ASVAB General Science Study Guide: Core Concepts

01 /

Build a map before memorizing isolated facts

An ASVAB General Science study guide should connect ideas across biology, chemistry, physics, and earth science. Start with a small map of each area, then attach definitions and examples. Memorizing random facts can leave you unable to distinguish two closely related concepts when the wording changes.

The official subtest description identifies physical and biological sciences as the scope. The examples below are a foundation review, not an exhaustive content blueprint or a prediction of particular questions. Use the General Science subject page to plan a focused practice session.

For every concept, ask three questions: What does it mean? What is an example? What similar concept should I distinguish it from? Those comparisons often reveal gaps more clearly than rereading a definition.

02 /

Biology: structure and function

Cells are the basic units of living organisms. In typical human cells, the nucleus contains most genetic material, the membrane controls exchanges with the surroundings, and mitochondria participate in cellular energy production. Learn what each structure does instead of memorizing a diagram without its functions.

For body systems, connect the organ to the process. The lungs support gas exchange; the heart pumps blood; the digestive system breaks down food and absorbs nutrients. A question about moving oxygen through the body can involve both respiratory and circulatory functions, so distinguish obtaining oxygen from transporting it.

Plants use photosynthesis to store energy in chemical form using light, carbon dioxide, and water. Cellular respiration releases usable energy from nutrients. Plants carry out respiration as well as photosynthesis. Avoid the misconception that respiration is only for animals or that all plant processes stop when the light disappears.

03 /

Chemistry: atoms, mixtures, and changes

An atom contains protons, neutrons, and electrons. Protons determine the element’s atomic number. Electrons carry negative charge; protons carry positive charge; neutrons have no net charge. An ion has a net charge because the balance of protons and electrons differs.

An element contains one kind of atom. A compound combines elements chemically in a fixed relationship. A mixture combines substances without requiring that fixed chemical combination. Salt water is a mixture; the dissolved salt itself is a compound. These categories describe different levels of the same sample.

A physical change alters form or state without creating a new substance, such as ice melting. A chemical change creates different substances, such as iron rusting. “A visible change happened” is not enough to classify it; ask whether the substance’s chemical identity changed. Acids and bases are another useful comparison: on the conventional introductory aqueous pH scale, below seven is acidic, above seven is basic, and seven is neutral.

04 /

Physics: forces, energy, and matter

Speed describes how fast distance changes; velocity also includes direction. Acceleration is a change in velocity over time. A vehicle can accelerate by changing direction even when its speed stays constant. Keep these definitions distinct rather than treating every motion word as a synonym.

Mass concerns the amount of matter, while weight is a gravitational force. Energy can change form: a moving object has kinetic energy, and a raised object has gravitational potential energy. In a basic falling-object model, potential energy decreases while kinetic energy increases, with the detailed outcome depending on effects such as air resistance.

Heat transfer occurs by conduction through contact, convection through moving fluids, and radiation through electromagnetic waves. A metal spoon warming in soup illustrates conduction; circulating warm water illustrates convection. Use a concrete example for each mechanism, then practice telling them apart in a new setting.

05 /

Earth science and a focused review routine

Weather describes short-term atmospheric conditions; climate describes longer-term patterns. A rainy afternoon does not by itself establish a region’s climate. In the water cycle, evaporation changes liquid water to vapor, condensation produces liquid droplets, and precipitation returns water from the atmosphere to the surface.

Connect rock types to formation. Igneous rocks form from cooled molten material, sedimentary rocks from accumulated material that becomes consolidated, and metamorphic rocks from existing rock altered by heat and pressure. The formation process is a better memory cue than the name alone.