Biosphere II is a huge dome-covered self-contained structure located outside Phoenix, Arizona. Biosphere II was built to try to duplicate, in miniature, earth's biosphere and ecosystems, and use the information gained from the experiment to help design similar habitats on the moon and Mars. The habitat contained small versions of many of the earth's ecosystems, including an ocean with a coral reef, mangrove wetlands, grassland, a desert, an agricultural system, and a human habitat. Eight men and women were sealed inside the habitat for a proposed two-year stay. The air, water, and food for the "biospherians" all came from inside the sealed habitat, and their only contact with the outside was through computers and telephones. Before the two years were up, however, the experiment failed. Supplemental oxygen was pumped into the facility, and food supplies were provided through the airlocks. What caused the failure of the experiment? It was traced to nutrient pollution. The soil in some of the Biosphere ecosystems was unusually rich in nutrients. These excess nutrients caused a huge population explosion in decomposer bacteria, which led to oxygen depletion. To stabilize the environment in the habitat and become self-sufficient again, it would be helpful to :Question 4 options: Select oneadd nitrates and phosphates to the terrestrial and aquatic ecosystemsadd consumers to use carbon dioxide and nutrients and produce oxygen moleculesadd producers to absorb excess carbon dioxide and nutrients and produce oxygen moleculesadd decomposers to recycle nutrients in the soil and wateradd carbon dioxide to restart the carbon cycle

answer: 45

explanationyou have to add as well to be it could be

the african cheetah.

this species has a relatively low level of genetic

variation because the population was reduced to a small size approxi-

mately 10,000 to 12,000 years ago.

chapter   outline

24.1

genes in populations and the hardy-

weinberg equation

24.2

factors that change allele and genotype

frequencies in populations

24.3     sources of new genetic variation

population   genetics

24

until   now,   we   have   primarily   focused   our   attention   on   genes  

within   individuals   and   their   related   family   members.   in   this  

chapter   and   chapters   25   and   26   ,   we   turn   to   the   study   of   genes   in  

a   population   or   species.   the   field   of

population   genetics

  is   con-

cerned   with   changes   in   genetic   variation   within   a   group   of   indi-

viduals   over   time.   population   geneticists   want   to   know   the   extent  

of   genetic   variation   within   populations,   why   it   exists,   and   how   it  

changes   over   the   course   of   many   generations.   the   field   of   popu-

lation   genetics   emerged   as   a   branch   of   genetics   in   the   1920s   and  

1930s.   its   mathematical   foundations   were   developed   by   theoreti-

cians   who   extended   the   principles   of   gregor   mendel   and   charles  

darwin   by   deriving   formulas   to   explain   the   occurrence   of   geno-

types   within   populations.   these   foundations   can   be   largely   attrib-

uted to three scientists: sir ronald fisher, sewall wright, and j. b. s.

haldane.   as   we   will   see,   support   for   their   mathematical   theories  

was provided by several researchers who analyzed the genetic com-

position   of   natural   and   experimental   populations.   more   recently,  

population   geneticists   have   used   techniques   to   probe   genetic  

variation   at   the   molecular   level.   in   addition,   staggering   advances  

in   computer   technology   have   aided   population   geneticists   in   the  

analysis   of   their   genetic   theories   and   data.   in   this   chapter,   we   will  

explore   the   genetic   variation   that   occurs   in   populations   and   con-

sider   the   reasons   why   the   genetic   composition   of   populations   may  

change over the course of several generations