Bioenergetics and Ecosystem Energy Dynamics Practice Test Review

Vocabulary flashcards covering chemical reaction thermodynamics, enzyme kinetics, ATP cycle mechanisms, cellular work, autotrophic processes, and ecological energy transfer.

Activation Energy

The energy required to initiate a reaction, measured from the reactants to the peak of a reaction energy diagram rather than from the products to the peak.

Endergonic Reaction

A chemical reaction that requires an input of free energy available for cellular work, distinct from heat-transfer descriptions such as endothermic.

Active Site

The specific region of an enzyme whose shape, charge, polarity, and hydrogen bonding determine substrate binding.

Enzyme Saturation

A state in which nearly all enzyme active sites are occupied by substrate, causing the reaction rate to plateau because available enzymes limit the rate.

Competitive Inhibitor

A molecule that competes directly with the substrate for the active site of an enzyme, reducing binding opportunities and slowing the reaction rate.

Adenosine Triphosphate (ATP)

An immediate energy carrier composed of adenine, ribose, and three phosphate groups that transfers energy to cellular processes.

Adenosine Diphosphate (ADP)

A molecule consisting of adenine, ribose, and two phosphate groups that can be recycled with inorganic phosphate to regenerate ATP.

ATP Hydrolysis

The reaction in which ATP reacts with water to form ADP and inorganic phosphate, releasing usable free energy overall.

Phosphorylation

The transfer of a phosphate group to another molecule, which can alter a protein's shape or activity and couple ATP use to cellular work.

ATP Synthase

A protein complex that directly powers ATP formation using the energy of hydrogen ions flowing down an electrochemical gradient.

Thylakoid Membrane

The membrane structure in chloroplasts where chloroplast ATP synthase is located, analogous to the inner mitochondrial membrane in mitochondria.

Chemosynthesis

The process by which autotrophs build organic food molecules using energy from inorganic chemical reactions rather than sunlight.

Primary Producer

An autotrophic organism that captures energy and stores it in organic molecules to support the food web.

Omnivore

A consumer that feeds on both producers and animals.

Decomposer

An organism that breaks down dead organic matter by digesting it externally and absorbing the nutrients.

Detritivore

An organism that feeds by directly ingesting detritus, such as an earthworm.

Food Web

An interconnected network joining multiple food chains that illustrates alternative food sources and predators within an ecosystem.

Biomass Pyramid

An ecological pyramid that illustrates the total amount of living tissue present at each trophic level.

Pyramid of Numbers

An ecological pyramid that counts individual organisms at each trophic level, which can become inverted when a few large producers support many herbivores.