10 public questions tagged with this topic.
A broad-based triangular age pyramid indicates a high birth rate and a rapidly growing population. This follows from NCERT principle where the relation explains the outcome clearly for students in simple steps.
Ref: NCERT Biology Textbook for Class XI and XII (Botany section), Chapter: Morphology and Anatomy of Flowering Plants, Topic: Plant structure and tissue systems.
An age pyramid represents the proportion of individuals in different age groups within a population, providing insights into its growth trend.
Ref: NCERT Class 12 Biology Chapter 11: Organisms and Populations Population Attributes - Birth Death Sex Ratio Age Distribution
Population density is influenced by natality (birth rate), mortality (death rate), immigration (arrival), and emigration (departure).
Ref: NCERT Class 12 Biology Chapter 11: Organisms and Populations Population Attributes - Birth Death Sex Ratio Age Distribution
A bell-shaped age pyramid represents a stable population with nearly equal birth and death rates.
Ref: NCERT Class 12 Biology Chapter 11: Organisms and Populations Population Attributes - Birth Death Sex Ratio Age Distribution
The simplest two-sample Lincoln–Petersen mark–recapture model assumes demographic and geographic closure between sampling occasions. No births, deaths, immigration, or emigration should change the population or alter the proportion of marked individuals. Under closure, the marked fraction after thorough mixing remains interpretable, allowing M/N ≈ R/C and N ≈ MC/R. Quadrat and transect methods sample spatial units and do not inherently require a closed population in the same formal sense, although movement during counting can still create error. Satellite methods track individuals and may expl
Ref: Ecology: Concepts and Applications, Molles, 9th Ed., Ch. 9
In the standard continuous population-growth notation, b denotes the per-capita birth rate: the expected number of births contributed per individual per unit time. Multiplying b by population size gives the total birth input B = bN under a homogeneous model. Similarly, d is the per-capita death rate and D = dN. Their difference gives the instantaneous per-capita growth rate r = b − d, leading to dN/dt = (b − d)N for a closed population. A raw birth number is an absolute count and is usually written B, so distinguishing uppercase totals from lowercase per-capita rates prevents dimensional error
Ref: Ecology: Concepts and Applications, Molles, 9th Ed., Ch. 11
“Rectangular” for which age structure has equal width for all age groups. This relationship follows from the ecological mechanism represented by the terms in the item, not merely from an association between their names. Selection favors the schedule that increases lifetime reproductive success under local mortality and resource conditions. Body size, development time, fecundity, parental investment, and generation length consequently tend to covary. The remaining alternatives—“Pyramid”, “Bell-shaped”, “Urn-shaped”—refer to different states, processes, or scales and therefore do not express the
Ref: Ecology: Concepts and Applications, Molles, 9th Ed., Ch. 10
“qx” for which of the following is a measure of age-specific death rate. This relationship follows from the ecological mechanism represented by the terms in the item, not merely from an association between their names. Life-history traits reflect allocation among growth, maintenance, survival, and reproduction. Energy invested in many offspring cannot simultaneously be invested in large offspring, prolonged care, or future breeding, creating measurable trade-offs. The remaining alternatives—“lx”, “dx”, “mx”—refer to different states, processes, or scales and therefore do not express the same c
Ref: Ecology: Concepts and Applications, Molles, 9th Ed., Ch. 10
“Group of individuals of the same age” for a cohort refers to. This relationship follows from the ecological mechanism represented by the terms in the item, not merely from an association between their names. Survivorship curves summarize age-specific mortality: Type I concentrates loss late in life, Type II approximates a constant hazard, and Type III concentrates loss early. They are empirical patterns, not rigid taxonomic rules. The remaining alternatives—“Entire population”, “A single individual”, “Randomly selected population”—refer to different states, processes, or scales and therefore
Ref: Ecology: Concepts and Applications, Molles, 9th Ed., Ch. 10
