biology questions

there are 150 saguaro cacti plants per sq kilometer in a certain area of Arizona desert. To what population characteristic does this information refer?

population density

as resources in a population become less available, population growth

reaches carrying capacity

what does the range of a population tell you that density does not?

the areas inhabited by a population

in Rwanda, there are more young children than teenagers, and more tenagers than adults. This age structure indicates a population that

will double in 30 years

demographic transition is change from high birth rates and high death rates to

low birth rates and low death rates.

which would be least likely to be affected by a density-dependent limiting factor

A small, scattered population

How can a demographer, or scientist who studies demography, predict how a population will change in the future?

A demographer studies the social and economic factors that affect a population and the age structure in order to predict how it will change.

What is a density-independent limiting factor? Give two examples.

A density-independent limiting factor is a limiting factor that affects all populations regardless of size, such as a rainstorm, drought, fire, and certain human activities

Discuss four ways population size can change.

A population will increase or decrease in size depending on how many individuals are added to it or removed from it. There are two ways individuals can be added to a population. Individuals can be born into the population, or they can move into it from outside the population, or immigrate. There are two ways individuals can be removed from a population. They can die, or they can move out of the population, or emigrate.

Differentiate between density-dependent and density-independent limiting factors.

Density-dependent limiting factors become limiting only when population density—the number of organisms in a given area—reaches a certain level. These factors include competition, predation, parasitism, and disease. Density-independent limiting factors affect all populations in similar ways, regardless of population size. These limiting factors include weather, natural disasters, and certain human activities, such as damming rivers and clear-cutting forests.

Sequence the historical events that contributed to the current human population growth

During most of human history, population growth was slow. Food was hard to find, and there was no cure or treatment for diseases. Death rates and birthrates were high. With the beginning of agriculture, life became easier. The food supply became more reliable. With the Industrial Revolution, other advances, such as medicine and improved healthcare and sanitation, reduced the death rate and made it possible to live longer. This is when the human population began to grow exponentially

How does emigration affect population size?

Emigration is the movement of individuals out of a population and reduces its size if all other factors are equal

Differentiate between exponential and logistic growth

Exponential growth occurs when the individuals in a population reproduce at a constant rate. At first, the size of the population increases slowly, then it increases more and more rapidly until it approaches an infinitely large size. Under ideal conditions with unlimited resources, a population will grow exponentially. Exponential growth does not continue in natural populations for very long. Resources become less available as the population grows, and the rate of population growth slows down. Logistic growth occurs when a population's growth slows or stops following a period of exponential growth.

about 500 years ago, the worlds population started

Growing more rapidly

What is a density-independent limiting factor? Give two examples.

Limiting factors, such as food scarcity and diseases, kept the human population growth rate low.

how does population growth in the U.S. compare with that of China and India?

Population growth has slowed in the United States, but China and India are only in the beginning stage of demographic transition where the population is still growing rapidly.

what can cause a population to grow

The birthrate becomes higher than the death rate.

Explain the limiting factors that control population growth.

Under ideal conditions, populations will continue to grow if there are not factors that limit their growth. Some factors in a population's environment that can limit growth are predation, competition, parasitism, and disease. Other limiting factors are climate extremes and human activities.

under conditions of logistic growth, population size will rise and fall around an average point called a(an)

carrying capacity

if a population grows larger than the carrying capacity of the environment the

death rate may rise

which are two ways a population can decrease in size

decreased birthrate and emigration

resource shortages triggered by increasing population size are density-_____________limiting factors

dependent

which of the following is not likely to be a limiting factor on the sea otter population

drought

social and __________ factors explain why some countries have high growth rates while other countries grow slowly or not at all

economic

when individuals in a population reproduce at a constant rate, it produces a growth pattern called

exponential growth

in countries like india, the human population is growing

exponentially

what will reduce competition within a species' population

fewer individuals

which density-dependent factors, other than the predator/prey relationship affected the populations of moose and wolves on isle royale?

food availability for the moose and disease for the wolf

when an individual moves into a population from a different population it is called

immigration

zero population growth is a characteristic of _________________ growth

logictic