General Biology: From Evolution to Ecosystems

Comprehensive flashcards covering the key principles of life, evolution, taxonomy, botany, zoology, and ecology as detailed in the lecture transcript.

Essential Properties of Life

Living organisms share three core properties: they are composed of one or more cells, carry out metabolism and energy transfer using $ATP$, and possess encoded hereditary information in $DNA$.

Origin of Photosynthesis

A major evolutionary event that occurred approximately $2000\,mya$.

Evolution of Eukaryotic Cells

The development of complex cells with compartmentalized organelles, occurring around $1500\,mya$.

Cambrian Explosion

A massive diversification of life forms occurring approximately $500\,mya$.

LUCA

Acronym for Last Universal Common Ancestor, which divided into the three domains: Eubacteria, Archaea, and Eukarya.

Binary Fission

The primary method of cell division used by prokaryotes (bacteria and archaea).

Endosymbiosis Evidence

The theory is supported by mitochondria and chloroplasts having circular $DNA$ similar to bacteria, ribosomes similar to bacterial ribosomes (vulnerable to antibiotics), and replication via binary fission rather than mitosis.

Genetic Variation

Differences in versions (alleles) of genes found in individuals within a population.

Evolution

Genetic change in a population over generations, which may lead to the development of new species.

Gene Flow

The movement of alleles from one population to another through the migration of individuals or gametes like sound-blown pollen.

Genetic Drift

Changes in allele frequency in small populations due to chance alone; its magnitude is inversely related to population size.

Bottleneck Effect

A drastic reduction in population size due to natural forces (drought, disease), resulting in survivors that carry a random genetic sample of the original population.

Founder Effect

Occurs when a few individuals become the founders of a new, isolated population, leading to the loss of certain alleles.

Fitness

A condition in evolutionary biology where an organism has an advantage, allowing it to leave more offspring than others.

Directional Selection

A type of selection acting on multi-gene traits that shifts the population toward one extreme (high or low).

Stabilizing Selection

A type of selection that favors intermediate traits rather than extremes.

Disruptive Selection

A type of selection that favors both extremes (low and high) over intermediate traits.

Homologous Structures

Body parts that share similar anatomy due to common ancestry, even if their functions differ.

Vestigial Structures

Reduced structures inherited from ancestors that may no longer serve a major purpose.

Convergent Evolution

When unrelated or distantly related organisms independently evolve similar traits due to experiencing similar environmental pressures.

Biological Species Concept

Defines a species as a group of actually or potentially interbreeding natural populations that are reproductively isolated from other such groups.

Prezygotic Isolating Mechanisms

Barriers that prevent the formation of a zygote, such as ecological, behavioral, temporal, or mechanical isolation.

Allopatric Speciation

Speciation that occurs when populations are separated by geographic barriers, stopping gene flow.

Punctuated Equilibrium

An evolutionary model showing long periods of little change (stasis) followed by rapid evolutionary change.

Phylogeny

A hypothesis of relationships among species, often represented as an evolutionary tree.

Ancestral Characteristic

A similarity inherited from the most recent common ancestor of an entire group.

Principle of Parsimony

The rule that favors the hypothesis requiring the fewest assumptions or the least number of evolutionary changes.

Monophyletic Group

A group that includes the most recent common ancestor and all of its descendants.

Paraphyletic Group

A group that includes the most recent common ancestor but only some of its descendants.

Hyphae

Long, slender filaments of cells joined end-to-end that make up the body of a fungus.

Mycorrhizae

Mutualistic symbiotic interactions between fungi and plant roots, where fungi increase nutrient absorption and plants supply sugars.

Stramenopiles

A group of protists characterized by fine hairs on their flagella, including brown algae, diatoms, and oomycetes.

Haplodiplontic Life Cycle

A cycle where both haploid (gametophyte) and diploid (sporophyte) stages are multicellular.

Tracheophytes

Vascular plants that possess xylem for water transport and phloem for nutrient transport.

Gymnosperms

Plants with 'naked seeds' and single fertilization, lacking flowers and fruits; includes conifers, cycads, gnetophytes, and ginkgophytes.

Angiosperms

The dominant plant group on Earth today, characterized by flowers and seeds enclosed within a fruit.

Red Tide

Harmful algal blooms of dinoflagellates that release toxins (dinotoxins) which can kill wildlife and accumulate through biomagnification.

Phylum Porifera

Sponges, which differ from other animals by lacking true tissues/organs and having an asymmetrical body plan.

Blastula

A cleavage stage following fertilization consisting of a hollow ball of cells surrounding a fluid-filled cavity called the blastocoel.

Triploblastic Germ Layers

The three layers established during gastrulation: ectoderm (skin/nerves), mesoderm (muscle/bone), and endoderm (lining of gut).

Protostomes

Animals in which the blastopore develops into the mouth first.

Radula

A rasping, tongue-like structure used by molluscs for feeding, such as scraping algae or drilling through shells.

Tagmata

Specialized body segments in arthropods, such as the head, thorax, and abdomen.

Water Vascular System

The hydraulic system in echinoderms used for movement, where water moves through a madreporite into canals and tube feet.

Chordata Characteristics

Four features shared by chordates: a hollow dorsal nerve cord, pharyngeal pouches, a notochord, and a postanal tail.

Amniotes

Animals like reptiles, birds, and mammals that have adaptations for land including amniotic eggs and skin with plates or scales.

Ectotherms

Organisms that do not use metabolism to produce body heat, typically having temperatures that match their environment.

Random Spacing Pattern

A population distribution where individuals do not interact strongly with each other or the environment; rare in nature.

Intrinsic Rate of Increase ($r$)

The rate of population increase calculated by the formula $r = (b - d) + (i - e)$.

Carrying Capacity ($K$)

The maximum population size that an environment can support based on limited resources like water, space, and light.

Ecological Footprint

The amount of productive land and water required to support an individual at their standard of living for their lifetime.

Fundamental Niche

The full range of environmental conditions and resources a species could potentially use based on its physiological tolerances.

Competitive Exclusion Principle

The rule stating that two species with the same niche cannot coexist; the more efficient species will eliminate the other.

Batesian Mimicry

A defensive strategy where a palatable species mimics a distasteful or toxic species.

Primary Succession

Ecological changes occurring on a bare, lifeless substrate where organisms move in and change the habitat.

Transpiration

The process by which $90\%$ of the water that enters the atmosphere from terrestrial ecosystems passes through plants.

Greenhouse Effect

The process where atmospheric gases trap heat from the sun; enhanced by human activities like burning fossil fuels, resulting in a global temperature increase.

Trophic Levels

The hierarchical levels in a food web: primary producers (autotrophs), herbivores, primary carnivores, secondary carnivores, and detritivores.

Rain Shadow

A phenomenon where moist air releases precipitation on the windward side of a mountain, leaving dry air to descend on the leeward side.

Oligotrophic Lake

A lake characterized by crystal clear water, low nutrients, high oxygen levels, and very little organic material.

Biomagnification

The process where certain pollutants, like the insecticide $DDT$, become more concentrated in organisms higher up the food chain.

Zoonotic Diseases

Contagious diseases that move between animals and humans, making up $60\%$ of human pathogens.

Endemic Species

A species found naturally in only one specific geographic area.

Biodiversity Hotspot

An area characterized by high endemism where species are disappearing at a rapid rate.