4 public questions tagged with this topic.
Diatoms are photosynthetic plankton and are described as chief producers in oceans. Their silica-containing walls accumulate to form diatomaceous earth, which is used in polishing and the filtration of oils and syrups.
Ref: NCERT Class 11 Biology Chapter 2: Biological Classification Protista - Chrysophytes and Dinoflagellates
“Lantana camara” for invasive species from tropical america. This relationship follows from the ecological mechanism represented by the terms in the item, not merely from an association between their names. Management outcomes depend on scale and context: suppressing abundance at one site does not guarantee regional eradication when dispersal reconnects treated and untreated populations. The remaining alternatives—“Eichhornia crassipes”, “Prosopis juliflora”, “Merops viridis”—refer to different states, processes, or scales and therefore do not express the same causal relationship. Species management must identify the demographic stage and ecological process that most strongly limits population growth. Prevention, early detection, removal, habitat manipulation, and biological control act at different points in an invasion or recovery trajectory. This distinction matters because similar surface patterns can arise through different mechanisms, whereas ecological prediction depends on identifying the mechanism that actually changes rates. The cited framing is therefore most useful when treated as a conditional biological claim, with assumptions about scale and environmental context kept explicit.
Ref: Ecology: From Individuals to Ecosystems, Begon et al., 5th Ed., Ch. 21
“High phenotypic plasticity” for success of invasive species depends on. This relationship follows from the ecological mechanism represented by the terms in the item, not merely from an association between their names. Effective control reduces propagule pressure or population growth without causing unacceptable non-target effects. Repeated monitoring is necessary because seed banks, dormant stages, recolonization, and density-dependent compensation can reverse short-term gains. The remaining alternatives—“Specialized needs”, “Low competitive ability”, “Limited dispersal”—refer to different states, processes, or scales and therefore do not express the same causal relationship. Management outcomes depend on scale and context: suppressing abundance at one site does not guarantee regional eradication when dispersal reconnects treated and untreated populations. Linking the wording to measurable consequences for fitness, abundance, or flux gives the conclusion its scientific meaning and prevents a purely mnemonic interpretation. Field observations could test this account by measuring the proposed driver and the demographic or ecosystem response while controlling plausible confounding factors.
Ref: Ecology: From Individuals to Ecosystems, Begon et al., 5th Ed., Ch. 21
Without prey or another usable food source, predator intake falls to zero while metabolic maintenance, mortality, and emigration continue. In the Lotka–Volterra equation dP/dt = baNP − mP, setting prey density N to zero gives dP/dt = −mP. Predator abundance then declines exponentially at rate m, assuming a closed population and no immigration. Stabilization would require replacement of deaths through feeding-supported reproduction or external subsidy, while increase is impossible under the model because prey conversion supplies the positive growth term. Oscillation also requires reciprocal feedback between both populations and cannot continue when one is absent. Real predators may persist temporarily on stored reserves, enter dormancy, migrate, scavenge, or switch to alternative prey, so “absence of prey” must mean absence of all effective food. Those mechanisms change the model assumptions rather than the basic energetic conclusion. The population-level decline arises from the balance of births and deaths, not because every individual dies immediately when prey disappear.
Ref: Ecology: Concepts and Applications, Molles, 9th Ed., Ch. 14
