Organisms and Populations

Birth rate, Death rate, Sex ratio, Age distribution

Population attributes are characteristics that apply only to groups, not individuals. Birth rate, death rate, sex ratio, and age distribution are all population-level attributes. Individual height is a characteristic of an individual organism, not a population attribute.

Natality, Immigration

Population density increases due to natality (births) and immigration (individuals moving into the habitat). Mortality (deaths) and emigration (individuals leaving the habitat) decrease population density.

Broad base

A growing population has many young individuals, creating a broad base in the age pyramid. A narrow base indicates a declining population, while equal width suggests a stable population.

Ectoparasite

Cuscuta is a parasitic plant that grows on the external surface of host plants, making it an ectoparasite. Endoparasites live inside the host body, while brood parasites lay eggs in other species' nests.