IB BIO --- ALL TERMS

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70S Ribosomes

Small ribosomes found in prokaryotic cells, as well as in the mitochondria and chloroplasts of eukaryotic cells, responsible for protein synthesis.

80S Ribosomes

Larger ribosomes found in eukaryotic cells that synthesize proteins.

Abiotic factors

A non-living component of the environment, such as temperature, light, or water availability, that influences the survival and reproduction of organisms.

Absorption

The process by which digested nutrients are transported into the body, primarily occurring in the small intestine.

Absorption spectrum

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

Acetylcholine

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

Action Potential

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

Action spectrum

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

Activation Energy

The minimum amount of energy required to start a chemical reaction.

Active site

A small region on an enzyme where the substrate binds, formed by a specific sequence of amino acids.

Active transport

The movement of molecules or ions across a membrane against their concentration gradient, which requires energy.

Adaptations

Traits that increase an organism's fitness in response to environmental factors.

Adaptive radiation

The evolutionary process by which a single ancestral species rapidly diversifies into many species, each specialized to exploit a different ecological niche.

Adhesion

The attraction between water molecules and other surfaces, enabling water to cling to them and move against gravity.

Adrenal gland

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

Albedo

Measures the reflectivity of a surface.

Allele

A variation of a gene.

Allele frequency

Refers to how common a particular allele is within a population, expressed as a proportion or percentage.

Allelopathy

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

Allopatric speciation

Occurs when populations are physically separated by a geographical barrier.

Alternative splicing

A process that enables a single gene to produce multiple protein variants.

Amphipathic

A molecule that has both hydrophilic (water-attracting) and hydrophobic (water-repelling) regions.

Anabolic Reactions

Metabolic processes in which smaller molecules are built into larger, more complex molecules using energy.

Anaerobic respiration

A form of respiration that occurs without oxygen.

Analogous structures

Anatomical features in different species that serve similar functions but do not share a common evolutionary origin.

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.

Antibiotics

Chemical substances that kill or inhibit the growth of bacteria by targeting bacterial structures and processes that do not exist in human cells.

Anticodon

A sequence of three nucleotides on a transfer RNA (tRNA) molecule that is complementary to a codon on a messenger RNA (mRNA) strand.

Antigen

Foreign molecules, usually proteins or glycoproteins, that trigger an immune response.

Aquaporin

Specialized proteins that facilitate water movement across cell membranes.

Asexual reproduction

A process where a single parent produces offspring without the involvement of gametes.

Assimilation

The process by which absorbed nutrients are transported to cells and used for growth, repair, and energy production.

ATP

A nucleotide, similar to those that make up DNA and RNA.

ATP Synthase

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

Atrioventricular valves

Valves located between the atria and ventricles that prevent the backflow of blood.

Autotroph

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

B lymphocytes (B cells)

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

Base substitution

A gene mutation where one nucleotide in the DNA sequence is replaced by another.

Binomial name

A two-part Latinized name that uniquely identifies a species.

Biochemical Oxygen Demand (BOD)

Measures the oxygen required by microorganisms to decompose organic matter.

Biodiversity

The total variety of life on Earth.

Biological Species Concept (BSC)

Defines a species as a group of organisms capable of interbreeding and producing fertile offspring.

Biomagnification

The increase in toxin concentration at each successive trophic level in a food chain.

Biome

Large-scale groupings of ecosystems sharing similar abiotic factors.

Biotic factors

A living organism that shapes its environment.

Blood clotting

A rapid, highly coordinated response that transforms liquid blood into a semi-solid gel, sealing the wound.

Brain

The central organ of the nervous system, responsible for processing sensory information, coordinating responses, and controlling various bodily functions.

Buoyancy

Buoyancy is the upward force exerted by a fluid (liquid or gas) on an object immersed in it.

C-value paradox

The C-value paradox refers to the lack of correlation between genome size and organismal complexity.

Calvin Cycle

The Calvin Cycle is a biochemical pathway that incorporates CO₂ into organic molecules using energy and electrons from ATP and NADPH.

Capillary action

Capillary action refers to the movement of water through narrow spaces, even against gravity.

Carbon fixation

The process of converting inorganic carbon dioxide (CO₂) into organic molecules.

Carbon sequestration

Carbon sequestration refers to the process of capturing and storing carbon dioxide (CO₂) from the atmosphere to mitigate the effects of climate change.

Carbon Sink

An ecosystem that absorbs more carbon than it releases.

Carbon source

An ecosystem that releases more carbon than it absorbs.

Carrying capacity

Carrying capacity is the maximum population size that an ecosystem can sustain indefinitely without degrading the habitat.

Catabolic reactions

Catabolic reactions are metabolic processes in which larger molecules are broken down into smaller molecules, releasing energy in the process.

Catalysis

The process of increasing the rate of a chemical reaction by using a substance called a catalyst, which is not consumed during the reaction.

Cell cycle

The cell cycle is a series of stages that a cell goes through to grow, replicate its DNA, and divide into two daughter cells.

Cell respiration

Cell respiration is a series of metabolic processes that convert energy stored in carbon compounds, such as glucose and fatty acids, into ATP.

Cell theory

A fundamental principle of biology stating that all living organisms are composed of one or more cells, the cell is the basic unit of structure and function in all living things, and all cells arise from pre-existing cells.

Cell wall

The cell wall is a rigid, protective layer located outside the plasma membrane of certain cells, including prokaryotes, plants, fungi, and some protists.

Cerebellum

The part of the brain responsible for coordinating voluntary muscle movements, balance, and motor control.

Cerebral hemispheres

The cerebral hemispheres are the largest part of the brain, responsible for higher-order functions like decision-making, memory, and voluntary movement.

Channel protein

A specialized protein embedded in the membrane, allowing specific ions or molecules to diffuse across.

Chi-squared test

The chi-squared test is a statistical method used to assess whether the occurrences of two species in a given area are due to chance or due to some form of association.

Chloroplast

An organelle found in plant and algal cells that is responsible for photosynthesis, the process of converting light energy into chemical energy.

Chromatography

Chromatography is a technique used to separate and identify components of a mixture based on their differing affinities for a stationary phase and a mobile phase.

Chromosomes

Chromosomes are the carriers of genetic information in all living organisms.

Circadian Rhythm

The 24-hour biological cycle that regulates physiological processes, including sleep.

Climate change

Long-term shifts in temperature, precipitation, and other environmental factors that can alter the conditions of an ecosystem.

Clone

A group of genetically identical organisms or cells derived from a single parent.

Closed system

A system that only exchanges energy with its surroundings, not matter.

Clotting factors

Proteins in the blood that play a crucial role in the formation of blood clots.

Codon

A codon is a sequence of three nucleotides in DNA or RNA that specifies a particular amino acid or a start/stop signal during protein synthesis.

Cohesion

The attraction between water molecules due to hydrogen bonding.

Collision theory

Collision theory states that in order for a reaction to occur, the reacting molecules must collide with sufficient energy and in the correct orientation.

Community

A community includes all the populations of different species living together in the same area and interacting with each other.

Compartmentalization

The organization of cellular activities into distinct membrane-bound structures or regions within a cell.

Competitive exclusion principle

Two species cannot coexist indefinitely in the same ecological niche if resources are limiting.

Concentration Gradient

The difference in concentration of a substance (e.g., oxygen or carbon dioxide) between two regions.

Condensation

Condensation is a reaction where two molecules combine, releasing water.

Continuous variation

Continuous variation describes traits that exhibit a range of phenotypes without distinct categories.

Control center

The control center processes the information received from the receptors and determines the appropriate response to maintain stability.

Controlled Variables

Controlled variables are factors kept constant to ensure that changes in the dependent variable (e.g., photosynthesis rate) are due to the independent variable (e.g., CO2 concentration).

Convergent evolution

Convergent evolution is when distantly related organisms independently evolve similar traits or behaviors to adapt to similar environments.

Coronary arteries

Coronary arteries are specialized vessels branching from the aorta.

Correlation coefficient

A statistical measure that quantifies the strength of a relationship between two variables.

Cryo-EM (cryogenic election microscopy)

An advanced form of electron microscopy that studies biomolecules (especially proteins) in their natural, hydrated state.

Cytokinesis

Cytokinesis is the process of dividing the cytoplasm of a parent cell into two daughter cells.

Cytoplasm

The cytoplasm is the jelly-like substance inside a cell, excluding the nucleus, where various cellular activities occur.

Cytoskeleton

A network of protein fibers, including microtubules, microfilaments, and intermediate filaments.

Decomposers

Decomposers are organisms that break down dead organic matter, releasing energy and nutrients back into the ecosystem.

Degenerate

Multiple codons code for the same amino acid, reducing the impact of mutations.

Dehydrogenation

The removal of hydrogen atoms (and their electrons) from a molecule during oxidation.

Denaturation

Denaturation is the process by which the three-dimensional structure of an enzyme is altered, leading to the loss of its function.

Depolarization

A change in the membrane potential of the presynaptic neuron, making it more positive.

Diastolic blood pressure

The diastolic pressure is the pressure exerted on the walls of the arteries when the heart is in the relaxation phase (diastole), and the ventricles are filling with blood.

Dichotomous Key

A dichotomous key is a tool that simplifies the identification of organisms. It operates through a series of paired statements that describe contrasting traits.