carbs and lipid

Question 1

What is a monomer?

Answer 1

Monomers are small identical or similar molecules which can be condensed to make larger molecules called polymers.

Question 2

What is a polymer?

Answer 2

Polymers are large molecules made from condensing 3 or more
identical or similar monomers together.

Question 3

State and describe the type of reaction involved in breaking a
chemical bond.

Answer 3

Hydrolysis – addition of water to break a named chemical
bond

Question 4

State and describe the type of reaction involved in forming a chemical bond

Answer 4

Condensation – removal of water to form a named chemical
bond

Question 5

name the bond between carbohydrate monomers

Answer 5

glyosidic bond

Question 6

what monosaccharides make up the disaccharides

Answer 6

sucrose = glucose and fructose
lactose = glucose and galactose
maltose - glucose and glucose

Question 7

Describe the biochemical test for the non-reducing sugar

Answer 7

benedict’s test gives negative result
Add HCl and heat to 95 degrees
Neutralise with NaHCO3
Add benedict’s solution and heat to 95 degrees
Red precipitate shows presence of non reducing sugar

Question 8

Describe the potassium iodide test for starch

Answer 8

Add potassium iodide solution
Black shows presence of starch

Question 9

explain 3 ways in which starch molecules are adapted for their function in plant cells

Answer 9

1.Insoluble SODoesn’t affect water potential;
OR
2.Helical/coiled SOCompact;
OR
3.Large molecule SOCannot leave cell

Question 10

describe how the structure of glycogen is related to its function

Answer 10

-helical so compact
-polymer of glucose so easily hydrolysed
-branched so provides more ends for respiratory substrate
-glucose so provides respiratory substrates for energy
-insoluble so doesn’t affect water potential

Question 11

Explain how the structure of cellulose relates
to its function

Answer 11

Long straight unbranched chains of beta glucose
Joined by hydrogen bonds
Form microfibrils
Many weak hydrogen bonds are strong in large numbers
Providing strength to cell wall

Question 12

describe how a triglyceride is formed

Answer 12

one glycerol and three fatty acids
three condensation reactions and the removal of three molecules of water
creating 3 ester bonds

Question 13

what is an unsaturated fatty acid

Answer 13

double bonds between carbon

Question 14

Compare and contrast the structure
and properties of triglycerides and
phospholipids

Answer 14

-Both contain ester bonds (between glycerol and fatty acid);
-Both contain glycerol;
-Fatty acids on both may be saturated or unsaturated;
-Both are insoluble in water;
-Both contain C, H and O whereas phospholipids also contain P;
-Triglyceride has three fatty acids whereas phospholipid has two fatty acids plus phosphate group;
-Triglycerides are hydrophobic/non-polar and phospholipids have hydrophilic and hydrophobic region;
-Phospholipids form monolayer (on surface)/micelle/bilayer (in water) whereas triglycerides don’t;

Question 15

describe the emulsion test

Answer 15

crush sample to release lipid
mix with ethanol and shake
add water and shake
form cloudy white emulsion

Question 16

describe the biuret test

Answer 16

add biuret reagent to sample
purple shows protein is present

Question 17

describe the biochemical test for a reducing sugar

Answer 17

add bendicts solution and heat to 95 degrees
red precipitate shows reducing sugar

Question 18

describe alternate ways to measure the concentration of a reducing sugar

Answer 18

filter and dry precipitate
find the mass

Question 19

how do you make a calibration curve for a reducing sugar and use it to find an unknown concentration

Answer 19

-make several known concentrations of -named reducing sugars-
-carry out benedict’s test on each sample
-use colorimeter to measure absorbance of light in each sample
-plot calibration curve with concentration on x axis and absorbance of y value
-find the concentration of unknown using the calibration curve