Chapter Summary
Organisms and Populations explains how living organisms interact with each other and with their environment. It covers concepts like habitat, niche, abiotic factors, adaptations, population growth, population interactions (predation, competition, mutualism), and the ecological principles that govern these relationships.
50 Questions and Answers
Ecology is the branch of biology that deals with the interactions between organisms and their environment.
A habitat is the natural environment where an organism lives and grows.
A niche refers to the functional role and position a species occupies in its ecosystem.
Temperature, water, light, and soil are the major abiotic factors.
Adaptations are structural, physiological, or behavioral traits that help organisms survive and reproduce in specific environments.
A population is a group of individuals of the same species living in a defined geographical area at a given time.
Population density is the number of individuals per unit area or volume of habitat.
Natality refers to the birth rate or the number of new individuals born in a population during a given period.
Mortality is the death rate or the number of individuals dying in a population during a given period.
Emigration is the number of individuals leaving a population, while immigration is the number of individuals entering a population.
Carrying capacity is the maximum number of individuals of a species that an environment can support sustainably.
Exponential growth occurs when resources are abundant and population increases rapidly in a J-shaped curve.
Logistic growth occurs when resources become limited, producing an S-shaped growth curve as population stabilizes at carrying capacity.
Population interactions are relationships between two species, such as predation, competition, mutualism, parasitism, and commensalism.
Predation is a biological interaction where one organism (predator) kills and eats another organism (prey).
Lichens are an example of mutualism between algae and fungi.
Competition is an interaction where two species compete for the same limited resources, negatively affecting both.
Commensalism is a relationship in which one species benefits while the other is neither harmed nor helped.
Parasitism is a relationship in which one species (parasite) benefits at the expense of the host.
Clownfish living among sea anemones is an example of commensalism.
Amensalism is an interaction where one species is harmed while the other is unaffected.
Ecological succession is the gradual and natural change in the species composition of a community over time.
r-strategists are species that produce a large number of offspring with minimal parental care, e.g., insects.
K-strategists are species that produce fewer offspring but provide significant parental care, e.g., humans.
Migration is the regular movement of animals from one region to another, usually in response to seasonal changes.
Hibernation is a state of dormancy in animals during winter to conserve energy.
Aestivation is a period of dormancy in animals during hot and dry conditions to avoid desiccation.
Allen’s rule states that animals in colder regions have shorter ears and limbs to minimize heat loss.
Bergmann’s rule states that animals in colder climates are larger in size compared to those in warmer regions.
Acclimatization is the process by which organisms adjust to gradual environmental changes.
Habitat is the physical place an organism lives, while niche is its functional role in the ecosystem.
Primary succession occurs in lifeless areas where there was no previous community, e.g., bare rocks.
Secondary succession occurs in previously inhabited areas where the community was disturbed or destroyed.
In desert animals, the ability to concentrate urine to conserve water is a physiological adaptation.
Population ecology helps in understanding population growth, resource management, and conservation strategies.
It is a technique used to estimate population size by capturing, marking, releasing, and recapturing individuals.
A survivorship curve represents the number of individuals surviving at different ages in a population.
Density-independent factors affect population size regardless of density, e.g., natural disasters.
Density-dependent factors affect population size based on its density, e.g., competition, disease.
It is a mathematical model that describes predator-prey interactions in an ecosystem.
Biomagnification is the increase in concentration of toxic substances as they move up the food chain.
A keystone species has a disproportionately large effect on its ecosystem compared to its abundance.
Ecological footprint measures the amount of biologically productive land and water required to support human activities.
Resource partitioning is the process where species reduce competition by using different resources or niches.
Endemic species are those found only in a particular region and nowhere else in the world.
Extinction is the permanent disappearance of a species from Earth.
Ecological equivalents are species living in different geographical regions but occupying similar niches.
A metapopulation is a group of spatially separated populations of the same species that interact through migration.
Altruism is a behavior where an individual reduces its own fitness to benefit another individual.
Population ecology is the study of populations in relation to the environment, including density, growth, and regulation.