Digestive system

Question 1

What is digestion?

Answer 1

The breakdown of large, insoluble food molecules into smaller soluble molecules to be absorbed into the bloodstream

Question 2

Function of the mouth/salivary glands

Answer 2

Where food enters and is broken down mechanically by teeth or chemically by amylase produced in salivary glands

Question 3

Function of the oesophagus

Answer 3

Moves food to the stomach

Question 4

Function of the stomach

Answer 4

Where digestion continues, churns the food mechanically as it is a muscular organ = turn into a liquid to increase surface area digestion
produces enzymes for digestion of proteins
Produces HCl to aid enzyme digestion

Question 5

Pancreas

Answer 5

Produces enzymes that are taken to the duodenum (top of small intestine)
CONTINUE digestion of starch and protein and START the digestion of lipids

Question 6

Function of the liver

Answer 6

Produces bile

Question 7

Function of the gallbladder

Answer 7

Stores bile before releasing it into the duodenum (top of small intestine)

Question 8

Function of the duodenum

Answer 8

Where food is mixed with enzymes + bile and neutralised to be broken down even further

Question 9

Function of the small intestine

Answer 9

Where nutrients are absorbed into the blood via villi
Continue digestion of protein and lipids

Question 10

Function of the large intestine

Answer 10

Where water is reabsorbed

Question 11

Function of the rectum

Answer 11

Where faeces is stored

Question 12

Function of the anus

Answer 12

Where faeces leaves the body

Question 13

Adaptations of the stomach

Answer 13

Secretes HCl to kill off any harmful bacteria
Produces enzymes to speed up digestion, also they work best in acidic conditions
Stomach muscles tissues that can contract rapidly to churn food, contain lots of mitochondria to get energy

Question 14

Adaptations of the small intestine

Answer 14

Contains microvilli for a larger surface area so more diffusion happens at the same time
Thin walls with capillaries on the outside so a shorter diffusion distance into the bloodstream
Good blood supply for higher diffusion gradient

Question 15

Adaptations of oesophagus

Answer 15

Can expand and contract (muscular) to let food and liquid pass to the stomach

Question 16

What are digestive enzymes?

Answer 16

Biological catalysts that speed up the rate of digestion of large molecules into smaller ones without changing the reaction

Question 17

How do enzymes work in digestion?

Answer 17

Through the catabolic lock and key method
An enzyme’s active site and food molecule are complementary in shape: only works on that specific molecule.
Attached together then large molecule broken down
Then repeat

Question 18

Amylase

Answer 18

Produced in salivary glands and pancreas
Breaks down starch to simple sugars
Needs slightly acidic to neutral

Question 19

Protease

Answer 19

Produced in stomach, pancreas and small intestine
Breaks down protein to amino acids
Both acidic and alkali proteases

Question 20

Lipase

Answer 20

Produced in pancreas
Breaks fats into fatty acids and glycerol

Question 21

Pepsin

Answer 21

Produced in stomach but works in duodenum
Breaks protein into peptides
A more neutral-alkali optimum pH so bile works alongside it

Question 22

Denaturing

Answer 22

When an enzymes active side changes and can’t work on that substrate anymore
Due to the temperature or pH getting too high

Question 23

Factors effecting how effective the enzyme is

Answer 23

Temperature
pH levels
Pressure
Surface area
Enzyme and substrate concentration

Question 24

Optimum

Answer 24

All enzymes have an exact pH and temperature where its activity is highest
If it goes above the enzyme denatures

Question 25

How does Bile help digestion?

Answer 25

Enzymes in the duodenum’s optimum pH is alkali After being in the stomach the food molecules are acidic Bile neutralises the small intestine to be less acidic to help the enzymes

Question 26

How does bile help lipase?

Answer 26

Emulsifies (breaks down) fat globules into fat droplets to give a larger surface area for lipase to work on.

Question 27

Enzyme rate of reaction

Answer 27

Amount of product formed / reactant used ——————————————————————— Time

Question 28

What are enzymes made out of?

Answer 28

Proteins that are made up of chains of amino acids

Question 29

Where is amylase produced?

Answer 29

Salivary glands Pancreas

Question 30

Where is protease produced?

Answer 30

Pancreas Stomach Small intestine

Question 31

Where is lipase produced?

Answer 31

Pancreas

Question 32

What are the main nutrients in foods?

Answer 32

Carbohydrates (starch) Protein Lipids (fats)

Question 33

Where are digested molecules absorbed into the bloodstream?

Answer 33

In the small intestine via diffusion and active transport

Question 34

How does the small intestine have a large surface area?

Answer 34

Is 5m long Contains villi (many shapes) that are divided into microvilli

Question 35

How does the small intestine having a good blood supply help?

Answer 35

It can rapidly remove away the products of digestion To increase the concentration gradient

Question 36

How does the small intestine having a thin membrane help digestion?

Answer 36

Shortens the diffusion path

Question 37

If molecules aren’t absorbed by diffusion how are they absorbed in the small intestine?

Answer 37

Via active transport

Question 38

How are enzymes structured?

Answer 38

Made out of proteins (amino acids) Have a groove (cut) called active site where substrate attaches to

Question 39

Where is protease produced?

Answer 39

Stomach Pancras Small intestine

Question 40

How does digestion of proteins work?

Answer 40

Proteins = chains of amino acids Protease breaks it into singular amino acids to be absorbed into bloodstream Once absorbed in cells = chains again then formed into human proteins

Question 41

How does digestion of starch work?

Answer 41

Starch = chain of glucose Amylase breaks it into simple sugars (no chain)

Question 42

Where is amylase found?

Answer 42

Salivary glands Pancreas

Question 43

How does digestion of lipids work?

Answer 43

Lipid = glycerol + 3 fatty acids Lipase breaks it down into glycerol and fatty acids (no longer attached) With help of bile

Question 44

Where is lipase found?

Answer 44

Pancreas Small intestine

Question 45

How does bile work?

Answer 45

Emulsifies lipid globule into smaller lipid droplets Increases the surface area Increases rate of breakdown helping lipase Also neutralises stomach acid as it is alkaline to increase rate of lipid digestion as lipase works best in neutral conditions

Question 46

How does temperature effect enzyme activity?

Answer 46

Increasing temp = enzyme moves faster so more collisions per second between substrate and active site At certain temp it acts at fastest possible rate (optimum) Beyond that activity falls to 0 Because the shape of active site has changed = no longer fits substrate = denatured = no activity

Question 47

How does pH effect enzyme activity?

Answer 47

Has the optimum at a more specific pH, any above or below that and it will begin to denature Much less gradual than temperature

Question 48

If the temperature of an enzyme is too low, has it denatured?

Answer 48

No In terms of temperature it only denatures if it exceeds ABOVE the optimum not below Unlike pH, denatures above or below

Question 49

What are the products of digestion used for?

Answer 49

Build new carbohydrates, lipids and proteins Some of the glucose for respiration

Question 50

What is the optimum temperature for most human enzymes?

Answer 50

37°C Because it’s our average body temperature