environment

1. colorless, odorless, and highly toxic gas that forms during the incomplete combustion of carbon-containing materials.
5. type of population pyramid-- somewhat equal proportion, stable
7. any form of precipitation with acidic components, such as sulfuric or nitric acid that fall to the ground from the atmosphere.
10. total population divided by total land area
13. act of leaving a country to live in another.
16. type of population pyramid--lower percentage of younger people
18. colorless and odorless gas.
19. are plants, animals, or microbes that have had their DNA altered using genetic engineering.
20. the introduction of harmful materials into the environment.
21. type of population pyramid--more people due at a high age level, slow life expectancy, and high in birth and death rate.

2. the process where too many nutrients, mainly nitrogen and phosphorus, are added to bodies of water.
3. which prevents poor people from growing or buying enough food.
4. having, at all times, both physical and economic access to sufficient food to meet dietary needs for a productive and healthy
6. encompasses crop and livestock production, aquaculture, and forestry for food and non-food products.
8. Graphical representations of the distribution of various age groups in a population.
9. increase of toxic substances when going along a food chain from a lower level to a higher level
11. pattern of spacing among individuals within the boundaries of the population at a great time.
12. since 1960, about 88% of the increase in global food production
14. Two parents bearing two children can be replaced by their offspring.
15. refers to the relative number of males and females.
17. colorless and odorless gas in low concentrations but with irritating odor in high concentrations. Causes acid concentration and precipitation.