Enzyme Exam Questions Flashcards
Describe and explain the difference between the two curves. (5)
(A technician investigates the effect of temperature on the rate of an enzyme-controlled reaction. The graph shows ‘time after start of reaction’ against ‘concentration of product in mixture’. The curve at 37 degrees has a steep quick increase then curves to plateau, reaching just under 15 conc of product. The 25 degrees curve is a straight diagonal line up to 10 conc of product.)
- initial rate of reaction is faster at 37^c
- because more kinetic energy
- so more E-S complexes formed
- then it plateaus
- as all substrate has been used up
(Read Q2 in as booklet)
A student concluded from a graph of the data in Table 5 that the bacterium lives at 15^c.
Does the data support the students conclusion? Give reasons for your answer. (4)
YES:
- expect optimum temp of the enzyme to be same
- optimum temp for enzyme seems to be 15^c
NO:
- need data from more temps (10^c - 20^c)
- data for only isolated enzyme
(Read Q2 in as booklet)
Suggest two variables the biochemist controlled when investigating the effect of the temp on the rate of breakdown of a protein by the protease. (1)
- pH
- concentration of protease
Many humans are unable to digest lactose. A scientist investigated the production of lactose-free milk. He produced gel beads containing the enzyme lactase and places the beads in a column. He poured milk (milk A) into the column over the beads.
Milk A contains no glucose. Milk B contains glucose. Explain why milk B contains glucose. (1)
- lactase is hydrolysed into glucose and galactose
Many humans are unable to digest lactose. A scientist investigated the production of lactose-free milk. He produced gel beads containing the enzyme lactase and places the beads in a column. He poured milk (milk A) into the column over the beads.
The enzyme was trapped within the gel beads. Suggest one advantage of trapping the enzyme within the gel beads. (1)
- want a product that is just milk not milk and enzyme
- also you can reuse the enzyme
Galactose has a similar structure to part of the lactose molecule. Explain how galactose inhibits lactase. (2)
- galactose is a competitive inhibitor to active site of lactose
- fewer E-S complexes formed
A student investigated the effect of loose concentration on the hydrolysis of lipids.
He took a beaker containing a suspension of lipids. He placed a pH probe attached to a data logger into the beaker. After 5 minutes, he added the lipase solution. The data logger recorded the pH.
The student did not add a buffer to the lipas solution.
Explain why. (1)
It would keep the pH constant and the student was measuring change in pH
A student investigated the effect of loose concentration on the hydrolysis of lipids.
He took a beaker containing a suspension of lipids. He placed a pH probe attached to a data logger into the beaker. After 5 minutes, he added the lipase solution. The data logger recorded the pH.
Give two variables the student would have controlled in this investigation. (2)
- vol of lipase
- temp
- volume of suspension of lipids
A student investigated the effect of loose concentration on the hydrolysis of lipids.
He took a beaker containing a suspension of lipids. He placed a pH probe attached to a data logger into the beaker. After 5 minutes, he added the lipase solution. The data logger recorded the pH.
Give the suitable control for this investigation (1)
Boiled lipase solution
A student investigated the effect of loose concentration on the hydrolysis of lipids.
He took a beaker containing a suspension of lipids. He placed a pH probe attached to a data logger into the beaker. After 5 minutes, he added the lipase solution. The data logger recorded the pH.
The graph shows what happened after he added the lipase solution ( time plotted against pH, curve starts at pH 8 and it steadily curves downwards until it plateaus at pH 4.5).
Explain the result shown in the graph. (2)
- fatty acids produced
- curve levels off as all the substrate is used up
A student investigated the effect of loose concentration on the hydrolysis of lipids.
He took a beaker containing a suspension of lipids. He placed a pH probe attached to a data logger into the beaker. After 5 minutes, he added the lipase solution. The data logger recorded the pH. The graph shows what happened after he added the lipase solution ( time plotted against pH, curve starts at pH 8 and it steadily curves downwards until it plateaus at pH 4.5).
The student repeated the same experiment with a higher conc if lipase solution. Describe and explain the results you would expect him to get. (3)
- faster fall of pH and levels off at the same point
- more e-s complexes formed
- same amount of fatty acids produced
