Biological molecules

Question 1

What elements are lipids made of?

Answer 1

CHO : carbon, hydrogen, oxygen

Question 2

What is the test for lipids?

Answer 2

ethanol emulsion

Question 3

What are lipids made up of?

Answer 3

fatty acids and glycerol ; triglyceride

Question 4

What are proteins made up of?

Answer 4

amino acids

Question 5

What elements are proteins made of?

Answer 5

CHON ; Carbon, Hydrogen, Oxygen and Nitrogen

Question 6

How do you test for the presence of proteins?

Answer 6

Biuret’s solution

Question 7

What elements are carbohydrates made up of?

Answer 7

CHO ; Carbon, Hydrogen, Oxygen

Question 8

How do you test for the presence of starch?

Answer 8

Iodine solution

Question 9

How do you test for the presence of glucose?

Answer 9

Benedict’s solution

Question 10

What are monosaccharides?

Answer 10

simple sugars like glucose and fructose

Question 11

What are disaccharides?

Answer 11

simple sugars joined together to form disaccharides. e.g. sucrose, lactose, maltose

Question 12

What are polysaccharides?

Answer 12

1000s of sugar molecules joined to make complex carbohydrates. Used as storage molecules because they are less soluble

Question 13

What are enzymes?

Answer 13

proteins that are biological catalysts that increase the rate of reaction by providing an alternative pathway with a lower activation energy

Question 14

What is the lock and key theory?

Answer 14

Substrate collides with the enzyme and binds with the active site of the enzyme. By binding to the active site the chemical bonds in the substrate molecules and so the reaction occurs by an alternative pathway with a lower activation energy. Once the reaction has occurred, the products do not fit with the active site so they are released. The active site has a specific shape and so does the substrate.

Question 15

What is an active site?

Answer 15

Part of the enzyme that is complementary to the shape of the substrate

Question 16

Why might an enzyme denature?

Answer 16

If exposed to extreme pH or temperatures above optimum temperature. This will mean the enzyme’s active site is no longer complementary to the substrate.

Question 17

What can speed up an enzyme controlled reaction?

Answer 17

Increasing temperature -> increase in kinetic energy
Addition of more substrates or enzymes will speed up reaction -> more to reactive with
Because enzymes are proteins, they are held together by amino acids so change in pH or temp may disrupt these forces. Optimum pH optimum temp.

Question 18

What colour does Benedicts solution go if glucose is present?

Answer 18

green - yellow - orange - brick red

Question 19

What colour does Biuret’s solution go if protein is present?

Answer 19

purple

Question 20

What colour does Ethanol go if lipids are present?

Answer 20

cloudy

Question 21

What colour does Iodine go if starch is present?

Answer 21

blue/black

Question 22

Which food test needs heating?

Answer 22

benedicts

Question 23

Which food test needs shaking?

Answer 23

lipids

Question 24

What is the lock and key theory?

Answer 24

active site and substrate binding