigation
Identify the independent variable (what the investigator changes), the dependent variable (what is measured), and constants. Include a control group, repeat trials, and graph the manipulated variable on the x-axis.
Traps. Confusing mass with weight or heat with temperature; calling a hypothesis a theory; stating the Sun's distance causes seasons; attributing phases to Earth's shadow; describing metamorphic rock as melting directly into sedimentary rock; placing decomposers at the top of an energy pyramid.