Human Nutrition

Question 1

What are the biological food molecules?

Answer 1

Protein, Carbohydrate and Lipids

Question 2

What are the chemicals present in Carbohydrates

Answer 2

Carbon, Hydrogen and Oxygen

Question 3

What carbohydrates are monomers

Answer 3

The simple sugars such as glucose and fructose

Question 4

What carbohydrates are polymers

Answer 4

Glycogen and Starch (can be broken down into smaller molecules by enzymes in mout and small intestine)

Question 5

What are proteins made up of?

Answer 5

Long chains of amino acids. A protein is a polymer, a amino acid is a monomer

Question 6

What are amino acids made up of (proteins)

Answer 6

Carbon, Hydrogen, Oxygen, Nitrogen

Question 7

What are the chemicals present in Lipids?

Answer 7

Carbon, Hydrogen and Oxygen

Question 8

REMEMBER: lipids are not polymers

Question 9

What enzyme breaks down starch (carbs)?

Answer 9

Amylase into maltose (smaller sugars)

Question 10

Where Amylase made?

Answer 10

Salivary Glands, Pancreas and Small Intestine

Question 11

What enzyme breaks down proteins?

Answer 11

Protease into amino acids

Question 12

Where is protease made?

Answer 12

Stomach (called pepsin), Pancreas and the small intestine

Question 13

What enzyme breaks down lipids?

Answer 13

Lipases, into glycerol and fatty acids

Question 14

Where is Lipase made?

Answer 14

In the pancreas and small intestine

Question 15

What is bile?

Answer 15

It speeds up the process of digesting lipids (not an enzyme) and is released from the gal bladder

Question 16

How does bile help digestion?

Answer 16

It emulsifies the lipids which increases surface area for the lipase enzymes to break them down

Question 17

What is the role of an enzyme?

Answer 17

They are biological catalysts that increase the rate of chemical reaction without being used up

Question 18

How does temperature effect enzyme activity?

Answer 18

At low temperatures the rate of reaction is low because few enzyme-substrate complexes are formed as the enzyme and substrate molecules are moving around so slowly that they rarely collide.
At higher temperatures, the rate of reaction is much higher as enzyme-substrate complexes are formed as the enzyme and substrate molecules are moving around so quickly that they collide more often.
Above the optimum however, high temperatures cause enzymes to denature meaning the active site will change shape and if this happens the substrate cannot bind to the active site.

Question 19

Practical: investigate enzyme activity and change of temp

Answer 19

Test tube of Starch solution is placed in Water bath of set temperature for several minutes (0, 10, 20, 30, 40, 50, 60°C)
Solution of Amylase enzyme is added into test tube of Starch solution
Immediately after Amylase is added into test tube, pipette is used to add droplets of mixture into wells
Immediately after mixture is added into wells, a few drops of Iodine solution is added
Process is repeated in increments of fixed time (seconds) until Iodine turns orange, indicating that Starch has completely broken down into Glucose
Time taken for Starch to be completely broken down is compared to that of each respective temperature (time taken for Iodine solution to turn orange with each respective temperature)

Question 20

Practical: investigate enzyme activity and change of pH

Answer 20

Add a drop of iodine to each of the wells of a spotting tile
Use a syringe to place 2 cm3 of amylase into a test tube
Add 1cm3 of buffer solution (at pH 2) to the test tube using a syringe
Use another test tube to add 2 cm3 of starch solution to the amylase and buffer solution, start the stopwatch whilst mixing using a pipette
Every 10 seconds, transfer a droplet of the solution to a new well of iodine solution (which should turn blue-black)
Repeat this transfer process every 10 seconds until the iodine solution stops turning blue-black (this means the amylase has broken down all the starch)
Record the time taken for the reaction to be completed
Repeat the investigation with buffers at different pH values (ranging from pH 3.0 to pH 7.0)

Question 21

How does temperature effect enzyme activity?

Answer 21

Further away from optimum temp, active site denatures