asvab science

Hypothesis

A testable explanation or prediction for a scientific observation.

Independent variable

The variable in an experiment that is intentionally changed or manipulated by the experimenter.

Dependent variable

The variable in an experiment that is measured or observed to determine the effect of the independent variable.

Control group

The experimental group that does not receive the experimental treatment or change, serving as a baseline for comparison.

Observation

Information gathered directly using physical senses or scientific measuring tools.

Inference

A logical conclusion or interpretation drawn from observations and prior knowledge.

SI base unit for length

Meter ($m$)

SI base unit for mass

Kilogram ($kg$)

SI base unit for time

Second ($s$)

Basic unit of life

Cell

Nucleus (cellular)

The membrane-bound organelle that contains genetic material ($DNA$) and controls cell activities.

Mitochondria

Organelles that carry out cellular respiration to produce most of a cell's usable energy ($ATP$).

Ribosomes

Cellular structures responsible for protein synthesis.

Cell membrane

A selectively permeable membrane that regulates what enters and leaves the cell.

Cell wall

A rigid outer layer present in plant cells, fungi, and bacteria that provides structural support.

Chloroplast

The organelle found in plant and algal cells where photosynthesis takes place.

Diffusion

The passive movement of particles from an area of higher concentration to an area of lower concentration.

Osmosis

The diffusion of water molecules across a selectively permeable membrane.

Gas taken in by plants during photosynthesis

Carbon dioxide ($CO_2$)

Gas released by plants during photosynthesis

Oxygen ($O_2$)

Main usable chemical energy source for cellular work

Adenosine triphosphate ($ATP$)

Cellular respiration

The metabolic process by which cells break down nutrients to release stored energy in the form of $ATP$.

DNA (Deoxyribonucleic acid)

The double-stranded nucleic acid molecule that stores genetic information.

Gene

A specific sequence of $DNA$ on a chromosome that encodes instructions for a specific trait or function.

Mitosis

Cell division resulting in two genetically identical diploid somatic (body) cells.

Meiosis

Cell division producing four genetically unique haploid gametes (sex cells) with half the original chromosome number.

Dominant trait

A genetic trait expressed when at least one dominant allele is present in the genotype.

Recessive trait

A genetic trait that is expressed only when two copies of the recessive allele are present.

Mutation

A permanent change in the nucleotide sequence of an organism's $DNA$.

Arteries

Blood vessels that carry blood away from the heart.

Veins

Blood vessels that carry blood back toward the heart.

Hemoglobin

The iron-containing protein in red blood cells that reversibly binds and transports oxygen.

Alveoli

Tiny air sacs in the lungs where gas exchange ($O_2$ and $CO_2$) takes place with surrounding capillaries.

Organ that produces bile

Liver

Organ that stores and concentrates bile

Gallbladder

Small intestine

The part of the digestive tract where most chemical digestion and nutrient absorption occur.

Homeostasis

The maintenance of a stable internal state within a cell or organism.

Producer (autotroph)

An organism that synthesizes its own food using energy from the environment (e.g., sunlight).

Consumer (heterotroph)

An organism that obtains energy by feeding on other living organisms or organic matter.

Decomposer

An organism that breaks down dead organic material and recycles nutrients back into an ecosystem.

Mutualism

A symbiotic relationship in which both participating organisms benefit.

Parasitism

A symbiotic relationship in which one organism benefits while the host is harmed.

Proton

A positively charged subatomic particle located in the nucleus of an atom.

Electron

A negatively charged subatomic particle residing in the electron cloud surrounding the atomic nucleus.

Neutron

A subatomic particle located in the nucleus of an atom that carries no net electrical charge.

Atomic number

The total number of protons present in the nucleus of an atom of an element.

Mass number

The sum of the number of protons and neutrons in an atomic nucleus ($\text{Mass number} = \text{protons} + \text{neutrons}$).

Isotopes

Atoms of the same element with identical numbers of protons but different numbers of neutrons.

Cation

A positively charged ion formed when an atom loses electrons.

Anion

A negatively charged ion formed when an atom gains electrons.

Group 18 elements on the Periodic Table

Noble gases (elements characterized by low chemical reactivity).

Ionic bond

A chemical bond formed by the electrostatic attraction between oppositely charged ions, involving electron transfer.

Covalent bond

A chemical bond formed when two atoms share one or more pairs of valence electrons.

Law of conservation of mass

A principle stating that matter is neither created nor destroyed in a chemical reaction.

Acidic solution pH range

A solution with a $\text{pH} < 7$

Basic (alkaline) solution pH range

A solution with a $\text{pH} > 7$

Formula for density

$$\text{Density} = \frac{\text{mass}}{\text{volume}}$$

Avogadro's number (particles in one mole)

$$6.02 \times 10^{23}\text{ particles}$$

Formula for speed

$$\text{Speed} = \frac{\text{distance}}{\text{time}}$$

Acceleration

The rate of change of velocity over time ($a = \frac{\text{change in velocity}}{\text{time}}$).

Newton's First Law of Motion

An object remains at rest or moves at a constant velocity unless acted upon by an unbalanced external force.

Newton's Second Law of Motion equation

$$F = m a$$

Newton's Third Law of Motion

For every action force, there is an equal and opposite reaction force.

Kinetic energy

The energy an object possesses due to its motion ($E_k = \frac{1}{2}m v^2$).

Potential energy

Energy stored in an object due to its position, condition, or chemical structure.

Formula for work in physics

$\text{Work} = \text{Force} \times \text{distance}$ ($W = F d$)

Formula for mechanical power

$\text{Power} = \frac{\text{Work}}{\text{time}}$ ($P = \frac{W}{t}$)

Ohm's Law equation

$V = I R$ (where $V$ is voltage, $I$ is current, and $R$ is resistance)

Electrical conductor

A material that allows electrical charges to flow through it easily.

Electrical insulator

A material that resists the flow of electric current.

Three primary solid layers of Earth (outer to inner)

Crust, mantle, and core

Igneous rock

Rock formed by the cooling and solidification of molten magma or lava.

Sedimentary rock

Rock formed by the accumulation, compaction, and cementation of mineral and organic particles.

Metamorphic rock

Rock derived from existing rocks transformed by intense heat, pressure, or chemical activity.

Weathering vs. Erosion

Weathering breaks down rock at Earth's surface; erosion transports the weathered fragments.

Primary cause of Earth's seasons

The tilt of Earth's rotational axis relative to its orbital plane around the Sun.

Milky Way

The galaxy that contains our Solar System.

Density calculation: mass = $20\text{ g}$, volume = $5\text{ cm}^3$

$$\text{Density} = \frac{20\text{ g}}{5\text{ cm}^3} = 4\text{ g/cm}^3$$

Work calculation: force = $20\text{ N}$, distance = $3\text{ m}$

$$\text{Work} = 20\text{ N} \times 3\text{ m} = 60\text{ J}$$

Electric current calculation: voltage = $12\text{ V}$, resistance = $4\text{ }\text{ohms}$

$$I = \frac{V}{R} = \frac{12\text{ V}}{4\text{ }\text{ohms}} = 3\text{ A}$$