Topic 4 / Biological Molecules

Question 1

What chemicals make up carbohydrates?

Answer 1

Carbon, Hydrogen, Oxygen

Question 2

What chemicals make up protein?

Answer 2

Carbon, Hydrogen, Oxygen, Nitrogen

Question 3

What chemicals make up fats?

Answer 3

Carbon, Hydrogen, Oxygen, Phosphorus

Question 4

Starch and glucose from glucose

Answer 4

starch is made of 100s of glucose molecules joined together to form chains. It’s an important storage substance in the plastids of plant cells.

Question 5

Cellulose from glucose

Answer 5

cellulose is even more chains of glucose molecules. these chains are grouped together to form microscopic fibres, which form the cell wall in plant cells

Question 6

Proteins from amino acids.

Answer 6

proteins are made of long chains of simpler chemicals than carbon, hydrogen (etc.) called amino acids.

Question 7

fats and oils from fatty acids and glycerol

Answer 7

a molecule of fat/oil is made of 3 fatty acid molecules and 1 molecule of glycerol

Question 8

Test: iodine solution for starch

Answer 8

1. starch powder in test tube w/ warm water 2. drops of iodine 3. dark blue colour should be produced

Question 9

Test: benedict’s solution for reducing sugar

Answer 9

1. equal volume of glucose and benedicts in test tube 2. place tube in beaker of boiling water 3. change from clear blue, to green, to yellow and to red.

Question 10

Test: Biuret for protein

Answer 10

1. add sodium hydroxide and copper sulfat to albumen. 2. purple indicates protein

Question 11

Test: Ethanol for fat

Answer 11

1. shake cooking oil with ethanol until fat dissolves 2. pour into water, white solution will form bc of fat/oil

Question 12

Test: DCPIP for vitamin C

Answer 12

1. add lemon juice and orange juice to DCPIP

2. if it takes more orange than lemon to decolourize the DCPIP, orange has less vitamin C

Question 13

Different amino acid sequences –> different shape to proteins

Answer 13

A change in gene sequence can lead to a different amino acid being added to a chain instead of the normal one. This causes a change in protein structure and function.

Question 14

Relating shape and structure of proteins to their function.

Answer 14

Shape of an enzyme (in protein) creates an active site. Antibodies have different binding sites for bacteria and each pathogen has antigens that are a particular shape, so specific antibodies are needed.

Question 15

Describing DNA Structure.

Answer 15

dna is made up of 2 strands coiled together that form a double helix: each strand has chemicals called bases. cross links between the strands are formed by the bases. Bases pair up: A&T, C&G

Question 16

Importancy of water as a solvent.

Answer 16

Transport - carries ions in plants up xylem vessels. plasma is also made from water and transports CO2, food, hormones as well as blood cells.

Digestion - breaks down and dissolves food molecules. in plants, combines with CO2 for sugar.

Excretion - powerful solvent for urea, salts, spent hormones and drugs. the water has a diluting effect, reducing toxicity in excretory materials.