Biological molecules

Question 1

What elements are found in carbohydrates?

Answer 1

Carbon, hydrogen and oxygen

Question 2

What elements are found in proteins?

Answer 2

Carbon, hydrogen, oxygen, nitrogen (and sometimes sulfur)

Question 3

What elements are found in lipids (fats)?

Answer 3

Carbon, hydrogen, oxygen

Question 4

What is the structure of a lipid?

Answer 4

Large molecules made up of 3 fatty acids

and 1 glycerol molecule

Question 5

What is the structure of proteins?

Answer 5

• Large molecules made up of long chains of amino acids

- There are 20 different amino acids

Question 6

What is the structure of carbohydrates?

Answer 6

Large molecules made up of starch and glycogen from simple sugars

Question 7

Give some examples of proteins found in the human body

Answer 7

• Collagen and keratin found in skin and nails
• All enzymes
• Haemoglobin

Question 8

What is the food test for starch?

Answer 8

• Add iodine

- Positive result: turns blue/black

Question 9

What is the test for glucose?

Answer 9

• Heat with water and Benedict’s solution

- Blue solution turns brick red in the presence of glucose

Question 10

What is the test for protein?

Answer 10

• Add Biuret reagent

- Positive result: purple

Question 11

What is the test for fat?

Answer 11

• Add ethanol
• Add water
• Positive result: milky white emulsion

Question 12

Define enzyme

Answer 12

• Biological catalyst
• Speeds up a reaction
• Without being used up

Question 13

Define metabolism

Answer 13

Rate at which chemical reactions take place in the body

Question 14

Key enzyme terms:

Answer 14

• Substrate - molecule an enzyme acts upon

- Active site - area on an enzyme where substrate attaches

Question 15

Describe and explain the effect of too high temperature on enzyme activity

Answer 15

• Decreases activity

- Enzyme denatures and substrate can no longer fit the active site

Question 16

Why does decreasing the temperature decrease enzyme activity?

Answer 16

• Lower kinetic energy

- Fewer collisions between enzymes and substrates

Question 17

Why is it important that we control our internal temperature?

Answer 17

Too high - enzymes denature
Too low - enzymes work too slowly (little kinetic energy) and can’t catalyse chemical reactions
fast enough

Question 18

Describe and explain the effect of too high or too low pH on enzyme activity

Answer 18

• decreases activity

- enzyme denatures and substrate can no longer fit the active site