Carrying Capacity: The size of the population that can be supported indefinitely on the available resources and services of that ecosystem.
Clade: A group of organisms that consists of a common ancestor and all its lineal descendants.
Ecological Niche: The role and space that an organism fills in an ecosystem, including all its interactions with the biotic and abiotic factors of its environment.
Evolution: Change in the genetic composition of a population during successive generations, which may result in the development of new species.
Fragmented: Disorganised; broken down; disjointed or isolated.
Genome: All the genetic material in the chromosomes of an organism, including its genes and DNA sequences.
Isolated: Detached, separate, or unconnected with other things; one-off; something set apart or characterised as different in some way.
Keystone Species: A plant or animal that plays a unique and crucial role in the way an ecosystem functions.
Macroevolution: The variation of allele frequencies at or above the level of species over geological time, resulting in the divergence of taxonomic groups, in which the descendant is in a different taxonomic group to the ancestor.
Microevolution: Small-scale variation of allele frequencies within a species or population, in which the descendant is of the same taxonomic group as the ancestor.
Polygenic Inheritance: When one characteristic is controlled by two or more genes.
Unit 3 Topic 1: Describing Biodiversity
Biodiversity
Biodiversity: The diversity of species and ecosystems in a given area.
Species Richness: The number of different species in a given area.
Species Evenness: The relative abundance of each species in a community.
Simpson's Diversity Index: A measure used to quantify biodiversity, accounting for both species richness and evenness.
Abiotic Factors: Non-living environmental factors that affect ecosystems (e.g., climate, substrate, area size/depth).
Species Interactions: Relationships between different species in an ecosystem, such as predation, competition, symbiosis, and disease.
Classification Processes
Biological Classification: A hierarchical system used to categorize organisms based on similarities in physical features, methods of reproduction, and molecular sequences.
Linnaean System: A classification system based on similarity of physical features.
Molecular Phylogeny: The study of evolutionary relationships between species based on molecular sequences (also called cladistics).
Clade: A group of organisms that includes a common ancestor and all of its descendants.
Cladograms: Diagrams used to infer evolutionary relationships based on common ancestry, bifurcation, and physical change.
K and r Selection: Two reproductive strategies, with K-selection favoring fewer offspring with higher survival and r-selection favoring many offspring with lower survival.
Interspecific Hybrid: An organism resulting from the mating of two different species that does not produce fertile offspring (e.g., mule, Equus mulus).
Species Interactions
Predation: An interaction where one organism kills and eats another.
Competition: An interaction where organisms compete for limited resources, such as food or space.
Symbiosis: A close and long-term interaction between two different species, which may be mutualistic, commensal, or parasitic.
Disease: An interaction where one organism, typically a pathogen, harms another organism.
Ecological Concepts
Microhabitat: A small or specialized habitat within a larger ecosystem.
Ecoregion: A large geographical area defined by distinct ecological characteristics.
Stratified Sampling: A sampling technique used to estimate population density, distribution, and environmental gradients.
Ecological Surveying Techniques: Methods such as quadrats and transects used for data collection in ecological studies.
Bias Minimisation: Reducing errors in sampling through techniques like random-number generators and calibrating equipment.
Ecosystem Classification
Old-Growth Forests: Forests that have developed over a long period without significant disturbance.
Productive Soils: Soils that support high levels of biological productivity.
Coral Reefs: Marine ecosystems known for their biodiversity and productivity, often classified for effective ecosystem management.
Unit 3 Topic 2: Ecosystem Dynamics
Functioning Ecosystems
Solar Energy Transfer: The process of converting light energy into chemical energy through photosynthesis, and transferring this energy through biotic components of an ecosystem.
Biomass: The total mass of living organisms in a given area or ecosystem at a specific time, which serves as energy storage for ecosystems.
Energy Transfer in Ecosystems: The flow of energy through food chains, webs, and pyramids, with energy lost through radiation, reflection, and absorption.
Trophic Levels: The hierarchical levels in an ecosystem based on the energy transfer, including producers, primary consumers, secondary consumers, etc.
Food Chain: A linear sequence of organisms where each is eaten by the next member in the chain, representing the transfer of energy.
Food Web: A complex network of interconnected food chains within an ecosystem.
Gross and Net Productivity: Gross productivity refers to the total amount of energy captured by producers, while net productivity is the energy left after subtracting the energy used for respiration.
Energy Flow Diagrams: Diagrams that illustrate the movement of energy through ecosystems, including productivity at various trophic levels.
Transfer and Transformation of Matter
Carbon Cycle: The movement of carbon between the atmosphere, living organisms, and the Earth's surface through processes like respiration, photosynthesis, and decomposition.
Water Cycle: The continuous movement of water through the environment via processes such as evaporation, condensation, and precipitation.
Nitrogen Cycle: The process by which nitrogen is converted into various chemical forms as it circulates through the atmosphere, soil, and living organisms.
Ecological Niche: The role of an organism within its ecosystem, including its habitat, feeding relationships, and interactions with other species.
Competitive Exclusion Principle: The concept that two species competing for the same resources cannot coexist at constant population values.
Keystone Species: A species that has a disproportionately large effect on the structure of its community, often playing a critical role in maintaining ecosystem balance.
Population Ecology
Carrying Capacity: The maximum population size of a species that an ecosystem can support without degradation of resources.
Limiting Factors: Biotic and abiotic factors that limit the growth, abundance, or distribution of a population (e.g., food, water, space).
Population Growth Rate: The rate at which a population increases or decreases, influenced by birth, death, immigration, and emigration.
Lincoln Index: A method used to estimate the size of a population based on the capture, marking, and recapture of individuals.
Exponential Growth: A type of population growth where the population size increases rapidly due to abundant resources, resulting in a J-shaped curve.
Logistic Growth: A type of population growth where the growth rate slows as the population approaches its carrying capacity, resulting in an S-shaped curve.
Changing Ecosystems
Ecological Succession: The process by which ecosystems change over time, often following disturbance. It involves the gradual replacement of one community by another.
Pioneer Species: The first species to colonize a disturbed area, typically characterized by traits such as nitrogen fixation, tolerance to extreme conditions, and rapid seed germination.
Climax Community: A stable and mature community that results from ecological succession, where species composition remains relatively unchanged over time.
Primary Succession: Succession that occurs in an area that has never been previously colonized (e.g., after a volcanic eruption).
Secondary Succession: Succession that occurs in an area that has been disturbed but still contains soil and some organisms (e.g., after a forest fire).
Impact of Human Activity: Human activities such as deforestation, pollution, and climate change can reduce biodiversity and affect the speed, magnitude, and duration of ecosystem changes.
Unit 4 Topic 1: DNA, Genes, and the Continuity of Life
DNA Structure and Replication
Deoxyribonucleic Acid (DNA): A double-stranded molecule that contains the genetic instructions for the development and functioning of living organisms.
Histones: Proteins that bind to DNA and help in the formation of chromosomes in the nucleus.
Prokaryotic DNA: DNA found in the cytosol of prokaryotes, which is unbound and circular in structure.
DNA in Mitochondria and Chloroplasts: DNA found in the mitochondria and chloroplasts of eukaryotic cells, which is distinct from nuclear DNA.
Nucleotide Composition: The basic building blocks of DNA, consisting of a phosphate group, a sugar (deoxyribose), and a nitrogenous base.
Complementary Base Pairing: The pairing of specific nitrogenous bases in DNA (adenine with thymine, and cytosine with guanine) through hydrogen bonds.
Helicase: An enzyme that unwinds the double helix of DNA and separates the strands during DNA replication.
DNA Polymerase: An enzyme responsible for forming new complementary strands of DNA during replication, working in a 5’ to 3’ direction.
Cellular Replication and Variation
Meiosis: A type of cell division that reduces the chromosome number by half, resulting in four non-identical haploid cells.
Homologous Chromosomes: Chromosomes that are similar in shape, size, and genetic content, but may carry different alleles.
Crossing Over: A process during meiosis where homologous chromosomes exchange segments, contributing to genetic variation.
Recombination: The process of forming new combinations of genes during crossing over, increasing genetic diversity.
Spermatogenesis: The process of sperm cell production in males, resulting in four haploid cells from one diploid cell.
Oogenesis: The process of egg cell production in females, resulting in one functional haploid egg and three non-functional polar bodies.
Independent Assortment: The random distribution of homologous chromosome pairs during meiosis, contributing to genetic diversity.
Random Fertilization: The random combination of sperm and egg during fertilization, further contributing to genetic variation in offspring.
Gene Expression
Genome: The complete set of genes or genetic material present in a cell or organism.
Gene: A segment of DNA that codes for a functional product, such as a protein or RNA molecule.
Coding DNA (Exons): DNA sequences that contain the instructions for making proteins.
Noncoding DNA: DNA sequences that do not code for proteins but may have regulatory or other functions, including functional RNA, centromeres, telomeres, and introns.
Functional RNA: RNA molecules that are not translated into proteins but have other functions, such as transfer RNA (tRNA).
Introns: Noncoding regions of a gene that are transcribed into RNA but are spliced out before translation into protein.
Transcription: The process by which a gene’s DNA sequence is copied into messenger RNA (mRNA) in the nucleus.
Translation: The process by which the mRNA is used as a template to synthesize a protein at the ribosome, involving tRNA, codons, and anticodons.
Gene Expression: The process through which a gene’s information is used to synthesize a functional product (protein or RNA).
Transcription Factors: Proteins that regulate the transcription of specific genes by binding to DNA sequences.
Phenotypic Expression: The observable traits of an organism, influenced by both genetic and environmental factors.
HOX Transcription Factor Family: A group of transcription factors that regulate the development of body structures in animals.
Sex-Determining Region Y (SRY): A gene that regulates the development of male sex characteristics in humans.
Mutations
Point Mutation: A mutation where a single base pair in the DNA sequence is altered, potentially changing one amino acid in the protein.
Frameshift Mutation: A mutation caused by the insertion or deletion of a nucleotide in the DNA sequence, shifting the reading frame of the gene.
Non-Disjunction: A failure of chromosomes to separate properly during cell division, leading to aneuploidy (incorrect chromosome number).
Aneuploidy: A condition where an organism has an abnormal number of chromosomes, often resulting from non-disjunction.
Mutagens: Physical or chemical agents that cause mutations in the DNA.
Physical Mutagens: Mutagens such as UV radiation, ionizing radiation, and heat that can damage DNA.
Chemical Mutagens: Mutagens such as certain chemicals that can induce mutations in the DNA sequence.
Human Karyotype: A display of the chromosome pairs of a human, used to identify ploidy changes and predict genetic disorders.
Inherited Mutations: Mutations in genes that are passed from parents to offspring, potentially affecting genetic variation.
Inheritance
Genotype: The genetic constitution of an individual, consisting of their alleles.
Phenotype: The observable physical traits of an organism, influenced by its genotype and environment.
Autosomal Dominant: A pattern of inheritance where a dominant allele on an autosome (non-sex chromosome) determines the phenotype.
Sex-linked Inheritance: A pattern of inheritance where genes located on the sex chromosomes (X or Y) influence traits.
Multiple Alleles: A genetic situation where more than two alleles exist for a given gene, contributing to variability in traits.
Polygenic Inheritance: Inheritance of traits controlled by two or more genes, resulting in a continuous range of phenotypic expression.
Punnett Square: A diagram used to predict the genotypic and phenotypic outcomes of genetic crosses.
Frequency Histogram: A graphical representation of the distribution of genotypes or phenotypes in a population.
Biotechnology
Recombinant DNA: DNA that has been artificially modified by combining genetic material from different sources.
Isolation of DNA: The process of extracting DNA from a biological sample for further analysis or modification.
Restriction Enzymes: Enzymes that cut DNA at specific sequences, used in recombinant DNA technology.
Plasmid Vector: A small circular DNA molecule used to insert foreign DNA into a host cell.
DNA Ligase: An enzyme that joins DNA fragments together, facilitating the creation of recombinant DNA.
Bacterial Transformation: The process by which bacteria take up foreign DNA, often used to amplify recombinant DNA.
DNA Sequencing: A technique used to determine the exact sequence of nucleotides in a DNA molecule, often used to map species' genomes.
DNA Profiling: A technique used to identify unique genetic information for forensic or paternity testing.
Polymerase Chain Reaction (PCR): A technique used to amplify small amounts of DNA, making it easier to study or use in experiments.
Gel Electrophoresis: A method used to separate DNA fragments by size, often used in DNA analysis and profiling.
Success Rate of Biotechnology Techniques: The effectiveness of a genetic biotechnology technique, such as recombinant DNA, PCR, or DNA profiling, often evaluated through outcome data.
Unit 4 Topic 2: Continuity of Life on Earth
Evolution
Evolution: The gradual change in the characteristics of species over successive generations due to natural selection and other mechanisms.
Microevolution: Small-scale evolutionary changes that occur within a species or population, often involving changes in allele frequencies.
Macroevolution: Large-scale evolutionary changes that occur over long periods of time, leading to the formation of new species or groups of species.
Evolutionary Radiation: A rapid diversification of species from a common ancestor, often following a mass extinction or environmental change.
Mass Extinctions: Events in Earth's history when large numbers of species go extinct in a relatively short period of time, often leading to new evolutionary opportunities for survivors.
Phylogenetic Relationships: The evolutionary connections between species, often determined by comparing genetic material (e.g., DNA sequences).
Comparative Genomics: The study of similarities and differences in the genetic makeup of different species to provide evidence for evolution.
Natural Selection and Microevolution
Natural Selection: A process where environmental pressures favor certain phenotypes, leading to increased survival and reproduction of organisms with advantageous traits.
Selective Advantage: A characteristic or trait that increases an organism's chances of survival and reproduction in a particular environment.
Phenotypic Selection: The selection of traits in a population based on their phenotype, leading to changes in allele frequencies over generations.
Allele Frequency: The relative frequency of an allele (version of a gene) in a gene pool of a population.
Types of Phenotypic Selection:
Stabilising Selection: Selection that favors intermediate phenotypes, reducing variation in a population.
Directional Selection: Selection that favors one extreme phenotype, leading to a shift in the population's traits.
Disruptive Selection: Selection that favors extreme phenotypes at both ends, leading to a bimodal distribution of traits.
Microevolutionary Change: Small changes in the genetic composition of a population due to processes like mutation, gene flow, and genetic drift.
Mutation: A change in the DNA sequence that can introduce new genetic variation into a population.
Gene Flow: The transfer of alleles between populations through migration or interbreeding, influencing genetic variation.
Genetic Drift: Random fluctuations in allele frequencies due to chance events, particularly in small populations.
Speciation and Macroevolution
Speciation: The process by which new species arise from an existing population, often through the accumulation of microevolutionary changes.
Macroevolutionary Changes: Large-scale evolutionary changes that lead to the formation of new species or groups of species over time.
Divergent Evolution: Evolutionary pattern where two or more species evolve from a common ancestor, leading to increased differences between them.
Convergent Evolution: Evolutionary pattern where unrelated species evolve similar traits due to similar environmental pressures.
Parallel Evolution: Evolutionary pattern where species that are closely related evolve similar traits independently in response to similar environmental factors.
Coevolution: The process where two or more species influence each other's evolution through reciprocal selective pressures.
Modes of Speciation:
Allopatric Speciation: Speciation that occurs when populations are geographically isolated, preventing gene flow.
Sympatric Speciation: Speciation that occurs without geographic isolation, often through behavioral or ecological differences.
Parapatric Speciation: Speciation that occurs when populations are partially isolated but still have some gene flow, often due to environmental gradients.
Mechanisms of Isolation: Processes that prevent gene flow between populations, including geographic, reproductive, spatial, and temporal isolation.
Genetic Diversity: The variety of genetic traits within a population, which is crucial for the survival and adaptability of species.
Population Bottlenecks: Events that significantly reduce genetic diversity in a population, often leading to increased extinction risks.
