Paper 2 Flashcards
Explain the function of this ATP hydrolase
- enzyme that catalyses hydrolysis reaction of ATP, breaking it down into ADP and Pi
- releases energy to be used in the active transport of sodium ions out of cell and potassium ions into cell via the sodium-potassium pump
Explain how the movement of Na+ out of the cell allows the absorption of glucose into the cell lining the ileum
- lowers concentration of Na+ inside cell, maintaining concentration gradient from the ileum into the cell for sodium
- sodium ions travel by co-transport, transporting glucose with them:
- Na+ moves down diffusion gradient from ileum into cell
- glucose moves against concentration gradient into cell
Describe two features you would expect to find in a cell specialised for absorption
- large surface area for absorption, provided by microvilli, and increases the number of channel/carrier proteins
- large number of mitochondria to produce large amounts of ATP for active/co-transport
Draw phospholipids on Figure 2 to show how the carrier protein would fit into the cell-surface membrane
(draw 8 phospholipids)
Describe how amino acids join to form a polypeptide so there is always NH2 at one end and COOH at the other end. (Draw a diagram)
- one amino acid contains both an amine and a carboxyl group
- condensation reaction forms a peptide bond between amine of one amino acid and carboxyl of another amino acid
- in the chain, there is one free amine group and one free carboxyl group at each end
Use your knowledge of lipid digestion to explain the differences in the results for samples A and B shown in table 1 (no absorption has occurred)
- lipase enzyme hydrolyses the ester bond in triglycerides to a molecule of glycerol and 3 fatty acids, causing it to decrease concentration
- in A, not all the triglycerides have been hydrolysed (only 82%)
- so fatty acid concentration lower than B, and triglyceride concentration is higher
- in B, all triglycerides were hydrolysed
- (because) B was collected 30mins later than A
- so more digestion/hydrolysis of triglycerides occurred
Explain why the scientist immediately heated the lipid samples to 70 degrees C for 10 minutes
- to denature the lipase digestive enzymes
- no further lipid hydrolysis occurs after removal from the gut
- this will maintain the same lipid concentration outside of the gut
Describe the role of micelles in the absorption of fats into the cells lining the ileum
- lipids hydrolysed by lipases to form monoglycerides and fatty acids
- micelles are a single layer of phospholipids which form around the insoluble molecule of glycerol and fatty acids
- micelles contain bile salts and fatty acids; make the fatty acids more soluble in water
- micelles transport the glycerol and fatty acids to the epithelial cells lining the ileum
- glycerol and fatty acids then diffuse into the cell to be absorbed
Put a cross in the box to show which step RUBISCO catalyses
A (step 1)
Put a cross in the box to show which step requires reduced NADP and ATP
B (step 2)
Put a cross in the box next to the number of these carbohydrates (fructose, a glucose, b glucose, sucrose) that are monosaccharides
C (3)
Put a cross in the box next to the number of these polysaccharides (amylopectin, amylose, cellulose, glycogen) found in plants
C (3)
Using the information in the table, describe the effect of temperature on the rate of photosynthesis, when light intensity and CO2 percentage are both high
- as temp increases, rate of photosynthesis increases
- a 10°C increase in temp from 20-30°C results in photosynthesis rate increasing by 38.46%
Suggest values for the rate of photosynthesis in groups K and L. Give reasons for your answer
- K = 220°C
- bc temperature is higher than G but light intensity is the same
- L = 340°C
- bc TEMP higher is than H
- and LIGHT INTENSITY is higher than K
Complete the photosynthesis diagram by writing the correct word/words
- oxygen
- inorganic phosphate ions
- GP
