Digestion + Absorption

Question 1

What happens during digestion of lipids? (3)

Answer 1

• Lipid droplets are mixed with bile salts to form smaller droplets, which increase SA for faster hydrolysis by lipase
• Bile salts, glycerol + fatty acids form micelles
• Micelles make fatty acids soluble in water + bring fatty acids to surface of membrane

Question 2

What happens during lipid absorption? (4)

Answer 2

• Fatty acids are absorbed by simple diffusion
• At the S.E.R, fatty acids, glycerol recombine to form triglycerides
• At Golgi body, triglycerides are modified, proteins are added to form chylomicrons + are packaged into vesicles
• Chylomicrons are transported into a lymph vessel by exocytosis then enter blood

Question 3

What makes up a micelle?

What do the micelles do?

Answer 3

Bile salt, glycerol, fatty acids

Make fattiy acids soluble in water + bring fatty acids to the surface of epithelial cells membrane

Question 4

What’s the first thing that happens in lipid digestion?

Why?

Answer 4

• Lipid droplets are mixed with bile salts to form smaller droplets (emulsified)
• Smaller droplets increase surface area for faster hydrolysis by lipase

Question 5

Where is lipase produced?

What does lipase hydrolyse what into what?

Answer 5

Pancreas

Hydrolyses lipids into gylcerol, fatty acids and monogylcerides

Question 6

Where is bile:

• Produced
• Stored
• Released

Answer 6

• Liver
• Gall Bladder
• Small Intestine

Question 7

Describe the role of enzymes in the digestion of proteins in a mammal? (4)

Answer 7

• Endopeptidase hydrolyses peptide bonds within polypeptide chain to produce a shorter polypeptide (which increases surface area to make digestion faster + more efficient)
• Exopeptidase hydrolyses at terminal ends to produce dipeptides
• Dipeptidase hydrolyses dipeptides into amino acids

Question 8

Describe how amino acids are absorbed from the ilium into the blood? (6)

Answer 8

• Na+ are actively transported out of epithelial cell into the blood (by sodium potassium pump)
• This creates a conc. gradient of Na+ (between lumen and cell)
• Na+ and amino acids enter by facilitated diffusion
• Na+ diffuses into cell down its conc. gradient
• Amino acids move into cell against its conc. gradient
• Amino acids moves into blood by facilitated diffusion

Question 9

Describe how glucose is absorbed from the ilium to the blood? (6)

Answer 9

• Na+ are actively transported out of epithelial cell into the blood by sodium potassium pump
• This creates a conc. gradient of Na+ (between lumen and cell)
• Na+ and glucose enter by facilitated diffusion using co-transporter protein
• Na+ diffuses into cell down its conc. gradient
• Glucose moves into cell against its conc. gradient
• Glucose moves into blood by facilitated diffusion

Question 10

Describe the role of the enzymes of the digestive system in the complete breakdown of starch? (3)

Answer 10

• Salivary amylase hydrolyses starch into maltose
• By hydrolysing glycosidic bonds
• Maltose is hydrolysed into glucose by maltase

Question 11

What do standard deviations show?

Answer 11

Spread of data around the mean

Question 12

Why is having a standard/benchmark/control value on a graph important?

Answer 12

For comparison

Question 13

Suggest why micro moles are used?

Suggest one practical advantage of measuring masses of frogs compared with measuring their volumes?

Answer 13

Avoids using many decimal places

Easier to find mass because of irregular shapes

Question 14

Explain why oxygen uptake is a measure of metabolic rate in organisms?

Answer 14

Oxygen is used in respiration, which provides energy

Question 15

Explain why viruses are described as acellular + non-living? (2)

Answer 15

• Not made from cells
• Cannot replicate unless in a host cell