biological molecules

Question 1

what are carbohydrates

Answer 1

made from Carbon, Hydrogen and Oxygen (CHO)

Question 2

what are fats and oils

Answer 2

made from Carbon, Hydrogen and Oxygen (CHO)

Question 3

what are proteins

Answer 3

made from Carbon, Hydrogen, Oxygen, Nitrogen and sometimes Sulfur (CHON(S))

Question 4

what are the basic units (monomers)

Answer 4

• simple sugars
• fatty acids and glycerol
• amino acids

Question 5

what are larger molecules (macromolecules)

Answer 5

• starch and glycogen
• fats and oils
• proteins

Question 6

test for starch

Answer 6

Add few drops of iodine, +ve result = blue-black colour

Question 7

test for reducing sugar

Answer 7

Add Benedict’s reagent, then mixture is heated in water bath for 2 to 3 minutes. +ve result = brick-red precipitate, -ve result = remains blue

Question 8

test for proteins

Answer 8

Add few drops of Biuret reagent, +ve result = mauve colour

Question 9

test for fats

Answer 9

Emulsion test; ethanol is added to mixture, and this is poured into a test tube with an equal amount of distilled water, +ve result = milky-white emulsion

Question 10

test for vitamin C

Answer 10

Decolourisation of DCPIP shows that a vitamin C is probably present.

Question 11

what are chromosomes

Answer 11

Chromosomes are made of a molecule called DNA

Each chromosome is a very long molecule of tightly coiled DNA

Question 12

structure of DNA

Answer 12

Two strands coiled together to form a double helix

Question 13

what are DNA bases

Answer 13

Each strand contains chemicals called bases

Cross-links between strands are formed by pairs of bases

Question 14

what are the DNA base pairs

Answer 14

The bases always pair up in the same way:

A and T

C and G