4. Biological Molecules

Question 1

Carbohydrates

Answer 1

CHO

Compounds found in living things composed of carbon, hydrogen and oxygen.

Useful for a fast source of energy

Monomer - Monosaccharide

Question 2

Starch

Answer 2

A type of carbohydrate

Function - Energy and nutrient storage

Source - Chloroplasts and cytoplasm in plant cells

Question 3

Cellulose

Answer 3

A type of carbohydrate

Function - Structural support

Source - Plant cell walls

Question 4

Glycogen

Answer 4

A type of carbohydrate

Function - Energy and nutrient storage

Source - Liver and muscles

Question 5

Monosaccharide

Answer 5

One glucose molecule

Question 6

Disaccharide

Answer 6

2 glucose molecules joined with bonds

Question 7

Polysaccharide

Answer 7

Several glucose molecuse joined with bonds

Question 8

Monomer

Answer 8

Building block of a biological molecules

Question 9

Proteins

Answer 9

Biological molecule made of the monomer amino acids.

Compounds of - Carbon (C), Hydrogen (H), Oxygen (O), Nitrogen (N)

(some proteins contain very small amounts of sulfur and selenium)

Functions

Provide structural support
Amino acids make up DNA
Proteins are used in muscle build-up

Question 10

Lipids

Answer 10

(Fats and Oils)

Compounds - Carbon (C), Hydrogen (H), Oxygen (O)

Fats are found in solid state, oils in lquid state –> both are fats

Monomers - Glycerol + three fatty acids

Most common fat/lipid in animals is triglyceride

Function

Long term energy + insulation

Question 11

How many types of amino acids are there?

Answer 11

20 (naturally occuring) types

Question 12

Testing for reducing sugars.

Answer 12

Benedict’s test

Add water to a test tube. Add a food source to that test tube. Then add a couple of drops of Benedict’s solution.

Blue - No sugar
Green or Yellow - Traces of sugar
Orange - Moderate amount of sugar
Red - Large amounts of sugar

Question 13

Test for starch

Answer 13

Add a couple of drops of iodine to the food source.

Orange-brown - No starch
Blue-black - Starch is present

Question 14

Test for fats and oils

Answer 14

Add ethanol in the test tube with the food solution Place bungs on the test tube and then gently shake it.

If a milky emulsion is formed there are fats and oils in the substance.

CHECK WITH MISS CHIPPINDALL

Question 15

Test for proteins

Answer 15

Add a couple of drops of biuret solution. Gently shake/swirl

Light purple - Protein is present
Light blue - No protein

Question 16

Test for vitamin C

Answer 16

Add a couple of drops of DCPIP (which is blue). Gently swirl.

Small amount of blue colour disappears - Small amount of Vitamin C
Large amount of blue colour disappears - Large amount of Vitamin C

Question 17

DNA (extended)

Answer 17

A large molecule made from bases, and which carries genetic information in the form of genes.

They are large molecules containing many atoms. DNA consists of two strands coiling together to form a double helix.

Each strand contains 3 main chemicals (phosphates, sugars called deoxyribose and nitrogen-containing bases.)

Phosphates + sugars form the backbone of the strands.
Nitrogen containing bases are located in the centre of the molecule.

Question 18

Bases of DNA

Answer 18

There are four bases - A, T, C and G

They always pair up this way.

• A with T
• C with G

Therse are called complementary base pairs.