PCB 3043 - Exam 1 Questions with Correct Answers Latest Update 2025/2026

PCB 3043 - Exam 1 Questions with Correct Answers Latest Update 2025/2026 Ecology - Answers The scientific study of the relationships between organisms and their environment John Graunt - Answers Used simple mathematical populations to demonstrate that populations are limited and cannot grow without restriction Two Laws of Population Growth: - Answers 1. Populations have the potential to grow rapidly 2. They can't grow forever at high rates. Populations must be regulated such that rapid growth is limited phenomenon Sir Ronald Ross - Answers Worked as a military physician in India, demonstrated the malarial oocysts in the gut tissue of female Anopheles mosquito Doubling time - Answers The number of years needed to double a population, assuming a constant rate of natural increase Population - Answers A group of individuals that belong to the same species and live in the same area Growth rate equation - Answers Birth rate - Death rate Demography - Answers The study of the age structure and growth rate of populations Density - Answers The number of individuals in relation to the space or volume in which they occur Distribution - Answers The geographic and ecological range of a population Dispersion - Answers The spacing of individuals with respect to one another Mark-recapture method - Answers A sampling technique used to estimate wildlife populations; individuals (numbering M) are captured, marked, and released; we assume that they mix freely and completely with the rest of the population; then we capture some individuals again, count the total number of individuals caught (n) and the number of those that were marked previously (x) Estimated population size - Answers N=nM/x; #marked/total number= #marked in resample/#resampled Population pyramids - Answers Show the number of individuals (or percent in different age classes) going up and down, with males on the left and females on the right Per-capita rate - Answers Per individual rate Per-capita birth rate (b) - Answers The probability of an individual having offspring during some time period Per-capita death rate - Answers The probability of an individual dying in a specified period of time dN/dt - Answers Population growth rate = population births - population deaths (bN-dN); change in population size/change in time; N(b-d) or rN What does r equal when the population is increasing? - Answers Positive What does r equal when the population is decreasing? - Answers Negative What does r equal when the population is stable? - Answers 0 Fecundity - Answers Reproductive output under ideal conditions, limited by genetics, not the environment Fertility - Answers The actual reproduction in a given environment. Note that it must be less or equal to the fecundity Immigration rate - Answers Number of individuals that join the population per unit time Emigration rate - Answers Number of individuals that leave the population per unit time Rate of population change per capita (per individual) - Answers r = births - deaths + immigration - emigration Exponential growth equation - Answers r or R sub 0 must be constant and either positive (slopes up) or negative (slopes down) Discrete growth - Answers All individuals pass through life stages at the same time, often common in organisms affected by seasons; Nt+1 = Nt x R0 Continuous growth - Answers Individuals in a population are relatively independent in terms of when they are born, reproduce, and die. This results in overlapping generations Continuous exponential growth rate - Answers Nt = N0^ert or dN/dt = rN Discrete exponential population growth rate - Answers Nt = N0 x R0^t Per-capita growth equation - Answers (1/N) x (dN/dt) = r Genetic bottleneck - Answers When a population severely declines due to environmental events (e.g., disease or hurricanes) or human activities. Such events reduce the genetic variation of a population. These population size reductions and the loss of genetic variation leave the populations susceptible to environmental changes, like climate change or a shift in available resources. Due to the smaller population size after a bottleneck event, inbreeding increases and unfavorable alleles can accumulate Thomas Malthus - Answers Demographer from around 1800 who studied population growth in England and the United States; he wrote an influential book on population dynamics in which he suggested that food or other resources limit population growth; he also specifically noted that as population density increases, the quality of conditions decrease because of competition for resources; for humans, he suggested that this leads to men postponing marriage, increases in crime and disease, while also lowering moral standards Density dependent growth model - Answers