Topc 3

Question 1

What is digestion?

Answer 1

The process in which large insoluble molecules in food are hydrolysed into smaller, soluble molecules that can be absorbed across the the cell membranes into the blood stream and delivered to cells in the body.

Question 2

What are proteins hydrolysed to?

Answer 2

Amino acids

Question 3

What are carbohydrates hydrolysed into?

Answer 3

Simple sugars

Question 4

What are lipids hydrolysed to?

Answer 4

A mixture of glycerol and fatty acids

Question 5

What are the components of the human digestion system and their functions?

Answer 5

-glands- the salivary glands and glands in the pancreas produce digestive juices

-stomach & small intestine- the sites of digestion

-the liver- produces bile

-small intestine site of absorption

-large intestine- site of water reabsorption

Question 6

What is the order of the digestive system?

Answer 6

1. Mouth
2. Oesophagus
3. Stomach
4. Small intestine

5.large intestine

Question 7

What are the three main types of digestive enzymes?

Answer 7

1. Carbohydrases
2. Proteases
3. Lipases

Question 8

Where does the digestions of carbohydrates take place?

Answer 8

Mouth and small intestine

Question 9

Describe the process of how carbohydrates are digested?

Answer 9

1. Amylase is produced by the salivary gland and pancreas
2. In the mouth Amylase hydrolyses the glycosidic bond in starch converting it to maltose
3. Then in the small intestine the membrane bound disaccharidases Maltese attached to the cell membrane of the the epithelial cell lining the ileum
4. Hydrolyses the glycosidic bond in maltose which produces glucose
5. Then glucose is transported across the cell membranes of the ileum epithelial cells via specific transporter proteins.

Question 10

Where does the digestion of carbohydrates take place?

Answer 10

Mouth and small intestine

Question 11

Describe the process of digestion of lipids?

Answer 11

1. Emulsification in the stomach happens first, which consists of bile salts emulsifying lipids
2. Which creates small lipids droplets
3. Then lapse break down the lipid droplets into monoglycerides and fatty acids which stick with bile salts forming micelles.

Question 12

What is an advantage of emulsification?

Answer 12

Increases the surface are which creates a bigger area for lipases to work on, increasing the rate of digestion

Question 13

Where are bile salts produced?

Answer 13

In the liver

Question 14

Describe how proteins are digested?

Answer 14

-proteins are broken down by a combination of proteases and or peptidases

• these hydrolyse the peptide bonds between amino acids

Question 15

What are endopeptidases, exopeptidases and dipeptidase?

Answer 15

Endopeptidases- hydrolyse the peptide bond within the protein

Exopeptidases- they hydrolyse the peptide bond at the end of the protein molecules

Dipeptidases- they act to separate the two amino acids that separate the two amino acids that make up a dipeptide by hydrolysing the peptide bond between them.

Question 16

How is glucose absorbed across the ileum epithelial into the blood stream?

Answer 16

1. Sodium ions are actively transported out of the ileum epithelial cell into the blood- by a potassium sodium pump
2. Creating a concentration gradient (higher conc of sodium ions in lumen of the ileum compared to inside the cell)
3. Sodium ions diffuse from the lumen of the ileum into the epithelial cell down the conc gradient via sodium- glucose co-transporter proteins
4. Because co transporter has carried glucose into the cell with the sodium= higher concentration of glucose inside the cell
5. Glucose diffuses out of the cell into the blood down the conc gradient through a protein channel by facilitated diffusion

Question 17

How are amino acids (protein product) absorbed across the ileum epithelium Into the blood stream?

Answer 17

-amino acids are absorbed by co transport in a similar way to glucose

• sodium ions are actively transported out of the ileum epitheal cells into the blood

-creating a sodium ion conc gradient

• sodium ions can then diffuse from the lumen of the ileum into the epithelial cells through a sodium dependent transporter protein, carrying the amino acid with them

Question 18

How do you calculate surface area to volume ratio?

Answer 18

Surface area divided by volume

Question 19

How does a size of a organism determine their surface area and why?

Answer 19

-Smaller organisms have a larger surface area to volume ratio

• because they don’t need any additional adaptations to meet their needs for transport across their surface
• they can diffuse gases across there surface- simple diffusion

Question 20

Why do large organisms have a smaller surface area to volume ratio?

Answer 20

Because they have higher metabolic rate which demands efficient transport of waste out of cells and reactants into the cells

Question 21

What are the key structures of the human gas exchange system?

Answer 21

-alveoli

-bronchioles

-bronchi

-trachea

• lungs

Question 22

What is pulmonary ventilation?

Answer 22

The total volume of air that is moved into the lungs during one minute. (Dm3 min -1)

Question 23

What is the equation for pulmonary ventilation?

Answer 23

Tidal volume X ventilation rate

Question 24

How is the alveoli adapted to gaseous exchange?

Answer 24

-There are many- large surface area

-very thin- short diffusion distance

-surrounded by network of capillaries- maintained concentration gradient