Organisation Topic 2

Question 1

Glands (salivary and pancreas)

Answer 1

Produce digestive juices containing enzymes which breakdown food

Question 2

Stomach

Answer 2

Produces hydrochloric acid to kill bacteria and create an optimum pH for the protease enzyme to work

Question 3

Small intestine

Answer 3

Soluble molecules are absorbed into the blood

Question 4

Liver

Answer 4

Produces bile which is stored in the hall bladder and helps with the breakdown of lipids

Question 5

Large intestine

Answer 5

Absorbs water from undigested food to produce faeces which passes out of your body through the rectum and anus

Question 6

Enzymes

Answer 6

Biological catalysts ( a substance that increases the rate of reaction without being used up)
They break up large molecules and join small ones
Protein molecules

Question 7

Lock and key hypothesis

Answer 7

The shape of the substrate is complementary to the shape of the active site, so when they bond it forms an enzyme-substrate complex
Once bound, the reaction takes place and the products are released from the surface of the enzyme

Question 8

What to enzymes require

Answer 8

Optimum temperature (around 37) and pH (varies)

Question 9

What happens to the enzyme when temperature increases above its optimum

Answer 9

Rate of reaction rapidly decreases and eventually reaction stops. When temperature becomes too hot, the bonds in the structure will break therefore changing the shape of the active site so the substrate can no longer fit in. Now the enzyme is denatured

Question 10

What do carbohydrases do and where are they produced

Answer 10

They convert carbohydrates into simple sugars e.g. amylase breaks starch down into maltose
It is produced in salivary glands, pancreas and small intestine (most of the starch you eat is digested here)

Question 11

What do proteases do and where are they produced

Answer 11

They convert proteins into amino acids e.g. pepsin
This is produced in the stomach, other forms can be found in pancreas and small intestine

Question 12

What do lipases do and where are they produced

Answer 12

They convert lipids into fatty acids and glycerol
Produces in the pancreas and small intestine

Question 13

which test determines whether a solution is a carbohydrate

Answer 13

iodine test for starch (turns blue/black)

Question 14

which test determines whether a solution is a protein

Answer 14

biuret test for protein (turns purple)

Question 15

which test determines whether a solution is a lipid

Answer 15

sudan III test for lipids ( lipids will separate and top layer will turn bright red)

Question 16

where is bile produced, stored, and released

Answer 16

produced in the liver, stored in the pancreas and released in the small intestine

Question 17

what are the 2 roles of bile

Answer 17

it is alkaline to neutralise the hydrochloric acid which comes from the stomach- enzymes in the small intestine have a higher (more alkaline) pH those in the stomach
it breaks down large drops of fat into smaller ones (emulsifies it)

Question 18

what is the independent variable in the effect of pH on the rate of reaction of amylase required practical

Answer 18

the pH of the buffer solution

Question 19

what is the dependent variable in the effect of pH on the rate of reaction of amylase required practical

Answer 19

time taken for reaction to complete (for all starch to be digested by the amylase)

Question 20

describe how to investigate the effect of pH on the enzyme amylase

Answer 20

1. Place one drop of iodine solution into each well of a spotting tile
2. Measure 2cm cubed of amylase and pH 4 buffer solution into a measuring cylinder and mix
3. Put 2cm cubed of starch into a test tube and add 2cm cubed of the amylase in pH 4 buffer into the starch. At this point start the timer
4. after 20 seconds pipette 1 drop of the starch and amylase in pH 4 solution
5. Repeat this every 20 seconds until the starch does not turn the iodine blue, but yellow this means that all of the starch has broken down
6. record the time it took for all starch to be broken down
7. repeat using different levels of pH buffer