IB SL1 Biology 2025 Finals Exam Pratice

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Species

Groups of organisms that can potentially interbreed to produce offspring.

Reproductive Isolation

When members of a species are separated into separate populations and cannot interbreed.

Community

Populations of different species living and interacting with each other in a given area.

Ecosystem

A community and its interactions with the abiotic environment.

Autotrophs

Organisms that obtain inorganic nutrients from the environment or make their own food.

Heterotrophs

Organisms that obtain organic nutrients from other organisms.

Consumers

Heterotrophs that feed on living organisms by ingestion.

Detritivores

Heterotrophs that obtain organic nutrients from detritus by internal digestion.

Saprotrophs

Heterotrophs that obtain organic nutrients from dead organisms by external digestion.

Nutrient Cycling

The process of maintaining the supply of inorganic nutrients through the recycling of organic matter.

Herbivores

Consumers that feed principally on plant matter.

Carnivores

Consumers that feed principally on animal matter.

Omnivores

Consumers that have a principal diet composed of both plant and animal matter.

Scavengers

Consumers that feed on dead and decaying carcasses.

Detritus

Dead, particulate organic matter.

Humus

Decaying leaf litter intermixed within the topsoil.

Saprotrophs

Heterotrophs that obtain organic nutrients from dead organisms by external digestion.

Nutrient Cycling

The process of maintaining the supply of inorganic nutrients through the recycling of organic matter.

Water Cycle

The continuous movement of water within the Earth and atmosphere.

Phosphorus Cycle

The cycling of phosphorus, an essential component of DNA and energy-storing molecules, in ecosystems.

Sulfur Cycle

The cycling of sulfur, an essential component of proteins and enzyme cofactors, in ecosystems.

Nitrogen Cycle

The cycling of nitrogen, a major component of the Earth's atmosphere, in ecosystems.

Mesocosms

Self-contained ecosystems that can be self-sustaining over long periods.

Chi-Squared Test

A statistical test used to determine the association between two species in a given environment.

Quadrat Sampling

A method used to determine the presence and abundance of species within a defined area.

Species Interactions

The interactions between different species within an ecosystem.

Positive Associations

Interactions between species that benefit both organisms, such as predator-prey relationships and symbiotic relationships.

Negative Associations

Interactions between species that result in competition for resources and detriment to one or both species.

Competition

The interaction between two organisms that lowers the fitness of one due to the presence of the other.

Niches

The functional position and role of an organism within its environment.

Energy Flow

The continuous supply of energy in ecosystems to fuel life processes and replace energy lost as heat.

Trophic Levels

The position an organism occupies within a feeding sequence.

Food Chains

Linear feeding relationships between species in a community.

Arrows

Represent the transfer of energy and matter as one organism is eaten by another (arrows point in the direction of energy flow)

Food Chain

The sequence of organisms in which each organism is the food source for the next organism in the chain

Energy Loss

The loss of energy stored in organic molecules through processes such as respiration, excretion, and uneaten portions of food

ATP

Adenosine triphosphate, a molecule that stores and releases energy for cellular processes

Heat

Thermal energy released as a by-product of chemical reactions in organisms

Energy Conversion

The process of converting chemical energy into other forms such as kinetic energy, electrical energy, and light energy

Exothermic

Reactions that release thermal energy (heat) as a by-product

Heat Energy

Energy released from organisms and lost from the ecosystem

Energy Efficiency

The efficiency of energy transformations in living organisms, typically around 10% efficient

Biomass

The total mass of a group of organisms, consisting of carbon compounds contained in cells and tissues

Trophic Levels

The different levels in a food chain or food web, representing the transfer of energy and matter between organisms

Pyramids of Energy

Graphical representations of the amount of energy at each trophic level in a food chain

Ecological Productivity

The rate of generation of biomass in an ecosystem

Primary Production

The production of chemical energy in organic compounds by producers

Gross Primary Production (GPP)

The total amount of chemical energy created by producers in a given time period

Net Primary Production (NPP)

The amount of chemical energy that is not consumed by respiration

Secondary Production

The generation of biomass by heterotrophic organisms (consumers)

Food Web

A diagram that shows how food chains are linked together into more complex feeding relationships

Ecological Pyramids

Graphical representations of the relative amounts of a specific component at different trophic levels in an ecosystem

Pyramid of Numbers

Shows the relative number of organisms at each stage of a food chain

Pyramid of Biomass

Shows the total mass of organisms at each stage of a food chain

Biomagnification

The increase in concentration of a substance (such as a pollutant) at higher trophic levels in a food chain

Ocean Acidification

The decrease in pH of the ocean due to increased absorption of carbon dioxide, leading to harmful effects on marine organisms

Carbon Cycling

The exchange of carbon between different spheres of the Earth, including the atmosphere, lithosphere, hydrosphere, and biosphere

Combustion

The process of burning organic compounds, releasing carbon dioxide into the atmosphere

Climate Change

Changes in global temperatures and climate patterns due to increased concentrations of greenhouse gases in the atmosphere

Greenhouse Gases

Gases that absorb and emit long-wave radiation, trapping heat in the atmosphere

Conservation

The protection and maintenance of natural resources, including plants, animals, and habitats

In situ Conservation

The preservation of plant and animal species within their natural habitat

Ex situ Conservation

The preservation of plant and animal species outside their natural habitats, often in captivity or controlled environments

Captive breeding

The practice of raising and breeding animals in controlled environments, such as zoos, to increase their chances of survival.

Botanical gardens

Dedicated areas where a diverse range of plant species are collected, cultivated, and exhibited for educational and conservation purposes.

Seed banks

Secure locations that store and categorize seeds to safeguard and maintain the genetic diversity of plants.

Microorganisms

Tiny living organisms not visible to the naked eye, including bacteria, viruses, fungi, protozoa, and algae, found everywhere.

Autotrophy

Self-sufficient in nutrient production, utilizing inorganic sources to synthesize organic compounds like photosynthesis in plants.

Aerobic Respiration

Requires oxygen for breaking down organic compounds, yielding more energy, common in many bacteria, fungi, and higher organisms.

Gram Staining

Technique categorizing bacteria into Gram-positive (retain dye) and Gram-negative (lose dye) based on cell wall characteristics.

Bactericides

Substances killing or inhibiting bacterial growth through various modes like disrupting cell membrane integrity or interfering with cell wall synthesis.

Fermenters

Controlled environments for microbial fermentation processes converting substrates into products, used in food, pharmaceuticals, and biofuel industries.

Lag Phase

Initial adjustment period in microbial growth, followed by logarithmic, stationary, and death phases, influenced by factors like nutrients and temperature.

Batch Culture

Closed system with fixed medium, exhibiting lag, log, stationary, and death phases, suitable for small-scale experiments.

Pathway Engineering

Modifying or constructing biological pathways in organisms for desired compound production or specific functions.

Transgenics

Introduction of foreign genes into an organism's genome to create genetically modified organisms with specific traits not naturally present.

Oxidation

Addition of oxygen to the pollutant molecule.

Reduction

Removal of oxygen or addition of hydrogen.

Hydrolysis

Breakdown of a compound by reaction with water.

Conjugation

Combining the pollutant with another substance to make it more water-soluble.

Detoxification

Pollutant is rendered less harmful.

Bioactivation

Pollutant is transformed into a more toxic substance (less common).

Biodegradation

Pollutant is completely broken down into harmless components.

Pollutant type

Chemical structure and properties determine how it can be metabolized.

Organism

Different species have varying metabolic capabilities.

Environmental conditions

Temperature, pH, and nutrient availability can affect metabolism.

Biofilms

Complex communities of microorganisms attached to a surface and embedded in a self-produced matrix of extracellular polymeric substances (EPS).

Quorum Sensing

Microorganisms alter gene expression in response to changes in population density.

Disease Markers

Measurable substances indicating the presence, severity, or risk of a disease.

Surface Markers

Molecules found on the surface of cells or tissues.

Genetic Markers

Alterations in DNA sequence or gene expression.

Metabolic Markers

Substances produced or used by the body during metabolism.

DNA Microarrays

Collection of microscopic DNA spots to measure gene expression levels.

cDNA Microarrays

Contain cDNA spots representing different genes for gene expression analysis.

PCR Analysis

Laboratory technique to amplify specific DNA sequences for detection or quantification.

ELISA

Test using enzymes and color changes to identify a substance.

Germline gene therapy

Raises concerns about genetic manipulation of future generations.

Equity and access

Concerns about the fairness of expensive treatments.

Bioinformatics

Interdisciplinary field combining biology, computer science, statistics, and information technology to analyze biological data.

Comparative genomics

Compares genome sequences of different species to understand biological functions, identify disease-causing genes, and develop new therapies.