B3

Question 1

What is a cell

Answer 1

It is the basic building block of life.

Question 2

What is a tissue?

Answer 2

A tissue is a group of cells of the same type.

Question 3

What is an organ?

Answer 3

It is a group of tissues that work together to perform a function.

Question 4

What is an organ system?

Answer 4

It is a group of organs working together for e.g. circulatory system

Question 5

What is a organelle?

Answer 5

It is a smaller thing in a cell for e.g. mitochondria

Question 6

What is digestion?

Answer 6

Digestion is the process where large molecules are broken down into smaller molecules to be absorbed into the blood.

Question 7

What is the order of the digestion system?

Answer 7

1) Digestion starts in the mouth - where food is chewed and saliva added.
2) Food goes down the oesophagus and enters the stomach.
3) The stomach churns the food and hydrochloric acid is added.
4) Then it enters the small intestine where digested food is absorbed into the blood stream.
5) Anything remaining enters the large intestine where water is absorbed.
6) Finally any undigested food exits via the anus.

Question 8

What do the villi do in the small intestine?

Answer 8

The villi provide the small intestine with a large surface area so more digested food can be absorbed into the blood stream.

Villi also have a good blood supply to assist quick absorption

They also have a one cell thick wall so that the nutrients have a shorter distance to diffuse over

Question 9

What is the function of a liver?

Answer 9

It produces bile

Question 10

What is the function of the stomach?

Answer 10

Breaking down large insoluble molecules into smaller soluble molecules

Question 11

What is the function of the small intestine?

Answer 11

It produces protease, lipase and amylase enzymes
It is also the place where digested food is absorbed into the blood

Question 12

What is the function of the large intestine?

Answer 12

It absorbs excess water from the food

Question 13

Give an example of a simple sugar

Answer 13

Sucrose, glucose

Question 14

What are lipids?

Answer 14

They are fats and oils

Question 15

What do the salvary glands produce?

Answer 15

Amylase enzyme in the saliva

Question 16

What does the pancreas produce?

Answer 16

Protease, amylase and lipase enzymes

Question 17

What is a protein?

Answer 17

A molecule that is made up of long chains of amino acids

Question 18

What is an enzyme?

Answer 18

Its a biological catalyst

Question 19

Whats another thing that the stomach does?

Answer 19

-It pummels the food with its muscular walls
-It produces the protease enzyme, pepsin.
-It produces hydrochloric acid

Question 20

What enzyme catalyses starch and what does it break it into?

Answer 20

Amylase(carbohydrase) catalyses starch and turns it into maltose

Question 21

What is a catalyst?

Answer 21

It is a substance that speeds up a chemical reaction without getting used up or changed

Question 22

What enzyme catalyses protein and what does it break it into?

Answer 22

Protease catalyses protein and breaks it up into amino acids

Question 23

What enzyme catalyses lipids and what does it break it up into?

Answer 23

Lipase catalyses lipids and breaks it up into glycerol and fatty acids

Question 24

What does bile do and where is it stored and produced?

Answer 24

Bile neutralises the stomach acid and emulsifies fats
Bile is produced in the liver
It is stored in the gall bladder before its released into the small intestine

It breaks down lipids into smaller droplets so that the lipase enzyme has a bigger surface area to work on so it breaks down lipids quicker.

It neutralises stomach acid so that the lipase is at its optimum pH to break down fat

Question 25

What does every enzyme have?

Answer 25

Every enzyme has a active site

Question 26

What is the thing called that binds to the active site?

Answer 26

Substrate

Question 27

What 2 things can change the rate of an enzyme-catalysed reaction?

Answer 27

Temperature and pH

Question 28

What happens if the temp gets too hot on the enzyme?

Answer 28

Some of the bonds holding the enzyme together will break and this changes the shape of the enzymes active site making the substrate not fit anymore. The enzyme is said to be DENATURED. This is the same with pH

Question 29

At what temp and pH do most enzymes work best at?

Answer 29

Temp-37, pH-7

Question 30

At what pH does pepsin (the enzyme that breaks down proteins) work best at?

Answer 30

pH 2 because it lives in acidic conditions

Question 31

How do you calculate the rate of reaction?

Answer 31

Rate=1000/time

Question 32

How can you investigate the effect of pH on enzyme activity (required practical)?

Answer 32

1 ) Use the syringe to place 2 cm3 of amylase solution into a test tube.
2 ) Use another syringe to add 1 cm3 of pH buffer solution to the test tube.
3 ) Place the test tube into a water bath set at 30 C and leave for 5 minutes.
4 ) Whilst waiting, add a drop of iodine solution into each dimple of a spotting tile.
5 ) After 5 minutes, use another syringe to add 2 cm3 of starch to the amylase/buffer solution, start the stop clock and leave it on throughout the test. Mix using a plastic pipette.
6 ) Remove a drop of amylase/starch/buffer mixture after 30 seconds and add to the first drop of iodine on your spotting tile.
7 ) Wait another 30 seconds. Then remove a second drop of the mixture to add to the next drop of iodine.
8 ) Repeat step 6 until the iodine solution and the amylase/buffer/starch mixture remains orange.
9 ) Record the time taken for the amylase to fully digest the starch.
10 ) Repeat the whole procedure with a different pH buffer.

Question 33

What can you use to test for sugars? And what colour will the food change?

Answer 33

Benedict’s solution and it will change from blue to green to yellow to brick-red depending on how much sugar is in the food

Question 34

How do you test for starch? And what colour will the food change?

Answer 34

Use Iodine solution and the food will change from browny-orange to black or blue-black

Question 35

How do you test for proteins? And what colour will the food change?

Answer 35

Use Biuret test and the food will change from blue to purple

Question 36

What do you use to test for fats? And what colour will the food change?

Answer 36

Ethanol and the ethanol will change from colourless to milky white

Question 37

How does an enzyme catalyse a reaction (lock and key method) ?

Answer 37

First the substrate would bind to the enzymes active site because the shape of the active site and substrate would complimentary. This would cause bonds between the substrate molecules to break to produce smaller molecules