2 - Biological Molecules

Question 1

What are carbohydrates?

Answer 1

• Contain carbon, hydrogen and oxygen

- Examples include starch and glycogen

Question 2

What is starch made of?

Answer 2

Maltose

Question 3

What is glycogen made of?

Answer 3

Glucose

Question 4

What are proteins?

Answer 4

• Contain carbon, hydrogen, oxygen and nitrogen

- Made of long chains of amino acids

Question 5

What are lipids?

Answer 5

• Contain carbon, hydrogen and oxygen

- Made of fatty acids and glycerol

Question 6

Describe a test for glucose

Answer 6

• Use Benedict’s reagent
• Add to a sample and heat but don’t boil
• Colour change from blue to green-yellow-orange-red (depending on concentration)

Question 7

Describe a test for starch

Answer 7

• Use iodine

- Colour changes from brown/orange to blue/black

Question 8

Carbohydrates

Answer 8

Found - pasta, rice, sugar

Functions - provides energy

Question 9

Lipids

Answer 9

Found - butter, oily fish

Functions - provides energy, acts as an energy store and provides insulation

Question 10

Proteins

Answer 10

Found - meat, fish

Function - needed for growth and repair of tissues and to provide energy in an emergency

Question 11

Vitamin A

Answer 11

Found - liver

Function - helps to improve vision and keeps hair and skin healthy

Question 12

Vitamin C

Answer 12

Found - oranges

Function - prevents scurvy

Question 13

Vitamin D

Answer 13

Found - eggs, sunlight

Function - helps calcium absorption

Question 14

Calcium

Answer 14

Mineral ion
Found - milk, cheese
Function - helps makes bones and teeth

Question 15

Iron

Answer 15

Mineral ion
Found - red meat
Function - helps make haemoglobin for healthy blood

Question 16

Water

Answer 16

Found - food and drink

Function - for every bodily function. Also for replacing water lost by sweating, breathing and urination

Question 17

Dietary fibre

Answer 17

Found - wholemeal bread

Function - aids the movement of food through the alimentary canal

Question 18

What are the energy requirements?

Answer 18

Activity level - more active = more energy needed
Age - younger = more energy for growth
Pregnancy - pregnant = more energy needed for the baby to develop

Question 19

Describe an experiment to find the energy from food

Answer 19

• Find a food that burns easily e.g. peanuts or pasta
• Weigh a small amount and put it on a mounted needle
• Add 25cm3 of water to a boiling tube (held with a clamp)
• Measure the temperature of the water then set fire to the food (away from the water)
• Put the flame directly under the water and keep relighting until not possible
• Measure the temperature of the water again
• Energy in food = mass of water x temperature change of water x 4.2 (amount of energy to raise the temperature of 1g by 1*C)
• Energy per gram of food = energy in food / mass of food

Question 20

What is the function of bile?

Answer 20

• Produced in the liver
• Stored in the gall bladder
• Released in the small intestines
• Neutralises the acidic stomach so enzymes can work best
• Emulsifies fats so there is a bigger surface area for the lipase enzymes to work on (makes digestion faster)

Question 21

Amylase

Answer 21

Converts starch to maltose

Question 22

Maltase

Answer 22

Converts maltose to glucose

Question 23

Protease

Answer 23

Converts proteins into amino acids

Question 24

Lipase

Answer 24

Converts lipids into glycerol and fatty acids

Question 25

What do digestive enzymes do?

Answer 25

They break down large, insoluble molecules into small, soluble ones

Question 26

What is the alimentary canal?

Answer 26

Your gut

• Mouth
• Oesophagus
• Stomach
• Liver
• Pancreas
• Gall bladder
• Small intestines
• Large intestines
• Anus

Question 27

Mouth

Answer 27

• Salivary glands produce amylase enzyme

- Teeth break down food mechanically

Question 28

Stomach

Answer 28

• Pummels food with muscular walls
• Produces protease enzyme (pepsin)
• Produces HCl to kill bacteria and acidify the stomach

Question 29

Liver

Answer 29

• Produces bile

Question 30

Pancreas

Answer 30

• Produces protease, amylase and lipase enzymes

- Releases them into the small intestines

Question 31

Gall bladder

Answer 31

• Where bile is stored

Question 32

Small intestines

Answer 32

• Produces protease, amylase and lipase enzymes to complete digestion
• Where the nutrients are absorbed out of the alimentary canal into the body

Question 33

Large intestines

Answer 33

• Where excess water is absorbed from food

Question 34

Anus

Answer 34

• Where faeces leave the body

Question 35

What is peristalisis?

Answer 35

Circular waves of muscle contractions to help the movement of food through the alimentary canal

Question 36

What are the stages of digestion?

Answer 36

1 - Ingestion
2 - Digestion
3 - Absorption 
4 - Assimilation
5 - Egestion

Question 37

What is ingestion?

Answer 37

1 - Putting food or drink into the mouth

Question 38

What is digestion?

Answer 38

2 - The break down of large insoluble molecules into small soluble ones. Can be chemical or mechanical

Question 39

What is absorption?

Answer 39

3 - The process of moving molecules through the walls of the intestines into the blood

• Digested food is absorbed in the small intestines
• Water is absorbed in the large intestines

Question 40

What is assimilation?

Answer 40

4 - When digested molecules move into body cells and become part of the cell (e.g. when amino acids are assimilated they are used to become cellular proteins)

Question 41

What is egestion?

Answer 41

5 - The removal of undigested molecules in the form of faeces through the anus

Question 42

What are villi? How are they used for absorption?

Answer 42

• Millions of them cover the walls of the small intestines
• There are microvilli on each villi
• This increases the surface area for absorption
• Only one permeable layer thick so not far to travel
• Good blood supply