Organisation- Digestive System

Question 1

The digestive system is an _____ _______. Several organs work together to digest and absorb _________.

Answer 1

The digestive system is an organ system. Several organs work together to digest and absorb nutrients.

Question 2

Enzymes are ___________ ________ used in the digestive system. Enzymes are biological _________.

Answer 2

Enzymes are specialised proteins used in the digestive system. Enzymes are biological catalysts.

Question 3

Enzyme function can be described as the ‘____ and ___ model’.

Answer 3

Enzyme function can be described as the ‘lock and key model’.

Question 4

The _________ binds to the active site on the enzymes.

Answer 4

The substrate binds to the active site on the enzymes.

Question 5

An enzyme _________ when the active site changes _____ and the substrate can no
longer bind to the enzyme.

Answer 5

An enzyme denatures when the active site changes shape and the substrate can no
longer bind to the enzyme.

Question 6

High ____________ and the wrong __ denature enzymes.

Answer 6

High temperatures and the wrong pH denature enzymes.

Question 7

Carbohydrase enzymes break down _____________ into ______ _______.

Answer 7

Carbohydrase enzymes break down carbohydrates into simple sugars.

Question 8

________ is a type of carbohydrase which breaks down starch into sugars

Answer 8

Amylase is a type of carbohydrase which breaks down starch into sugars

Question 9

Lipase enzymes break down ____ into _____ _____ and ________.

Answer 9

Lipase enzymes break down fats into fatty acids and glycerol.

Question 10

Protease enzymes break down _______ in to _____ ______.

Answer 10

Protease enzymes break down protein in to amino acids.

Question 11

Bile is made in the _____ and stored in the ____ _______.

Answer 11

Bile is made in liver and stored in the gall bladder.

Question 12

____ neutralises the substances from the stomach and helps to emulsify fats.

Answer 12

Bile neutralises the substances from the stomach and helps to emulsify fats.

Question 13

Different chemicals test for different nutrient groups. Which chemical tests for starch? What’s the colour change?

Answer 13

Iodine tests for starch – pale yellow to blue/black

Question 14

Different chemicals test for different nutrient groups. Which chemical tests for sugar? What’s the colour change?

Answer 14

Benedicts tests for sugar – blue to brick red

Question 15

Different chemicals test for different nutrient groups. Which chemical tests for protein? What’s the colour change?

Answer 15

Biuret reagent tests for protein – blue to purple

Question 16

Different chemicals test for different nutrient groups. Which chemical tests for fats? What’s the colour change?

Answer 16

Ethanol tests for fats – clear to cloudy

Question 17

what are the three main nutrients found in food

Answer 17

carbohydrates protein and lipids

Question 18

are these nutrients large or small molecules

Answer 18

large meaning they have to be digested

Question 19

During digestion what breaks down the large molecules into smaller molecules

Answer 19

enzymes

Question 20

What happens in the mouth when digesting food

Answer 20

The food is chewed and the saliva begins to digest the starch into smaller sugar molecules

Question 21

After the mouth where does the food go and what happens here

Answer 21

food passes through the oesophagus and into the stomach and the enzymes then start to digest the proteins

Question 22

what acid is found in the stomach to help the enzymes to digest the proteins

Answer 22

hydrochloric acid

Question 23

true or false?
the food spends several hours in the stomach

Answer 23

true

Question 24

What happens in the stomach to help turn the food into a fluid

Answer 24

The stomach muscles contract to create a churning motion which increases the surface area for enzymes to digest

Question 25

where does the fluid go after the stomach and what happens

Answer 25

small intestine and chemicals are produced from the liver and pancreas

Question 26

the pancreas releases enzymes, what does this help the digestion of?

Answer 26

starch, protein and lipids

Question 27

what does bile do

Answer 27

speed up the digestion of lipids
and neutralises the acid released from the stomach

Question 28

what does the small intestine do to help the digestion of protein and lipids?

Answer 28

the walls release enzymes

Question 29

How are the small food molecules absorbed into the blood stream by the small intestine

Answer 29

by active transport or diffusion

Question 30

what happens in the large intestine

Answer 30

water is absorbed into the bloodstream
and the faces is released from the body

Question 31

true or false?
enzymes are not specific and can break down many things

Answer 31

false
enzymes are very specific and can only fit perfectly to one active site

Question 32

where do you find proteases

Answer 32

stomach, pancreas, small intestine

Question 33

what are proteins

Answer 33

long chains of chemicals called amino acids

Question 34

what happens when we digest proteins

Answer 34

the protease enzyme convert the protein back to the individual amino acids which are then absorbed into the blood stream

Question 35

how are human proteins made

Answer 35

when the amino acids are joined together in a different order

Question 36

what is starch made of

Answer 36

starch consists of a chain of glucose molecules

Question 37

where is amylase found

Answer 37

saliva, and in the pancreatic fluid

Question 38

what is a lipid molecule made of

Answer 38

a molecule of glycerol attached to three molecules of fatty acids

Question 39

where is lipase found

Answer 39

in the pancreatic fluid and the small intestine

Question 40

bile emulsifies the Lipid
why is this good?

Answer 40

it massively increases the surface area of the lipid droplets

Question 41

why can bile neutralize the stomach acid

Answer 41

because it is alkaline

Question 42

what happens tp the reaction if you increase the temperature

Answer 42

the activity of the enzymes increase meaning the reaction rate increases

Question 43

why does a rising temperature increase the rate od reaction

Answer 43

the enzyme and substrate are moving quicker and so there are more collisions per second between the substrate and the active site

Question 44

what’s the optimum temperature

Answer 44

the temperature in which the enzymes are working st the fastest possible rate

Question 45

for human enzymes what’s the optimum temperature

Answer 45

37 degrees celsius (human body temp)

Question 46

what happens once you increase the temperature past the optimum

Answer 46

activity of the enzyme rapidly decreases to 0

Question 47

why is this?

Answer 47

at high temperatures, the enzyme molecule vibrates and the shape of the active site changes

Question 48

what is it called when the active site no longer fits the substrate

Answer 48

the active site has denatured

Question 49

what happens to the active site of an enzyme if conditions are too acidic or to alkaline

Answer 49

the activity drops to 0

Question 50

true or false?
each enzyme has the same optimum ph

Answer 50

false
each enzyme has a specific optimum ph and work better or worse depending on it

Question 51

required practical : effect of ph on amylase

Answer 51

1. place 1 drop of iodine into each well of a spotting tile
2. take 3 test tubes and place 2 cm^3 of startch solution into the first, amylase into the second and a buffer solution into the third
3. place all 3 test tubes into a water bath at 30 degrees celsius and leave for 10 minutes
4. combine 3 test tubes into 1 and stir with a stiring rod, keep in water bath and start stop watch
5. after 30 seconds use a stirring rod to transfer 1 drop of the solution into each well of the spotting tile
6. the iodine will turn blue/ black if the startch is present
7. take a sample every 30 seconds and when the iodine remains orange that means all the starch has been used up - this means the reaction has finished
8. repeat the experiment multiple times but use different ph buffer solutions

Question 52

what are the problems with this practical

Answer 52

• only taking samples every 30 seconds meaning we only have an appointment time for the reaction to complete
• it is not always obvious when the reaction has stopped as the colour change can be subtle

Question 53

required practical: food tests

Answer 53

1. take the food sample and grind this with distilled water using a mortar and pestle - you want to make a paste
2. transfer the paste to a beaker and add more distilled water. stir so the chemicals in the food dissolve in the water
3. filter solution to remove suspended food particles
4. add 2cm^3 into a beaker and add your indicator

Question 54

how do you test for sugar

Answer 54

place 2cm^3 of you food solution. add 10 drops of benedict solution which is a blue colour. place the test tube containing the solution into a beaker with half filled hot water. leave this for 5 minutes. if sugar is present then the benedict’s will change colour.

Question 55

when testing for sugar, what does it mean if the benedict’s solution turns green

Answer 55

that there’s a small amount of sugar

Question 56

when testing for sugar, what does it mean when the benedict’s solution turns yellow

Answer 56

there’s more sugar present

Question 57

when testing for sugar, what does it mean if the benedict’s solution turns brick red

Answer 57

that there’s lots of sugar present

Question 58

what sugars does benedict’s solution work for

Answer 58

reducing sugars

Question 59

how is the small intestine adapted for absorption

Answer 59

• length of around 5m - large surface area for absorption
• interior covered in villi which increase the surface area for the absorption of molecules