IB HL Biology Topic C - Interaction and interdependence (incomplete)

Catalyst

A substance that allows a reaction to proceed at a faster rate or under different conditions than otherwise possible.

Enzymes

Biological catalysts that are not consumed by the specific reactions they catalyse, allowing chemical reactions to proceed within a biologically relevant passage of time.

DNA replication

The process of making an identical copy of a DNA strand, which would be unable to occur within the lifetime of a cell without enzymes.

Chemical digestion

The breakdown of food into smaller molecules that can be absorbed by the body, which would be unable to happen within the period of transit through the digestive tract without enzymes.

Temperature regulation

Enzymes allow chemical reactions to proceed at biologically appropriate temperatures, preventing the need for higher temperatures that could denature cell components.

Homeostasis

The ability of an organism to maintain internal stability and balance despite external changes, which would not be maintained without enzymes preventing denaturation of cell components.

Metabolism

The totality of all enzyme-catalysed reactions that occur within a living cell or organism, representing the sum total of all the chemistry happening.

Enzyme specificity

The characteristic of enzymes requiring many different types for various reactions, allowing control over metabolism through the regulation of these specific enzymes.

Anabolic Reactions

Metabolic reactions that build up complex molecules from simpler ones, involving condensation reactions and examples like glucose production in photosynthesis.

Catabolic Reactions

Metabolic reactions that break down complex molecules into simpler ones, involving hydrolysis reactions and examples like glucose breakdown in cell respiration.

Enzyme

A globular protein acting as a biological catalyst, speeding up chemical reactions without being consumed, named after the substrate it reacts with and having an active site for binding.

Active Site

The region on the enzyme's surface where the substrate binds, composed of a few amino acids and interacting with the substrate's shape and chemical properties.

Enzyme-Substrate Complex

Formed when a substrate binds to the enzyme's active site, leading to the conversion of the substrate into a product.

Induced Fit Model

Describes how the enzyme's active site undergoes a conformational change upon substrate binding to improve binding and catalysis, allowing for broad specificity.

Enzyme Catalysis

Occurs when substrate and enzyme collide in the correct orientation, influenced by molecular motion and collisions, with increased rates by higher temperatures and substrate concentrations.

Denaturation

A structural change in the enzyme due to external factors like high temperatures or extreme pH, disrupting the active site and affecting enzyme-substrate interactions.

Temperature, pH, Substrate Concentration

Factors affecting enzyme activity, with temperature affecting kinetic energy, pH altering enzyme charge and shape, and substrate concentration influencing enzyme activity up to a saturation point.

Rate of Reaction

Calculated as the inverse of the time taken for the reaction to proceed, determining the speed of the enzyme-catalyzed reaction.

Activation Energy

The energy required for a chemical reaction to proceed, lowered by enzymes to speed up reactions, with exergonic reactions releasing energy and endergonic reactions requiring energy.

Heat Generation

Occurs during metabolic reactions due to energy inefficiencies, utilized by endotherms to maintain body temperature and influenced by metabolic activity levels.

Metabolic Pathways

Organized chains or cycles of enzyme-catalyzed reactions, with linear pathways (e.g., glycolysis) and cyclical pathways (e.g., Krebs cycle), allowing for regulation through intermediates.

Non-Competitive Inhibition

Involves an inhibitor binding to an allosteric site on the enzyme, causing a conformational change that prevents substrate binding, exemplified by cyanide poisoning.

Competitive Inhibition

Occurs when an inhibitor competes with the substrate for the enzyme's active site, blocking substrate binding, with statins as an example of cholesterol-lowering drugs.

Feedback Inhibition

A negative feedback mechanism where the end product of a metabolic pathway inhibits an enzyme from an earlier step, regulating product levels.

Mechanism-Based Inhibition

Irreversible binding of an inhibitor to the active site, forming a covalent bond and permanently inhibiting the enzyme, illustrated by penicillin's action on bacterial cell wall synthesis.

ATP

Adenosine triphosphate, the cell's energy currency, containing three phosphate groups that store energy in their bonds and releasing energy when hydrolyzed.

Ecosystems as open systems

Systems where both energy and matter can enter and exit

Closed systems

Systems that only exchange energy across their boundary

Sunlight

Principal source of energy for most ecosystems

Photoautotrophic organisms

Organisms like green plants and some bacteria that use sunlight as an energy source

Chemoautotrophic bacteria

Bacteria in ecosystems like caves and hydrothermal vents that use energy from chemical processes

Trophic levels

Positions in a feeding sequence within an ecosystem

Food chains

Linear feeding relationships between species in a community

Food webs

Diagram showing complex feeding relationships in an ecosystem

Decomposers

Organisms essential for recycling matter in ecosystems

Autotrophs

Organisms that synthesize carbon compounds from inorganic substances using external energy sources

Heterotrophs

Organisms that obtain carbon compounds from other organisms for synthesis

Cell respiration

Process where energy is released by the oxidation of carbon compounds

Classification of organisms into trophic levels

Positioning organisms at their highest trophic level when constructing food webs to maintain arrow direction

Construction of energy pyramids

Graphical representation of energy at each trophic level in a food chain, expressed in energy per area per time units

Pyramid of energy

Graphical representation of energy at each trophic level in a food chain, measured in units like kJ m-2 year-1

Energy loss in food chains

Energy transformations are ~10% efficient, with about 90% of available energy lost between trophic levels

Biomass

Total mass of organisms, consisting of carbon compounds in cells and tissues, used to measure energy added to organisms

Heat loss in cell respiration

Heat loss to the environment in autotrophs and heterotrophs due to conversion of chemical energy to heat in cell respiration

Energy losses in ecosystems

Energy and biomass decrease between trophic levels, limiting the number of trophic levels in ecosystems.

Higher trophic levels

Levels in a food chain that receive less energy and biomass, requiring larger quantities of food to obtain sufficient amounts.

Unviable trophic level

Occurs when the energy needed to hunt food surpasses the energy available from the food eaten.

Fossil Fuels

Organic compounds compacted underground for millions of years, resulting in coal, oil, and natural gas as non-renewable energy sources.

Keeling Curve

Continuous measurement of atmospheric CO2 concentrations since 1958 at Mauna Loa Observatory, showing annual fluctuations, increasing trends, and highest levels recorded.

Cell Respiration

Process involving breakdown of organic molecules to produce ATP, releasing carbon dioxide as a by-product, with removal facilitated by passive diffusion.

Compensation Point

Balance point in autotrophs where CO2 uptake by photosynthesis equals CO2 production by respiration, resulting in zero net carbon dioxide assimilation.

Nutrient Recycling

Constant recycling of chemical elements required by organisms like carbon, nitrogen, and phosphorus through autotrophs, heterotrophs, and saprotrophs in ecosystems.

Biogeochemical Cycle

Pathway of a chemical substance through Earth's biotic and abiotic spheres, such as the carbon cycle and other essential nutrient cycles.

Population

Interacting groups of organisms of the same species living in an area

Natality

Increases population size through reproduction (births)

Immigration

Increases population size from external populations

Mortality

Decreases population size as a result of death

Emigration

Decreases population size due to loss to external populations

Population Size Equation

Population Size = (Immigration + Natality) - (Mortality + Emigration)

Population Sampling

Identifying individual numbers in small areas and extrapolating to estimate population totals

Quadrat Sampling

Using a rectangular frame to establish population densities, suitable for non-motile species

Capture-Mark-Release-Recapture

Method to estimate population size of motile species by marking and recapturing individuals

Lincoln Index

Formula: Estimated Population = (n1 × n2) ÷ n3, used in capture-mark-release-recapture method

Limiting Factors

Environmental conditions controlling the rate of population growth

Density-Dependent Factors

Environmental factors influenced by the relative size of a population

Density-Independent Factors

Environmental factors not influenced by the relative size of a population

Negative Feedback

Return of a system to its original state, controlling population size by density-dependent factors

Exponential growth pattern (J curve)

Occurs in an ideal, unlimited environment with no competition initially, resulting in a J-shaped curve

Logistic growth pattern (S curve)

Occurs when environmental pressures slow the rate of growth as population approaches a finite carrying capacity, resulting in an S-shaped curve

Biotic potential

The maximal growth rate for a given population in an ideal environment with unlimited resources

Carrying capacity

The maximum number of a species that can be sustainably supported by the environment

Population clocks

Provide current projections of estimated populations based on recorded data, often using assumed rates of change

Sigmoidal growth curve

Demonstrated by stable populations in a fixed geographic space, following three key stages: exponential growth, transitional phase, and plateau phase

Intraspecific competition

Competition within the same species for resources, often the strongest type of competition

Cooperation in intraspecific relationships

Complex behaviors developed to minimize the impact of direct competition within a species

Community

Consists of all living things in an ecosystem, including all populations of all species

Herbivory

The act of eating only plant matter; can be harmful or beneficial to plant species as a whole.

Predation

Biological interaction where one organism (predator) hunts and feeds on another organism (prey), affecting population levels.

Pathogenicity

Capacity of a microbe to cause damage in a host resulting in disease, impacting population carrying capacity.

Symbiosis

Close and persistent interaction between two species, which can be obligate or facultative.

Mutualism

Ongoing interaction between two species where both benefit from the interaction.

Mucivores

Herbivores that feed on plant sap.

Granivores

Herbivores that feed on seeds.

Folivores

Beetles that feed voraciously on leaves/foliage, causing crop failure.

Frugivores

Fruit-eating animals that spread seeds through their feces, promoting seed dispersal.

Commensalism

Symbiotic relationship where one species benefits while the other is unaffected.

Anemone

Protects clownfish in a mutualistic relationship.

Clownfish

Provides fecal matter for food in a mutualistic relationship with anemone.

Barnacles

Transported to plankton-rich waters by whales in a commensalistic relationship.

Ticks

Parasites that feed on the blood of their canine host.

Chytridiomycosis

Amphibian disease caused by the fungus Batrachochytrium dendrobatidis.

Rhizobium

Bacteria that fixes atmospheric nitrogen in exchange for carbohydrates in a mutualistic relationship with plants.

Mycorrhiza

Fungi that grows in association with orchid roots, supplying nutrients and water in exchange for carbohydrates.

Plover birds

Clean crocodile teeth by picking food morsels from between their jaws in a mutualistic relationship.

Honey bees

Gather nectar from flowers and distribute pollen between plants, mediating plant life cycle in a mutualistic relationship.

Fabaceae

Legume family of plants that form mutualistic relationships with nitrogen-fixing bacteria.

Zooxanthellae

Algae that photosynthesize within the protective environment of the polyp's endodermis, feeding the coral.

Competition

Describes the interaction between two organisms where the fitness of one is lowered by the presence of the other. It can be intraspecific (within the same species) or interspecific (between different species).

Competitive exclusion

One species uses resources more efficiently, driving the other species to local extinction.

Resource partitioning

Both species alter their use of the environment to divide resources between them.