organisation

Question 1

why do enzymes have optimum pH

Answer 1

They all have a certain pH they work best at and work most efficiently. E.g pepsin works best at pH 2.

Question 2

what happens to the enzyme if the temperature is too high?

Answer 2

• The active site of the enzyme will start to change shape and the unique substrate will no longer fit meaning the enzyme has denatured and can no longer catalyse the reaction.

Question 3

describe the practical for investigating enzymatic reactions.

Answer 3

• drop of iodine solution into well of spotting tile.
• place bunsen burner on heat proof mat, tripod and gauze over it. Beaker of water on top of tripod and heat to 35 degrees.
• use syringe to add 1cm of amylase and 1cm of buffer solution.
• Use syringe to add 5cm of starch solution and mix immediately as well as starting a stop clock.
  -Take a fresh sample every 30 seconds with a dropping pipette. When iodine solution is brown, starch is no longer present.
  -Repeat with different pH values of buffer solution to investigate how fast it takes for amylase to break the proteins down into maltose

Question 4

What 2 things do bile do in the stomach?

Answer 4

• Neutralises the stomach acid for the enzymes to work best in alkaline condtions.
• Emulsifies fat and breaks it down into tiny droplets and gives the enzyme a bigger surface area to work on - increasing rate of digestion.

Question 5

Where is amylase produced?

Answer 5

• small intestine
• pancreas
• salivary glands

Question 6

Where are proteases made?

Answer 6

• stomach
• pancreas
• small intestine

Question 7

Where are lipases produced?

Answer 7

• pancreas and small intestine

Question 8

What is the food test for Sugars?

Answer 8

• prepare food sample and transfer 5cm to test tube.
  -Prepare water bath at 75c
  -Add Benedicts solution to test tube.
  -Place in water bath for 5 minutes and if sugar is present it will turn to green, yellow or brick red.

Question 9

What is the test for starch?

Answer 9

• Add few drops of iodine to 5cm of food sample.
  -Shake gently and if present it will turn black or blue black.

Question 10

What is the test for proteins?

Answer 10

• add 2cm of food sample
• add 2cm of biuret solution and gently shake
• it will change from blue to purple if it is present

Question 11

What is the test for Lipids?

Answer 11

• add 3 drops of Sudan III and gently shake
• it stains lipids red and if it is present, the mixture will sepeare into two layers and the top layer will be bright red.

Question 12

Where is the pacemaker?

Answer 12

-right atrium wall

Question 13

describe the path of blood in the heart

Answer 13

• blood flows into the pulmonary vein and the vena cava.
• it contracts and pushes it into the ventricles that also contract and push it out through the pulmonary artery and aorta and out of the heart to supply blood to the body

Question 14

what is meant by a transpiration stream?

Answer 14

it is the movement of water from the roots to the leaves via the xylem when water is evaporated via the stoma.