Junkao Science Knowledge flashcards
Junkao Science Knowledge · Build recall with a focused review session.
32 cards. Read the term and the definition here. The deck at the top of this page is optional.
- Independent variable
- The factor deliberately changed by the experimenter in a controlled experiment; its effect on the dependent variable is what the experiment measures.
- Control group
- The group in an experiment that receives no treatment or a placebo, providing a baseline for comparison with the experimental group.
- Dependent variable
- The factor measured in response to changes in the independent variable; it is the outcome the experimenter observes and records.
- Falsifiable hypothesis
- A testable statement predicting a specific observable outcome that could be shown false by evidence; untestable claims fall outside scientific inquiry.
- Percent error
- The absolute difference between a measured value and an accepted value, divided by the accepted value, then multiplied by 100 to express it as a percentage.
- Precision versus accuracy
- Precision is the agreement among repeated measurements; accuracy is how close a measurement is to the true or accepted value.
- SI base units
- The seven fundamental units: meter, kilogram, second, ampere, kelvin, mole, and candela, from which all other SI units are derived.
- Dimensional analysis
- A conversion method that multiplies a quantity by ratios equal to one so unwanted units cancel, leaving the desired unit.
- Law of conservation of mass
- In a closed system, the total mass of the reactants equals the total mass of the products; atoms are rearranged, never created or destroyed.
- Atomic number
- The number of protons in an atom's nucleus; it determines the element's identity and equals the number of electrons in a neutral atom.
- Balanced chemical equation
- An equation in which the number of atoms of each element is equal on both sides, satisfying conservation of mass; only coefficients are adjusted.
- Exothermic reaction
- A chemical reaction that releases energy to its surroundings, usually as heat, so the products have lower energy than the reactants.
- Newton's second law
- The net force on an object equals its mass times its acceleration; acceleration is directly proportional to net force and inversely proportional to mass.
- Kinetic energy
- The energy of motion, calculated as one-half the mass times the square of the velocity; doubling speed quadruples kinetic energy.
- Weight versus mass
- Mass is the amount of matter and stays constant; weight is the gravitational force on that mass and changes with local gravity.
- Conservation of mechanical energy
- In the absence of friction, the sum of kinetic and potential energy in a system remains constant as energy transforms between forms.
- Wave speed equation
- Wave speed equals frequency multiplied by wavelength; for a given medium, higher frequency means shorter wavelength.
- Ohm's law
- Current through a conductor equals voltage divided by resistance; resistance is measured in ohms and current in amperes.
- Series versus parallel circuits
- Series circuits share one current path and sum resistances; parallel circuits share voltage across branches and divide current among them.
- Electromagnetic induction
- A changing magnetic field through a conductor induces a voltage; this principle underlies generators and transformers.
- Mitosis versus meiosis
- Mitosis produces two genetically identical diploid cells for growth; meiosis produces four haploid gametes with genetic variation for reproduction.
- Genotype versus phenotype
- Genotype is an organism's allele combination; phenotype is the observable trait resulting from that genotype and environmental influences.
- Natural selection
- Heritable variations that improve survival and reproduction become more common in a population over generations, driving evolutionary change.
- DNA base pairing
- In DNA, adenine pairs with thymine and cytosine pairs with guanine; this complementary pairing enables accurate replication and transcription.
- Trophic levels
- Feeding positions in a food chain: producers, primary consumers, secondary consumers, and decomposers; energy decreases at each higher level.
- Carrying capacity
- The maximum population size an ecosystem can sustain indefinitely given available food, water, space, and other limiting resources.
- Photosynthesis equation
- Six carbon dioxide molecules plus six water molecules, using light energy, produce one glucose molecule and six oxygen molecules.
- Keystone species
- A species whose removal causes disproportionate disruption to its ecosystem, often collapsing food webs and reducing biodiversity.
- Plate tectonics
- The theory that Earth's lithosphere is divided into moving plates whose interactions cause earthquakes, volcanoes, and mountain building.
- Cause of seasons
- Earth's seasons result from its axial tilt of about 23.5 degrees, which changes the angle and duration of sunlight through the year.
- Inverse-square law
- A physical quantity such as gravitational or light intensity decreases in proportion to the square of the distance from its source.
- Moon phases
- The changing appearance of the Moon caused by the varying angle between Earth, the Moon, and the Sun as the Moon orbits Earth.