Chemical Elements & Biological Compounds

Question 1

Magnesium

Answer 1

• Constituent of chlorophyll
• Needed for photosynthesis
• Lack of leads to chlorosis (yellow leaves)

Question 2

Iron

Answer 2

• Constituent of haemoglobin
• Involved in transportation of oxygen in blood
• Lack leads to anaemia

Question 3

Calcium

Answer 3

• Structural component of bones and teeth

Question 4

Phosphate

Answer 4

• Needed for making nucleotides e.g. ATP

Question 5

Why is Water Dipolar ?

Answer 5

• Slightly negative charged oxygen, slightly positive charged hydrogen

Question 6

Why is Water a Good Solvent ?

Answer 6

• Dipolar molecule
• Easily dissolve charged particles

Question 7

Why can Water form Hydrogen Bonds ?

Answer 7

• Slightly negative oxygen is attracted to slightly positive hydrogen.

Question 8

Why is there Surface Tension in Water ?

Answer 8

• Water molecules attract each other and create lattices (Cohesion)
• Hydrogen bonds between water molecules creates surface tension

Question 9

Why does Water have High Latent Heat ?

Answer 9

• Many hydrogen bonds, large amount of heat needed for temperature change
• Requires lots of energy to break bonds

Question 10

Monosaccharides

Answer 10

• Single sugars containing carbon, hydrogen, oxygen
• Name depends on number of carbons (triose-3)

Question 11

Disaccharide

Answer 11

• Two monosaccharides bonded together by condensation reaction, loss of water forming a glycosidic bond

Question 12

Polysaccharide

Answer 12

• Many monosaccharides bonded together forming glycosidic bonds

Question 13

What makes a Polysaccharide good energy store ?

Answer 13

• Unable to diffuse in and out of cell
• Compact
• Insoluble

Question 14

Alpha Glucose

Answer 14

Hydroxyl group below C4, H above

Question 15

Beta Glucose

Answer 15

Hydroxyl group above C4, H below

Question 16

Isomers

Answer 16

Same chemical formula, different atom arrangement

Question 17

Starch

Answer 17

• Main energy store in plants
• Made of amylose and amylopectin

Question 18

Structure of Amylose

Answer 18

• 1-4 glycosidic bonds
• Forms single helix
• Alpha glucose

Question 19

Structure of Amylopectin

Answer 19

• 1-4 and 1-6 glycosidic bonds
• Forms branched structure increasing surface area for hydrolysis to occur
• Alpha glucose

Question 20

Glycogen

Answer 20

• Energy store in humans
• Has a more branched structure than amylopectin
• 1-4 and 1-6 glycosidic bonds
• Alpha glucose

Question 21

Cellulose

Answer 21

• Present in plant cell walls
• Beta glucose
• 180 degree rotations
• Hydrogen bonds between rotated glucose forming microfibrils

Question 22

Chitin

Answer 22

• Exoskeletons
• Beta glucose
• 180 degree rotation
• Hydrogen bonds between rotated glucose forming microfibrils
• Strong, light, waterproof

Question 23

Functions of Lipids

Answer 23

• Energy reserve
• Thermal insulation
• Protection
• Waterproofing
• Metabolic Water

Question 24

Triglycerides

Answer 24

1 glycerol molecule bonded to 3 fatty acids by condensation reaction forming an ester bond

Question 25

Phospholipid

Answer 25

- Phosphate group and 2 fatty acids - Phosphate group is hydrophilic - Fatty acid tails are hydrophobic

Question 26

Saturated Fats

Answer 26

Hydrocarbon chain fully bonded to hydrogen atoms

Question 27

Unsaturated Fats

Answer 27

- Hydrocarbon chain includes double bond. - Not fully bonded to hydrogen atoms - Creates a kink in the structure

Question 28

Effect of Saturated Fats on Health

Answer 28

- Atherosclerosis (build up of fatty deposits in arteries) - LDL - low density lipoproteins - Leads to angina then heart attack

Question 29

Effect of Unsaturated Fats on Health

Answer 29

- Results in body manufacturing high density lipoproteins (HDL) - These carry harmful fats to the liver for disposal

Question 30

Amino Acids

Answer 30

Order of 20 amino acids determine structure therefore function

Question 31

Dipeptide

Answer 31

Two amino acids bonded together by a condensation reaction, loss of water forming a peptide bond

Question 32

Polypeptide

Answer 32

Many amino acids bonded together by peptide bonds

Question 33

Primary Proteins

Answer 33

Linear sequence of amino acids in polypeptide chain

Question 34

Secondary Protein

Answer 34

- Alpha helix/Beta pleated sheet - Hydrogen bonds between =O and -COOH

Question 35

Tertiary Protein

Answer 35

- Disulphide bridges, Ionic bonds, Hydrophobic interactions - Gives globular proteins their shape

Question 36

Quaternary Protein

Answer 36

- 2 or more polypeptide chains in tertiary form combined

Question 37

Types of Globular Protein

Answer 37

- Antibodies - Enzymes - Plasma Proteins - Hormones

Question 38

Properties of Globular Proteins

Answer 38

- Compact, folded into spherical molecules - Insoluble in water

Question 39

Structural Functions of Fibrous Proteins

Answer 39

- Polypeptides in parallel chains - Sheets with crosslinks

Question 40

Properties of Fibrous Proteins

Answer 40

- Insoluble in water - Strong - Tough

Question 41

Example of Globular Protein

Answer 41

- Haemoglobin - 4 folded polypeptides and a ham group

Question 42

Example of Fibrous Proteins

Answer 42

- Collagen - Single fibre containing 3 polypeptide chains interwined - Very stable