Encounters with Life: lab quiz 2 Flashcards


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created 5 years ago by Devalon_N_Burk
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1

Would Benedict's reaction give a positive with all carbohydrates? Why?

no, because the reagent only tests for simple sugars

2

Benedict's reagent is a test for what?

simple carbs/reducing sugars/monosaccharides/disaccharides

3

Does paper contain starch?

yes

4

What chemical elements are present in starch?

carbon, hydrogen, and oxygen

5

what is a reducing sugar?

all monosaccharides and some disaccharides/any sugar capable of acting as a reducing agent

6

what are the component molecules making up of triglycerides?

fatty acids & glycerol

7

dry cleaners often use carbon tetrachloride. What stains would this remove?

oil & wax compounds

8

what are the building blocks of protein?

amino acids

9

how would you determine whether milk contains reducing sugars?

test with Benedict's reagent

10

what are the positive color change when using Benedict's reagent?

green to brick-red or brown

11

what could you say about a substance if it did not turn blue-black with iodine?

there is no starch present

12

Is CO2 (carbon dioxide) considered organic? why?

no, it does not contain hydrogen

13

Biuret's reagent is made up of. . .

sodium hydroxide or potassium hydroxide and a dilute solution of copper sulfate

14

what does hydrolysis mean?

a process in which water is used to split a substance into smaller particles

15

the hydrolysis of sucrose resulted in the presence of what two sugars?

glucose and fructose

16

are glucose and fructose reducing sugars?

yes, they are monosaccharides

17

organic compound

a compound that contains carbon in the form of chains or rings

18

inorganic compound

a compound that is not of animal or plant origin ; does not contain carbon

19

the elements most often found in living organisms are. . .

carbon, hydrogen, oxygen, nitrogen, & phosphorous

20

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

21

list the 3 types of carbohydrates with examples.

monosaccharide - glucose

dissacharide - sucrose

polysaccharide - starch

22

polymer

large molecule made up of chains or rings of monomers/

23

how are polymers formed?

dehydration synthesis

24

monomer

Simple one-unit molecules that make up complex molecules

25

dehydration synthesis

the joining of two molecules or compounds following the removal of water

26

hydrolysis

breaking polymers into monomers by adding water

27

why has water been included as one of the test materials for reducing sugars, starch, and protein?

to act as a control

28

reducing sugars are usually. . .

monosaccharides

29

monosaccharides release. . .

electrons

30

what reagent is used to test for reducing sugars?

Benedict's reagent

31

what is formed and settled out of a solution

precipitate

32

what chemical substance is used to detect the presence of starch?

iodine

33

the largest class of lipids are. . .

triglycerides

34

lipids are soluble in. . .

ether, acetone, and chloroform

35

why are lipids so important to living systems?

1. concentrated source of energy

2. thermal insulation

3. shock absorber for organs, muscles, and bones

36

give an example of emulsion.

oil and water

37

give an example of an emulsifier

detergent

38

emulsion

droplets of one liquid suspended in another/each insoluble in the other

39

emulsifier

a substance that stabilizes an emulsion

40

name the chemical substance used to indicate the presence of lipids

sudan IV

41

what reagent is used to test for the presence of protein in food?

Biuret's reagent

42

If protein is present, the tested substance will turn ____ when mixed with Biuret's reagent.

violet

43

When reducing sugars is present, the copper ions in the Benedict's Reagent are reduced to

metallic copper/copper I ions

44

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.

45

If substance turns black what are you testing for

organic and non organic

46

Sugar, Meat and Flour are all

organic

47

Table salt and baking soda are

non organic

48

The a substance turns blue black what is it positive for and what test is used.

Positive for Starch, using the Starch test

49

If a spot turns transparent to translucent

positive for lipids

50

If a pH level is above 7 the compound is a. . .

base/alkaline

51

If a compound has a pH level of 7 it is. . .

neutral

52

If a compound has a pH level below 7 it is. . .

acidic

53

example of an acid compound is. . .

lemon juice

54

example of a base compound is. . .

baking soda

55

example of a neutral compound is. . .

distilled water

56

what does pH stand for?

potential of hydrogen