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Ch. 53 - Population Ecology
All textbooksCampbell 12th EditionCh. 53 - Population EcologyProblem 5
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Chapter 53, Problem 5

Based on current growth rates, Earth's human population in 2019 will be closest to a. 2.5 million. b. 4.5 billion. c. 7.5 billion. d. 10.5 billion.

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Identify the problem: The question asks for the closest estimate of Earth's human population in 2019 based on current growth rates.
Understand the context: As of recent years leading up to 2019, global population growth has been a significant topic in demographics, with estimates usually ranging in the billions.
Eliminate implausible answers: Option a (2.5 million) is far too low for a global population, which has been in the billions for decades. Option d (10.5 billion) is too high compared to recent growth trends.
Consider recent data: As of the late 2010s, the world population was estimated to be around 7 to 8 billion. This makes options b (4.5 billion) and c (7.5 billion) the most plausible.
Choose the best estimate: Given the trends and estimates around the year 2019, the closest and most accurate estimate would be option c, 7.5 billion.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Human Population Growth

Human population growth refers to the increase in the number of individuals in a population. It is influenced by factors such as birth rates, death rates, immigration, and emigration. Understanding these dynamics is crucial for predicting future population sizes and addressing related challenges.
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The Human Population

Demographic Transition Model

The Demographic Transition Model (DTM) describes the transition of a country from high birth and death rates to lower birth and death rates as it develops economically. This model helps explain population growth patterns and can be used to estimate future population sizes based on current trends.
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Global Population Estimates

Global population estimates are statistical approximations of the number of people living on Earth at a given time. These estimates are derived from census data, surveys, and statistical models, and they provide insights into population trends, which are essential for planning resources and services.
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Estimating Earth’s Human Carrying Capacity
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Textbook Question

A population's carrying capacity a. may change as environmental conditions change. b. can be accurately calculated using the logistic growth model. c. increases as the per capita population growth rate decreases. d. can never be exceeded.

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Scientific study of the population cycles of the snowshoe hare and its predator, the lynx has revealed that a. predation is the dominant factor affecting prey population cycling. b. hares and lynx are so mutually dependent that each species cannot survive without the other. c. both hare and lynx population sizes are affected mainly by abiotic factors. d. the hare population is r-selected and the lynx population is K-selected.

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Analyzing ecological footprints reveals that a. Earth's carrying capacity would increase if per capita meat consumption increased. b. current demand by industrialized countries for resources is much smaller than the ecological footprint of those countries. c. it is not possible for technological improvements to increase Earth's carrying capacity for humans. d. the ecological footprint of the United States is large because per capita resource use is high.

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The observation that members of a population are uniformly distributed suggests that a. resources are distributed unevenly. b. the members of the population are competing for access to a resource. c.the members of the population are neither attracted to nor repelled by one another. d. the density of the population is low.

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Textbook Question

According to the logistic growth equation dNdt=rN(K−N)K a. the number of individuals added per unit time is greatest when N is close to zero. b. the per capita population growth rate increases as N approaches K. c. population growth is zero when N equals K. d. the population grows exponentially when K is small.

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During exponential growth, a population always a. has a constant per capita population growth rate. b. quickly reaches its carrying capacity. c. cycles through time. d. loses some individuals to emigration.

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