biological compounds

Question 1

State the isomer found in cellulose and starch (1)

Answer 1

• cellulose - beta
• starch - alpha

Question 2

Explain how the tructure of starch and celluloe related to functions as storage and structural molecule (4)

Answer 2

starch
* amylose/ amylopectin
* glycosidic bond alpha 1-4
* molecules coil and branch in amylopectin
* eay to remove glucose
cellulose
* alternate unit rotate/180
* straightchain only
* hydrogen bonds / cross linking
* gives strength of stability / microfibrils

Question 3

State the type of reaction ivolved in the breakdown of the monoglyceride (1)

Answer 3

hydrolysis

Question 4

Apart from energy storage state two function of triglycerides in a mammal (2)

Answer 4

• protection of internal organs against impact
• thermal insultation
• buoynacy waterproofing skin
• source of metabolic water

Question 5

Explain why triglycerides are not conidered polymers (1)

Answer 5

glycerol and fatty acid have different structures

Question 6

Stearic acid has the chemical formula C17H35COOH and oleic acids has the chemical formula C17H33COOH what type of fatty acid is oleic acid (2)0

Answer 6

• oleic acid is unsaturated
• contains at least one C=C double bond
• not fully saturated with hydrogen atoms

Question 7

Decribe a biochemical test for the prescence of glucose in a solution (2)

Answer 7

• add benedicts test and boil
• change from blue to brick red

Question 8

Explain why a positive result is seen with glucose with benedicts test but not for sucrose (1)

Answer 8

• sucrose is a non reducing sugar

Question 9

What is the role of magnesium , iron, phosphate, calcium (4)

Answer 9

• magnesium - component of chlorophyll
• iron - component of haemoglobin
• phosphate - coponent of nucleic acids/DNA/RNA/nucleotide
• calcium - hardens bone / teeth

Question 10

Name the bond between parallel chains of cellulose (1)

Answer 10

• hydrogen bonds

Question 11

Explain the importance of hydrogen bonding in the role of cellulose in plant cell wall (2)

Answer 11

• holds together cellulose chains / form microfibril
• stengthen cell walls / strong /rigin
• can resit turgor/ osmotic pressure/ prevent plant cells bursting

Question 12

Name chemical reaction by which monomers join together to form cellulose (1)

Answer 12

condensation

Question 13

In chitin what additional compound replaces one of OH group in each of its monosaccharides (1)

Answer 13

• amino acid / glucosamine / amine

Question 14

State the structural role of chitin in insects and describe its properties that make it suitable for this role (1)

Answer 14

• exoskeleton - strong / waterproof/light/rigidty / tough

Question 15

Name the storage polysaccharide found in animal cells and plants cell (2)

Answer 15

• animal - glycogen
• plant - starch

Question 16

What are the products formed when a triglyceride is broken down (2)

Answer 16

• glycerol
• 3 fatty acids

Question 17

What is the types of bond broken in a triglyceride and describe the process (3)

Answer 17

• ester
• hydrolysis
• chemical insertion of bond

Question 18

Describe two functions of lipids in plants (2)

Answer 18

• energy storage
• respiratory substrate
• source of energy
• waxy cuticle
• leaf waterproofing
• membrane structure

Question 19

State how the structure of a saturated fatty acid differs from the structure of an unsaturated fatty acid (2)

Answer 19

• saturated - no double bonds
• fewer hydrogen atoms
• comparative reasons

Question 20

Describe a test to show that a solution contains amino acids (2)

Answer 20

• add biuret test
• blue to purple

Question 21

Suggest a problem that could aride in using this test if very low concnetration of polymer present in solution (1)

Answer 21

• little colour change
• mauve may be masked

Question 22

State the inorganic ion present in haem group (1)

Answer 22

iron

Question 23

Why does haemoglobin have a quantenary structure (2)

Answer 23

• four polypeptide chain
• in tertiary form

Question 24

Name how alpha helix structure is maintained (2)

Answer 24

hydrogen bonding

Question 25

state the level of protein structure shown by haemoglobin (1)

Answer 25

quantenary

Question 26

Name two types of bonds present to maintain 3D shape of the polypeptide chain (1)

Answer 26

* disulphide bond * ionic bond * hydrogen bond * hydrophobic interactions

Question 27

Describe two ways in which the structure of phospholipids differ from triglycerides (2)

Answer 27

phospholipid * 2 fatty acids * phosphate head * hydrophillic head and hydrophobic fatty acid tails triglyceride * 3 fatty acids * no phosphate * non polar / hydrophobic

Question 28

Name the type of bond formed between two amino acids (1)

Answer 28

peptide

Question 29

Name the molecule produced when lactose is broken down (1)

Answer 29

glucose and galactose