B6.3 - Digestion

Question 1

What are the 4 types of human teeth

Answer 1

incisors
canines
premolars
molars

Question 2

features of the incisors

Answer 2

they are at the front of the mouth
Chisel-shaped and flat
Used for biting off food (good with plant material)
8 incisors 4 bottom 4 top

Question 3

features of canines

Answer 3

They are sharp and pointy
they piece and hold food, particularly meat so it can be chewed
4 canines two bottom two top

Question 4

features of premolars

Answer 4

Helps with cutting and crushing off tough food like meats
Grinds plant material
Large grinding surface
8 pre molars 4 bottom 4 top

Question 5

features of molars

Answer 5

at the back of the mouth
Have large grinding flat surfaces for chewing
for crushing and grinding food
12 molars 6 bottom 6 top

Question 6

What is the top of a crown covered in

Answer 6

hard material called enamel

Question 7

What is the second layer of the tooth

Answer 7

the dentine

Question 8

The tooth is filled with

Answer 8

pulp which contains blood vessels and nerves

Question 9

Cement covers the surface of the

Answer 9

tooth’s root

Question 10

The two parts of a tooth are the

Answer 10

crown and the root

Question 11

a soft tissue called

Answer 11

gum surrounds the teeth and jaw bone

Question 12

What are the causes of dental decay

Answer 12

Many bacteria living in the mouth and feed on trapped food particles

the bacteria respire sugar in food and release acid called plaque

Plaque is very acidic and spreads by corroding the enamel and dentine until it reaches the pulp cavity where tooth ache occurs

Question 13

What are some measures to prevent tooth decay

Answer 13

Brushing your teeth with toothpaste
Flossing to remove food particles from the mouth
Avoiding acidic foods and drinks

Question 14

Explain why toothpaste is used to prevent tooth decay

Answer 14

It is alkaline and so neutralizes acid near teeth

Contains antibacterial substances such as mint to kill bacteria.

Contains fluoride which helps strengthen enamel and reduce acidic damage.

Fluoride also helps remove trapped food particles and plaque

Question 15

Where is bile produced, stored and secreted

Answer 15

produced in the liver
stored in the gall bladder
secreted from the bile duct and used in the small intestine

Question 16

What is the problem with digestion of fats without bile

Answer 16

Fats do not mix in aqueous mixtures and remain as insoluble large droplets.

This gives a small surface area for lipase enzymes to work on slowing the rate of digestion

Question 17

What is the importance of bile

Answer 17

It emulsifies fats breaking them up into smaller droplets

The surface area increases and the rate of digestion becomes much faster

It also is alkaline and helps neutralize stomach acids that reach the small intestine

Question 18

What are digestive enzymes

Answer 18

a group of enzymes produced in the cells lining parts of the digestive system and secreted into the alimentary canal to mix with food.

Question 19

What is the function of digestive enzymes

Answer 19

catalyze the breakdown of larger insoluble food molecules into smaller soluble molecules that are small enough to be absorbed into the bloodstream

Question 20

What are some digestive enzymes and what do they break down

Answer 20

Amylase: Break down starch
Protease: Break down protein
Lipase: Break down lipids/fats

Question 21

What is carohydrase

Answer 21

a type of digestive enzyme that breaks down carbohydrates. An example of one is amylase

Question 22

All about amylase

Answer 22

Action sites: Small intestine and mouth

Substrate: Starch

Produced: Salivary glands and pancreas

Amylase breaks down starch to glucose

Question 23

All about protease

Answer 23

Action sites: Stomach and small intestine

Produced: Stomach wall and pancreas

Protease breaks down protein to amino acids

Question 24

What enzyme breaks down maltose

Answer 24

maltase. It breaks down maltose into glucose

Question 25

All about lipase

Answer 25

Action sites: Stomach and small intestine

Produced: Pancreas

Lipase breaks down lipids into molecules called glycerol and fatty acids

Question 26

What are the types of protease

Answer 26

Pepsin (works in stomach) and trypsin (works in small intestine)

Question 27

Enzymes that digest food work best in

Answer 27

acidic environments and suitable temperatures

Question 28

Special cells in the lining of the stomach secrete

Answer 28

HCI into the stomach to create right conditions for enzymes

Question 29

What is the importance of HCI in the stomach

Answer 29

Creates right conditions for optimum enzyme activity
Optimum pH for protease activity
Kills microorganisms and bacteria in food

Question 30

In the small intestine enzymes from

Answer 30

the pancreas work best in slightly alkaline conditions

Question 31

Gastric juices from the stomach entering the duodenum provide

Answer 31

a suitable pH for enzyme action

Question 32

What is the importance of villi

Answer 32

Increases the internal surface area of the small intestine which:

increases the rate of transport and absorption of food molecules across the small intestine wall.

Question 33

The surface area of cells lining the villi increased further with the help of

Answer 33

tiny microvilli

Question 34

Explain why a thin layer helps rate of diffusion increase in villi

Answer 34

A thin layer of cells makes sure digested food molecules don’t need to travel far to be absorbed into the blood.

Question 35

Explain why lots of blood capillaries helps rate of diffusion increase in villi

Answer 35

Well supplied blood capillaries can absorb more food molecules from small intestine to rest of body and supply fresh blood keeping the concentration gradient between digested food in intestine and cells in body high as possible. This leads to faster rate of diffusion

Question 36

What are the adaptations of the villi to increase rate of diffusion

Answer 36

Covered in thin layer of cells
Lots of blood capillaries
Contain lacteal

Question 37

Describe how lacteal helps increase rate of diffusion in villi

Answer 37

Villi contain lacteals which carry fat droplets separately from the rest of the food molecules as they don’t dissolve well in blood. This makes sure the rate of diffusion doesn’t slow down.