BIO 220 Human Population Growth Paper

BIO 220 Human Population Growth Paper

BIO 220 Human Population Growth Paper

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There are different perspectives on human population growth and the dynamics associated with population change. Go to CIA World Factbook website (https://www.cia.gov/library/publications/the-world-factbook/rankorder/2119rank.html) and choose one developed (not the United States) and one developing country and compare the following and answer the questions:

Attached is the worksheet that needs to be completed and also a resource paper that you might need to answer the questions.. BIO 220 Human Population Growth Paper

Some resources that might help with this assignment:

Read “The Human Impact on the Ecosystem: Past, Present and Future,” by Chiarelli, from Journal of Biological Research (2012).

URL:

Read “Population Growth and the Environment” and “Toxins in the Environment” in Environmental Science: The Human Impact on Natural Resources.

URL:

http://gcumedia.com/digital-resources/grand-canyon-university/2015/environmental-science_the-human-impact-on-natural-resources_ebook_1e.php

Read “Fourth National Report on Human Exposure to Environmental Chemicals,” by the Center for Disease Control and Prevention (2017).

URL:

http://www.cdc.gov/exposurereport

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BIO-220 Lecture 3

Population Growth and the Environment

Factors that Regulate Population Growth

• Intrinsic factors: Operate within the individual organism or between species within the same species.
• Extrinsic factors: Come from outside the population.
• Biotic factors: Caused by living organisms.
• Abiotic factors: Caused by nonliving components of the environment.

Density Independent Factors

These factors act regardless of the number of organisms in the population. Natural disasters fall into this category. This could be unseasonably cold or hot weather, drought, heavy rain, severe storms or geologic hazards. These factors don’t necessarily regulate the population; however, they can have a very strong impact on a population and determine how many individuals compose the population.

Density-Dependent Population Factors

• Interactions within species: This occurs when individuals within a species compete for the same resources. When this happens, the stronger, quicker, smarter, and more aggressive members are more likely to survive. Another way that resources are controlled is territoriality. A section or area is guarded against other individuals in the population. In addition, the successful individuals are more likely to mate and have offspring.
• Interactions between species: This interaction generally refers to the relationship between predator and prey. In this relationship the prey as a whole may benefit from this relationship because sick or weak members of the population are killed. Predation also maintains a healthy balance of numbers of prey and predator.
• Stress and crowding: Very high-density populations can experience stress shock or stress-related diseases. Symptoms of this condition include reduced fertility, low resistance to infectious diseases, and pathological behavior.

Factors That Influence Population Growth

• Fertility: In developing countries, food shortages, poor health, and cultural practices limit the total fertility. As a whole, the world’s average fertility rate is 2.6. However, growth rates are lower now than at any time since World War II. This indicates a possible decline in the population by 2050.
• Mortality: Developing countries with limited health care and sanitation have higher crude death rates compared to developed countries. Death rates are affected by the population’s age. Countries with a higher number of young adults and children have lower crude death rates compared to older populations.
• Life Span and Life Expectancy: Life span describes the oldest age that a particular species is known to survive. Life expectancy is the average that a newborn infant can expect to attain in a given population. One of the main reasons for the population rise in the past 300 years is declining mortality. Women almost always have higher life expectancies than men (Cunningham & Cunningham, 2010).

Perspectives on Population Growth

• Malthus’s view: Argues that many social and environmental problems are influenced by excess population growth.
• Marx’s view: Posits that poverty and environmental degradation are caused by oppression and exploitation. In this scenario, population growth is the result of the problem, not the cause (Cunningham & Cunningham, 2010).

Principles of Toxicology

Toxicology uses biology and chemistry to explain the effect of poisons on biological systems. The target of a toxicant refers to the macromolecule, cell, organ, or biochemical process that is altered by the toxicant. The mechanism of action of the toxicant describes how the toxicant alters the biological system (Conklin, 2000).

Not all toxicants are deadly. Toxicants may produce disease, tissue damage, genetic changes, or cancer.

For example, consider carbon monoxide (CO). This poisonous gas is released from the combustion of fossil fuels (car exhaust) and cigarette smoke. The CO molecule competes with O₂ for the same binding sites on hemoglobin. The hemoglobin molecule cannot distinguish between the two molecules, so CO gets transported in the blood instead of O₂, causing oxygen starvation of the tissues (in fact, carbon monoxide binds more tightly than O₂). At lower concentrations, this can cause changes in heart rhythm, headache, weakness, nausea, dizziness, and dim vision. At greater concentrations, CO poisoning leads to unconsciousness, coma, convulsions, and possibly death. The effects of CO intoxication can be reversible, except when severe oxygen deprivation causes permanent neurologic damage. Thus, the target of carbon monoxide poisoning is hemoglobin and its mechanism of action is competitive binding to hemoglobin causing hypoxia (oxygen deprivation)” (Conklin, 2000, par. 3).

Length of exposure is not the only important aspect of exposure. Another important factor is the dosage. This is important because a chemical can produce a specific biological effect based on dosage. The biological effect caused by the exposure is called the response. Usually, a higher the dose results in a greater the response. However, this is not always the case (Conklin, 2000).

Effects of Toxins

• Toxins can be recognized as foreign by white blood cells and cause an immune response. This is direct action.
• Toxins can act indirectly by changing the chemistry of foreign materials making them antigenic and eliciting an immune response.
• Toxins can disrupt normal hormone functions (endocrine disrupters).
• Some toxins specifically attack nerve cells and affect the nervous system.
• Toxins can alter genetic material (DNA) in cells.
• Toxins cause abnormalities during fetal growth and development.
• Toxins can cause carcinogenic.

References

Conklin, S. (2000). Some Basic Principles of Toxicology. Retrieved February 5, 2011, from http://www.toxicology.org/ai/FA/toxenrich_basic.pdf

Cunningham, W. P., & Cunningham, M. A. (2010). Environmental Science: A Global Concern. New York, NY: McGraw-Hill.

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