3. Biological Molecules

Question 1

What are monosaccharides?

Answer 1

Simplest carbohydrates that are soluble and can dissolve in blood and be transported e.g glucose, fructose and lactose

Question 2

What are polysaccharides?

Answer 2

Formed from many thousands of monosaccharide molecules and are insoluble do make good stores of energy e.g starch, glycogen and cellulose.

Question 3

All biological molecules contain the elements…

Answer 3

Carbon
Hydrogen
Oxygen

Question 4

Hydrolysis reaction

Answer 4

This reaction is when large molecules are broken down into smaller ones by the addition of water.

Question 5

Condensation reaction

Answer 5

Small molecules can be joined together to form larger molecules by the removal of water.

Question 6

Antigen

Answer 6

Something on the pathogen surface which triggers the immune system.

Question 7

Antibodies

Answer 7

Chemical in your white blood cell to destroy antigens.

Question 8

Water is an important solvent:

Answer 8

Allows excretory materials e.g drugs, hormones, urea and salts to dissolve-transport.
Water has a diluting effect, reducing toxicity of the excretory materials.
Helps break down food molecules as part of digestion.
Blood plasma- 92% water. Transport medium for dissolved substances and numerous blood cells.

Question 9

Dna is made of simple biological molecules called…

Answer 9

Nucleotides

Question 10

Chromosomes

Answer 10

Large molecules of DNA and humans have 23 pairs of these in the nucleus of every cell (except sex cells or gametes: sperm and egg)

Question 11

Benefit of DNA helical shape?

Answer 11

More compact

If you coil it up protects bases inside.

Question 12

Benedicts test is for…

Answer 12

Reducing sugars:
Benedicts solution
BLUE👉 BRICK RED(if a green/yellow colouration shows a low conc. of sugar is present.)
heat minimum 70 degrees celsius

Question 13

Iodine test is for…

Answer 13

Starch:
Iodine in potassium iodide solution
ORANGE/BROWN👉 BLUE/BLACK

Question 14

Biuret test is for…

Answer 14

Protein:
Biuret solution (alkaline copper sulphate)
BLUE👉PURPLE

Question 15

Emulsion test is for…

Answer 15

Lipids:
Ethanol then shake carefully then add water
If a CLOUDY WHITE EMULSION forms- presence of lipid.

Question 16

DCPIP test is for…

Answer 16

Vitamin C:
If liquid, do not need an extract. But if solid need to make an extract out of it by grinding, crushing or chopping a small amount and put it into a test tube.
Add a similar amount of distilled water and stir w. A glass rod. (Allow to stand for a few minutes.)
Draw up some of the clear liquid into a pipette.
Add a drop in one at a time into a test tube containing DCPIP.
LIGHT BLUE👉DECOLOURED
The greater the conc., the greater the rate of decolorisation of vitamin C is present.

Question 17

What are reducing sugars?

Answer 17

Glucose, fructose, maltose,lactose and galactose BUT NOT SUCROSE.

Question 18

Why do we add in ethanol into the emulsion test for lipids?

Answer 18

So that the food is dissolved so the emulsion can form. Otherwise would just be watery food.

Question 19

Enzymes

Answer 19

Are proteins that function as biological catalysts, substances that increase the rate of chemical reactions without being changed👉important in all living organisms to chieve reaction speeds necessary to sustain life.

Question 20

What structure do all enzymes have?

Answer 20

A ‘tertiary shape’, the third lot of folding of amino acid chain.

Question 21

What is the enzyme called that converts glucose to fructose?

Answer 21

Isomerase

Question 22

What do you do if an enzyme has become denatured and you don’t want it to contaminate your product?

Answer 22

You can immobilise the enzyme in gel beads or on reagent sticks.(get stuck to it)