3.3 Organisms exchange substances with their environment - Digestion and Absorption

Question 1

What is the process of digestion?

Answer 1

Hydrolysis of large biological molecules into smaller molecules that can be absorbed across cell membranes.

Question 2

Where does the digestion of carbohydrates begin?

Answer 2

In the mouth.

Question 3

What are the two main enzymes involved in carbohydrate digestion?

Answer 3

• Amylases
• Membrane-bound disaccharidases.

Question 4

What is the role of amylase in carbohydrate digestion?

Answer 4

It hydrolyses polysaccharides into the disaccharide maltose by hydrolysing glycosidic bonds.

Question 5

Where is amylase produced?

Answer 5

• Pancreas
• Salivary glands.

Question 6

What are the two membrane-bound disaccharidases mentioned?

Answer 6

• Sucrase
• Lactase.

Question 7

What do sucrase and lactase hydrolyse into monosaccharides?

Answer 7

• Sucrose
• Lactose.

Question 8

Fill in the blank: The digestion of carbohydrates is completed in the _______.

Answer 8

ileum.

Question 9

What is the function of glycosidic bonds in carbohydrate digestion?

Answer 9

They are hydrolysed by enzymes to break down carbohydrates.

Question 10

Which part of the digestive system follows the mouth in carbohydrate digestion?

Answer 10

Duodenum.

Question 11

True or False: The ileum is where carbohydrates are first digested.

Answer 11

False.

Question 12

List the glands that produce amylase.

Answer 12

• Parotid gland
• Sublingual gland
• Submandibular gland.

Question 13

What is maltose?

Answer 13

A disaccharide produced by the hydrolysis of polysaccharides.

Question 14

What are the three enzymes that hydrolyse proteins?

Answer 14

• Endopeptidases
• Exopeptidases
• Dipeptidases

These enzymes play different roles in the digestion of proteins.

Question 15

What is the function of endopeptidases?

Answer 15

Hydrolyse peptide bonds between amino acids in the middle of a polymer chain.

Endopeptidases initiate the breakdown of protein by targeting internal peptide bonds.

Question 16

What is the role of exopeptidases in protein digestion?

Answer 16

Hydrolyse peptide bonds between amino acids at the end of a polymer chain.

Exopeptidases act on the terminal ends of protein chains.

Question 17

What do membrane-bound dipeptidases hydrolyse?

Answer 17

Peptide bonds between two amino acids.

Dipeptidases are crucial for the final stages of protein digestion.

Question 18

Where does protein digestion start in the human body?

Answer 18

Stomach

The acidic environment of the stomach activates digestive enzymes.

Question 19

In which part of the digestive system is protein digestion fully completed?

Answer 19

Ileum

The ileum is responsible for the absorption of nutrients after digestion.

Question 20

Protein digestion continues in which part of the digestive system?

Answer 20

Duodenum

The duodenum receives enzymes from the pancreas that further digest proteins.

Question 21

Fill in the blank: Proteins are large polymer molecules that can be _______ by three enzymes.

Answer 21

hydrolysed

Hydrolysis is the process of breaking down proteins into smaller peptides and amino acids.

Question 22

What enzyme is responsible for the digestion of lipids?

Answer 22

Lipase

Lipase is produced in the pancreas.

Question 23

What substance is produced in the liver that aids in lipid digestion?

Answer 23

Bile salts

Bile salts emulsify lipids to form tiny droplets.

Question 24

What are the products of lipid digestion by lipase?

Answer 24

Monoglycerides and fatty acids

Lipase breaks the ester bonds in triglycerides.

Question 25

What is the process called that increases the surface area of lipids for digestion?

Answer 25

Emulsification ## Footnote Emulsification is achieved by bile salts.

Question 26

What are micelles?

Answer 26

Tiny droplets formed from emulsified lipids ## Footnote Micelles increase the efficiency of lipid digestion.

Question 27

What are the two stages of lipid digestion?

Answer 27

* Physical (emulsification & micelle formation) * Chemical (Lipase) ## Footnote These stages enhance the digestion process.

Question 28

Fill in the blank: Lipase hydrolyses lipids into _______ and fatty acids.

Answer 28

glycerol ## Footnote Some monoglycerides may also be produced.

Question 29

True or False: Bile salts are produced in the pancreas.

Answer 29

False ## Footnote Bile salts are produced in the liver.

Question 30

What is the role of bile salts in lipid digestion?

Answer 30

To emulsify lipids ## Footnote This creates small droplets for enhanced lipase action.

Question 31

What is the significance of increasing the surface area of lipids during digestion?

Answer 31

Enables faster hydrolysis by lipase ## Footnote More surface area allows lipase to act more effectively.

Question 32

What are micelles?

Answer 32

Water-soluble vesicles formed from fatty acids, glycerol, monoglycerides, and bile salts. ## Footnote Bile salts make the fatty acids and micelles water-soluble.

Question 33

What is the role of micelles in digestion?

Answer 33

They deliver fatty acids, glycerol, and monoglycerides to the epithelial cells of the ileum for absorption.

Question 34

How do fatty acids and monoglycerides enter epithelial cells?

Answer 34

Via simple diffusion due to being non-polar and lipid-soluble.

Question 35

What is formed when fatty acids link together?

Answer 35

Triglycerides.

Question 36

Where does the absorption of digestion products occur in mammals?

Answer 36

Across the cells lining the ileum.

Question 37

What structures increase the absorption surface area in the ileum?

Answer 37

Villi and microvilli.

Question 38

What is the function of villi in the ileum?

Answer 38

To maximize absorption by increasing surface area.

Question 39

What is the significance of the thin walls of the ileum?

Answer 39

They decrease the diffusion distance.

Question 40

What maintains a steep concentration gradient in the ileum?

Answer 40

The network of capillaries surrounding the epithelial cells.

Question 41

Fill in the blank: Micelles are formed from _______.

Answer 41

[fatty acids, glycerol, monoglycerides, bile salts]

Question 42

True or False: Microvilli are larger than villi.

Answer 42

False.

Question 43

What are lipids digested into?

Answer 43

Monoglycerides and fatty acids

Question 44

What enzymes are involved in lipid digestion?

Answer 44

Lipase and bile salts

Question 45

What are the tiny structures formed during lipid digestion called?

Answer 45

Micelles

Question 46

How do fatty acids and monoglycerides enter epithelial cells?

Answer 46

By simple diffusion across the cell surface membrane

Question 47

Where are triglycerides modified back after entering the epithelial cells?

Answer 47

Inside the endoplasmic reticulum and Golgi body

Question 48

What are chylomicrons formed from?

Answer 48

Fatty globules combining with proteins

Question 49

Where do chylomicrons enter after being extruded from the epithelial cell?

Answer 49

A lacteal (lymph capillary)

Question 50

Fill in the blank: Fatty acids link to form _______.

Answer 50

Triglycerides

Question 51

True or False: Micelles can easily diffuse into epithelial cells due to the non-polar nature of fatty acids and monoglycerides.

Answer 51

True

Question 52

What transports chylomicrons away from the intestine?

Answer 52

Lymph in the lacteal

Question 53

What is the primary purpose of co-transport in digestion?

Answer 53

To absorb glucose and amino acids from the lumen to the gut

Question 54

What must be true for facilitated diffusion of glucose and amino acids?

Answer 54

Higher concentration of glucose and amino acids in the lumen compared to the epithelial cell

Question 55

Why is active transport needed for glucose and amino acid absorption?

Answer 55

There is usually more glucose in the epithelial cells

Question 56

What is the first step in the co-transport process of glucose and amino acids?

Answer 56

Sodium ions are actively transported out of the epithelial cell into the blood in the capillary

Question 57

What effect does the active transport of sodium ions have on their concentration in the epithelial cell?

Answer 57

It reduces the sodium ion concentration in the epithelial cell

Question 58

How do sodium ions move back into the epithelial cell?

Answer 58

They diffuse from the lumen down their concentration gradient

Question 59

What type of protein do sodium ions diffuse through during co-transport?

Answer 59

Co-transporter protein

Question 60

What additional molecules can be transported into the epithelial cell along with sodium ions?

Answer 60

Glucose or amino acids

Question 61

How do glucose or amino acids move from the epithelial cell to the blood?

Answer 61

By facilitated diffusion

Question 62

Fill in the blank: Sodium ions are actively transported out of the epithelial cell into the _______.

Answer 62

blood

Question 63

True or False: Co-transport allows glucose and amino acids to be transported into epithelial cells against their concentration gradient.

Answer 63

True

Question 64

What is the end result of digestion?

Answer 64

Digestion ends with the release of smaller biological molecules.

Question 65

What are peristalsis and its role in digestion?

Answer 65

Peristalsis is the muscular contraction that moves food through the digestive tract.

Question 66

What are the main types of enzymes involved in digestion?

Answer 66

Digestive enzymes include amylases, proteases, and membrane-bound lipases.

Question 67

How are amino acids and glucose absorbed in the small intestine?

Answer 67

Absorption of amino acids and glucose is by co-transport.

Question 68

What links digestion to biological molecules?

Answer 68

Digestion links to biological molecules through hydrolysis.

Question 69

How does the absorption of lipids relate to cell organelles?

Answer 69

Absorption of lipids links to the function of cell organelles.

Question 70

What is the connection between digestion and enzyme action?

Answer 70

Digestion links to enzyme action through the breakdown of food.

Question 71

What types of transport are involved in the absorption of glucose and amino acids?

Answer 71

Absorption links to transport across membranes - active and co-transport.

Question 72

Fill in the blank: Digestion links to _______ through hydrolysis.

Answer 72

[biological molecules]

Question 73

True or False: Peristalsis is a chemical process involved in digestion.

Answer 73

False

Question 74

What is required for facilitated diffusion of glucose and amino acids from the lumen to the gut?

Answer 74

A higher concentration of glucose and amino acids in the lumen compared to the epithelial cell

Question 75

Why is active transport needed for the absorption of glucose and amino acids?

Answer 75

There is usually more glucose in the epithelial cells than in the lumen

Question 76

What is the first step in the co-transport process of glucose and amino acids?

Answer 76

Sodium ions are actively transported out of the epithelial cell into the blood in the capillary

Question 77

What effect does the active transport of sodium ions have on their concentration in the epithelial cell?

Answer 77

It reduces the sodium ion concentration in the epithelial cell

Question 78

How do sodium ions move back into the epithelial cell?

Answer 78

By diffusing down their concentration gradient from the lumen

Question 79

What type of protein do sodium ions diffuse through during co-transport?

Answer 79

Co-transporter protein

Question 80

What additional molecules can attach to the co-transporter protein along with sodium ions?

Answer 80

Glucose or amino acids

Question 81

What is the process by which glucose or amino acids move from the epithelial cell to the blood?

Answer 81

Facilitated diffusion

Question 82

Fill in the blank: Sodium ions are actively transported out of the epithelial cell into the _______.

Answer 82

blood in the capillary

Question 83

True or False: Sodium ions can diffuse into the epithelial cell against their concentration gradient.

Answer 83

False

Question 84

List the key terms associated with the co-transport of glucose and amino acids.

Answer 84

* Epithelial cell * Sodium ions * Glucose * Amino acids * Concentration gradient

Question 85

What is the primary function of digestion?

Answer 85

To break down food into smaller, absorbable components.

Question 86

What are peristalsis and its role in digestion?

Answer 86

Peristalsis is the wave-like muscle contractions that move food through the digestive tract.

Question 87

What are the types of enzymes involved in digestion?

Answer 87

Digestive enzymes include amylases, proteases, and lipases.

Question 88

How are amino acids and glucose absorbed?

Answer 88

By co-transport mechanisms.

Question 89

Fill in the blank: Absorption of lipids links to the function of _______.

Answer 89

cell organelles

Question 90

How does digestion relate to biological molecules?

Answer 90

Digestion links to biological molecules through hydrolysis.

Question 91

What links enzyme action to digestion?

Answer 91

The breakdown of food by enzymes.

Question 92

What types of transport are involved in the absorption of glucose and amino acids?

Answer 92

Active transport and co-transport.

Question 93

True or False: Digestion does not involve enzyme action.

Answer 93

False

Question 94

What are the roles of digestive enzymes?

Answer 94

* Break down carbohydrates * Break down proteins * Break down lipids

Question 95

What is hydrolysis in the context of digestion?

Answer 95

The chemical breakdown of a compound due to reaction with water.

Question 96

List the main components involved in the process of digestion.

Answer 96

* Enzymes * Muscle contractions * Biological molecules

Question 97

What is the significance of membrane-bound enzymes in digestion?

Answer 97

They help to digest nutrients directly at the site of absorption.