organisation(digestion)

Question 1

give the 5 levels of organisation in order

Answer 1

cell
tissues
organs
organ systems
organism

Question 2

define a cell in terms of organisation

Answer 2

the basic building blocks of all living organisms

Question 3

what is a tissue?

Answer 3

a tissue is a group of cells that have similar structures

Question 4

what is an organ?

Answer 4

an organ is a group of different tissues working together to perform a specific function

Question 5

what is an organ system?

Answer 5

groups of organs working together eg circulatory system

Question 6

explain how an adaptation of the digestive system helps with absorption of food molecules

Answer 6

the surface of the small intestine is folded, and has projections called villi which increases the surface allowing absorption to occur faster and more efficiently

Question 7

where is bile produced and stored?

Answer 7

bile is made in the liver and stored in the gallbladder

Question 8

what is bile’s role in the digestive system?(2)

Answer 8

bile neutralises hydrochloric acid from the stomach and emulsifies fat to form small droplets with a large surface area meaning they can be broken down quicker by lipase

Question 9

what does amylase break down?

Answer 9

amylase breaks down starch into smaller sugars-glucose (maltose)

Question 10

where is amylase produced?

Answer 10

the salivary glands, pancreas and small intestine

Question 11

how are carbohydrates broken down?

Answer 11

carbohydrates are broken down by the enzyme amylase

Question 12

how are proteins broken down?

Answer 12

proteins are broken down by the enzyme protease

Question 13

what does protease break proteins into?

Answer 13

amino acids

Question 14

where is protease produced?

Answer 14

the stomach,pancreas and small intestine

Question 15

how are fats(lipids) broken down?

Answer 15

fats are broken down by the enzyme lipase and bile

Question 16

what does lipase break fats into?

Answer 16

lipase breaks fats into glycerol and fatty acids

Question 17

where is lipase produced?

Answer 17

pancreas and small intestine

Question 18

what are enzymes?

Answer 18

enzymes are biological catalysts that are made of protein and have a specific shape

Question 19

what is the role of a catalyst?

Answer 19

to speed up reactions without being used up or changed

Question 20

describe the lock and key theory

Answer 20

this is the idea that enzymes work because they have an active site with a shape that is complementary to the substance being acted on allowing the substrate to fit into the active site

Question 21

what does denatured mean (in terms of enzymes)?

Answer 21

this is when the enzyme stops working and is no longer able to function because the shape of the active has changed and therefore the substrate will no longer fit preventing any reactions to be sped up/occur

Question 22

explain the affect of increasing temperature on the rate of enzymes

Answer 22

initially as the temperature increases the rate of reaction will also increase because the enzyme and the substrate molecules will move around faster and collide more frequently. However after the temperature reaches around 37 degrees the reaction will begin to slow as the enzyme becomes denatured.

Question 23

give the food test for starch and the positive result

Answer 23

test: add a few drops of iodine solution to the food sample
result-if starch is present the iodine will change colour from orange to blue-black

Question 24

give the food test for sugars and the positive result

Answer 24

test-add 10 drops of benedict’s solution to food solution and place the test tube into a hot water bath and leave for five minutes
result-if sugars are present the solution will change colour from blue to either green,yellow,or brick red depending on how much sugar is present.

Question 25

give the food test for proteins and the positive result

Answer 25

test-add 2cm of food solution to 2cm of biuret solution result-if protein is present the biuret solution will change colour from blue to lilac/purple

Question 26

give the food test for lipids and the positive result

Answer 26

test-add a few drops of distilled water and a few drops of ethanol to unfiltered food solution and gently shake result-if lipids are present then a white cloudy emulsion will form

Question 27

why is the small intestine considered the most important part of the entire digestive system? (2 reasons)

Answer 27

1.its where most of the digestion takes place 2.its where the nutrients are absorbed from the intestines into the bloodstream

Question 28

give three adaptations of the small intestine which helps with the absorption of food molecules/nutrients

Answer 28

1.there are many villi giving them a large surface area for diffusion-provides more space for molecules to move across a membrane,this will increase the rate of diffusion as more molecules can diffuse at the same time 2.there walls are only one cell thick-short diffusion pathway 3.they have a good supply of blood from the capillaries-maintains a strong concentration gradient resulting in faster diffusion

Question 29

what is digestion?

Answer 29

the process of breaking down large food molecules into smaller molecules which are easier to be absorbed

Question 30

what is absorption?

Answer 30

process of absorbing these small food molecules into the body (bloodstream)

Question 31

what three things does the stomach do to aid digestion?

Answer 31

1.contracts its muscular walls to churn and mix the food 2.produces pepsin-which is a type of protease enzyme and helps to break proteins down into amino acids 3.it produces hydrochloric acid which kills microorganisms and provides the right ph for the pepsin to function

Question 32

give steps 1-2 for the factors affecting enzyme action required practical

Answer 32

1.place one drop of iodine solution into each well of a spotting tile using a pipette 2.get three test tubes,in the first add 2cm cubed of starch solution,second add 2cm cubed of amylase solution and in the 3rd add 2cm cubed of ph 5 buffer solution

Question 33

give steps 3-4 for the factors affecting enzyme action required practical

Answer 33

3.place all three test tubes in a water bath at 30 degrees and leave this for 10 minutes to allow the solutions to reach the correct temperature 4.combine the 3 solutions into one test tube and mix with a stirring rod,return this to the water bath and start a stopwatch

Question 34

give steps 5-6 for the factors affecting enzyme action required practical

Answer 34

5.after 20 seconds,use the stirring rod or a pipette to transfer one drop of solution to a well in the spotting tile which contains iodine-this should turn blue-black to indicate that starch is present 6.take a sample every 20 seconds and repeat step 5 until the iodine remains orange showing that starch is no longer present and the reaction is finished-record the time taken for this

Question 35

give steps 7-8 for the factors affecting enzyme action required practical

Answer 35

7.repeat the whole experiment several times using different ph buffers eg ph 6,7 and 8 8.record your results and plot a graph to compare how ph affects the rate of enzyme action

Question 36

what is the main role of the large intestine?

Answer 36

to reabsorb water

Question 37

what is the main role of the rectum?

Answer 37

to store faeces until they are ready to be released