B3-Organisation And The Digestive System

Question 1

What is a tissue?

Answer 1

A group of similar cells working together

Question 2

What is an organ

Answer 2

A collection pf dofferent tissues working together to preform a function

Question 3

What is an organ system?

Answer 3

A collection of organs working together

Question 4

What is an organism?

Answer 4

A collection of organ systems working together

Question 5

What is the function pf the mouth in the idgestuve system?

Answer 5

• Teeth grind the food up
• Food is mixed with saliva (saliva contains a digestuve enzyme called amylase)
• Tongue pushes food to back of throat to be swallow

Question 6

What is the use of the stomach in the digestive system?

Answer 6

• Temporary storage facility for food that is being digested
• Stretchy, muscular bat
• Muscles create churning pattern to mix food with digestive enzymes
• Acid activates the protease enzymes to break up large protein molecules

Question 7

What is the function of the large intestine innthe digestive system?

Answer 7

• Any undigested food now enters the large intestine
• No digestion takes place but over 90% of water absorbtion occurs
• This forms faeces which move tot he rectum throught he process of peristalsis

Question 8

What is the function of the small intestine in the digestive system?

Answer 8

• Partly digested food enter small instestine from stomach
• Bile and pancreatic juices are added to neutralize acid from stomach
• The pancreatic juices contain enzymes to break down fats, carbohydrates and proteins
• Proteins and nutrients are absorbed by the villi into the blood

Question 9

What is the role of lipids in our body and whcih food are a good source of this nutrient?

Answer 9

They are the most efficent energy store in the body and an important source of energy in the diet. They are also important within cell membranes, and nervous system
* All oils (eg: olive oil and corn oil)
* Butter
* Margarine
* Cheese
* Cream

Question 10

What role does carbohydrates play in the body and which foods are a good source of this nutrient?

Answer 10

Carbohydrates provide us with the fuel that makes all other reactions of life possible. They act as an energy source and help control blood glucose metabolism
* Bread
* Potatoes
* Rice
* Pasta

Question 11

Why role does protein play in the body and which foods are a good source of this nutrient?

Answer 11

Proteins are used for growth of cells to repair tissues as well as the basis for all enzymes, used within the digestuve system to break down foods for the absorbtion of nutrients. They also act as antibodies and hormones such as insulin

• Fish
• Meat
• Cheese
• Eggs
• Pulses

Question 12

What are the individual parts of a lipid?

Answer 12

Glycerol molecule, 3x fatty acid chains

Question 13

What are the individual parts of protein and what is the entire protein chain called

Answer 13

Individual amino acids, polypeptic chain

Question 14

What are the individual parts of carbohydrates and what is the entire carbohydrate chain called

Answer 14

Individual glucose molecules
A starch molecule (complex carbohydratej

Question 15

What is the chemical used for starch?

Answer 15

Iodine solution

Question 16

What is the chemical used for sugar?

Answer 16

Benedict’s solution

Question 17

What is the chemical used for protein?

Answer 17

Biuret solution

Question 18

What is the chemical used for lipds/ fats?

Answer 18

Ethanol

Question 19

What is the method of test for starch?

Answer 19

1 Place a small amount of food on the spotting tile.
2 Add a few drops of iodine solution to the food on the spotting tile.
3 Yellow–red iodine solution turns blue–black if starch is present.
4 Record your result in the results table.
5 Repeat steps 1–4 for other types of food.

Question 20

What is the method of test for sugar?

Answer 20

1 Place a small amount of food in a test tube.
2 Add enough Benedict’s solution to cover the food.
3 Place the test tube in a warm water bath for 10 minutes.
4 Blue Benedict’s solution turns brick red on heating if a sugar such as glucose is present.
5 Record your result in the results table.
6 Repeat steps 1–5 for other types of food.

Question 21

What is the method of test for lipids/ fats?

Answer 21

1 Place a small amount of food into a test tube.
2 Add a few drops of ethanol to the test tube.
3 Shake the test tube and leave for 1 minute.
4 Pour the solution into a test tube of water.
5 Ethanol added to a solution gives a cloudy white layer if a lipid is present.
6 Record your result in the results table.
7 Repeat steps 1–6 for other types of food.

Question 22

What is the method of test for protein?

Answer 22

1 Place a small amount of food in a test tube.
2 Add 1 cm3 of Biuret reagent. Alternatively add 1 cm3 of
sodium hydroxide solution and then add a few drops of copper sulfate solution.
3 Blue Biuret reagent turns purple if a protein is present.
4 Record your result in the results table.
5 Repeat steps 1–4 for other types of food.

Question 23

What are enzymes?

Answer 23

Enzymes are special proteins that are involved in metabolism (reactions in the body). They are catalysts and can build, break or change molecules.

Question 24

What are digestive enzymes?

Answer 24

Digestive enzymes break food into small soluble molecules that can be absorbed into the blood and delivered around the body

Question 25

What is the active site?

Answer 25

The area of the enzyme that is complementary to the substrate

Question 26

What is it called when the enzyme binds to the substrate?

Answer 26

Enzyme substrate complex

Question 27

What is the name of enzyme which breaks carbohydrates down?

Answer 27

Carbohydrase
Area: in the mouth and small intestine
Product: Glucose

Question 28

What is the name of enzyme which breaks proteins down?

Answer 28

Protease
Area: Stomach, small intestine
Product: Individual amino acids

Question 29

What is the name of enzyme which breaks lipids/ fats down?

Answer 29

Lipase
Area: Small intestine
Product: Glycerol molecule and fatty acids

Question 30

Explain why enzyme activity increases as temperature increases (up to an optimum)

Answer 30

As temperature increases, there is greater thermal energy resulting in greater kinetic energy. This results in a higher frequency of collisions between the enzymes and substrate and collidisions with greater energy. This results in more enzyme substrate complexes, therefore, increasing enzyme activity.

Question 31

Explain why enzyme activity rapidly decreases with increasing temperature beyond the optimum?

Answer 31

Enzyme activity rapidly decreases with increasing temperature beyond the optimum temperature as vibrations within the enzyme caused by kinetic energy break the intermolecular forces between the protein chains, resulting in the enzymes becoming denatured. This means the substrate can no longer fit into the enzyme as it is no longer complememtary to the substrate and an enzyme substrate complex cannot be made. As a result of this, enzyme activity rapidly decreases.

Question 32

Explain why enzyme activity decreases as the pH increases above/ decreases below the optimum pH

Answer 32

Within enzymes, the amino acids attract eachother as they have different, opposite charges. However, changin the pH scale will affect the charges of the amino acid molecules. Extremes of pH therefore denature the enzyme-substrate complex as the active site is no longer complementary to the substrate, resulting in low enzyme activity.

Question 33

Why does pH affect the way an enzyme works?

Answer 33

pH affects the enzyme works as it interupts the hydrogen bonds between molecules within the enzyme. This changes the specific formation of the enzyme and it denatures, so the active site is no longer complementary to the substrate and enzyme activity decreases. However thos occurs at different pHs for each enzyme.