Asample of a white powder is given to you to identify. you can use the benedict test, the lugol test, the biuret test, and the sudan red test to identify it. if the white powder was an starch, how would each of the tests turn out

The test to confirm the presence of starch is Benedict's test

Explanation:

Benedict solution is used to test for simple carbohydrates (reducing sugars such as monosaccharides and some disaccharides). It has a blue colour because of the presence of copper (in the form of CuSO₄) in the benedict solution.

The white powder can be dissolved in water to make a saturated solution. When few drops of benedict's solution (blue colour) is added to about 1 ml of the white powdered solution and then subjected to heat (perhaps in a water bath), a green/yellow/orange/red precipitate will indicate the presence of starch (reducing sugar).

Biuret test is used to test for protein. It also has a blue colour which is also due to the presence of copper (in the form of CuSO₄) in the biuret solution.

When few drops of biuret solution is added to about 1 ml of the white powdered solution, there will be no colour change to violet/pink/purple which would have signified the presence of protein.

Sudan red test is used to identify/test for lipids. It has a red colour as evident from the name. It is a fat-soluble dye and would not dissolve in water. It basically stains lipids.

If few drops sudan red dye is added to the white powdered solution, the solution will not dissolve/stain the solution since it is not soluble in water.

From the above, it can be deduced that Benedict test will confirm the white powder to be starch

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