Topic 1 BIO MOLECULES- carbohydrates

Question 1

What is sugar?

Answer 1

A soluble carbohydrate (usually a monosaccharide or disaccharide)

Question 2

What is a monosaccharide?

Answer 2

Single (mono) sugar (saccharide) units

Question 3

glucose+fructose

Answer 3

sucrose+water

Question 4

glucose+galactose

Answer 4

lactose+water

Question 5

What is the food test for starch

Answer 5

iodine solution/potassium iodide solution

Question 6

What results do you get from the test for starch

Answer 6

positive- blue/black
negative- stays yellow/brown

Question 7

What is the food test for sugar?

Answer 7

• benedict’s

Question 8

What are the results for a non reducing sugar?

Answer 8

stays blue

Question 9

What are the results for a reducing sugar

Answer 9

sample forms a green or yellow or orange or brick red precipitate (the higher the concentration of reducing sugar the further the colour changes)

Question 10

name 3 monosaccharides

Answer 10

glucose
fructose
galactose

Question 11

name 3 disaccarides

Answer 11

sucrose
maltose
lactose

Question 12

name 3 polysaccharides

Answer 12

startch
glycogen
cellulose

Question 13

is starch soluble or insoluble

Answer 13

insoluble

Question 14

What is the function of starch?

Answer 14

stores energy for plants

Question 15

Where is starch found and in what form

Answer 15

plants in the form of grains

Question 16

What is a starch made up of

Answer 16

alpha glucose molecules linked together by glyosidic bonds

Question 17

How are unbranched chains adapted for there function

Answer 17

coiled so can be stored in small cells

Question 18

What forms a glucose which is used in respiration

Answer 18

hydrolose

Question 19

How are branched chains adapted for their function

Answer 19

has many ends so can be broken off to form monomers more easily

Question 20

Where is glycogen found

Answer 20

animal and bacterial cells

Question 21

What are the differences between glycogen and starch

Answer 21

-Glycogen is more highly branched than starch (amylopectin)
-Glycogen branches every 10-15 glucose, amylopectin has branching every 25 glucose molecules

Question 22

Is glycogen a major carbohydrate store in animals

Answer 22

yes

Question 23

Where is glycogen stored

Answer 23

small granules in muscles and liver

Question 24

Describe the structure and the function of cellulose?

Answer 24

-Betaglucose-inverted and normal glucose molecules form alternating glycosidic bonds to form straight, unbranched chains
-Hydrogen bonding- H bonds form between parallel strands, creating strong and stable molecules of cellulose
-Microfubrilis- parallel chains group to form microfibrils
-Fibrils- microfibrils group into fibrils that provide greater strength

Question 25

What is starch is made up of ?

Answer 25

Two polysacharides: -amylose -amylopectin

Question 26

What is amylose

Answer 26

unbranched chain of glucose molecules joined by 1'4 glycosidic bonds which as a result is coiled and stores a lot of energy compactly

Question 27

What is amylopectin

Answer 27

branched glucose molecules joined by 1,4 and 1,6 glycosidic bonds

Question 28

What happens at the end of the branches of amylopectin?

Answer 28

hydrolysis of the glycosidic bonds and they can be acted upon by enzymes and release energy

Question 29

What happens when starch is hydrolysed

Answer 29

A glucose can be transported easily

Question 30

What is a carbohydrate

Answer 30

molecules which consist of only carbon oxygen and hydrogen and they are long chains of sugar units called saccharides

Question 31

how is a glyosidic bond formed

Answer 31

a condensation reaction between two monosaccharides

Question 32

how are disaccharides formed

Answer 32

the condensation of two monosaccharides

Question 33

How is maltose formed

Answer 33

condensation of two glucose molecules

Question 34

how is sucrose formed

Answer 34

condensation of a glucose molecule and a fructose molecule

Question 35

how is lactose formed

Answer 35

condensation of a glucose molecule and a galactose molecule

Question 36

hoiw are polysaccarides formed

Answer 36

the condensation of many glucose units

Question 37

how is cellulose formed?

Answer 37

condensation of b glucose

Question 38

What is the unique bond?

Answer 38

-Glycosidic

Question 39

What do the 3 monosaccharides have in common?

Answer 39

-They are isomers of each other (they have the same chemical formula but the atoms are arranged differently)

Question 40

What is the difference between alpha glucose and beta glucose?

Answer 40

-Alpha glucose- OH is on the bottom right -Beta glucose- H is on the bottom right

Question 41

What is the structure of starch?

Answer 41

-Compact, coiled structure- a lot of glucose can be stored in a small space -Large insoluble- does not diffuse out of cells so does not affect osmotic pressure within the cell -Easily hydrolysed to glucose- valuable for respiration -Amylopectin branching- more sites for hydrolytic enzymes to work, therefore glucose can be released faster

Question 42

What is glycogen?

Answer 42

-Polysaccharide -Made up of repeating alpha glucose units -Only found in animal cells

Question 43

Why is cellulose different to the other 2 polysaccharides?

Answer 43

-Made up of glucose molecules rather than alpha-glucose

Question 44

What is a reducing sugar?

Answer 44

-A sugar that will donate electrons to another chemical therefore reducing the other substance

Question 45

What is oxidation

Answer 45

-The gain of oxygen -The loss of electrons -The loss of hydrogen

Question 46

What is reduction

Answer 46

-The loss of oxygen -The gain of electrons -The gain of hydrogen

Question 47

OIL RIG

Question 48

What is Benedict's solution made up of?

Answer 48

-Alkaline solution of copper (II) sulfate

Question 49

What is the method for Benedict's test for reducing sugars

Answer 49

-Add a sample in liquid form to a test tube -Add an equal volume of benedicts reagent -Heat in a boiling (100c) water bath for 5 mins

Question 50

What colour will the precipitate be if reducing sugars are present? Why?

Answer 50

-Red -Because the copper II sulfate has been reduced to copper I oxide which is an insoluble red precipitate

Question 51

What is the method to test for non-reducing sugars?

Answer 51

-Carry out benedicts test ] -Add dilute HCL and boil gently -Add Na HCO3 -Retest the sample with benedicts solution

Question 52

How does the hydrochloric acid show results for a non-reducing sugar

Answer 52

-It hydrolyses any disaccharides into their monosaccharides, therefore showing a positive result in the second test -The sodium hydrogen carbonate neutralises the hydrochloric acid

Question 53

What colour does the solution turn if there is a positive result for starch?

Answer 53

blue/black