A2 Biological Molecules

Question 1

Name the bond that joins two monosaccharides.

Answer 1

Glycosidic

Question 2

Name the disaccharide formed when two glucose molecules are joined.

Answer 2

Maltose

Question 3

Name the type of reaction used to join monosaccharides together.

Answer 3

Condensation reaction

Question 4

Name the carbohydrate formed when glucose and fructose are joined together.

Answer 4

Sucrose

Question 5

Name the sugar made when galactose and glucose condense

Answer 5

Lactose

Question 6

Name three monosaccharides

Answer 6

Glucose, fructose and galactose

Question 7

Name 2 polysaccharides

Answer 7

Starch, glycogen and cellulose

Question 8

Which elements are found in carbohydrates?

Answer 8

Carbon, hydrogen and oxygen.

Question 9

Name the 2 molecules made when 2 glucose molecules are joined by a glycosidic bond

Answer 9

Maltose and water

Question 10

Which type of glucose is used to make starch?

Answer 10

Alpha glucose

Question 11

Which type of glucose is used to make cellulose?

Answer 11

Beta glucose

Question 12

Give three uses of phosphate in living organisms.

Answer 12

Makes phospholipids, ATP, DNA, RNA

Question 13

Name the three different molecules found in ATP

Answer 13

Ribose, adenine and phosphate

Question 14

Why is iron needed in living things

Answer 14

Used to make haemoglobin which transports oxygen round the body.

Question 15

Name the building blocks of triglycerides.

Answer 15

Glycerol and fatty acids.

Question 16

What is the difference between a saturated and unsaturated fatty acid?

Answer 16

Saturated fatty acids have single carbon bonds between the carbon atoms.
Unsaturated fatty acids have at least one carbon clarion double bond.

Question 17

How do you test for a lipid?

Answer 17

Add ethanol to the test solution.
Mix gently
Pour liquid into cold water

Question 18

What is a positive and negative result for a biochemical test for lipid

Answer 18

Positive - White emulsion

Negative - clear

Question 19

Name the elements found in lipids

Answer 19

Carbon, hydrogen and oxygen.

Question 20

How many carbon atoms are found in glycerol

Answer 20

3

Question 21

Name the bond formed when a fatty acid and glycerol join.

Answer 21

Ester bond

Question 22

Name the type of reaction used to join fatty acids and glycerol

Answer 22

Condensation reaction

Question 23

Name the type of reaction used when lipid is digested.

Answer 23

Hydrolysis

Question 24

Describe how to test for starch

Answer 24

Add iodine to the test solution

Question 25

Describe the colour produced in a positive and negative test for starch.

Answer 25

Positive - blue or black | Negative- yellow, orange, brown

Question 26

Describe how to test for a reducing sugar

Answer 26

Add Benedict's solution | Heat in a waterbath

Question 27

What colour is produced by a positive Benedict's test?

Answer 27

Green, yellow, orange, brick red

Question 28

What colour is a negative result for a reducing sugar?

Answer 28

blue

Question 29

Name 3 reducing sugars

Answer 29

Glucose, fructose, galactose, maltose, lactose

Question 30

Name a non-reducing sugar

Answer 30

Sucrose

Question 31

Describe how to test for a non-reducing sugar

Answer 31

Obtain a negative Benedict's test Add acid and heat Add sodium hydrogen carbonate until it stops fizzing. Add Benedict's solution and heat

Question 32

Water has a high specific heat capacity. What does this mean?

Answer 32

It takes a lot of energy to change the temperature of water.

Question 33

Water has a high latent heat of vapourisation. What does this mean? Why is this feature of water important in humans?

Answer 33

Takes a lot of heat to change liquid water into water vapour. Used for cooling the body. The evaporation of sweat removes heat from the skin/blood.

Question 34

Water is a polar molecule. What does this mean?

Answer 34

It has a slight positive and negative charge. The hydrogen atoms gain a slight positive charge and the oxygen atom gains a slight negative charge.

Question 35

Water is an excellent solvent. What does this mean and why is it important?

Answer 35

Water allows lots of solutes to dissolve in it. | Chemicals dissolve in the water in the blood and can be carried round the body to every cell.

Question 36

Name the bond that joins cellulose molecules together.

Answer 36

Hydrogen bonds

Question 37

Give three features of starch that make it an ideal storage molecule.

Answer 37

Large insoluble molecule. Osmotically inactive. Glucose can by easily removed/add in a single reaction. Branched molecule with lots of ends to add/remove glucose at any one time. Folded to make it compact.

Question 38

Why is ATP a good intermediate energy source?

Answer 38

Single step hydrolysis reaction releases energy. Energy released in small amounts Energy can be transferred to other molecules to make them more reactive.

Question 39

Name the enzyme used to make ATP.

Answer 39

ATP synthetase

Question 40

Name the enzyme used to hydrolyse ATP.

Answer 40

ATP hydrolase

Question 41

Why are sodium ions required in the body.

Answer 41

Needed to do-transport glucose and amino acids from the ileum into the epithelium cells.

Question 42

Water molecules show cohesion.what does this mean and state where it is important in biology.

Answer 42

Water molecules are hydrogen bonded to each other. Supports columns of water in xylem vessels - transpiration Produce surface tension - allows animals to 'walk' on water surface.

Question 43

Name two types of reaction that involve water.

Answer 43

Condensation and hydrolysis.

Question 44

In which processes is ATP made?

Answer 44

Respiration and photosynthesis.

Question 45

Complete the reaction ATP + water ->

Answer 45

ADP and Pi

Question 46

Name the monomers used to make proteins.

Answer 46

Amino acid

Question 47

How many different types of amino acids are there?

Answer 47

20

Question 48

Name the bond that joins two amino acids together.

Answer 48

Peptide

Question 49

Name the 2 substances made when two amino acids are joined together.

Answer 49

Dipeptide | Water

Question 50

What is a polypeptide?

Answer 50

Many amino acids joined together by peptide bonds.

Question 51

Name the elements found in amino acids.

Answer 51

Nitrogen, carbon, hydrogen and oxygen.

Question 52

Name 3 biological molecules which contain nitrogen.

Answer 52

Proteins/amino acids (eg haemoglobin, chlorophyll) ATP DNA/RNA nucleotides/bases (eg mRNA, tRNA, rRNA) NAD/NADP/FAD cAMP

Question 53

How is the structure cf cellulose suited to its function?

Answer 53

Beta glucose form long straight chains Strong glycosidic bonds between glucose molecules Hydrogen bonds between cellulose molecules add strength Cellulose arranged into microfibrils and then fibres adding strength

Question 54

``` Name the monomers for the following polymers Protein Glycogen Cellulose DNA ```

Answer 54

Protein - amino acids Glycogen - alpha glucose Cellulose - beta glucose DNA - nucleotides

Question 55

What happens in a condensation reaction?

Answer 55

A chemical bond forms between 2 molecules and a water molecule is produced.

Question 56

What happens in a hydrolysis reaction?

Answer 56

A water molecule is used to break a chemical bond between 2 molecules

Question 57

Describe how colorimetry could be used to find the unknown concentration of a glucose solution

Answer 57

Make standard solutions of glucose with known concentrations Carry out a standardised Benedict's test on each concentration and the unknown solution Record absorbance of % transmission values Plot calibration curve - absorbance or % transmission (y axis), concentration (x axis) Record absorbance or % transmission value of unknown sample. Use calibration curve to read off concentration