LET March 2023 Majorship General Science Review

A set of 150 comprehensive vocabulary flashcards covering the actual March 2023 Licensure Examination for Teachers (LET) General Science majorship exam.

Inorganic Compound

A chemical compound that does not contain carbon-hydrogen bonds, exemplified by water ($\text{H}_2\text{O}$).

Nerve Cell

The longest cell in the human body, specialized for conducting electrical impulses throughout the nervous system.

Carbon (in Human Body)

The second most abundant chemical element in the human body, accounting for approximately $18\%$ of total body mass.

Alzheimer's Disease

A progressive neurological disorder that causes memory impairment, resulting in the loss of both old and new memories.

Omnivore

An organism whose diet includes both plant and animal matter (e.g., humans who consume cattle that eat grass).

Commensalism

A symbiotic relationship in which one species benefits while the other is neither helped nor harmed (e.g., orchids growing on tree branches or birds nesting in trees).

Atom

The fundamental unit of matter, historically termed "indivisible" because it was originally believed to be the smallest possible particle.

Anion

An atom or group of atoms that has gained one or more electrons, giving it a net negative electrical charge.

Convergent Evolution

The evolutionary process whereby organisms from different ancestral origins independently develop similar structures or characteristics due to similar selective pressures.

Inorganic Chemistry

The branch of chemistry primarily devoted to the study of non-carbon substances, specifically minerals and metals.

Domain

The highest and broadest taxonomic rank in the biological classification of life, situated above the kingdom level.

Archaea

One of the three primary biological domains of life, consisting of single-celled prokaryotic microorganisms distinct from Bacteria and Eukarya.

Genus

The taxonomic rank ranking above species and below family that zebras, horses, donkeys, and mules share due to close anatomical similarities.

Biochemistry

The scientific discipline that explores the chemical processes, substances, and transformations occurring within living organisms.

Phenotype

The composite of an individual organism's observable physical traits and characteristics resulting from the expression of its genes.

Mutation

A permanent change in the nucleotide sequence of an organism's DNA, which can be induced by mutagens such as radiation.

Gene Splicing

A recombinant DNA technique in which a specific section of DNA is excised from an organism and inserted or supplemented into a bacterial plasmid.

Wavelength

The physical spatial distance between two successive identical points of adjacent waves, such as crest-to-crest or trough-to-trough.

Beaker

A flat-bottomed, cylindrical glass container with a pouring lip used in laboratories for mixing, measuring, and pouring chemical solutions.

Biotechnology

The commercial and industrial application of living biological systems, organisms, or cellular components to produce diverse products.

Crucible

A small, cup-like porcelain receptacle designed to withstand high temperatures when heating chemicals in a laboratory.

Frequency

The number of complete wave cycles that pass a fixed reference point per unit of time, representing the rate of wave occurrence.

Pasteurization

The process of heating liquid foods (such as packaged or unpackaged milk and juices) to a mild temperature to destroy pathogenic bacteria without significantly altering flavor or nutrients.

Tundra

A cold, treeless terrestrial biome characteristic of the Arctic, analogous to the hot, arid desert biome of the Sahara.

Gravitational Pull (Earth vs. Moon)

The attractive gravitational force that is greater on Earth than on the Moon, causing identical physical objects to weigh significantly more on Earth.

Greenhouse Gases

Atmospheric gases that absorb and emit radiant thermal energy, heavily produced by industrial sectors such as plastic and cement manufacturing.

Plant Cell Organelles

Distinct eukaryotic cellular structures characteristic of plants, notably the cellulose cell wall, large central vacuole, and plastids.

Incubation Period

The temporal interval between initial exposure to a pathogen, toxic chemical, or radiation and the first clinical appearance of signs and symptoms.

Hubble's Law

The cosmological principle connecting galactic redshift to cosmic expansion, demonstrating that distant celestial bodies recede at speeds proportional to their distance.

Human Genome Project

The collaborative international scientific initiative successfully organized to map and determine the complete nucleotide base sequence of the human genome.

Displacement

A vector quantity measuring the net change in position of an object, whose magnitude is always less than or equal to the total distance traveled.

Mercury's Daytime Temperature

The extreme surface temperature on planet Mercury nearest the Sun, reaching up to approximately $430\,^\circ\text{C}$.

Urea

The first organic chemical compound ($\text{CO}(\text{NH}_2)_2$) to be synthesized in a laboratory from inorganic starting reagents.

Quaternary Period

The most recent and current geological period of the Cenozoic Era, extending from approximately 2.58 million years ago to the present day.

Ecological Organization (Least to Greatest)

The sequential hierarchical arrangement of ecological levels from simplest to most complex: Organism $\rightarrow$ Population $\rightarrow$ Community $\rightarrow$ Ecosystem $\rightarrow$ Biome $\rightarrow$ Biosphere.

Ecological Organization (Largest to Smallest)

The sequential hierarchical arrangement of ecological levels from broadest to narrowest: Biosphere $\rightarrow$ Ecosystem $\rightarrow$ Community $\rightarrow$ Population $\rightarrow$ Organism.

Solar Prominence

A large, bright gaseous loop or projection extending outward from the Sun's surface into the lower corona.

Autoclave

A laboratory pressure vessel that utilizes high-pressure saturated steam to achieve physical sterilization of equipment by killing bacteria, viruses, and endospores.

Data Table

A structured method of organizing and presenting scientific data into systematic rows and columns, as illustrated by the substance and density dataset.

Refractive Index

The ratio comparing the speed of light in a vacuum to its speed through a medium, which equals approximately $1.5$ for standard crown glass.

Predation

A biological interaction where one living organism (the predator) captures, kills, and feeds on another organism (the prey), such as a human hunting wildlife for food.

Radioactive Decay

The spontaneous nuclear transformation where an unstable atomic nucleus emits ionizing particles and electromagnetic radiation to form a different nucleus.

Protists

A diverse eukaryotic grouping consisting of unicellular or simple multicellular animal-like (protozoa) and plant-like (algae) microscopic organisms.

Hierarchy of Threats to Biodiversity

The ranked sequence of major environmental drivers threatening global biodiversity from most to least severe: Climate change $\rightarrow$ Pollution $\rightarrow$ Loss of habitat $\rightarrow$ Alien species.

Mount Pinatubo

An active Philippine stratovolcano that erupted cataclysmically in 1991, ejecting massive ash plumes and aerosols into the global atmosphere.

Richter Scale

A base-10 logarithmic scale historically used in seismology to measure the total amount of energy released and the magnitude of an earthquake.

Alexander Fleming

The Scottish microbiologist who discovered the bactericidal substance penicillin derived from Penicillium notatum in 1928.

Electric Power Formula ($P = V \times I$)

The formula calculating electric power rating by multiplying voltage by current; a device drawing $3\,\text{A}$ at $120\,\text{V}$ consumes $360\,\text{W}$.

Coulomb's Law

The electrostatic law stating that the electric force between two stationary charges is proportional to the product of their charges and inversely proportional to the square of the distance separating them.

Homogeneous Solution

A single-phase chemical mixture or pure fluid with uniform physical and chemical properties throughout, exemplified by pure water.

Stoichiometry

The quantitative study and calculation of relative proportions, masses, and mole ratios between reactants and products in a balanced chemical reaction.

Hydrolysis in Digestion

The enzyme-mediated chemical process of cleaving macronutrient polymers into smaller absorbable units through the addition of water molecules.

Plant-Specific Organelles

Subcellular botanical structures absent in animal cells: chloroplasts, rigid cell wall, central vacuole, plasmodesmata, and amyloplasts.

Electric Generator

An electromechanical device that converts mechanical rotational energy into electrical energy via electromagnetic induction.

Herbivore

A primary consumer adapted anatomically and physiologically to feed exclusively on photosynthetic plant material.

Wind

The bulk horizontal movement of atmospheric air across Earth's surface driven by differences in atmospheric pressure.

Triglyceride

A major lipid molecule formed by glycerol and three fatty acid chains, characterized by a low melting point, insolubility in water, and solubility in organic ether.

Robert Hooke

The English polymath who first coined the word "cell" after observing hollow microscopic compartment structures in thin slices of bottle cork.

Mitochondrion

The cell organelle responsible for generating the majority of cellular chemical energy (ATP) that possesses its own distinct mitochondrial DNA.

Chemical Energy

The potential energy stored within electrochemical bonds, such as that retained within a portable power bank used to recharge a mobile device.

Organic Chemistry

The specialized field of chemistry focused on the structure, synthesis, properties, and chemical reactions of carbon-containing compounds.

Enzymology

The specialized branch of biochemistry that investigates the kinetics, mechanism, and molecular regulation of enzyme-catalyzed chemical reactions.

Ocean Ecosystem

The largest aquatic biome on Earth, covering approximately $71\%$ of the global planetary surface.

Renewable Energy

Energy collected from natural resources that naturally regenerate on a human timescale, offering reliable alternatives to fossil fuel depletion.

Saccharide

The basic structural monomer and fundamental carbohydrate repeating unit, encompassing monosaccharides like glucose.

Stomata

Microscopic pores distributed across plant leaves regulated by guard cells that allow the exchange of oxygen and carbon dioxide gases.

Diagnostic Blood Test

A medical laboratory analysis of blood components; while infections like syphilis and HIV are diagnosed via serology, gonorrhea is traditionally identified via genital swab cultures.

Complete Blood Count (CBC)

The most routinely ordered laboratory hematology panel, quantitatively assessing erythrocytes, leukocytes, and platelets.

Proteins

Complex macromolecules constructed from amino acid chains that serve vital biological functions including tissue construction, cellular repair, and enzymatic catalysis.

Milky Way Galaxy

The barred spiral galaxy containing our Solar System, named historically for its visible appearance resembling a trail of spilled milk across the night sky.

Ordinate

The vertical Cartesian coordinate (commonly termed the y-axis) used to define point elevation in a two-dimensional plane.

Nominal Scale

A qualitative categorization scale based solely on named labels or identifiers, which does not represent quantitative numerical frequency counts.

Homeostasis

The biological process whereby organisms maintain dynamic physiological equilibrium, exemplified by internal respiration and waste excretion.

DNA

Deoxyribonucleic acid, the macromolecule containing the genetic instructions responsible for biological inheritance, development, and cellular functioning.

Steel

A commercial alloy predominantly consisting of iron with a minor fraction of carbon, classified as a metallic alloy rather than a carbon-based substance.

Historical Timeline of Microbiology

The chronological sequence of key microbiological milestones: Antonie van Leeuwenhoek (microscopy) $\rightarrow$ Louis Pasteur (pasteurization) $\rightarrow$ Joseph Lister (antiseptic surgery).

Wilhelm Johannsen

The Danish botanist and geneticist who first introduced the term "gene" in 1909 to describe Mendelian units of heredity.

Pictograph

A statistical visual chart that uses pictorial symbols or icons to represent numerical values and categorical data.

Adenosine Triphosphate (ATP)

The high-energy organic phosphate molecule that functions as the primary universal chemical energy currency of living cells.

Lunar Gravity

The gravitational force exerted by the Moon, which is roughly one-sixth that of Earth, resulting in lower apparent weight on the lunar surface.

Mutagen

A physical or chemical agent—such as ultraviolet (UV) radiation or mutagenic chemicals—that alters genetic material and increases the frequency of mutations.

Preventive Medicine

The branch of medicine focusing on preventing disease onset, closely coupled with modern genetic engineering techniques to correct genetic disorders.

Regenerative Medicine

A biomedical discipline that focuses on repairing, regenerating, or replacing damaged human cells, tissues, and organs using stem cell therapy.

Secondary Consumer

A consumer trophic position occupied by carnivores and omnivores (such as humans) that feed upon herbivorous primary consumers.

Exoplanet Detection Methods

Established scientific techniques used by astronomers to find extrasolar planets, notably radial velocity, the transit method, and direct imaging.

Neutralization Reaction

A stoichiometric chemical reaction between an acid and a base that produces water ($\text{H}_2\text{O}$) and an ionic salt.

Decomposition Reaction

A chemical transformation where a single chemical substance breaks down into simpler constituent compounds or elements ($2\text{H}_2\text{O}_2 \rightarrow 2\text{H}_2\text{O} + \text{O}_2$).

Abscissa

The horizontal Cartesian coordinate (commonly termed the x-axis) denoting the horizontal position of a point in a coordinate plane.

Monera

The historic biological kingdom encompassing single-celled prokaryotic microorganisms, distinguished from eukaryotic plants, animals, and fungi.

Direct Current (DC)

An electrical current that flows continuously in a single, unidirectional path with constant polarity, characteristic of chemical batteries.

Speed of Light in Crown Glass

The reduced phase velocity of light inside crown glass, which propagates at approximately $66.3\%$ of the vacuum speed of light ($c$).

Coulomb Force Calculation

The calculated electrostatic repulsive force between charges of $+0.5\,\text{C}$ and $+2\,\text{C}$ at a distance of $3\,\text{m}$, yielding approximately $9.986 \times 10^8\,\text{N}$.

Axis of Rotation

The straight imaginary line around which a spinning body rotates, symmetrically dividing the rotating sphere into two equal halves.

Hemodialysis

A medical procedure that substitutes for impaired renal function by filtering metabolic wastes, toxins, and excess water from the blood.

Covalent Bond

A chemical bond formed by the electrostatic attraction between atoms that share one or more pairs of valence electrons, typically between non-metals.

Synthesis Reaction

A chemical combination reaction where two or more distinct elemental or compound reactants join to produce a single product ($2\text{Na} + \text{Cl}_2 \rightarrow 2\text{NaCl}$).

Analogous Structures

Morphological traits in distinct species that execute similar functional roles due to similar ecological niches, rather than shared evolutionary ancestry.

Sleet

A form of solid winter precipitation consisting of small, frozen translucent ice pellets formed by freezing raindrops before striking the surface.

Water (Cellular Content)

The most abundant chemical constituent of living cells, typically accounting for roughly $70\%$ to $80\%$ of total cellular mass.

Chemical Subscript

The small number positioned slightly below an element's chemical symbol indicating the exact stoichiometric count of that atom in a molecule.