Section 3. Enzymes for Biology, A Level - revisedeck

3. Enzymes

A section of Biology, 9700

Listing 10 of 276 questions

A student carried out experiments to investigate the effect of enzyme concentration on the rate of hydrolysis (break down) of protein in milk. When the enzyme and milk were mixed, the protein was hydrolysed and the mixture changed from cloudy to clear. The student investigated five different enzyme concentrations and recorded the time taken to reach the end-point for each. What is an appropriate control for this investigation?

9700_s17_qp_11

MCQ

2017

Paper 1, Variant 1

View

Neutrase® is an enzyme that is used to hydrolyse proteins in solution. When the enzyme is mixed with a 2% protein solution the reaction mixture changes from white to colourless. A student carried out an experiment to find the effect of copper sulfate and potassium sulfate on the activity of Neutrase®. The student made four reaction mixtures in test-tubes A to D. Test-tubes A to C contained equal volumes of protein solution and 0.1 cm3 of solutions of copper sulfate or potassium sulfate. Test-tube D contained the same volume of protein solution and 0.1 cm3 of water. 0.5 cm3 of a 1% Neutrase® solution was added to test-tube A and immediately placed into a colorimeter. The colorimeter was used to measure the intensity of light that is absorbed by the solution over 100 seconds. The procedure was repeated with the other reaction mixtures, B, C and D. The results are shown in . 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 time / s D water C 0.01 mol dm–3 potassium sulfate B 0.01 mol dm–3 copper sulfate A 0.05 mol dm–3 copper sulfate absorbance Suggest and explain why measuring the absorbance of the reaction mixture over 100 s is a suitable method for determining the activity of Neutrase®. With reference to : • describe the effects of copper sulfate solution and potassium sulfate solution on the activity of Neutrase® • suggest explanations for the effects that you have described. Neutrase® can be immobilised in alginate. Immobilised Neutrase® is used in the food industry to produce foods with high nutritional content. Explain the advantages of using immobilised enzymes, such as Neutrase®, compared with using the same enzymes free in solution.

9700_s19_qp_21

THEORY

2019

Paper 2, Variant 1

View

An indicator mixed with agar forms a pink colour. The pink-coloured agar becomes colourless when put in acid. Blocks of pink-coloured agar are cut to different sizes and put in acid. All other variables are kept constant. Which block becomes colourless most quickly?

9700_s21_qp_13

MCQ

2021

Paper 1, Variant 3

View

An enzyme is completely denatured at 50 °C. A fixed concentration of this enzyme is added to a fixed concentration of its substrate. The time taken for completion of the reaction is measured at different temperatures. Which graph shows the results?

9700_w13_qp_11

MCQ

2013

Paper 1, Variant 1

View

Pyrophosphatase enzymes catalyse a hydrolysis reaction. pyrophosphate ions substrate phosphate ions product pyrophosphatase In experiment 1, a scientist studied the rate of this reaction, using a colorimeter. The absorbance of the solution was measured at regular intervals until all of the pyrophosphate ions had been converted into phosphate ions. In experiment 2, the scientist repeated the procedure with a higher concentration of pyrophosphatase. All other variables were standardised. Which graph shows the effect of increasing the concentration of pyrophosphatase?

9700_w24_qp_11

MCQ

2024

Paper 1, Variant 1

View

Farmers can use insecticides to remove parasites from their sheep. Some of these insecticides act as inhibitors of the enzyme acetylcholinesterase. Suggest and explain how an inhibitor of acetylcholinesterase could work. Acetylcholinesterase inhibitors affect nerve impulse conduction. Explain the effects of the inhibition of acetylcholinesterase at a synapse. Suggest one way of reducing the effects of acetylcholinesterase inhibitors.

9700_m20_qp_42

THEORY

2020

Paper 4, Variant 2

View

Two enzyme experiments were carried out. The first, experiment X, was carried out at a constant temperature of 37 oC. During the second experiment the temperature was increased from 37 oC to 80 oC. Which graph shows the results?

9700_s06_qp_1

MCQ

2006

Paper 1, Variant 0

View

The enzyme lysozyme secreted from tear glands forms deposits on contact lenses. Which ingredient would be effective in a contact lens cleaner for removing these deposits?

9700_s10_qp_11

MCQ

2010

Paper 1, Variant 1

View

The enzyme lysozyme secreted from tear glands forms deposits on contact lenses. Which ingredient would be effective in a contact lens cleaner for removing these deposits?

9700_s10_qp_12

MCQ

2010

Paper 1, Variant 2

View

The enzyme DNA polymerase is used in DNA replication. This enzyme was extracted from bacteria living in natural hot water springs where the water temperature is between 85 °C and 95 °C. Which graph would represent the relationship between temperature and the rate of DNA replication when catalysed by the enzyme from these bacteria?

9700_s15_qp_13

MCQ

2015

Paper 1, Variant 3

View

Questions Discovered

276