B3 - Organisation and the Digestive System

Question 1

Definition of a tissue

Answer 1

A group of cells with similar structure and function that work together to perform a task

Question 2

Definition of an organ

Answer 2

An organ is a collection of tissues that work together to perform a function

Question 3

Definition of an organ system

Answer 3

An organ system is a group of organs that make up an organism

Question 4

Different tissues in stomach

Answer 4

• Glandular - produces + secretes enzymes
• Muscular - churns food
• Epithelial - coats the stomach

Question 5

Adaptations of small intestines (4)

Answer 5

• Villi create a large surface area for more absorption
• Constant blood supply to maintain concentration gradient
• Long so more time to absorb molecules
• Short diffusion distance

Question 6

Function of large intestines

Answer 6

To absorb water from the food to form faeces

Question 7

Function of liver

Answer 7

Produces bile which is then stored in the gall bladder

Question 8

Different types of carbohydrates

Answer 8

Simple sugars and complex carbohydrates

Question 9

What are carbohydrates broken down into

Answer 9

Simple sugars e.g. glucose and sucrose

Question 10

What are lipids broken down into

Answer 10

• Fatty acids (lower the pH)
• Glycerol

Question 11

What are proteins broken down into

Answer 11

Amino acids

Question 12

Definition of an enzyme

Answer 12

An enzyme is a biological catalyst that speeds up the rate of reactions without being used up. They also control metabolism

Question 13

What is metabolism

Answer 13

The sum of all the reactions in the body

Question 14

Explain the lock and key theory

Answer 14

• Substrate attaches to active site of enzyme as the active site has a complementary shape to the substrate
• This forms an enzyme - substrate complex
• The enzyme splits the substrate into products yet is unchanged itself

Question 15

How many reactions will an enzyme catalyse

Answer 15

Only one. This is due to its active site shape being specific to the reaction/ substrate

Question 16

Function of digestive enzymes

Answer 16

To break down large food into small soluble molecules that can go into the bloodstream

Question 17

Explain the effects of temperature on enzymes + rate of reaction up to optimum temperature

Answer 17

As temp increases, rate of reaction increases due to more enzyme substrate collision but only up to the optimum temperature

Question 18

What happens to enzymes if the temperature increases above their optimum

Answer 18

• Chain of amino acids in enzyme unravel
• Substrate can no longer fit and rate of reaction drops rapidly
• Enzyme is denatured

Question 19

Effects of changing pH on enzymes

Answer 19

• Changing pH changes active site shape of enzyme
• Substrates no longer fit

Question 20

What type of enzyme breaks down carbs (with example)

Answer 20

Carbohydrases e.g. amylase

Question 21

Enzyme that breaks down proteins

Answer 21

Proteases

Question 22

Enzyme that breaks down fats/ lipids

Answer 22

Lipases

Question 23

Sites of production and action of amylase

Answer 23

• Production - salivary glands , pancreas
• Action - mouth, s. intestines

Question 24

Sites of production and action of protease

Answer 24

• Production - Stomach, pancreas, s. intestines
• Action - Stomach, s. intestine

Question 25

Sites of production and action of lipase

Answer 25

• Production - pancreas, s. intestines
• Action - s. intestines

Question 26

Functions of bile

Answer 26

• Emulsifying fats - makes fat droplets, larger SA for enzymes to work
• Neutralises HCl acid - provides optimum pH for enzymes

Question 27

Test for carbs + positive result indication

Answer 27

Iodine solution - goes from orange to black/purple

Question 28

Test for sugars + positive result indication

Answer 28

Benedict’s solution + HEATING - blue to brick red

Question 29

Test for protein + positive result indication

Answer 29

Buiret reagent - goes from blue to purple