IB Biology C - Interaction and Interdependence Key Definitions

A graph showing the percentage of light absorbed at each wavelength by a pigment or group of pigments.

Acetylcholine is a neurotransmitter found in many types of synapses, including neuromuscular junctions (where nerves connect to muscles).

The action potential is the rapid electrical signal generated when the neuron's membrane potential reaches a threshold.

A graph showing the rate of photosynthesis at each wavelength of light.

Activation energy is the minimum amount of energy required to start a chemical reaction.

The active site is a small region on an enzyme where the substrate binds. It is formed by a specific sequence of amino acids within the enzyme's overall three-dimensional structure.

Active transport is the movement of molecules or ions across a membrane against their concentration gradient (from low to high concentration), which requires energy.

Adaptations are traits that increase an organism’s fitness in response to environmental factors.

Small glands located above the kidneys responsible for producing hormones, including epinephrine.

Allelopathy occurs when plants release chemicals, called allelochemicals, into the soil to inhibit the growth of nearby plants.

A site on an enzyme other than the active site, where specific molecules can bind to regulate enzyme activity.

Anabolic reactions are metabolic processes in which smaller molecules are built into larger, more complex molecules using energy.

Anaerobic respiration is a form of respiration that occurs without oxygen.

Anthropogenic refers to changes in the environment caused by human activities.

Antibiotic resistance occurs when bacteria evolve mechanisms to survive exposure to antibiotics that would normally kill them.

Antibiotic secretion is a strategy used by microorganisms, like fungi and bacteria, to inhibit the growth of competing microbes.

Antibiotics are chemical substances that kill or inhibit the growth of bacteria by targeting bacterial structures and processes that do not exist in human (eukaryotic) cells.

Foreign molecules, usually proteins or glycoproteins, that trigger an immune response by being recognized by the immune system.

ATP is a nucleotide, similar to those that make up DNA and RNA.

The enzyme that uses the energy from the proton gradient to catalyze the synthesis of ATP from ADP and inorganic phosphate.

An autotroph is an organism that uses external energy sources to synthesize carbon compounds from simple inorganic substances.

Auxin is a phytohormone that regulates growth by promoting cell elongation.

White blood cells that recognize specific antigens and produce antibodies to neutralize pathogens.

Blood clotting is a rapid, highly coordinated response that transforms liquid blood into a semi-solid gel, sealing the wound. It prevents excessive blood loss from wounds and forms a protective barrier against pathogen entry.