Question | Answer |
for most of human history there have been fewer than | One Billion people on the planet |
Our numbers started to climb | in the 1800's |
Repoductive decisions regarding fertility that are made by individuals | obviously affect population size and growth |
Female determinants of fertility include | the timing of puberty, use of birth control, lowered fertility while breast feeding and the impact of education |
Population pyramids are diagrams | that provide summaries of current population sizes and serve as predictors of the potential for future population growth |
The demographic transition model is the same as variation among nations | as a nation moves toward a more "developed" economy, a decline in death rate occur's before a decline in birth rate |
The greatest potential for global population growth is in | developing nations |
An ecological footprint measures | average per capita amount of land need to provide people with the good and services they need and enable wastes to be disposed of |
Biodiversity | diversity of genes, of species, of communites/ecosystems and of ecological processes |
Species numbers often are used | as an index of an area's biodiversity |
More than ___________ species have been described, with perhaps _________ lurking out there | 1.5 million, 10 million |
On land, species numbers are greatest | in the tropics |
Many of these tropical species are __________, with geographic distributions that are naturally restricted | Endemics |
If an endemic vanishes from its naturally restricted home | then it's gone from everywhere |
What is a pollutant? | Something that is present in an area where it should be absent |
The story of DDT | By eating contaminated prey with DDT stored in fatty tissues, DDT became bioconcentrated in predators at higher levels in food webs |
Why did populations of many predatory birds start to decline? | DDT caused egg shells to thin and few live baby birds to hatch |
Our strategy today for pesticide resistance | Integrated Pest Management rather than outright pest eradication |
A growing number of chemicals disturb the hormonal control of reproduction | Either by mimicking the effects of natural hormones or blocking their effects |
Hormone disrupters have been shown to affect | cells growing in dishes, laboratory animals and wildlife |
The average woman in the U.S. has around this chance of developing breast cancer | 1 in 8 |
The latter states that | if the consequences of doing nothing might be bad, then maybe it's best to act now even if were aren't 100% certain whether those bad consequences will actually come about |
Carrying Capacity | the maximum number of people an environment can provide |
Endicrine Disruptor | disruptes the hormone production |