Biology 1306 Comprehensive Exam Review (Exams 1–4)

Vocabulary practice flashcards covering core biological topics across Exams 1 through 4, including the scientific method, macromolecules, cell structure, transport, the cell cycle, cellular respiration, photosynthesis, genetics, and molecular biology.

Homologous structures

Anatomical structures that share the same basic array of bones modified for different functions, such as the wing of a bat and the fin of a porpoise.

Scientific theory

A concept supported by experimental evidence that explains the facts in an area of study.

Inductive reasoning

A form of logical thinking that uses specific observations (such as observing that yellow jackets, wasps, and hornets all sting) to infer a general pattern or conclusion.

Deductive reasoning

A form of logical thinking that applies general principles to predict specific experimental results or testable hypotheses.

Independent variable

The variable that is manipulated or altered by researchers in an experiment, such as administering large doses of a nutritional supplement versus a sugar pill placebo.

Dependent variable

The outcome or response factor measured by researchers to determine the effect of the treatment, such as the length of time it takes to recover from a cold.

Atomic number

The fundamental characteristic of an element defined by the number of protons contained in the nucleus of a given atom.

Valence shell

The outermost electron shell of an atom, whose number of electrons dictates the chemical reactivity and bonding behavior of the element.

Polar covalent bond

A chemical bond formed by the unequal sharing of electrons between two atoms of differing electronegativities.

Hydrogen bond

A weak intermolecular attraction formed between a partially positive hydrogen atom and an electronegative atom (such as nitrogen in ammonia or oxygen between liquid water molecules).

Buffer

A chemical substance, such as bicarbonate ions in the blood, that absorbs excess hydrogen ions ($H^+$) to maintain a stable pH balance.

Dehydration reaction

A chemical condensation reaction that covalently links two monomers (such as joining glucose molecules into a disaccharide) accompanied by the loss of a water molecule.

Unsaturated fat

A lipid molecule containing one or more double bonds in its hydrocarbon fatty acid chains, producing kinks in the chain.

Purines

A class of double-ring nitrogenous bases found in nucleic acids, specifically comprising adenine and guanine.

Pyrimidines

A class of single-ring nitrogenous bases found in nucleic acids, comprising cytosine, thymine, and uracil.

Nucleus

A membrane-bound eukaryotic organelle that houses tightly packaged chromosomal DNA complexed with proteins.

Nucleolus

A specialized region within the eukaryotic nucleus that serves as the site for ribosome assembly.

Golgi apparatus

A eukaryotic organelle responsible for collecting, packaging, modifying, and transporting cellular molecules.

Cytoskeleton

A cellular scaffold composed of actin microfilaments, intermediate filaments, and microtubules that supports cell shape and organization.

Peroxisome

A specialized eukaryotic organelle that degrades toxic hydrogen peroxide into harmless water and oxygen.

Cell theory

A foundational biological doctrine established by Schleiden and Schwann stating that all organisms consist of one or more cells, the cell is the smallest living unit, and all cells arise by division of preexisting cells.

Osmosis

The net diffusion of water across a selectively permeable membrane from an area of lower solute concentration to an area of higher solute concentration.

Sodium-potassium pump

An active transport membrane protein that utilizes one molecule of ATP to export 3 sodium ions ($Na^+$) out of the cell while importing 2 potassium ions ($K^+$) in.

Pinocytosis

A form of endocytosis commonly referred to as 'cell drinking,' where a cell non-specifically engulfs droplets of extracellular fluid and dissolved solutes.

Binary fission

The asexual reproductive process in bacteria where a single cell replicates its DNA and divides into two nearly equal daughter halves.

Trisomy

An aneuploid condition in which an individual's cells contain an extra chromosome, resulting in a chromosomal complement of $2n+1$.

Sister chromatids

Two identical copies of a replicated chromosome joined together at the centromere by cohesin proteins before undergoing cell division.

Cytokinesis

The phase of the cell cycle during which the cytoplasm divides to partition the parent cell into two distinct daughter cells.

S phase

The synthesis stage of interphase during which the cell produces an exact duplicate copy of all its nuclear DNA.

Telophase

The final stage of mitosis characterized by the disassembly of the spindle apparatus, the re-formation of the nuclear envelope, and the decondensation of chromosomes.

Meiosis

A specialized form of nuclear division that reduces the chromosome number by half, converting diploid ($2n$) germ cells into haploid ($n$) gametes.

Crossing over

The reciprocal exchange of genetic material between non-sister chromatids of homologous chromosomes occurring during prophase I of meiosis.

Obligate intracellular parasite

An infectious biological entity, such as a virus, that can reproduce solely within a living host cell due to a lack of its own independent metabolic and biosynthetic machinery.

Endergonic reaction

A non-spontaneous chemical reaction requiring a net input of free energy, such as the synthesis of glucose from carbon dioxide and water.

First Law of Thermodynamics

The physical law of conservation stating that energy cannot be created or destroyed, but can only be transferred or transformed from one form to another.

Competitive inhibitor

A regulatory or pharmacological molecule that binds directly to the active site of an enzyme, physically preventing substrate binding.

Cofactors

Inorganic, nonprotein chemical components that assist enzymes in carrying out catalysis.

Activation energy

The initial threshold of energy required to destabilize existing chemical bonds and initiate a chemical reaction.

Substrate-level phosphorylation

The direct enzymatic formation of ATP from ADP by the transfer of a phosphate group from a high-energy metabolic intermediate.

Pyruvate oxidation

The intermediate metabolic process taking place in the mitochondrial matrix that decarboxylates pyruvate to produce acetyl-CoA, $CO_2$, and NADH.

Chemiosmosis

The generation of ATP driven by the flow of protons ($H^+$) back across a membrane through ATP synthase down a concentration gradient.

Chloroplast Anatomy: Region E

The stroma; the dense, fluid-filled interior space of the chloroplast enclosing the thylakoid membranes, which serves as the location for the Calvin cycle.

Stomata

Microscopic pores situated on the exterior surface of leaves that regulate gas exchange, allowing carbon dioxide to enter and oxygen to exit.

Photosystem

A light-harvesting complex composed of chlorophyll and accessory pigments embedded in the thylakoid membrane.

Calvin cycle

A cyclic sequence of light-independent photosynthetic reactions occurring in the stroma that fix carbon dioxide to assemble sugar molecules.

Alleles

Alternative variations or forms of the same gene residing at a particular locus on homologous chromosomes.

Recessive allele

An allele whose phenotypic expression is fully masked or unexpressed in the presence of a dominant allele.

Testcross

A diagnostic breeding experiment crossing an individual of dominant phenotype with an individual of homozygous recessive genotype to uncover whether the dominant organism is homozygous or heterozygous.

Incomplete dominance

A non-Mendelian inheritance pattern wherein heterozygous offspring display an intermediate phenotype blending the two parental alleles, such as pink carnations resulting from red and white parents.

Principle of Segregation

Mendel's foundational genetic law asserting that the two alleles present at a gene locus separate during gamete formation and remain distinct.

Polygenic inheritance

An inheritance mode wherein a single quantitative characteristic (such as skin color or human height) is collectively determined by multiple independent pairs of genes.

Semiconservative replication

The mechanism of DNA replication wherein each separated original parental strand serves as a template to build a newly synthesized complementary strand.

DNA helicase

The replication enzyme that unwinds and separates double-stranded DNA by breaking the weak hydrogen bonds connecting complementary base pairs.

DNA primase

An RNA polymerase enzyme that synthesizes a short RNA primer complementary to a single-stranded DNA template to initiate DNA synthesis.

DNA gyrase

A bacterial topoisomerase that relieves torsional strain (torque) in the double helix ahead of the progressing replication fork.

Okazaki fragments

Short stretches of DNA synthesized discontinuously along the lagging template strand during DNA replication.

Telomerase

A ribonucleoprotein enzyme that maintains chromosome length across successive cellular divisions by extending repetitive sequences at the ends of eukaryotic chromosomes.