Genetik — Mittelstufe (B1/B2) 2: Evolution & Ecology

[Deutsch] Genetik: Natural selection, speciation, population genetics, ecosystem dynamics, trophic levels, and biogeochemical cycles

Level
intermediate
Languages
de → de
Cards
32
Markdown
Genetik — Mittelstufe (B1/B2) 2: Evolution & Ecology (.md)

Flashcards (32)

#Front (Term / Question)Back (Definition / Answer)ExampleMultiple-Choice Options
1In phylogenetic systematics, what is a monophyletic group (clade)?A taxonomic grouping consisting of a most recent common ancestor and all of its descendants.
2What is adaptive radiation, and what conditions typically trigger it?The rapid evolutionary diversification of a single ancestral lineage into multiple ecologically distinct species, triggered by ecological opportunity, extinction of competitors, or novel adaptations.
3How do homologous structures differ from analogous structures in comparative anatomy?Homologous structures share common ancestral origin but may differ in function (e.g., human arm and bat wing); analogous structures perform similar functions but evolved independently via convergent evolution (e.g., bird wing and insect wing).
4What biochemical conversions are carried out by nitrifying bacteria in the soil?Two-step nitrification: Nitrosomonas converts ammonia (NH3) to nitrite (NO2-), and Nitrobacter oxidizes nitrite to nitrate (NO3-).
5In the Hardy-Weinberg equation p^2 + 2pq + q^2 = 1, what do p^2, 2pq, and q^2 represent?p^2 is the frequency of homozygous dominant individuals, 2pq is heterozygous individuals, and q^2 is homozygous recessive individuals in the population.
6How do density-dependent limiting factors differ from density-independent limiting factors?Density-dependent factors exert proportional effects as population density increases (e.g., disease, competition, predation); density-independent factors impact mortality regardless of density (e.g., hurricanes, wildfires).
7According to Raymond Lindeman's 10% rule in trophic ecology, what happens to energy across successive trophic levels?Only approximately 10% of the energy stored as biomass at one trophic level is transferred to the next; ~90% is lost as metabolic heat, respiration, and unconsumed waste.
8Contrast r-selected reproductive strategies with K-selected reproductive strategies.r-selected species produce numerous small offspring with little parental care and rapid maturation; K-selected species produce few large offspring with extensive parental investment and high survival rates.
9Why does the biogeochemical phosphorus cycle lack a significant gaseous atmospheric reservoir?Phosphorus compounds are non-volatile and remain primarily sequestered in sedimentary rock minerals, soil, and aquatic sediments.
10What is the defining difference between primary ecological succession and secondary ecological succession?Primary succession begins on completely lifeless, bare substrate devoid of soil (e.g., cooled lava, retreated glacier); secondary succession occurs where an existing community was disturbed but soil remains intact.
11What are the four essential postulates of Charles Darwin's theory of evolution by natural selection?1. Individuals within populations exhibit phenotypic variation. 2. Some variations are heritable. 3. More offspring are produced than can survive. 4. Individuals with favorable traits survive and reproduce more successfully.
12In population ecology, what mathematical parameter represents carrying capacity in the logistic growth equation dN/dt = rN(1 - N/K)?K, representing the maximum population size that a specific environment can sustainably support over time.
13Provide examples of prezygotic versus postzygotic reproductive isolating barriers.Prezygotic: temporal, behavioral, habitat, or mechanical isolation; postzygotic: hybrid inviability, hybrid sterility (e.g., mule), and hybrid breakdown.
14What does Gause's Principle of Competitive Exclusion state regarding two species with identical ecological niches?Two species competing for the exact same limiting resources cannot coexist indefinitely; the species with even a slight advantage will drive the other to local extinction or niche differentiation.
15Why are top predators vulnerable to biological magnification (biomagnification) of persistent pollutants like DDT or methylmercury?Lipophilic, non-biodegradable toxins accumulate in fatty tissues and increase in concentration at progressively higher trophic levels through consumption of contaminated biomass.
16What terrestrial biome is characterized by permafrost, low biodiversity, dwarf shrubs/mosses, and extremely low temperatures?The Arctic tundra.
17Distinguish between directional, stabilizing, and disruptive natural selection.Directional favors one phenotypic extreme; stabilizing favors intermediate phenotypes against both extremes; disruptive favors both phenotypic extremes over intermediates.
18What defines a keystone species in an ecological community?A species that exerts disproportionate control over community structure and biodiversity relative to its numerical abundance or biomass (e.g., sea otters, sea stars).
19What is a trophic cascade, as famously demonstrated by the reintroduction of gray wolves to Yellowstone National Park?An ecological process where an apex predator suppresses the abundance or alters the foraging behavior of herbivores, allowing suppressed plant communities to recover and reshaping ecosystem structure.
20In the global nitrogen cycle, which process converts inert atmospheric N2 gas into bioavailable ammonia (NH3/NH4+)?Biological nitrogen fixation, performed by prokaryotic nitrogenase enzymes in diazotrophs like Rhizobium and cyanobacteria.
21What ecological process occurs when excess agricultural nitrogen and phosphorus runoff enter aquatic ecosystems?Cultural eutrophication: dense algal blooms, microbial decomposition of dying biomass, profound dissolved oxygen depletion (hypoxia), and fish die-offs.
22What is the difference between allopatric speciation and sympatric speciation?Allopatric speciation occurs when a physical geographic barrier divides populations; sympatric speciation occurs within the same geographic area without physical isolation (e.g., via polyploidy or niche differentiation).
23What five baseline conditions must be met for a population to remain in Hardy-Weinberg equilibrium?1. No mutations. 2. Random mating. 3. No gene flow (no migration). 4. Infinite (very large) population size. 5. No natural selection.
24What is the difference between an organism's fundamental niche and its realized niche?The fundamental niche is the full theoretical range of environmental conditions and resources an organism could exploit without competition; the realized niche is the restricted portion it actually occupies in the presence of biotic interactions.
25What is the founder effect, and how does it alter allele frequencies in newly established populations?A form of genetic drift occurring when a small subset of individuals colonizes a new habitat, carrying only a non-representative sample of the original gene pool.
26What is the primary factor limiting net primary productivity (NPP) in open-ocean epipelagic waters?Micronutrient and macronutrient availability, particularly iron, nitrogen, and phosphorus.
27What defines a biological species according to Ernst Mayr's biological species concept?A group of interbreeding natural populations that are reproductively isolated from other such groups and produce viable, fertile offspring.
28How does a paraphyletic taxon differ from a polyphyletic taxon?A paraphyletic group includes a common ancestor but excludes some descendants (e.g., traditional reptiles excluding birds); a polyphyletic group includes taxa from multiple distinct evolutionary lineages without their common ancestor.
29How does Batesian mimicry differ from Müllerian mimicry in evolutionary ecology?In Batesian mimicry, a harmless palatable species mimics the aposematic warning coloration of a harmful species; in Müllerian mimicry, two or more unpalatable/toxic species converge on a shared warning pattern.
30How does genetic drift differ fundamentally from natural selection as an evolutionary mechanism?Genetic drift changes allele frequencies through random stochastic sampling errors irrespective of fitness; natural selection non-randomly selects adaptive traits.
31Which microbial process converts soil nitrates (NO3-) back into atmospheric N2 gas under anaerobic conditions?Denitrification, carried out by facultative anaerobic bacteria (e.g., Pseudomonas).
32What symbiotic relationship is characterized by one species benefiting while the other is neither helped nor harmed (+/0)?Commensalism (e.g., barnacles attaching to whales or epiphytic orchids on trees).