Topic 3

Question 1

What is the relationship between increasing size of an organism and surface area to volume ratio?

Answer 1

As the size of an organism increases the surface area to volume ratio decreases

Question 2

What enzyme is produced in the salivary glands?

Answer 2

salivary amylase

Question 3

What enzyme is produced in the stomach?

Answer 3

endopeptidase and exopeptidase

Question 4

What enzyme is produced in the pancreas?

Answer 4

pancreatic amylase, lipases

Question 5

What enzyme is produced in the ileum?

Answer 5

dipeptidase and dissacharidases

Question 6

Breakdown of starch (5)

Answer 6

• Food enters mouth, broken up by teeth and mixed with saliva
• Salivary amylase hydrolyses glycosidic bonds in starch producing maltose
• In the stomach salivary amylase is denatured due to acidic pH
• In small intestine pancreatic amylase continues to hydrolyse starch to maltose
• Maltose is hydrolysed to glucose by maltase in the membrane of epithelial cells so glucose can then be absorbed

Question 7

What are endopeptidases?

Answer 7

• hydrolyse peptide bonds within polypeptide chain

Question 8

What are exopeptidases?

Answer 8

• Hydrolyse peptide bonds at the end of protein

Question 9

What are dipeptidases?

Answer 9

Hydrolyse peptide binds between dipeptides into amino acids

Question 10

describe protein digestion

Answer 10

• Proteins hydrolysed by protease in the stomach
• endopeptidase hydrolyses peptide bonds within the polypeptide chain
  -produces shorter polypeptide chains and increases the surface are for the next enzyme making digestion faster and more efficient
• exopeptidase hydrolyse peptide bonds at the ends of protein removing one amino acid at a time producing dipeptides
• in the epithelial cells dipeptidase hydrolyse dipeptides into amino acids which can be used for facilitated diffusion, active transport

Question 11

Lipid digestion

Answer 11

1) large insoluble lipid droplets are mixed with bile salts to form smaller droplets - emulsification
2) smaller droplets increase surface area for faster hydrolysis by lipase
3) Triglycerides hydrolysed into glycerol, fatty acids and monoglycerides
4) bile salts, glycerol and fatty acids form micelles
5) Micelles make fatty acids soluble in water and bring fatty acids to the surface of epithelial cells
6) fatty acids enter epithelial cells by simple diffusion
7) at the SER fatty acids, glycerol are recombined to form triglycerides
8) at the Golgi: Triglycerides are modified, proteins are added to form lipoproteins (chylomicrons) and are packaged into vesicles.
9) chylomicrons are transported into lymph vessels by exocytosis then enter the blood

Answer 13

Strok

Question 14

Heart rate

Answer 14

Beats of heart per minute min-1

Question 15

Why do mammals require a double circulatory system?

Question 33

What is the shape of the oxygen dissociation curve

Answer 33

sigmoid

Question 37

What does the casparian strip do ?

Answer 37

Blocks water and mineral ions

Answer 46

The water could prevent the loss of water vapour through the stomata