Chapter 3 - Organisation and the digestive system

Question 1

Which forms which? organs, organ systems, tissues

Answer 1

tissues -> organs -> organ systems

Question 2

What is a tissue?

Answer 2

a group of similar cells that work together to carry out a particular function.

Question 3

What are 3 examples of tissues and what are their functions?

Answer 3

1. Muscular tissue, moves the stomach wall to churn up the food
2. Glandular tissue, makes the digestive juices to digest food
3. Epithelial tissue, covers the outside and inside of the stomach

Question 4

What is an organ system?

Answer 4

a group of organs working together to perform a particular function

Question 5

What is the function of the digestive system?

Answer 5

to break down and absorb food

Question 6

What 5 organs is the digestive system made up of and what are their functions?

Answer 6

1. glands (eg pancreas and salivary), produce digestive juices
2. stomach and small intestine, digest food
3. liver, produces bile
4. small intestine, absorbs soluble food molecules into your blood
5. large intestine, absorbs water from undigested food, leaving faeces

Question 7

What are 2 adaptations of the small intestine?

Answer 7

1. covered in villi, help make it possible to absorb the digested food molecules from the gut into the blood
2. good blood supply and short diffusion distances to the blood vessels, increases the diffusion and active transport from the small intestine to the blood

Question 8

Why can’t starch, proteins and fats pass through the walls of the digestive system? solution?

Answer 8

because they are too big so digestive enzymes break them into smaller molecules, like sugars, amino acids, glycerol and fatty acids.

Question 9

Why do they need to be made smaller?

Answer 9

so they can be absorbed into the bloodstream

Question 10

What do carbohydrases do? eg of a cabohydrase?

Answer 10

convert carbohydrates into simple sugars like maltose. amylase.

Question 11

Which 3 places is amylase made in?

Answer 11

the salivary glands, the pancreas and the small intestine

Question 12

What do proteases do?

Answer 12

convert proteins into amino acids

Question 13

Which 3 places is protease made?

Answer 13

the stomach (called pepsin when its in the stomach), the pancreas and the small intestine

Question 14

What are lipids and what do lipases do?

Answer 14

fats and oils. convert lipids into glycerol and fatty acids

Question 15

Which 2 places are lipases made?

Answer 15

the pancreas, the small intestine

Question 16

What does bile do? and why?

Answer 16

bile is an alkaline, it neutralises the hydrochloric acid, because it is too acidic for the enzymes in the small intestine to work, and makes conditions alkaline because they work best in alkaline.

Question 17

Where is bile produces, stored and released?

Answer 17

in the liver, in the gall bladder, the small intestine

Question 18

What else does bile do and why?

Answer 18

it emulsifies fats, it breaks down the fat into tiny droplets. this gives a much bigger surface area of fat for the enzyme lipase to work on, which makes digestion faster.

Question 19

Why is speeding up a reaction by increasing the temperature not good?

Answer 19

because it also speeds up the unwanted reactions as well and there’s a limit to the temperature before the cells start getting damaged and the bonds break. this will change the enzyme’s active site and the substance wont fit anymore so the enzyme is DENATURED

Question 20

What do enzymes do?

Answer 20

act as biological catalysts and reduce the need for high temperatures. we only have enzymes to speed up reactions in the body

Question 21

What is a catalyst?

Answer 21

a substance which increases the speed of a reaction, without being changed or used up in a reaction.

Question 22

What are enzymes?

Answer 22

they are all large proteins and all proteins are made up of chains of amino acids. these chains are folded into unique shapes.

Question 23

What is unique about an enzyme’s active site and what does it do?

Answer 23

it has a unique shape that fits onto the substance involved in a reaction

Question 24

What is a substrate?

Answer 24

the substance an enzyme reacts on

Question 25

Why do enzymes only catalyse one specific reaction?

Answer 25

because, in order for the enzyme to work, the substrate has to fit into the active site. if it doesn’t, the reaction won’t be catalysed

Question 26

What is the ‘induced fit’ model of enzyme action?

Answer 26

in real life, when the active site changes shape a little as the substrate binds to it to get a tighter fit

Question 27

What is an enzyme’s optimum temperature?

Answer 27

the temperature at which the enzymes work best at, often neutral (7)

Question 28

How does pH affect the enzyme’s?

Answer 28

if it is too high or too low, it interferes with the BONDS holding the enzyme together, this changes the shape of the active site and the enzyme is denatured

Question 29

What is 1 enzyme which doesn’t work best at pH 7?

Answer 29

pepsin. it works best at pH 2, meaning it is well suited to the acidic conditions.

Question 30

Why does the stomach produce hydrochloric acid?

Answer 30

to kill any bacteria. because the pepsin works best in acidic conditions

Question 31

What does the benedict’s solution test for?

Answer 31

sugars

Question 32

What does the iodine solution test for?

Answer 32

starch

Question 33

What does the biuret test test for?

Answer 33

proteis

Question 34

What does the Sudan III test test for?

Answer 34

lipids

Question 35

If reducing sugars are present, what colour will the solution turn to?

Answer 35

blue to green, yellow or brick red, depending on how much sugar is in the food

Question 36

If starch is present, what colour will the solution turn to?

Answer 36

browny-orange to black or blue black

Question 37

If protein is present, what colour will the solution turn to?

Answer 37

blue to pink or purple, if no protein is present, it will remain blue

Question 38

If lipids are present, what will happen to the mixture?

Answer 38

it will separate into 2 layers, the top will be bright red. if no lipids are present, no separate red layer will form.