Biology - Ecology, Biogeochemical Cycles, Organic Molecules, and Cell Systems

Species

Group of individuals that can produce fertile offspring.

Population

Organisms of one species living together in an area.

Ecosystem

Living and non-living factors in a specific place.

Producers

Organisms that produce energy through photosynthesis.

Consumers

Organisms that obtain energy by consuming others.

Trophic Levels

Assigned levels in a food chain based on energy acquisition.

Food Chain

Path of energy through trophic levels with arrows.

Food Web

Complex interactions of multiple connected food chains.

Ten-Percent Law

Only 10% of energy transfers between trophic levels.

Energy Pyramid

Diagram showing energy stored in trophic levels.

Biomass

Dry weight of organic matter in a trophic level.

Biomass Pyramid

Represents potential food available at each trophic level.

Biogeochemical Cycles

Movement of elements between living organisms and environment.

Water Cycle

Cycle of water between ocean, atmosphere, and land.

Carbon Cycle

Movement of carbon among living organisms and environment.

Nitrogen Cycle

Cycle of nitrogen from atmosphere to living organisms.

Evaporation

Liquid water returns to atmosphere as vapor.

Transpiration

Evaporation of water from plant surfaces.

Condensation

Water vapor cools and forms clouds.

Precipitation

Water droplets fall to earth as rain or snow.

Runoff

Surface water that flows back to oceans or lakes.

Percolation

Water seeping into soil to become groundwater.

Nitrogen fixation

Bacteria convert atmospheric nitrogen to ammonia.

Ammonification

Bacteria produce ammonia from decaying organic matter.

Nitrification

Conversion of ammonia to nitrates and nitrites.

Assimilation

Plants absorb nitrogen into organic compounds.

Denitrification

Conversion of nitrates to nitrogen gas.

Rhizobia

Bacteria that fix nitrogen in plant roots.

Phosphorus Cycle

Phosphorus is essential for DNA and RNA.

Nutrient Limitation

Scarcity of nutrients limits ecosystem productivity.

Limiting nutrient

Single nutrient that restricts ecosystem growth.

Primary productivity

Rate at which producers generate energy.

Fertilizers

Contain nitrogen, phosphorus, and potassium for crops.

Deforestation

Clearing forests leads to resource loss and climate change.

Greenhouse gas

Gas trapping heat in the atmosphere, e.g., CO2.

Fossil fuels

Combustible energy sources like coal and oil.

Dams

Structures to reserve water and generate electricity.

Aquatic species loss

Reduced water flow threatens riverine biodiversity.

Coastal deltas

Landforms formed by river sediment deposition.

Invasive species

Non-native species disrupting local ecosystems.

Sediment retention

Dams prevent sediment replenishing coastal ecosystems.

Erosion

Wearing away of land, often accelerated by human activity.

Decomposers

Organisms breaking down dead matter, recycling nutrients.

Overexploitation

Harvesting resources faster than they can reproduce.

Overfishing

A type of overexploitation affecting fish populations.

Biodiversity loss

Decline in species variety due to overexploitation.

Bluefin tuna

A slow-maturing fish species at risk of extinction.

Overexploited fish stocks

34% of global fish stocks are overexploited.

Water states

Water exists as solid, liquid, and gas on Earth.

High specific heat

Water temperature changes slowly when heated.

Hydrogen bonds

Strong attractions between water molecules.

Ice density

Ice is less dense than liquid water.

Cohesion

Molecules resist separation, creating surface tension.

Adhesion

Water molecules attract to other substances' molecules.

Xylem tubes

Plant structures that transport water from roots.

Polarity

Water molecules have distinct positive and negative ends.

Solvent

Substance that dissolves another substance (solute).

Universal solvent

Water dissolves many substances due to its polarity.

Like dissolves like

Polar substances dissolve polar substances, not nonpolar.

Strong acid

Completely ionizes in water, releasing H+ ions.

Hydrochloric acid (HCl)

Example of a strong acid in solution.

Weak acid

Partially ionizes in solution; example is carbonic acid.

Buffer

Chemicals that stabilize pH by donating/accepting ions.

Chemical bond

Attraction holding atoms together via electron interaction.

Covalent bond

Chemical bond formed by sharing electron pairs.

Covalent Bonding

Stable balance of attractive and repulsive forces sharing electrons.

Chemical Element

Substance with atoms having the same number of protons.

Atomic Number

Number of protons in an element's nucleus.

Hydrogen Bond

Weak bond from electrostatic attraction between molecules.

Ion

Atom or molecule with a net electric charge.

Ionic Bond

Electrostatic attraction between oppositely charged ions.

Isotope

Atoms with equal protons but different neutrons.

Nonpolar Molecule

Molecule without electrical charges or partial charges.

Electronegativity

Tendency of an atom to attract electrons.

Polar Molecule

Molecule with a separation of electric charge.

Acid

Substance that can donate a proton to another.

Base

Molecule or ion that accepts a hydrogen ion.

pH

Measure of acidity or basicity of a solution.

Solution

Homogeneous mixture of solutes dissolved in a solvent.

Solvent

Substance in which a solute dissolves.

Solute

Substance that dissolves in a solvent.

Molecule

Group of two or more atoms held by bonds.

Compound

Substance made from chemically joined different elements.

Adhesion

Attraction between dissimilar molecules or surfaces.

Cohesion

Attraction of molecules for others of the same kind.

Suspension

Heterogeneous mixture with visible particles suspended.

Mixture

Physical blend of substances preserving their identities.

Proton

Subatomic particle with a positive electrical charge.

Neutron

Neutral particle with slightly more mass than protons.

Electron

Negatively charged particle, bound or free.

Elements of Life

Carbon compounds form the basis of biological molecules.

Carbon

Key element forming four bonds, ideal for molecules.

Carbon

Element forming four covalent bonds, ideal for molecules.

Organic Compounds

Compounds mainly composed of carbon and hydrogen.

Monomers

Simpler organic subunits that build polymers.

Polymers

Molecules made of repeated monomers.

Hydrocarbons

Compounds made entirely of carbon and hydrogen.

Covalent Bonds

Strong bonds formed by sharing electron pairs.

Functional Group

Group of atoms imparting specific properties to compounds.

Hydroxyl Group

-OH group that makes alcohols from hydrocarbons.