B3 Organisation and the digestive system

Question 1

Hierarchy of living organisms

Answer 1

cells -> tissues -> organs -> organ systems -> organisms

Question 2

What are carbohydrates

Answer 2

composed of long chains of simple sugars

Question 3

What are the three types of carbohydrates

Answer 3

Starches, sugars and fibres

Question 4

What are the uses of starch and sugars

Answer 4

They give us energy

Question 5

What do fibres do

Answer 5

They prevent constipation

Question 6

What are proteins

Answer 6

composed of chains of amino acids

Question 7

Why do we need proteins

Answer 7

Growth

to repair the body

Question 8

Why do we need lipids

Answer 8

Energy

Insulation to keep us warm

Question 9

What are fats

Answer 9

composed of 3 fatty acids & 1 glycerol molecule

Question 10

What is the test for starchs

Answer 10

Iodine solution

Question 11

What is the sighs of positive result of starch’s

Answer 11

Orange colour goes blue/black colour

Question 12

What is the test for reducing sugars

Answer 12

Benedict’s solution

Question 13

What is the next step to test for reducing sugars

Answer 13

Heat gently for 10 min

Question 14

What is the sighs of positive result of reducing sugars

Answer 14

Blue colour goes brick-red colour

Question 15

What is the test for proteins

Answer 15

Biuret A and Biuret B

Question 16

What is the next step to test for proteins

Answer 16

Shake the test tube gently

Question 17

What is the sighs of positive result of proteins

Answer 17

Blue colour goes violet colour

Question 18

What is the test for lipids

Answer 18

Few drops of water and a few drops of ethanol

Question 19

What is the sighs of positive result of Lipids

Answer 19

White precipitate layer forms

Question 20

How those enzymes work

Answer 20

1) Enzymes are proteins. They speed up the rate of chemical reactions.
2) They have a specific shape called the active site

3)The active site is complementary to the shape of the substrate molecule. Like a ‘lock and
key’.

4)There are random collisions between the enzyme and the substrate molecule, when the
substrate enters the active site an enzyme – substrate complex is formed.

• Bonds are broken
• Produce are released.
• Enzyme can then be reused.

Question 21

How does high temperatures affect enzymes

Answer 21

both the enzyme and substrate molecules have more kinetic energy, therefore there are more frequent collisions, more enzyme substrate complexes are formed and more products are released. Over 40°C the enzyme starts to become denatured and no longer functions.

Question 22

How does pH affect enzymes

Answer 22

each enzyme has an optimum pH. They only work within a narrow range of pH. Higher/lower pHs cause the enzyme to become denatured.

Question 23

That is Bile

Answer 23

a green alkaline liquid produced by the liver and stored in the gallbladder. It neutralises stomach acid and emulsifies fats

Question 24

What are the digestive enzymes

Answer 24

Carbohydrase (amylase) enzymes

Protease enzymes

Lipase enzymes

Question 25

What are the production sites of protease, lipase and carbohydrate enzymes

Answer 25

The small intestine

Pancreas

Question 26

Where does protease enzymes work

Answer 26

Stomach

small intestine

Question 27

Where does lipase enzymes work

Answer 27

Small intestine

Question 28

Where does carbohydrates enzymes work

Answer 28

Mouth

small intestine

Question 29

Where is food absorbed into the bloodstream

Answer 29

small intestine

Question 30

Where is water reabsorbed back into the bloodstream

Answer 30

large intestine