Diet and digestion

Question 1

What calculation is used to find the energy content of a food sample?

Answer 1

Temp change x (25)ml x 4.2 / Mass

Question 2

What is the energy content of a food sample measured in?

Answer 2

KJ/g^-1

Question 3

What is an enzyme?

Answer 3

A biological catalyst - it speeds up the reaction without being used up

Question 4

Explain how enzymes work?

Answer 4

• Substrate binds to the active site
• Enzyme lowers activation energy -> reaction occurs
• Product is released from the active site

Question 5

What are the functions of Bile?

Answer 5

• Neutralises acids which optimises conditions for enzymes (pH 8)
• Emulsifies fats - breaks down droplets which increases surface area so enzymes can digest fats more rapidly.

Question 6

What are the functions of Hydro-Chloric acid (HCL)?

Answer 6

• Provides the optimum conditions for Pepsin (pH 2)

- Kills bacteria

Question 7

What enzymes are secreted from the pancreas?

Answer 7

Amylase, Trypsin and Lipase

Question 8

What is the optimum pH for enzyme activity? (and which are exceptions to this?)

Answer 8

8 is the optimum pH for all except Pepsin (2) and Amylase (mouth) (7)

Question 9

Which enzymes digest substances in the small intestine?

Answer 9

Amylase, Trypsin, Peptidases, Lipase and Maltase

Question 10

Which enzymes have protein as their substrate?

Answer 10

Pepsin and Trypsin