Free GED Science Exam Flashcards

The mitochondria - often called the 'powerhouse of the cell' - breaks down glucose in cellular respiration to release usable energy (ATP). This differs from the nucleus, which stores and directs genetic information rather than producing energy.

A plant cell. The cell wall gives rigid structural support (animal cells lack one), the large vacuole stores water for pressure support, and chloroplasts carry out photosynthesis - none of which appear in animal cells.

Cellular respiration (in mitochondria) consumes glucose and oxygen to release CO2, water, and ATP. Photosynthesis (in chloroplasts) does the reverse: it uses CO2 and water plus light energy to produce glucose and oxygen.

Mitosis produces 2 genetically identical daughter cells for growth and repair in body cells. Meiosis produces 4 genetically unique daughter cells (sex cells) with half the chromosome number, enabling sexual reproduction.

Tall. Phenotype is the observable trait; since T (dominant) is present, it masks the recessive t allele, so genotype Tt shows the dominant phenotype even though the plant carries one recessive allele.

Genotype ratio 1 TT : 2 Tt : 1 tt. Phenotype ratio 3:1 (3 tall to 1 short) because both TT and Tt produce the dominant tall phenotype - only tt shows the recessive trait.

Genotype is the genetic makeup written as allele letters (e.g., Bb). Phenotype is the physical, observable trait that genotype produces (e.g., brown eyes). Two different genotypes, like BB and Bb, can produce the same phenotype.

A mutation is a random change in a DNA sequence. It is not always harmful - mutations can be harmful, neutral, or beneficial, and beneficial mutations are the raw material for evolution by natural selection.

Individuals with traits better suited to their environment survive and reproduce at higher rates, passing those traits to offspring. Over many generations this shifts the population's trait frequencies - it is differential reproductive success, not an individual changing during its lifetime.

The fossil record, which shows transitional forms across geologic time, and molecular or anatomical evidence such as homologous structures and shared DNA sequences among related species.

An inherited trait that increases an organism's chance of survival and reproduction in its specific environment, such as a thick coat in a cold climate. Adaptations arise from natural selection acting on random mutations over generations, not from an organism intentionally changing.

A producer (a plant or algae) makes its own food through photosynthesis. A consumer must eat other organisms to obtain energy. A third group, decomposers, break down dead organic matter and recycle nutrients back into the ecosystem.

Commensalism. This differs from mutualism, where both species benefit, and parasitism, where one species benefits while the other is harmed - GED questions often ask you to tell these three relationships apart from a described scenario.

The prey population declines from increased predation, which then causes the predator population to decline due to reduced food supply - producing a cyclical, lagged rise-and-fall pattern between the two populations over time.

A biome is a large geographic region defined by its climate and dominant plant and animal life, such as desert, tundra, or rainforest. An ecosystem is smaller in scale: the community of organisms interacting with each other and their physical environment within a biome.

The respiratory system (lungs and airways). It works closely with the circulatory system, which pumps the newly oxygenated blood out to body tissues - GED questions often ask you to connect systems that work together.

The endocrine system releases hormones into the bloodstream for slower, longer-lasting chemical signaling, such as growth or metabolism. The nervous system sends fast electrical signals through neurons for immediate responses - both communicate, but they differ in speed and signal type.

It removes metabolic waste products, especially nitrogenous waste (urea) and excess water and salts, filtered from the blood mainly by the kidneys and eliminated as urine.

The circulatory system's job is pumping and transporting blood, oxygen, and nutrients throughout the body via the heart and vessels. The immune system uses cells that travel in the blood, such as white blood cells and antibodies, specifically to identify and fight pathogens - transport versus defense.

The number of protons, also called the atomic number. Changing the proton count changes the element entirely; changing the neutron count creates an isotope of the same element, and changing the electron count creates an ion.

Isotopes. They share the same atomic number (protons) and chemical behavior but have different mass numbers (protons plus neutrons) - some isotopes are radioactive and decay over time, which is the basis of radiometric dating.

An element is a pure substance made of only one type of atom, such as oxygen (O). A compound is two or more different elements chemically bonded together in a fixed ratio, such as water (H2O), and its properties differ from its component elements.

The total mass of the reactants must equal the total mass of the products. Atoms are rearranged into new substances during a reaction, but no atoms are created or destroyed.

Exothermic - it releases heat energy to its surroundings, which is why it feels warm. An endothermic reaction absorbs heat from its surroundings instead and would feel cool.

A catalyst speeds up the reaction rate by lowering the activation energy required, but it is not consumed or permanently changed by the reaction - it can be reused.

Increasing temperature (more particle collisions with more energy) and increasing the concentration or surface area of reactants (more particles available to collide and react).

Gas particles move quickly and spread apart with weak attractive forces, so they expand to fill any container. Liquid particles stay close together with moderate attraction, giving a fixed volume but a shape that flows to match its container.

Particles gain thermal energy, vibrate faster, and break free of the fixed positions holding them in a rigid solid structure, letting them move past one another as a liquid. Temperature stays constant at the melting point throughout the phase change.

A pH above 7 indicates a base; below 7 indicates an acid; exactly 7 is neutral, like pure water. Lower pH numbers mean stronger acids, and higher pH numbers mean stronger bases.

Water and a salt. The acid's H+ ions combine with the base's OH- ions to form water, while the remaining ions combine to form a salt - this is why neutralization moves the pH toward 7.

Newton's First Law, the law of inertia: an object at rest stays at rest, and an object in motion stays in motion at constant velocity, unless acted on by an unbalanced (net) force.

Force equals mass times acceleration (F = ma). A larger mass requires more force to reach the same acceleration; rearranged, acceleration equals force divided by mass.

The wall pushes back on you with an equal and opposite force. For every action force there is a reaction force equal in size and opposite in direction, acting on the other object.

Speed is only the rate of motion, a single number such as 60 mph. Velocity includes both rate and direction, such as 60 mph north - a car going around a curve at constant speed still has changing velocity because its direction changes.

At the top it has potential energy, stored energy due to its height. As it rolls down, that potential energy converts into kinetic energy, the energy of motion - total mechanical energy stays constant if no energy is lost to friction.

Energy cannot be created or destroyed, only converted from one form to another, such as chemical to kinetic, or transferred between objects. The total energy in a closed system stays constant.

A conductor, such as copper wire, allows electric current to flow through it easily. An insulator, such as rubber or plastic, resists and blocks the flow of electric current - insulators are used to coat wires safely.

A closed, complete loop - current only flows when the circuit path is unbroken from the power source through the components and back. An open circuit, such as a break or a switched-off point, stops current flow entirely.

Mountain ranges - the colliding plates crumple and push the crust upward, as with the Himalayas. This differs from a divergent boundary, where plates pull apart and new crust forms, often creating rift valleys or ocean ridges.

A transform boundary, where two plates slide horizontally past each other. Friction along the fault builds up stress that releases suddenly as an earthquake.

Crust (thin, outer rocky layer), mantle (thick, mostly solid but capable of slow flow), outer core (liquid iron-nickel), and inner core (solid iron-nickel at the center) - density and temperature increase toward the center.

Igneous rock. Sedimentary rock instead forms from compressed and cemented sediment layers, and metamorphic rock forms when existing rock is transformed by heat and pressure without melting.

The oldest layers are on the bottom and the youngest layers are on top, since each layer was deposited on top of the one before it - this lets scientists determine relative age from a rock layer's position.

Weather is the short-term, day-to-day condition of the atmosphere, such as temperature or precipitation, in a specific place. Climate is the long-term average weather pattern of a region measured over decades - a single cold day does not disprove a long-term warming trend.

Gases like carbon dioxide and methane trap heat radiating from Earth's surface, warming the atmosphere. A natural greenhouse effect is necessary to keep Earth warm enough for life; the concern is human activity intensifying it beyond natural levels, driving climate change.

Nuclear fusion - hydrogen atoms fuse together under extreme heat and pressure in the star's core to form helium, releasing massive amounts of energy as light and heat.

Earth's axial tilt of about 23.5 degrees, not distance from the Sun. As Earth orbits the Sun, the tilt causes different hemispheres to receive more direct sunlight at different times of year, producing seasons.

The light color - it is the variable the researcher deliberately changes. The dependent variable, plant growth or height, is what the researcher measures in response; a control group with standard light provides a baseline for comparison.

Mean equals the sum divided by the count: 25 divided by 5 = 5. Median is the middle value in the ordered list: 4. Mode is the most frequent value: 4. The GED tests reading these values from tables and graphs, not just applying formulas.

A steep upward trend indicates the measured (dependent) variable is rapidly increasing as the independent variable increases; a flat line indicates little to no change in the dependent variable - reading trend direction and steepness is a core science-practice skill on the GED.