GED (General Educational Development) Science Syllabus

What is the difference between a genotype and a phenotype?

Genotype is the genetic makeup (the alleles an organism carries); phenotype is the observable physical trait that results.

What is the difference between a dominant allele and a recessive allele?

A dominant allele is expressed whenever present and is shown by a capital letter; a recessive allele is expressed only when two copies are present and is shown by a lowercase letter.

In a cross between two heterozygous parents (Aa x Aa), what is the expected phenotype ratio?

3:1 dominant to recessive (genotype ratio 1 AA : 2 Aa : 1 aa).

What is a mutation, and how can it affect an organism?

A mutation is a change in the DNA sequence; it can be harmful, beneficial, or neutral, and it is the ultimate source of new genetic variation.

What is natural selection?

The process by which organisms with traits better suited to their environment survive and reproduce more successfully, passing those advantageous traits to offspring.

What does 'survival of the fittest' mean in evolutionary terms?

'Fitness' refers to reproductive success; the 'fittest' organisms are those best adapted to their environment and most able to survive and reproduce, not necessarily the strongest.

What evidence supports the theory of evolution?

Fossils, homologous anatomical structures, embryological similarities, vestigial structures, and shared DNA/molecular sequences among related species.

What is an adaptation?

An inherited trait that increases an organism's chance of survival and reproduction in its particular environment.

In an ecosystem, what is the role of a producer versus a consumer?

Producers (e.g., plants) make their own food through photosynthesis; consumers obtain energy by eating other organisms.

What is the difference between a herbivore, a carnivore, and an omnivore?

A herbivore eats only plants, a carnivore eats only other animals, and an omnivore eats both plants and animals.

Approximately how much energy is passed to the next level of a food chain, and where does the rest go?

About 10% of energy passes to the next trophic level; the remaining ~90% is lost mainly as heat through metabolism and life processes.

What is the role of decomposers in an ecosystem?

Decomposers (bacteria and fungi) break down dead organisms and waste, recycling nutrients back into the soil and environment.

What is the function of the respiratory system?

To take in oxygen and remove carbon dioxide, performing gas exchange in the lungs (alveoli) for the body's cells.

What is the main function of the circulatory system?

To transport blood carrying oxygen, nutrients, hormones, and wastes throughout the body, pumped by the heart.

What is homeostasis in the human body?

The maintenance of a stable internal environment (e.g., temperature, pH, blood sugar) despite changes in external conditions.

What is the basic structure of an atom?

A central nucleus of positively charged protons and neutral neutrons, surrounded by negatively charged electrons in surrounding energy levels.

What does the atomic number of an element represent?

The number of protons in the nucleus, which defines the identity of the element.

How are elements arranged in the periodic table?

By increasing atomic number; vertical columns (groups) share similar chemical properties and horizontal rows (periods) share the same number of electron shells.

What is the difference between an element and a compound?

An element consists of only one type of atom; a compound is two or more different elements chemically bonded in a fixed ratio.

What does the Law of Conservation of Mass state?

Matter cannot be created or destroyed in a chemical reaction; the total mass of the reactants equals the total mass of the products.

In a chemical equation, what is the difference between reactants and products?

Reactants are the starting substances written on the left of the arrow; products are the new substances formed, written on the right.

Why must chemical equations be balanced?

To satisfy the Law of Conservation of Mass; the number of each type of atom must be equal on both sides of the equation.

What is the difference between a physical change and a chemical change?

A physical change alters form or state without forming a new substance (e.g., melting); a chemical change produces a new substance with new properties (e.g., burning).

What does Newton's First Law of Motion (inertia) state?

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.

What is the formula relating force, mass, and acceleration (Newton's Second Law)?

Force = mass x acceleration (F = ma), where force is in newtons, mass in kilograms, and acceleration in m/s^2.

How is speed calculated, and what are its units?

Speed = distance / time; common units are meters per second (m/s).

What is the formula for work in physics?

Work = force x distance (W = Fd), measured in joules, when the force acts in the direction of motion.

How is power defined and calculated?

Power is the rate of doing work: Power = work / time (P = W/t), measured in watts.

What does the Law of Conservation of Energy state?

Energy cannot be created or destroyed, only transformed from one form to another or transferred; the total energy stays constant.

What are the three main layers of the Earth's interior?

The crust (thin outer layer), the mantle (thick middle layer of hot, semi-solid rock), and the core (outer liquid and inner solid, mostly iron and nickel).

What is the theory of plate tectonics?

Earth's outer shell is divided into large plates that slowly move on the mantle, causing earthquakes, volcanoes, and mountain formation at their boundaries.

What are the three main types of rock and how does each form?

Igneous rock forms from cooled magma/lava; sedimentary rock forms from compacted sediments; metamorphic rock forms when existing rock is changed by heat and pressure.

What are the main steps of the water cycle?

Evaporation (water to vapor), condensation (vapor to clouds), precipitation (rain/snow), and collection/runoff back into bodies of water.

What is the difference between weather and climate?

Weather is the short-term, day-to-day state of the atmosphere; climate is the average weather pattern of a region over a long period (typically 30+ years).

What is the greenhouse effect?

Gases such as carbon dioxide and methane trap heat radiated from Earth's surface in the atmosphere, warming the planet; excess greenhouse gases intensify global warming.

What is the difference between a renewable and a nonrenewable resource?

Renewable resources are naturally replenished within a human lifetime (e.g., solar, wind, water); nonrenewable resources form over millions of years and are depleted faster than replaced (e.g., coal, oil, natural gas).

Name one major human impact on the environment and its consequence.

Burning fossil fuels releases carbon dioxide, increasing the greenhouse effect and contributing to climate change (other valid answers: deforestation reduces habitat and oxygen; pollution harms ecosystems).

What keeps the planets in orbit around the Sun?

The Sun's gravity, which provides the centripetal force that holds the planets in their orbital paths.

What is the difference between a star, a planet, and a galaxy?

A star is a luminous ball of gas that produces its own light through fusion; a planet orbits a star and reflects light; a galaxy is an enormous collection of billions of stars, gas, and dust held together by gravity.