Tochigi Public High School Entrance Examination - Science flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Newton's first law

An object at rest, or moving at constant velocity, stays that way unless a net external force acts on it. Also called the law of inertia.

Ohm's law

The current through a conductor is proportional to the voltage across it and inversely proportional to its resistance: V = IR, with V in volts, I in amperes, R in ohms.

Conservation of energy

Energy can be transferred between objects or transformed between forms, but the total energy in a closed system stays constant; it is never created or destroyed.

Wave equation

Wave speed equals frequency multiplied by wavelength (v = fλ). Frequency is fixed by the source, while speed depends on the medium the wave travels through.

Series versus parallel circuits

In series, one path gives the same current everywhere and voltages add. In parallel, branches share the same voltage and currents add.

Electromagnetic induction

A changing magnetic field through a coil induces a voltage in it. Moving a magnet into or out of a coil, or rotating a coil, generates current.

Density and floating

Density is mass divided by volume. An object floats in a liquid when its average density is less than the liquid's density, and sinks when greater.

Physical versus chemical change

A physical change alters form or state without making a new substance; a chemical change produces new substances with different properties and is hard to reverse.

Distillation

A separation method that boils a liquid mixture and condenses the vapour, using differences in boiling point to collect a purer liquid component.

Atomic number and mass number

Atomic number counts protons and identifies the element. Mass number counts protons plus neutrons. Isotopes share atomic number but differ in neutron count.

Balancing chemical equations

Adjust coefficients so each element has the same atom count on both sides. Subscripts inside formulas stay fixed because changing them alters the substance.

Neutralisation reaction

An acid reacts with a base to produce a salt and water. Hydrogen ions and hydroxide ions combine, moving the pH of the solution toward neutral.

Mole and molar mass

One mole contains 6.0 × 10²³ particles and has a mass in grams equal to the molar mass. Amount in moles equals mass divided by molar mass.

Oxidation and reduction

Oxidation is loss of electrons or gain of oxygen; reduction is gain of electrons or loss of oxygen. Both always happen together in a redox reaction.

Combustion products

Burning a hydrocarbon in sufficient oxygen yields carbon dioxide and water. Limited oxygen gives carbon monoxide, a toxic gas, and soot.

Photosynthesis equation

Carbon dioxide plus water plus light energy gives glucose plus oxygen, catalysed in chloroplasts. Light energy is stored as chemical energy in glucose.

Mitochondria function

Organelles where aerobic respiration releases energy from glucose using oxygen, producing carbon dioxide and water. Cells with high energy demand contain many mitochondria.

Plant versus animal cells

Plant cells have a cellulose cell wall, chloroplasts and a large vacuole. Animal cells lack these but both share a nucleus, cytoplasm, membrane and mitochondria.

Osmosis

The movement of water across a semi-permeable membrane from a region of higher water concentration (lower solute) to lower water concentration, without using energy.

Mitosis versus meiosis

Mitosis makes two identical diploid cells for growth and repair. Meiosis makes four genetically varied haploid gametes, halving the chromosome number before fertilisation.

Dominant and recessive alleles

A dominant allele is expressed even when paired with a recessive one. A recessive trait appears only when both alleles are recessive, as in a 3:1 cross ratio.

Natural selection

Individuals vary; more offspring are produced than survive; those with inherited traits suited to the environment leave more offspring, so those traits become more common.

Energy in food chains

Only about ten percent of energy passes to the next trophic level; the rest is lost as heat and through excretion, limiting food chains to a few levels.

Producers and decomposers

Producers make organic matter from sunlight by photosynthesis. Decomposers break down dead organisms and waste, returning nutrients such as nitrogen to the soil.

P-waves and S-waves

P-waves are longitudinal and travel through solids and liquids. S-waves are transverse and cannot pass through liquids, revealing Earth's liquid outer core.

Three rock types

Igneous rock forms from cooling magma or lava; sedimentary rock forms from compacted deposited layers and may hold fossils; metamorphic rock forms under heat and pressure.

Cause of the seasons

Earth's axis tilts about 23.4 degrees, so each hemisphere receives sunlight at a steeper angle and for longer hours in its summer, regardless of distance from the Sun.

Moon phases

The changing visible fraction of the Moon's sunlit half, caused by the shifting angle between Earth, Moon and Sun during the Moon's monthly orbit.

Controlled experiment

A test that changes one independent variable, measures one dependent variable, and keeps all other conditions constant so the effect can be attributed to the variable.

Accuracy versus precision

Accuracy is closeness to the true value; precision is how closely repeated measurements agree. A systematic error reduces accuracy while repeated readings stay precise.

Hypothesis

A testable, falsifiable proposed explanation or prediction based on prior knowledge, which an experiment can support or contradict with evidence.

Observation versus inference

An observation is what is directly sensed or measured; an inference is an explanation or conclusion drawn from that evidence using prior knowledge.