Biological Molecules Pg6,7,13-16

Question 1

Define a CATALYST

Answer 1

A catalyst is a substance that can increase the speed of a reaction, without being changed or used up in the reaction.

Question 2

What do enzymes do

Answer 2

They speed up the useful chemical reactions in the body. These reactions are called metabolic reactions. They act as a biological catalyst

Question 3

What are enzymes made up of

Answer 3

Enzymes are all proteins which are made up of chain of amino acids.

Question 4

Define a substrate

Answer 4

It is a molecule that is changed during the reaction

Question 5

Each enzyme has a…

Answer 5

Each enzyme is folded into unique shapes and has an active site

Question 6

What is an active site

Answer 6

Active site is where a substrate joins on to the enzyme

Question 7

How many reactions do enzymes speed up

Answer 7

1 each

Question 8

For an enzyme to work, what has to be true

Answer 8

The substrate has to be the correct shape to fit into the active site

Question 9

What is a ‘lock and key’ model

Answer 9

A model where it shows how a specific substrate fit into the active site of an enzyme. Just like how a key fits into a lock

Question 10

What factors affect enzyme function

Answer 10

Temperature and pH

Question 11

Why does changing temperature affect enzymes

Answer 11

• Changing temperature increases the rate of an enzyme-catalysed at first.
• The enzyme and substrate have more energy.
• So they move about more and are more likely to collide
• and form enzyme-substrate complexes
• However, once optimum temperature is exceeded, rate of enzyme-catalysed decreases
• This is because the bond holding the enzyme together break and this changes the shape of the active site
• This causes the substrate to not fit any more
• THE ENZYME IS SAID TO BE DENATURED

Question 12

How does changing the pH affect enzymes

Answer 12

• The pH interferes with the bonds holding the enzyme together.
• This changes the shape of the active site and the enzyme denatures
  -All enzymes have an optimum pH that they work best at
• It is often pH 7

Question 13

How can you investigate how temperature affects enzyme activity

Answer 13

You can measure how fast a product appears or how fast a substrate disappears

Question 14

How can you measure how fast a product appears

Answer 14

• The enzyme catalase catalyses the breakdown of hydrogen peroxide into water and oxygen
• You can collect the oxygen and measure how much is produce in a set time
• Use a pipette to add a set amount of hydrogen peroxide to a boiling tube.
• Put the boiling tube into a 10 degrees (C) water bath
• Add a source of catalase (e.g. 1cm3 of potato) to the hydrogen peroxide and quickly attach the bung
• record how much oxygen is produced in the first minute.
• repeat 5 times and calculate the mean
• repeat at 20, 30, 40 degrees (C)
• Control any variables (e.g. pH, the potato used, the size of potato pieces, etc) to keep it a fair test

Question 15

How can you measure how fast a substrate disappears

Answer 15

• The enzyme amylase catalyses the breakdown of starch into maltose
• It is easy to detect starch using iodine solution - if starch is present the iodine solution will go from browny-orange to blue-black
• Put a drop of iodine solution into each well on the spotting tile. Every 10 seconds drop a sample of the mixture into a well using a pipette
• when the iodine solution remains browny-orange (starch is no longer present)
• record total time taken
• repeat with the water bath at different temperatures to see how it affects the time taken for the starch to be broken down.
• remember to control the variables

Question 16

How can you alter the experiments to test how temperature affect enzyme activity to see how pH affects enzyme activity

Answer 16

• Add a buffer solution with a different pH level to a series of different tubes containing the enzyme-substrate mixture
• control any variables (e.g. constant water bath temperature, and volume and concentrations are kept the same)

Question 17

What is carbohydrates made up of

Answer 17

Carbohydrates are made up of simple sugars.
They contain the elements: carbon, hydrogen and oxygen
Starch and glycogen are large, complex carbohydrates, which are made up of many smaller unit (e.g. glucose or maltose molecules) joined together in a long chain

Question 18

What is proteins made up of

Answer 18

Proteins are made up of Amino acids.
Proteins are long chains of amino acids.
They all contain the elements: carbon, hydrogen, oxygen and nitrogen

Question 19

What are lipids made up of

Answer 19

Lipids (fats and oils) are built from fatty acids and glycerol.
Lipids contain the elements: carbon, hydrogen and oxygen

Question 20

How do you make a food sample

Answer 20

• Get a piece of food and break it up using a pestle and mortar
• Transfer the group up food to a beaker and add some distilled water
• Give the mixture a good stir with a glass rod to dissolve some of the food
• Filter the solution with a funnel and filter paper to remove any solid bits of the food

Question 21

How do you test for glucose

Answer 21

• prepare food sample
• prepare water bath and set it to 75 degrees (C)
• add a few drops of benedict’s solution using a pipette
• If the food sample contains glucose, the benedict will change colour from blue to green or yellow in low concentrations and brick-red in high concentrations of glucose

Question 22

name some foods that contain glucose

Answer 22

Biscuits, cereal and bread

Question 23

How do you test for starch

Answer 23

• Make a food sample
• add a few drops of iodine solution and gently shake
• if samples contains starch the iodine solution will turn from browny-orange to blue-black

Question 24

name some foods that contain starch

Answer 24

pasta, rice, potatoes

Question 25

How do you test for protein

Answer 25

• prepare food sample
• add few drops of biuret solution using pipette
• if sample contains protein the biuret solution will turn from blue to pink or purple

Question 26

name some foods that contain protein

Answer 26

meat and cheese

Question 27

How do you test for lipids

Answer 27

• prepare sample of food
• add few drops of Sudan III solution and gently shake
• If sample contains lipids, the mixture will separate out into 2 layers. The top layer will be bright red. If there is no lipids in solution the layers wont separate out.

Question 28

What is the function of carbohydrates and name some food they are found in

Answer 28

Provide energy for the body. Found in pasta, rice and sugar

Question 29

What is the function of lipids and name some food they are found in

Answer 29

Provide energy, acts as an energy store and provides insulation. Found in butter, oily fish

Question 30

What is the function of proteins and name some food they are found in

Answer 30

Needed for growth and repair of tissues and to provide energy in emergencies. Found in meat and fish

Question 31

What is the function of vitamin A and name some food they are found in

Answer 31

Helps improve vision and keep your skin and hair healthy. Found in liver

Question 32

What is the function of vitamin C and name some food they are found in

Answer 32

Need to prevent scurvy. Found in fruits such as oranges

Question 33

What is the function of vitamin D and name some food they are found in

Answer 33

Needed for calcium absorption. Found in eggs

Question 34

What is the function of mineral ions such as calcium and name some food they are found in

Answer 34

Needed to make bones and teeth. Found in milk and cheese

Question 35

What is the function of mineral ions such as Iron and name some food they are found in

Answer 35

Needed to make haemoglobin for healthy blood. Found in red meat

Question 36

What is the function of water and name some food they are found in

Answer 36

Nearly every bodily function relies on water. we need a constant supply to replace water lost through urinating, breathing and sweating. Found in foods and drinks

Question 37

What is the function of dietary fibres and name some food they are found in

Answer 37

Aids the movement of food through the gut. Found in wholemeal bread and fruits

Question 38

What is a balanced diet

Answer 38

balanced diet is when you get all the essential nutrients your body needs and in the right proportions

Question 39

What are the 6 essential nutrients

Answer 39

carbohydrates, proteins, lipids, vitamins, minerals and water (and fibre to keep the gut in good working order)

Question 40

What types of people require different energy requirements

Answer 40

ACTIVITY LEVELS - active people require more energy than non-active people
AGE - Children and teenagers need more energy than older people, because they are generally more active and they need the energy to grow
PREGNANCY - Pregnant women require more energy than other women because they have to also provide more energy to their babies in order for them to develop.

Question 41

Describe the experiment to see how much energy is in food.

Answer 41

• Get a food that burns easily (dry food)
• Weigh a small amount of the wood and then stick it on a mounted needle
• Add a set volume of water to a boiling tube that is held with a clamp
• Measure the temperature of the water
• set fire to the food using Bunsen burner, make sure Bunsen isn’t near your water
• immediately hold you lit food under the boiling tube until it goes out. Then relight and hold it under the tube. repeat until food can’t catch on fire
  Measure final temperature of water.

Question 42

What is the equation to calculate amount of energy in the food

Answer 42

Energy in food ( J ) = Mass of water (in g) * Temperature change of water (in degrees (C)) * 4.2

1cm^3 of water = 1g of water
4.2 = amount of energy needed to raise the temperature of 1 g of water by 1 degrees (C)

Question 43

How to find energy per gram of food

Answer 43

Energy per gram of food (in J/g) = energy in food (in J) / mass of food (g)

Question 44

how to make energy in food experiment more reliable and valid

Answer 44

contain the boiling tube and lit food so energy isn’t lost to surroundings