Carbohydrates And Lipdis

Question 1

Monomer definition

Answer 1

Small identical or similar molecules which can be condensed to make larger molecules called polymers

Question 2

Polymers definition

Answer 2

Large molecules made from joining three or more identical or similar molecules together

Question 3

What is the ration of C:H:O

Answer 3

1:2:1
C6H12O6

Question 4

How are disaccharides formed and give examples

Answer 4

Condensation reaction between monosaccharides
Glucose-galactose and fructose

Question 5

How to form maltose

Answer 5

Condensation reaction between two alpha glucose molecules, forming glycosidic bonds, catalysed by Maltase

Question 6

How to form lactose

Answer 6

Condensation reaction between alpha glucose and galactose, joined by condensation reaction, catalysed by lactase

Question 7

How to form sucrose

Answer 7

Condensation reaction between alpha glucose and fructose, joined by glycosidic bond and catalysed by sucrase

Question 8

Which two monomers does starch break down to

Answer 8

Amylose and amylopectin

Question 9

Describe the structure of amylose

Answer 9

Carbon 1:4 glycosidic bonds so long and straight chains of alpha glucose which coil into a helix

Compact so is good for storage
Insoluble so doesn’t affect water potential
Large so cannot diffuse out of cells

Question 10

Describe the structure of amylopectin

Answer 10

Branched chain of alpha glucose molecules
Carbon 1:4 and 1:6 glycosidic bonds
This provides a large surface area for rapid hydrolysis by enzymes to release glucose for respiration
Insoluble so does not affect water potential
Large so cannot diffuse out of cells

Question 11

Describe the structure of glycogen

Answer 11

Only found in animal cells
Shorter chains- glycogen being more rapidly hydrolysed into glucose used in respiration
More highly branched
Larger surface area
Stored in muscles and liver
Insoluble so doesn’t affect water potential or diffuse out of cells

Question 12

Explain why this shape is important to its function in cells(spiral)

Answer 12

Helical so compact

Question 13

Explain one way in which starch molecules are adapted for their function in plant cells

Answer 13

1. Insoluble so doesn’t affect water potential
2. Helical so compact
3. Large so cannot leave cells

Question 14

Explains the structure of cellulose

Answer 14

Long straight, unbranched chains of beta glucose, joined together by many weak hydrogen bonds to form microfibrils
Every other beta glucose molecule rotates horizontally 180 to form a 1-4 glycosidic bonds

Question 15

Hydrogen bonds are important in cellulose molecules- explain why

Answer 15

Hydrogen bonds hold chains together, providing strength and rigidity, weak hydrogen bonds provide strength in large number

Question 16

Describe the test for a reducing sugar

Answer 16

1. Add equal volumes of Benedict’s solution
   2.heat to 95
   3.red/orange/yellow/green precipitate

Question 17

Describe how the
student would show
that a non-reducing
sugar was present in
a solution.

Answer 17

1. Complete Benedicts test and observe a negative result/stays
   blue
2. Add acid (HCl) to sugar solution AND Heat to 95 ⁰C;
3. Then neutralise with alkali (sodium hydrogen carbonate
   (NaHCO₃);
4. Add equal volumes of Benedict’s solution to the sugar solution;
5. Heat again to 95 ⁰C;
6. Red/orange/yellow/green precipitate;

Question 18

What type of test is using a colorimeter

Answer 18

Quantitive

Question 19

How to standardise the method

Answer 19

• samples should always be shaken before testing
• zero the colorimeter before use
• use the same filter throughout
• use the same volume for each reading

Question 20

Describe how you would produce a calibration curve

Answer 20

1. Make up different known concentrated solutions of named sugar
2. Carry out test on each sample
3. Take absorbance readings using a colorimeter
4. Plot a calibration curve- known conc on X axis and absorbance on Y
5. Find the concentration of the unknown sample using the calibration curve

Question 21

Test for starch

Answer 21

Add potassium iodide
Turns blue black in the presence of starch

Question 22

Properties and functions of triglycerides and phospholipids

Answer 22

Triglycerides are commonly found in food, phospholipids help form the cell membrane of a cell
Conduct heat slowly so good thermal and electrical insulators, stored around delicate organs such as the kidneys to protect them

Question 23

Emulsion test

Answer 23

Crush grind
Mix with ethanol and shake
Add water and shake
Forms a milky white emulsion

Question 24

What are the differences between a triglyceride and a phospholipid

Answer 24

Fatty acid removed and replaced with phosphate group