Encounters with Life: lab quiz 2 Flashcards
Would Benedict's reaction give a positive with all carbohydrates? Why?
no, because the reagent only tests for simple sugars
Benedict's reagent is a test for what?
simple carbs/reducing sugars/monosaccharides/disaccharides
Does paper contain starch?
What chemical elements are present in starch?
carbon, hydrogen, and oxygen
what is a reducing sugar?
all monosaccharides and some disaccharides/any sugar capable of acting as a reducing agent
what are the component molecules making up of triglycerides?
fatty acids & glycerol
dry cleaners often use carbon tetrachloride. What stains would this remove?
oil & wax compounds
what are the building blocks of protein?
how would you determine whether milk contains reducing sugars?
test with Benedict's reagent
what are the positive color change when using Benedict's reagent?
green to brick-red or brown
what could you say about a substance if it did not turn blue-black with iodine?
there is no starch present
Is CO2 (carbon dioxide) considered organic? why?
no, it does not contain hydrogen
Biuret's reagent is made up of. . .
sodium hydroxide or potassium hydroxide and a dilute solution of copper sulfate
what does hydrolysis mean?
a process in which water is used to split a substance into smaller particles
the hydrolysis of sucrose resulted in the presence of what two sugars?
glucose and fructose
are glucose and fructose reducing sugars?
yes, they are monosaccharides
a compound that contains carbon in the form of chains or rings
a compound that is not of animal or plant origin ; does not contain carbon
the elements most often found in living organisms are. . .
carbon, hydrogen, oxygen, nitrogen, & phosphorous
three major groups of organic compounds that compose living organisms with examples.
proteins/enzymes/helps produce tissue
lipids/fats, oils/stores energy
carbohydrates/sugar, starch/give the body energy
list the 3 types of carbohydrates with examples.
monosaccharide - glucose
dissacharide - sucrose
polysaccharide - starch
large molecule made up of chains or rings of monomers/
how are polymers formed?
Simple one-unit molecules that make up complex molecules
the joining of two molecules or compounds following the removal of water
breaking polymers into monomers by adding water
why has water been included as one of the test materials for reducing sugars, starch, and protein?
to act as a control
reducing sugars are usually. . .
monosaccharides release. . .
what reagent is used to test for reducing sugars?
what is formed and settled out of a solution
what chemical substance is used to detect the presence of starch?
the largest class of lipids are. . .
lipids are soluble in. . .
ether, acetone, and chloroform
why are lipids so important to living systems?
1. concentrated source of energy
2. thermal insulation
3. shock absorber for organs, muscles, and bones
give an example of emulsion.
oil and water
give an example of an emulsifier
droplets of one liquid suspended in another/each insoluble in the other
a substance that stabilizes an emulsion
name the chemical substance used to indicate the presence of lipids
what reagent is used to test for the presence of protein in food?
If protein is present, the tested substance will turn ____ when mixed with Biuret's reagent.
When reducing sugars is present, the copper ions in the Benedict's Reagent are reduced to
metallic copper/copper I ions
Testing for Organic and Non-Organic
Heat test tube with small amount of one substance, hold over heated flame. If deposit turns black, the substance left on tube wall is carbon.
If substance turns black what are you testing for
organic and non organic
Sugar, Meat and Flour are all
Table salt and baking soda are
The a substance turns blue black what is it positive for and what test is used.
Positive for Starch, using the Starch test
If a spot turns transparent to translucent
positive for lipids
If a pH level is above 7 the compound is a. . .
If a compound has a pH level of 7 it is. . .
If a compound has a pH level below 7 it is. . .
example of an acid compound is. . .
example of a base compound is. . .
example of a neutral compound is. . .
what does pH stand for?
potential of hydrogen