B3: The Digestive System

Question 1

What is a TISSUE?

Answer 1

A group of cells with a similar structure and function working together.

Question 2

What are ORGANS?

Answer 2

Collections of tissues.

Question 3

What tissues does the stomach contain and their function ? (6)

Answer 3

MUSCULAR tissue - to churn food/digestive juices together
GLANDULAR tissue - to produce digestive juices to break food down
EPITHELIAL tissue - covers inside/outside of the organ

Question 4

What are ORGAN SYSTEMS ?

Answer 4

Grouops of organs that work together to perform a specific function .

Question 5

What are glands and their function ?

Answer 5

Glands are organs that make one or more substances.

- they make/release digestive juices containing ENZYMES to break down food

Question 6

CARBOHYDRATES - function/what they are made up of

Answer 6

FUNCTION : provide us with fuel that make all other reaction of life possible
MADE OF : units of sugar

• SIMPLE SUGARS - carbs that contain only one or two sugar units
• COMPLEX CARBS - carbs containing long chains of simple sugar units bonded together

Question 7

LIPIDS - what they are/ function/ what they are made of

Answer 7

Lipids are fats and oils.

FUNCTION : efficient energy STORE in the body and important SOURCE of energy

MADE OF : 3 molecules of FATTY ACIDS and a molecule of GLYEROL

Question 8

PROTEINS - function/what they are made of

Answer 8

FUNCTION : used for building up cells/tissues of the body as well as a basis of all your ENZYMES!

MADE OF : long chains of amino acids

Question 9

TEST FOR : simple sugars, complex carbs, proteins, lipids
(BIBE)
How do you tell if the compound is present?

Answer 9

Glucose : BENEDICT’S TEST FOR SUGARS (blue-> brick red/brown )
Complex carbs : IODINE TEST FOR STARCH (yellow/red -> blue/black)

Proteins : BIURET TEST ( blue -> purple)

Lipids : ETHANOL TEST ( cloudy white layer)

Question 10

What is a catalyst ?

Answer 10

A substance that increases the rate of a chemical reaction .

NOT USED UP IN A REACTION!

Question 11

What are enzymes? How can they bind to specific substrate molecules?

Answer 11

• Large protein molecules
  The long chains of amino acids are folded to produce a molecule with an active site. This active site has a unique shape so it can bind to a specific substrate .

Question 12

What is metabolism ?

Answer 12

The sum of all the reactions in the cell or body .

Enzymes control metabolism .

Question 13

How does temperature effect enzyme action ?

Answer 13

• after optimum temperature amino acids unravel and active site loses shape
• substrate cant fit in active site
• enzyme is DENATURED

Question 14

How does pH effect enzyme action ?

Answer 14

change in pH affects forces between parts of protein that hold the protein/active site in shape

• the active site will change shape if pH changes
• enzyme cat be used as a catalyst anymore

Question 15

CARBOHYDRATES - enzyme that catalyses break down/ where enzyme is produced / where enzyme acts / product after breaking down

Answer 15

ENZYME : carbohydrase
PRODUCED : salivary glands /pancreas/small intestine
ACTS IN: mouth/ small intestine
PRODUCT : simple sugars

Question 16

PROTEINS - enzyme that catalyses break down/ where enzyme is produced / where enzyme acts / product after breaking down

Answer 16

ENZYME : Proteases
PRODUCED : stomach/ pancreas/small intestine
ACTS IN : stomach/small intestine
PRODUCT : amino acids

Question 17

LIPIDS - enzyme that catalyses break down/ where enzyme is produced / where enzyme acts / product after breaking down

Answer 17

ENZYME : lipase
PRODUCED : pancreas/small intestine
ACTS IN : small intestine
PRODUCT: fatty acids /glycerol

Question 18

What is digestion/what does it involve?

Answer 18

Involves break down of large insoluble substances into smaller soluble substances that can be absorbed into the blood across the wall of the small intestine.

Question 19

What are digestive enzymes produced by ?

Answer 19

By specialised cells in glands and in the lining of digestive system

Question 20

What conditions do stomach protease enzymes work best in ?

Answer 20

ACIDIC ( hence HCl in stomach)

Question 21

What conditions do enzymes made in the pancreas.small intestine work best in ?

Answer 21

ALKALINE

Question 22

What is BILE?

Answer 22

A fluid that is made/released in the LIVER, stored in the GALL BLADDER and released through the BILE DUCT.

Question 23

functions of BILE?

Answer 23

• Neutralise acid added to food in stomach for alkaline conditions
• Emulsifies fats - breaks large drops of fats into smaller droplets
  - increase SURFACE AREA of fats for lipase to act upon
  - speeds up breakdown of fats

Question 24

What causes coeliac disease?

Answer 24

The immune system mistakes substances found in gluten as a threat to the body so it attacked them

Question 25

How is the surface area of the small intestine increased?

Answer 25

By Villi with a network of blood vessels

Question 26

What are proteins used for/act as?

Answer 26

Enzymes
Antibodies
Hormones (like insulin)
Structural components of tissues (muscles/tendons)

Question 27

describe a test to show whether a person’s urine contains GLUCOSE? signs of a positive result? (2)

Answer 27

add BENEDICT’S SOLUTION to urine/ BOIL

- positive if goes from BLUE -> BRICK RED

Question 28

Why do ppl with coeliac’s have poor growth? (4)

Answer 28

• damaged villi REDUCE SA for absorbtion
• so fewer amino acids/glucose absorbed
• less glucose means less transfer of energy from respiration
• fewer amino acids available to build new proteins