NEET Organisms and Populations Flashcards

Vocabulary flashcards covering core concepts, adaptations, growth equations, and ecological interactions from the Organisms and Population lecture.

Ecology

The scientific study of interactions among organisms and between organisms and their physical (abiotic) environment.

Niche

The functional role of an organism in an ecosystem, defined by the specific resources it utilizes and the range of conditions it can tolerate.

Habitat

The physical place or "address" where an organism lives, shaped by both abiotic components (temperature, water, light, soil) and biotic factors (parasites, pathogens, predators, competitors).

Eurythermal Organisms

Organisms that are capable of tolerating and thriving across a wide range of temperatures, such as birds and mammals.

Stenothermal Organisms

Organisms that are restricted to and can tolerate only a narrow range of temperatures, such as many reptiles.

Euryhaline Organisms

Organisms that have the physiological capacity to tolerate a wide range of environmental salinities, such as salmon.

Stenohaline Organisms

Organisms that are limited to and can tolerate only a narrow range of salinity, such as sharks.

Homeostasis

The maintenance of a constant internal environment (such as constant body temperature and osmotic concentration) despite fluctuations in external conditions.

Regulators

Organisms that maintain internal homeostasis through physiological and behavioral means, such as thermoregulation and osmoregulation (e.g., all birds and mammals).

Conformers

Organisms whose internal body temperature or osmotic concentration changes directly with external ambient conditions, representing about $99\%$ of all animals and nearly all plants.

Allen's Rule

An ecological principle stating that mammals native to colder climates have shorter ears and limbs to minimize surface area and reduce body heat loss.

Blubber

A thick insulating layer of subcutaneous fat found beneath the skin of aquatic mammals like seals that prevents excessive heat loss.

Diapause

A physiological state of suspended development entered by many species of zooplankton in lakes and ponds to survive adverse environmental conditions.

Aestivation

A period of summer sleep or dormancy entered by animals such as certain snails and fishes to escape high temperatures and desiccation.

Hibernation

A state of metabolic slowdown and winter sleep undertaken by animals such as bears to survive low temperatures and food scarcity.

CAM Pathway

A specialized photosynthetic pathway in desert plants that keeps stomata closed during the day and open at night to minimize transpiration water loss.

Altitude Sickness

A physiological condition experienced at high altitudes ($>3{,}500\,\text{m}$) characterized by nausea, fatigue, and heart palpitations caused by low atmospheric pressure and reduced oxygen availability.

Natality ($B$)

The per capita birth rate in a population, referring to the number of individuals born during a given period of time.

Mortality ($D$)

The per capita death rate in a population, referring to the number of individuals dying during a specified time interval.

Age Pyramid

A graphic diagram showing the proportion of individuals within pre-reproductive, reproductive, and post-reproductive age groups in a population.

Intrinsic Rate of Natural Increase ($r$)

A fundamental parameter ($r = b - d$) representing the innate reproductive capacity and biotic potential of a species when assessing population growth.

Carrying Capacity ($K$)

The maximum population density of a given species that a specific habitat can sustainably support with its finite resources.

Exponential Growth

Unrestricted geometric population growth that occurs when resources are unlimited, producing a J-shaped curve modeled by $\frac{dN}{dt} = rN$.

Verhulst-Pearl Logistic Growth

A realistic population growth model exhibiting a sigmoid curve (lag, acceleration, deceleration, and asymptote) when resources are limited, expressed as $\frac{dN}{dt} = rN\left(\frac{K - N}{K}\right)$.

Phytophagous Insects

Insects that feed on plant sap and other plant tissues, constituting approximately $25\%$ of all known insect species.

Prudent Predators

Predators that do not overexploit their prey in nature, ensuring that prey populations do not collapse into extinction.

Pisaster

A predatory starfish of the American Pacific coast whose experimental removal caused the extinction of more than 10 species of intertidal invertebrates due to interspecific competition.

Cardiac Glycosides

Highly toxic defensive chemical compounds produced by the weed Calotropis that deter grazing cattle and goats by disrupting cardiac physiology.

Interference Competition

A form of competition where the feeding efficiency of one species is reduced by the interfering or inhibitory presence of another species, even when resources are abundant.

Competitive Release

The phenomenon in which a species restricted to a small geographic range dramatically expands its distribution when a competitively superior species is experimentally removed.

Gause's Competitive Exclusion Principle

The principle stating that two closely related species competing for identical limiting resources cannot coexist indefinitely, leading to the local elimination of the inferior competitor.

Resource Partitioning

An evolutionary strategy by which competing species coexist within the same habitat by choosing different feeding times or different foraging patterns.

Ectoparasites

Parasites that live and feed on the external surface of host organisms, such as lice on humans, ticks on dogs, marine copepods on fish, and Cuscuta on hedge plants.

Endoparasites

Parasites residing internally within the host's body organs (such as the liver, kidney, lungs, or red blood cells), exhibiting complex life cycles and simplified morphological structures.

Brood Parasitism

A specialized parasitic interaction among birds where the parasite (such as the cuckoo) lays its eggs in the host bird's nest (such as a crow), letting the host incubate and rear the young.

Commensalism

An interspecific interaction in which one species derives benefits ($+$,) while the other species remains completely unaffected and unharmed ($0$).

Amensalism

An interspecific ecological relationship in which one organism is inhibited or harmed ($-$) while the other remains completely unaffected ($0$), such as in antibiosis and allelopathy.

Mutualism

An obligate, mutually beneficial interaction between two different species ($+/+$), such as mycorrhizae, lichens, and fig-wasp interactions.

Sexual Deceit

A pollination mechanism in the Mediterranean orchid Ophrys, where a floral petal mimics the appearance and scent of a female bee to induce pseudocopulation by male bees.