Biology 11: Ecology, Genetics, Evolution, and Biodiversity

Comprehensive vocabulary flashcards covering Ecology, Population Biology, DNA, Mechanisms of Evolution, Evidence for Evolution, Reproductive Isolation, and Biological Taxonomy from Biology 11.

Ecology

The scientific study of the interactions between biotic and abiotic factors within the environment, combining aspects of chemistry, biology, and geology.

Biotic vs. Abiotic Factors

Biotic factors are the living components of an ecosystem (such as plants, animals, fungi, protists, bacteria, and archaea), while abiotic factors are the non-living chemical and physical elements (such as air, salinity, soil, temperature, light, water, minerals, pH, and humidity).

Autotroph

An organism (producer) that produces its own food, such as plants, algae, phytoplankton, and some bacteria.

Heterotroph

An organism (consumer) that does not make its own food and must obtain nutrients from other sources, including animals, fungi, most protozoa, and most bacteria.

Autotroph vs. Heterotroph

Autotrophs are producers that synthesize their own organic food molecules, whereas heterotrophs are consumers that depend on consuming other organisms for nutrition.

Trophic Levels and Energy Transfer

The sequential stages in a food chain where only approximately $10\%$ of energy is passed from one level to the next, resulting in a progressive decrease in biomass and energy toward higher levels.

Photosynthesis

The metabolic pathway occurring in plant cell chloroplasts where chlorophyll captures solar energy to convert carbon dioxide and water into glucose and oxygen, represented by the equation: $6\text{CO}_2 + 6\text{H}_2\text{O} + \text{solar energy} \rightarrow \text{C}_6\text{H}_{12}\text{O}_6 + 6\text{O}_2$.

The Scientific Method

The systematic, core procedure of inquiry consisting of six sequential steps: 1. Make an Observation, 2. Ask a Question, 3. Form a Hypothesis, 4. Conduct an Experiment, 5. Analyze Data & Draw Conclusions, and 6. Report Results.

Population Biology

The branch of biology that examines the populations of species, how they change through time, and how they interact with their environment.

Population Change

A descriptor of the total number of individuals present in a population over a specific period of time.

Habitat

The specific physical home, place, or geographical location where an organism resides.

Niche

The specific functional role or ecological 'job' that an organism performs within its environment.

Population Growth

The net increase or decrease in the size of a population over time, calculated using the formula: $\text{Population growth} = \text{birth rate} - \text{death rate} + \text{immigration rate} - \text{emigration rate}$.

Biotic Potential

The maximum theoretical reproductive rate at which a species could increase in population size under ideal, unrestrained conditions.

Limiting Factors

Specific environmental conditions, resources, or spatial restrictions that prevent a population from continuously growing.

Migration

The seasonal, round-trip movement of an entire animal population from one region to another and back.

Immigration

The movement of individuals entering and taking up permanent residence in a new geographic area.

Emigration

The permanent departure of individuals leaving their native home range or population.

Population Density

The degree of crowding within a population relative to the available space, calculated as: $\frac{\text{\# of organisms}}{\text{unit area or volume}}$.

Exponential Growth

Unrestricted population growth that accelerates rapidly over time, displaying a characteristic J-shaped curve when resources are unlimited.

Carrying Capacity

The maximum sustainable number of individuals of a given species that an environment can support over time with its available resources.

Logistic Growth

A pattern of population growth modeled by an S-shaped curve, where growth slows and levels off as population density approaches carrying capacity due to limited resources.

Predation and Parasitism

A $(+,-)$ relationship where one organism benefits by eating, poisoning, or consuming resources from another organism for nourishment, causing harm to the host or prey.

Predator-Prey Cycles

Regular, periodic population oscillations that occur over time as predator and prey abundance reciprocally influence one another.

Competition

A $(-,-)$ interaction in which both competing organisms are negatively affected while fighting over shared, limiting environmental resources.

Commensalism

A symbiotic relationship $(+,0)$ between two distinct species in which one organism benefits while the other remains entirely unaffected.

Mutualism

A mutually beneficial symbiotic relationship $(+,+)$ between two distinct species where both organisms derive a survival or reproductive advantage.

Primary Succession

The ecological process by which plant and animal communities establish and develop over time in an environment devoid of pre-existing soil.

Secondary Succession

The ecological process of ecosystem recovery and recolonization following a natural or anthropogenic disturbance where the underlying soil layers remain completely intact.

Great Bear Rainforest Management Act

A major provincial conservation initiative in British Columbia designed to monitor population dynamics, protect habitats and niches, mitigate habitat loss, and safeguard secondary succession by ensuring soil integrity after disturbances.

DNA (Deoxyribonucleic Acid)

The master biomolecule containing all genetic information and building instructions required to create, develop, and sustain living organisms.

Nucleotides

The individual monomeric chemical building blocks that compose DNA, consisting of a sugar, a phosphate group, and a nitrogenous base.

Nucleotide Strands

Linear chains of nucleotides covalently joined together into a rigid sugar-phosphate backbone with exposed nitrogenous bases.

Base Pairing

The sequence-specific, complementary chemical bonding holding two nucleotide strands together, wherein adenine binds exclusively with thymine ($A$ with $T$) and cytosine binds exclusively with guanine ($C$ with $G$).

Chromosomes

Dense, compact structures formed by looping DNA around specialized proteins, allowing genetic material to organize and fit within the nucleus during cell replication.

Genes

Functional segments of DNA located along chromosomes that carry the precise genetic instructions to synthesize proteins that determine phenotypic traits.

Adaptation

Any structural, behavioral, or physiological characteristic that enhances an organism's capacity to survive and reproduce within its specific environment.

Variation

The natural physical and genetic differences observed among individual organisms of the same species, ensuring no two individuals are genetically identical.

Passing on Traits (Heredity)

The biological transmission of genetic instructions (DNA) from parents to offspring across successive generations via reproduction.

Lamarck's Theory of Evolution

A 19th-century evolutionary model proposing that organisms alter physical traits throughout their lifetimes due to environmental pressures and pass these acquired traits to offspring via hypothetical particles called pangenes.

Weismann's Mice Experiment

An experimental test of Lamarckian inheritance in which the tails of mice were removed across $20$ successive generations; offspring consistently developed full tails, effectively disproving the inheritance of acquired traits.

Darwin and Wallace's Five Steps of Evolution

The foundational theory of natural selection structured into five sequential components: the struggle for existence, variation, natural selection, heredity, and speciation.

Sea Otter (Enhydra lutris)

A marine mammal of the North Pacific kelp forests with no blubber, possessing up to $150{,}000\,\text{hairs}/\text{cm}^2$, webbed hind flippers, foreleg pouches, tool-use behaviors, a metabolic intake requirement of $20\%\text{ to }25\%$ body weight daily, and acting as a keystone species by preying on sea urchins.

Corn / Maize (Zea mays)

A domesticated C4 photosynthetic crop with brace roots, synchronized wind pollination via separate male tassels and female silks, secondary pest-deterrent metabolites (benzoxazinoids), and an obligate mutualistic relationship with humans.

The Fossil Method

The examination of preserved physical remnants of ancient organisms to document gradual morphological transitions into modern species over geological timescales.

Transitional Forms

Fossil specimens that exhibit intermediate morphological traits connecting two distinct major groups of organisms, such as Eusthenopteron, Seymouria, Archaeopteryx, and Therapsids.

Biogeography

The scientific discipline studying the geographic distribution of species globally and the historical mechanisms—such as continental drift, glaciation, and extinction—that caused them.

Island Biogeography

The study of evolutionary dynamics within geographically isolated environments, showing how long-term isolation fosters unique species assemblages, such as Australia's marsupial fauna.

Pangea

An ancient supercontinent whose progressive breakup influenced modern species distribution, leaving ancestral groups (like reptiles) widely distributed globally, whereas newer groups (like mammals) evolved after the split in restricted regions.

Homologous Structures

Anatomical structures in different species that share an identical underlying internal blueprint because they were inherited from a common ancestor, even if their external form and modern function have diverged.

Divergent Evolution

The evolutionary pattern whereby related lineages diverge into distinct forms and functions as they adapt to differing environmental conditions and ecological niches.

Analogous Structures

Body structures that perform identical ecological functions but exhibit completely different internal anatomical blueprints, having evolved independently through convergent evolution rather than via shared ancestry.

Convergent Evolution

The process by which phylogenetically unrelated organisms independently evolve similar physical adaptations in response to similar environmental selective pressures.

Vestigial Structures

Degenerated, non-functional anatomical remnants of organs or bones that were fully functional in ancestral species, such as the human appendix or tailbone.

Comparative Embryology

The study of embryonic development across various taxa, demonstrating that early-stage embryos share morphological similarities and operate using a shared, ancestral genetic 'toolkit.'

Comparative Biochemistry

The comparative study of DNA sequences and protein amino acid compositions across taxa, indicating that closely related species share higher percentages of molecular similarity.

The Molecular Clock

The evolutionary principle stating that the accumulation of molecular sequence differences between two lineages is directly proportional to the amount of time that has elapsed since they diverged from a common ancestor.

Microevolution

The accumulation of small-scale allele frequency changes within a population's gene pool over a relatively brief period of time, driven by mutation, gene flow (migration), genetic drift, natural selection, and non-random mating.

Reproductive Isolation

The condition in which biological barriers prevent two populations of the same species from interbreeding and exchanging genetic material, causing independent microevolution and potentially leading to speciation.

Sexual Selection

A mode of natural selection where individuals evolve prominent courtship behaviors or morphological ornaments (such as peacock trains, frigatebird gular pouches, or fly eyestalks) that enhance mating success despite potential survival costs.

Geographic / Habitat Isolation

A pre-zygotic isolating barrier where populations inhabit completely different physical environments or are split by geographical formations (such as Kaibab and Abert's squirrels divided by the Grand Canyon), preventing reproduction.

Temporal Isolation

A pre-zygotic isolating mechanism where closely related species share a habitat but breed at differing times of day or separate seasons (e.g., Monterey pine releasing pollen in spring vs. Bishop pine in summer).

Behavioural Isolation

A pre-zygotic isolating mechanism where distinct mating calls, chemical pheromones, or specific courtship rituals (such as species-specific firefly light flash sequences) prevent cross-species mating.

Mechanical Isolation

A pre-zygotic barrier where anatomical incompatibility of reproductive organs physically prevents copulation or pollen transfer, exemplified by the lock-and-key claspers of damselflies.

Gametic Isolation

A pre-zygotic barrier where sperm and egg fail to fuse chemically, or sperm cannot survive in the reproductive tract, as seen between co-spawning purple and red sea urchins.

Hybrid Inviability

A post-zygotic barrier where genetic incompatibilities cause hybrid zygotes (such as sheep-goat crosses) to fail during embryonic development, leading to early mortality or spontaneous miscarriage.

Hybrid Sterility

A post-zygotic barrier where hybrid offspring develop into viable, healthy adults but cannot produce functional gametes due to chromosomal incompatibilities, such as a sterile mule resulting from a male donkey and female horse.

Hybrid Breakdown

A post-zygotic barrier where first-generation ($F_1$) hybrids are fully fertile and robust, but their subsequent ($F_2$) offspring are weak, deformed, or sterile, as observed in crosses between cultivated cotton species.

Macroevolution

Large-scale evolutionary patterns and changes occurring above the species level, illustrating the origin of major organismal groups from simple ancestors over approximately $4\text{ billion years}$.

Biodiversity

The collective variety, variation, and abundance of life forms present within a defined ecosystem or across the entire planet.

Taxonomy

The biological branch of science dedicated to the naming, describing, and classifying of organisms based on shared morphological and genetic characteristics.

Species

A group of closely related organisms capable of naturally interbreeding with one another to generate fertile, viable offspring.

Biological Hierarchy

The eight-tier nested classification structure used to categorize all life: Domain, Kingdom, Phylum, Class, Order, Family, Genus, and Species.

Domain Archaea

A biological domain of exclusively unicellular prokaryotes lacking peptidoglycan in their cell walls, possessing branched ether-linked membrane lipids, and frequently inhabiting extreme environments.

Domain Bacteria

A ubiquitous biological domain of exclusively unicellular prokaryotes whose cell walls contain peptidoglycan and whose cell membranes are composed of unbranched ester-linked lipids.

Domain Eukarya

A biological domain comprising unicellular and multicellular eukaryotic organisms with membrane-bound nuclei, unbranched ester-linked membrane lipids, and cell walls lacking peptidoglycan (composed of cellulose or chitin when present).