BIO-220 Exam 2 Study Guide

• Factors that limit population size (disease, war, famine, etc.)

  Population growth is checked by famine, disease, and cultural factors (e.g., late marriage).

  
  

  Regulate population through cultural taboos, abstinence and infanticide
• Carrying capacity


  - the number of organisms of a given species that can be sustained indefinitely in a given area.

  - Physical carrying capacity = "packing density, limited only by space and resources"

  - Cultural carrying capacity is always less
• Malthus vs. Marx

  1. Malthus

  a) Human population growth causes environmental degradation

  b) Thomas Malthus (1798) wrote An Essay on the Principle of Population in which he showed that human populations increase exponentially.

  
  

  2. Karl Marx

  a) Human population growth results from poverty and resource depletion
• Demography

  Two demographic worlds

  1. First is young and rapidly growing

  a) Less developed country

  i. 80% of the world's population

  ii. Accounts for 90% of projected growth

  iii. Africa, Asia, Latin America

  
  

  2. Second is wealthy and mostly shrinking

  a) North America, Japan, Western Europe

  i. Average age is about 40

  ii. Populations expected to stabilize or decline

  iii. Humans can raise the environmental carrying capacity through technology
• Demographic transitions


  A model of economics and cultural change to explain declining death and birth dates in industrializing nations
• Crude Birth Rate


  Number of births in a year per thousand. (Not adjusted for population characteristics such as number of women of child bearing age.)
• Crude Death Rate

  Number of deaths per thousand persons in a given year

  a) Poor countries average about 20 while wealthier countries average about 10.

  b) Some rapidly growing countries have very low crude death rates due to a high proportion of young people
• Total fertility rate


  An estimate of the average number of children a woman produces during her childbearing age.
• Zero Population Growth (ZPG)


  When the birthrate and death rate factors are balanced, the population size remains stable
• r & K growth models as compared to the human issue

  1. R species grow quickly and fall off quickly after surpassing the carrying capacity.

  - Humans are growing like this

  
  

  2. K species have slower growth and level off when reaching the carrying capacity
• 1st, 2nd, 3rd world countries; how they are classified

  Countries are classified by their life expectancy and their mortality rate
• Factors that affect life expectancy:

  - The availability of nutritious food.

  - Improvements in medical and health technology.

  - Better sanitation.

  - Awareness and availability of resources such as good health care.
• Poverty and population growth factors

  Poverty does cause population growth and population growth does cause poverty. Economic development means increasing control of both parts of the cycle; the ability to choose your family size, and the ability to make a living with something more than your hands and the hands of your children.
• Empowering women


  Education plays a significant role in empowering women to make decisions about their lives and reproductive behavior.
• The influence of education on population growth

  Poor women who cannot read tend to have more children when compared to educated women who live in places where their human rights are respected. Seventy percent of the world's poor and 64% of illiterate adults are women (Miller & Spoolman, 2009). This has to change in order to stabilize population growth and reduce environmental degradation.
• Antibacterial resistances

  99.9% - The .1% survives and continues to multiply causing more harm
• Toxicology


  the study of poisons and their effects on living systems
• Toxins


  Known poisons that damage or kill cells/tissues. Can be general or very specific. Often harmful even in dilute concentrations
• Hazardous Material


  Dangerous but not toxic (i.e. Flammable, explosive, irritant, acid, and caustic)
• Carcinogens


  substances that cause cancer
• Allergen


  substances that activate the immune system
• Endocrine disruptors


  Disrupt normal hormone functions.

  Environmental estrogens- environmental

  contaminants which cause reproductive problems

  in animals even at very low doses.

  (e.g., BPA, Dioxins, DEHP, phytoestrogens)
• Mutagen


  agents that damage or alter genetic material can lead to birth defects or tumors
• Teratogen


  specifically cause abnormalities during embryotic growth and development (ex. Alcohol- fetal alcohol syndrome)
• Neurotoxin


  metabolic poisons that specifically attack

  nerve cells; most are extremely toxic and fast acting.

  - Heavy metals kill nerve cells

  - Anesthetics and chlorinated hydrocarbons disrupt nerve cell membranes

  - Organophosphates and carbamates inhibit signal transmission between nerve cells
• Factors that determine toxicity

  - Permissible exposure limits (PELs)

  - Chemical's concentration

  - Target organism

  - Route of exposure
• Acute toxicity


  When the toxic effect of single or multiple exposures to a chemical result in sudden adverse effects, usually within 14 days of administration.

  
  

  a) Establishing the health risks from acute toxicity is usually simpler and easier compared to chronic toxicity.
• Chronic toxicity


  Occurs over a longer period and the adverse effects are less obvious.

  
  

  a) Establishing the health risks of chronic toxicity can be challenging because factors such as aging, exposure to other toxins, and infectious diseases make it difficult to accurately attribute the health risks associated with long-term exposure to a specific toxin.
• Effects of concentration toxicity

  It is important to note that the occurrence of chemicals within an organism does not automatically suggest acute or chronic toxicity. With the incorporation of new technology in analytical instruments, scientists and researchers are able to detect chemicals at extremely low levels. The toxicity of chemicals, however, is dependent on the chemical makeup, the concentration, the bioavailability of chemicals in its matrix, and the receptor organism under exposure. Some organisms are more susceptible to lower levels than others.
• Biomagnification


  a cell's ability to selectively absorb and store substances from its surroundings
• Bioaccumulation


  increased levels of toxic chemicals in organisms up the food chain as a result of consuming bioaccumulated toxic chemicals in their prey
• Fat soluble chemicals


  need a carrier to move through environment, but once inside the body they penetrated tissues easily and cross cell membranes. They are stored in body fat persist for many years.
• Water soluble chemicals

  move rapidly through the environment and have

  ready access to cells via tissue fluid
• Body burden

  Although the human body has an efficient system of eliminating toxic chemicals, prolonged exposure and elevated levels of toxic chemicals can cause harm to various organs involved in the efficient removal of toxic chemicals. These organs are equipped with mechanisms for repairing damaged cells; however, the frequent damage and repair of cells may adversely affect cell cycle controls, which can lead to uncontrolled mitosis (cell division) and the formation of tumors
• Persistent Organic Pollutants (POPs)

  organic compounds that are generally persistent in the environment
• Volatile Organic Compounds (VOCs)


  organic chemical compounds whose composition makes it possible for them to evaporate under normal indoor atmospheric conditions of temperature and pressure
• DDT, bald eagles, and soft egg shells; history

  Bald eagles were poisoned with DDT when they ate the contaminated fish. This caused their egg shells to not properly harden and then to break during incubation
• Risk Assessment


  A systematic process of evaluating the potential risks that may be involved in a projected activity or undertaking
• Risk Management


  Determine what environmental risks exist and then determine how to manage those risk in a way best suited to protect human health and the environment.
• Clean Water Act (1972)

  Regulate pollutant discharge into waters