Unit 1: Motion, Genetics, Chemical Reactions, and Earth Dynamics

Comprehensive vocabulary flashcards covering the core scientific inquiry units: motion, forces, human reproduction, molecular genetics, chemical bonding, reaction kinetics, and plate tectonics.

Scalar quantity

A physical quantity that has magnitude (size) only, without any direction.

Vector quantity

A physical quantity that possesses both magnitude (size) and a specific direction.

Distance

The total length of the path travelled by an object; a scalar quantity represented by the symbol $s$ and measured in metres ($\text{m}$).

Displacement

The straight-line change in position from a starting point to a finishing point with direction; a vector quantity represented by the symbol $\vec{s}$ and measured in metres ($\text{m}$).

Speed

A scalar quantity measuring how fast an object is moving, calculated using $v = \frac{s}{t}$ and measured in metres per second ($\text{m/s}$).

Velocity

A vector quantity defined as speed in a particular direction, calculated using $\vec{v} = \frac{\vec{s}}{t}$ and measured in metres per second ($\text{m/s}$).

Acceleration

The rate of change of velocity with respect to time; a vector quantity calculated using $\vec{a} = \frac{\vec{v}_f - \vec{v}_i}{\Delta t}$ and measured in metres per second squared ($\text{m/s}^2$).

Newton's First Law of Motion

The law stating that an object will remain at rest or continue moving at a constant velocity unless acted upon by an unbalanced external force.

Weight force

The force of gravity acting on an object, pulling it towards Earth.

Normal force

The support force exerted by a surface on an object in contact with it.

Balanced forces

Forces that are equal in size and act in opposite directions, resulting in a net force of $0\,\text{N}$ so that the object's motion remains unchanged.

Unbalanced forces

Forces that do not cancel each other out, resulting in a net force greater than $0\,\text{N}$ that causes an object to accelerate, decelerate, or change direction.

Newton's Second Law of Motion

The law stating that an object's acceleration depends on the net force acting on the object and its mass, expressed by the formula $\vec{F} = m\vec{a}$.

Newton's Third Law of Motion

The law stating that for every action force, there is an equal and opposite reaction force exerted on the interacting objects.

Gametes

Reproductive sex cells (sperm produced by the testes and ova produced by the ovaries) that each contain $23$ chromosomes in humans.

Meiosis

A type of cell division that produces four genetically distinct daughter cells (gametes), each containing half the number of chromosomes ($23$ chromosomes) of the parent cell.

Chromosomes

Large structures composed of DNA located in the nucleus that carry paired genetic information involved in transmitting traits across generations.

Gene

A specific segment of DNA located on a chromosome that contains instructions to make a protein.

DNA (Deoxyribonucleic acid)

The double-stranded helical molecule that stores and transmits inherited genetic information and controls protein production in living organisms.

Nucleotide

The chemical subunit of DNA and RNA consisting of a phosphate group, a five-carbon sugar (deoxyribose or ribose), and a nitrogenous base.

Mutation

A permanent change to the DNA nucleotide sequence (occurring via substitution, insertion, or deletion) that can produce new alleles and increase genetic variation.

Artificial selection

The process of selective breeding by humans to develop organisms with specific desirable traits.

Transgenic species

Organisms that have genetic material from another species incorporated into their own genome via biotechnology.

Element

A pure substance made up of only one type of atom that cannot be broken down into simpler substances by chemical reactions.

Compound

A pure substance made up of two or more different elements chemically bonded together in a fixed ratio.

Covalent compound

A chemical substance formed when two or more non-metal atoms share pairs of electrons.

Ionic compound

A chemical substance formed when metal atoms transfer electrons to non-metal atoms, creating oppositely charged ions held together by electrostatic forces.

Exothermic reaction

A chemical reaction that releases heat energy to the surroundings, causing the temperature of the environment to rise.

Endothermic reaction

A chemical reaction that absorbs heat energy from the surroundings, causing the temperature of the environment to drop.

Combustion

A fast, uncontrolled chemical reaction occurring at high temperatures that consumes fuel to release heat and light energy.

Respiration

A slow, controlled chemical reaction in living cells occurring at body temperature that releases energy stored chemically as ATP.

Rate of reaction

The change in the amount of a particular reactant or product per unit time ($\text{Average rate} = \frac{\Delta\,\text{amount of substance}}{\Delta t}$).

Collision Theory

A scientific model stating that chemical reactions occur only when reactant particles physically collide with correct spatial alignment and sufficient energy.

Activation energy ($E_a$)

The minimum threshold of kinetic energy required by colliding reactant particles to break existing bonds and initiate a chemical reaction.

Catalyst

A substance that speeds up a chemical reaction without being consumed by providing an alternative reaction pathway with a lower activation energy ($E_a$).

Lithosphere

The rigid, brittle outermost shell of the Earth composed of the crust and the uppermost solid portion of the mantle.

Asthenosphere

The hot, ductile layer of the upper mantle located directly beneath the lithosphere, where solid rock is soft enough to flow slowly.

Outer core

The extremely hot liquid layer of the Earth composed primarily of molten iron and nickel whose movements generate Earth's magnetic field.

Inner core

The dense central sphere of the Earth composed primarily of solid iron and nickel maintained under immense gravitational pressure.

Tectonic plates

Large, rigid slabs of rock comprising the Earth's lithosphere that move relative to one another atop the asthenosphere.

Mantle convection currents

The slow, cyclical circulation of heated, less dense rock rising from deep in the mantle and cooler, denser rock sinking, driving plate motion.

Slab pull

The major tectonic driving force where a dense, cold oceanic plate sinks into the mantle at a subduction zone under gravity, dragging the rest of the plate behind it.

Ridge push

The gravitational force where elevated, newly formed oceanic crust at mid-ocean ridges slides downward and outward away from the spreading center.

Divergent boundary

A tectonic plate boundary where two plates pull apart or move away from each other.

Convergent boundary

A tectonic plate boundary where two plates collide or move toward each other.

Transform boundary

A tectonic plate boundary where two plates slide horizontally past one another.