Biological Molecules

Question 1

What is a monosaccharide?

Answer 1

A simple sugar made up of 1 ring of carbon atoms

Question 2

What is a disaccharide?

Answer 2

A simple sugar made up of 2 rings of carbon atoms

Question 3

What is a polysaccharide?

Answer 3

A complex string and sugars that are chemically bonded together

Question 4

What is an example of a polysaccharide?

Answer 4

Starch

Question 5

What is one use for a fat?

Answer 5

Insulation

Question 6

What is the carbohydrate broken down for respiration?

Answer 6

Glucose

Question 7

Where is fructose often found?

Answer 7

Fruit and nectar

Question 8

What is blubber and what is it used for?

Answer 8

Blubber is a thick layer of fat under the skin of animals who live in cold climates. It keeps them insulated and warm, blubber is also buoyant, this helps artic animals such as polar bears.

Question 9

What is the difference between saturated and unsaturated fats?

Answer 9

Unsaturated fats are bent and not as close together as saturated acids. Saturated acids have only single C-C bonds whereas unsaturated acids have one or more double C=C bonds.

Question 10

What is a protein molecule?

Answer 10

A long chain of many small atoms called amino acids joined together.

Question 11

How many amino acids are there?

Answer 11

20

Question 12

What does exposure to high temperatures do to proteins?

Answer 12

Proteins can change shape irreversibly and cannot carry out its function. It has become denatured. Extreme pH can also denature proteins.

Question 13

What is the test for starch

Answer 13

The test for starch is iodine solution.
1. Take a small food sample and place in a spotting tile.
2. Add a few drops of iodine solution.
3. If starch is present, the iodine changes colour from orange to black/blue.

Question 14

What is the test for glucose?

Answer 14

The test for glucose is Benedict’s solution.
1. Grind a small food sample with distilled water.
2. Add the food mixture to a test tube.
3. Add enough Benedict’s solution to the test tube to cover the mixture and for it to turn blue.
4. Heat in a water bath at 80 degrees for 5 minutes.
5. If the mixture contains glucose it changes from blue to brick red. If it turns green, yellow or orange, glucose is present but there is a lower concentration.

Question 15

What is the test for protein?

Answer 15

The test for protein is Biuret solution.
1. Grind a small food sample with distilled water.
2. Add the food mixture to a test tube.
3. Add enough Biuret solution to the test tube to cover the mixture and for it to turn pale blue.
4. If protein is present, the mixture will turn from pale blue to purple.

Question 16

What is the test for lipids?

Answer 16

The test for lipids is the emulsion test.
1. Place a small sample, approximately 2 cm3 in a test tube.
2. Add 2 cm3 of ethanol and mix well.
3. Add 2 cm3 of water and shake again.
4. If the mixture turns a milky colour, then lipids are present in the food.

Question 17

What are enzymes?

Answer 17

Enzymes are biological catalysts that speed up chemical reactions.

Question 18

Explain how enzymes work.

Answer 18

Enzymes have a unique shape. Their active site has to be complementary is a substrate for the reaction to take place. The substrate enters the active site and forms an enzyme substrate complex. The reaction takes place and it becomes a enzyme product complex. The product leaves the enzyme and the enzyme remains unchanged.

Question 19

What does DENATURED mean for enzymes?

Answer 19

Denatured means when a protein, like an enzyme, is exposed to very high heat or extreme pH and its shape changes irreversibly. With enzymes, this means that the active site no longer complementary to the substrate and can’t react with it.