AP EXAM

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Malthus vs. Karl Marx

• Malthus- human population growth is not always desirable. Human pop can increase faster than food supplies resulting in famine, disease, and war

• Marx- pop growth was a symptom of poverty– Social justice for all is solution

• Neo-Malthusian’s- humans at carrying capacity• Neo-Marxists-must eliminate poverty• Others-technology will raise carrying capacity

Demography• Study of size, birth and death rate and distribution of humans• Highest growth rates in Africa, middle east• Crude birth is the number of live births/1,000• Crude death rate is number of deaths/1,000• Growth rate includes immigration and emigration• Replacement level fertility # of children a couple must have to replace

themselves• Total Fertility Rate- # of children born to a an avg woman during her

lifetime• Infant mortality rate-# of infants that die prior to one year old• Zero Population growth- pop is no longer increasing • AIDS is i altering age structure

Family Size

• Younger marriage = more likely to have more children• Educational opportunity results is postponing

marriage• Family planning and birth control important• Pension availability important- children expected to

care for parents• Religion is a factor• Culture• Women rights vs. Women as property

Graying population

• Large voting base may alter elections• Difficult to advance in jobs • Fewer workers supporting social security• Some countries are encouraging women to

have more children

US Population

• 800,000 immigrate legally• 500,000 immigrate illegally• 1950s Baby Boom at end of WWII• 1980s Echo Boom from baby boomers

reproducing• 307,006,550 = US population• California= 37 million

Demographic Transition

• Preindustrial stage: high infant mortality rates, malnutrition and disease due to lack of sanitation

• Transitional stage: decreased death rate due to medicine and sanitation and improved standard of living; high birth rates

• Industrial stage: stable death rates, birth rate begins to decrease

• Postindustrial stage: population approaches ZPG• Developing country poor need assistance to push into

transitional stage

Family Planning

• China: successful control– TFR from 6 in 1970 to 1.7– There are drawbacks to program– Disproportionate male to female ratio

Human Health

• Nontransmissible diseases cannot spread and may be result of poor choices (smoking)

• Transmissible/communicable are spread from person to person– Caused by pathogens, – Morbidity is illness– Mortality is death

• Chronic diseases (heart disease) are now present in developing countries

Emergent Disease

• Previously unknown or that have not been prevalent for 20 years

• Swine Flu, SARS, avian flu• Spanish influenza pandemic of 1918 similar to

avian flu• Ebola, Marburg and dengue have outbreaks• Civil wars in Africa causing people to move

closer to uninhabited areas increasing African sleeping sickness b/c tsetse fly

Ecological disease

• When a disease spreads quickly through animal populations

• Scientists concerned about elk and deer wasting disease in N. America and potential spread to humans– Spongiform encephalophathies similar to mad cow disease– Caused by prions and transmitted animal to animal

• Antibiotic resistance – on the rise as humans travel – overprescribing or taken incorrectly

Toxicology

• Study of adverse effects of toxins on living organisms– Disrupt normal metabolic activity– All toxins are hazardous• Not all hazardous materials are toxins

– Hazardous• Flammable, explosive, irritating, caustic, induces allergy

Immune System• The body will make immune proteins know as

antibodies in response to the antigen. When the body is re-exposed to the antigen, the antibodies are released in large numbers. Formaldehyde frequently triggers an allergic response in humans– Found in furniture, carpeting, and particleboard– Can result in sick building syndrome (SBS)– Mold spores, , carbon monoxide, nitrogen oxides, and

cigarette smoke also related to SBS– Pesticides and Polychlorinated biphenyls (PCBs)

weaken immune system

Neurotoxins

• Chlorinated hydrocarbons– (DDT, Dieldren, PCBs, and dioxins)

• Organophosphate and carbamate pesticides inhibit enzymes that break down neurotransmitter acetylcholine between neurons and skeletal muscle cells

Endocrine Disrupters

• Include hormone mimics, hormone blockers and metabolic disrupters

• Endocrine system functions in conjunction with the nervous system to maintain homeostasis– Male fish are feminized due to chemical pollutants– Alligators in Lake Apopka were severly affected by a DDT spill– DDT seems to interfere with sex hormones b/c women seem

to get more breast and vaginal cancers and men have low sperm counts and fertility

• Also includes: Dioxns, PCBs, phthalates in some plastics, several pesticides, and most of the heavy metals

Mutations

• Mutagens induce a change in DNA• Carcinogens cause cancer and many are also

mutagens• Teratogens are agents that affect embryonic

development, such as drugs or alcohol: radiation; heavy metals; or biological agents, such a Rubella virus– Thalidomide was used to treat nausea in pregnant

women, but caused limb deformation

Toxins

• Soluble in Water or soluble in oil– Water-soluble toxins are more dangerous b/c water is present

everywhere– Oil-soluble toxins are able to enter cells much more readily

than the water-soluble toxins• Accumulate in fatty tissue in living organisms

• Can be inhaled, ingested, or absorbed through skin– Inhaled is most dangerous as lungs absorb toxins due to their

structure– Other factors include: age, genetics, and workplace exposure– Some chemicals are nontoxic but your liver converts it into a

toxin• Example: is bacon

Bioaccumulation vs Biomagnification

• Bioaccumulation refers to the buildup of chemicals in the body tissues

• Biomagnification increase in concentration of a toxin in successive trophic levels, resulting in predators with highest concentration

• Chlorinated hydrocarbons are highly persistent and fat soluble, heavy metals such as lead and mercury are readily biomagnified

• Persistent organic pollutants can be biomagnified• Phthalates are persistent

– Found in polyvinyl chloride plastic and some deodorants and cosmetics– Endocrine disruptors – Most in US has phthalates in their tissues b/c of their high persistence

Top 20 toxins (CERCLA)

1. Arsenci2. Lead3. Mercury4. Vinyl Chloride5. Polychlorinated Biphenyls

(PCBs)6. Benzene7. Cadmium8. Benzo(a)pyrene9. Polycyclic aromatic

hydrocarbons10. Benzo(b)flouranthene

11. Chloroform12. DDT13. Aroclor 125414. Aroclor 126015. Trichloraethylelne16. Dibenz(a,h)anthracene17. Dieldrin18. Chromium, hexavalent19. Chlordane20. Hexachlorobutadiene

Chemical Interactions

• Chemicals may have additive response– The effect is the sum of individual responses– Rats exposed to lead and arsenic show twice the

toxicity of an exposure to just one of the toxins• Synergistic response exacerbates the response

to another substance• Antagonistic response negates the effects of

another chemical

Measuring Toxicity• Dose is amount of a toxin given to as test subject

– Typically, higher dose is more deleterious• Scientists create dose response curves• Threshold level is first dose at which the effects of the toxin first appear• LD50 (median lethal dose): the dose that kills one-half of the test animals or

lethal dose for 50 percent in two weeks– LC50: is for aquatic species subjected to lethal concentrations of a toxin in the water

surrounding their bodies– LD50 is typically given in mg/kg of body weight

– The lower the value of the , LD50 the greater the toxicity

• 50 mg or less per kg body weight = TOXIC Listing– Mammals used for testing, but not always able to predict human outcomes.

Thalidomide is an example.– LD50 Is for acute studies only

• Carcinogens, mutagens or teratogens- any amount could create an increased chance of damage in an individual

Undernourished vs. Malnourished

• Undernourished means that an individual is not obtaining the number of calories per day

• Malnourished means that a key nutrient is missing such as vitamin A– Folic acid linked to neural tube defects– TWO Protein deficiencies: kwashiorkor (just

protein) and Marasmus (under and malnutrition of protein)• Results in stunted growth, mental retardation, and weak

immune systems

Food shortages

• Famine– Food shortages, starvation, social upheaval and

economic turmoil– Increased migration to refugee camps

Types of food

• Three major types: Corn, Rice and Wheat– Also potatoes, barley, oats and rye– Fruits and vegetables small part of human diet– 60% of all meat is raised in developing countries,

but they consume only 1/5th • Feedlots associated with high water and air pollution

– Nitrates, fecal bacteria and hydrogen sulfide– Animal wastes stored in large lagoons (breached in bad

weather)– Increased infections and therefore resistance

Seafood• Accounts for ~15% of all animal protein ingested by humans• World’s fisheries suffer from overfishing and habitat

destruction• Harvest

– Funnel-shaped trawl nets: shrimp + benthic species– Trawl net: drag net through water forcing fish to the end of the net– Long-lining: shorter hooked lines attached to long fishing line

(sometimes miles)– Gill nets: vertical nets that fish swim into and gills stick

• Bycatch: nontarget species caught while fishing– Dragging trawl kills bycatch– USFWS: long lining threatening seabirds– Turtles trapped in trawl nets w/o TED (turtle exclusion device)

aquaculture

• Growing aquatic species for consumption• Dramatically decreases deaths of nontarget

species– Tilapia and catfish reared in inland ponds– Coastal fish farming can destroy estuaries and

mangrove swampls– Crustaceans farms(shrimp, lobster, oysters + clams)– Fish ranching raises fish to be released in the wild

Farm Policy

• Many countries subsidize farmers in food production

• US subsidizes corn, wheat, cotton, rice and peanuts

• Subsidies cause surplus and farmers can sell the crops cheaper than they cost to produce– In developing countries US subsidized food is cheaper

than local food– 2005 World Trade Organization illegalized American

subsidized food

Green Revolution

• Refers to development of high-yield crop plants– Derived from breeding through years of careful cultivation– Require optimum levels of fertilizers

• Transgenic organisms or GMO: contain genes from another organism– USDA concluded that transgenic foods are as safe as unaltered foods

so they do not require label– Benefits include higher yields, genes from any species may be used,

and toxins might be removed and resistance to stress and herbicides• Now resist Roundup resulting in a decrease in erosion

– Research indicates that it is unlikely for the genes to enter wild strains of the crops

Transgenic

• Bacillus Thuringiensis (Bt) gene added to plants that kill caterpillar and beetle larvae

• Goats modified to secrete various products in their milk

• Animals modified to grow more quickly on less food• People are concerned about GMOs– Bt toxin might damage monarchs– Allergies– Patenting organisms

• Genes can not be made, it must exist in another organism

Soil

• The weathered portion of the earth’s crust that can sustain life– Young soils are not leached of their nutrient– Older soils are leached and have little organic material remaining– The parent material of soil is rock broken down by chemical and

physical weathering• Humus is the dark-colored organic material that remains after

decomposition of leaf litter, droppings, and plant and animal remains• Leaching is when minerals or matter is dissolved in water percolating

downward• Zone of illuviation is the area in the deeper levels of the soil where the

leached matter is deposited• Illuvial material includes iron; humus and clay depending on soil

Soil Organisms

• Include bacteria and fungi (function as decomposers)

• Algae can be present on surface of soil• Round worms (nematodes) and segmented

worms assist with aeration• Insects (ants), roots, snakes, gophers,

groundhogs and moles all tunnel and aerate soil

Chemical Properties of Soil• pH of the soil should range between 6 and 7 for most plants

– At low pH: aluminum, iron, boron and manganese are more soluble and more available to plants (Al can be toxic if too much)

– Add ground sulfur or aluminum sulfate to increase acidity• Alkaline soil: potassium, iron and manganese are less available

– Add lime: to make soil more alkaline• Plants require nitrogen, potassium, phosphorus, calcium,

magnesium, and sulfur• Limiting Factors: nitrogen and phosphorus• Humus important for nutrients, water holding capacity,

aeration capacity, allowing root growth and increasing porosity of the soil

• Salinity can be a problem, especially in irrigated areas