Honors Biology Semester 1 Review: Characteristics of Life, Biomolecules, Enzymes, Energy, and Nutrient Cycles

Comprehensive vocabulary review flashcards covering characteristics of life, properties of water, macromolecule biochemistry, enzyme kinetics, cellular respiration, photosynthesis, lab safety, and biogeochemical nutrient cycles.

Metabolism

The overall term for all chemical reactions that occur within an organism to sustain life, encompassing both the synthesis (building up) and breakdown of materials.

Homeostasis

The physiological process by which an organism maintains a stable, constant internal environment despite changes in external conditions.

Autotroph

An organism that produces its own organic nutrients and energy from inorganic sources, typically using light energy through photosynthesis.

Heterotroph

An organism that cannot synthesize its own food and must obtain energy and nutrients by consuming other organisms.

Water Polarity

The unequal sharing of electrons between oxygen and hydrogen atoms in an $H_2O$ molecule, resulting in a partial negative charge on the oxygen atom and partial positive charges on the hydrogen atoms.

Hydrogen Bond

An intermolecular attraction formed between the slightly positive hydrogen atom of one polar molecule (such as water) and the slightly negative atom (such as oxygen) of an adjacent polar molecule.

Cohesion

The attractive force that holds molecules of the same substance together, such as hydrogen bonding between adjacent water molecules.

Adhesion

The attractive force between molecules of different substances, such as water molecules binding to plant xylem walls or glass surfaces.

Specific Heat

The amount of heat energy required to raise the temperature of a given mass of a substance by a specific amount; water has a high specific heat, allowing it to resist drastic temperature fluctuations.

Surface Tension

A measure of the cohesive forces at the liquid's surface that creates a barrier, allowing lightweight organisms such as water striders to walk on water.

Capillary Action

The upward movement of water through narrow spaces or tubes resulting from the combined interactions of adhesion to container walls and cohesion among water molecules.

Hydration Shell

The organized sphere of polar water molecules that surrounds and separates individual dissolved ions when an ionic compound (such as $NaCl$) dissolves in water.

Hydrophilic

A characteristic of polar or charged substances that readily interact with and dissolve in water.

Hydrophobic

A characteristic of nonpolar substances (such as lipids) that lack affinity for water and do not dissolve in it.

Dehydration Synthesis

A chemical reaction that covalently links monomer units together into a polymer by removing a molecule of water.

Hydrolysis

The cleavage of chemical bonds within polymers by the addition of a water molecule, breaking them down into monomers.

Primary Structure

The unique, linear sequence of amino acids in a polypeptide chain, held together by covalent peptide bonds.

Phospholipid

A structural lipid composed of a glycerol molecule joined to two hydrophobic fatty acid tails and a hydrophilic phosphate group, forming the fundamental bilayer of biological membranes.

Nucleotide

The monomer building block of nucleic acids, consisting of three components: a phosphate group, a five-carbon pentose sugar, and a nitrogenous base.

Bromelain

A protein-digesting enzyme found in fresh pineapple that breaks down proteins such as gelatin via hydrolysis.

Denaturation

A structural alteration in a protein or enzyme caused by extreme temperatures or non-optimal pH, disrupting its functional shape and active site.

Factors Affecting Enzyme Activity

Environmental variables—including temperature, pH, enzyme concentration, and substrate concentration—that dictate the rate of enzymatic catalysis.

Evapotranspiration

The combined transfer of water vapor into the atmosphere through evaporation from the soil or surface and transpiration from plant foliage.

Infiltration

The downward movement of precipitation water soaking through soil and rock layers to replenish groundwater reserves.

Sublimation

The phase transition in the water cycle where water transforms directly from a solid (ice/snow) into water vapor without entering the intermediate liquid phase.

Carbon Cycle

The biogeochemical cycle governing the movement and conversion of carbon through the atmosphere ($CO_2$), biological organisms (via photosynthesis and cellular respiration), organic matter, mineral carbon, and oceanic sinks.

Nitrogen Fixation

The bacterial or physical process of converting chemically unreactive atmospheric nitrogen gas ($N_2$, composing about $78\%$ of the atmosphere) into biologically usable forms such as ammonia ($NH_3$).

Nitrification

The microbial conversion of ammonia into nitrites and subsequently into nitrates ($NO_3^-$), the primary nitrogen form readily absorbed by plant roots.

Denitrification

The metabolic process carried out by specialized soil bacteria that converts nitrates back into atmospheric nitrogen gas ($N_2$), returning nitrogen to the atmosphere.

Ammonification

The decomposition process wherein decomposers break down nitrogenous organic wastes and decaying remains into ammonia.

Phosphorus Cycle

The biogeochemical movement of phosphorus through rock weathering, soil, waterways, and biological organisms, unique for having no significant gaseous atmospheric reservoir.

Algal Bloom

A dense, rapid proliferation of algae in an aquatic body, frequently triggered by nutrient enrichment such as excess agricultural fertilizer runoff containing phosphorus or nitrogen.

Adenosine Triphosphate (ATP)

The primary energy currency produced by cellular respiration that directly supplies metabolic energy for cellular functions.

Lactic Acid Fermentation

An anaerobic pathway occurring in human muscle cells and certain bacteria that converts pyruvate into lactic acid to regenerate electron carriers in the absence of oxygen.

Alcoholic Fermentation

An anaerobic metabolic process performed by yeast and selected microorganisms that converts sugars into ethanol and carbon dioxide.

Iodine Test

A biochemical indicator assay used to detect starch, which produces a distinctive color shift from yellow-brown to blue-black upon binding starch polymers.

Wafting

A safe laboratory procedure where chemical vapors are gently waved toward the nose using an open hand rather than inhaling directly from a vessel.