Biology
UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS
General Certificate of Education
Advanced Subsidiary Level and Advanced Level
CHAPTERS CLASSIFIED:ENZYMES
9700/2
BIOLOGY
Paper 2 Structured Question AS
For year 2014
Candidates answer on the Question Paper.
No Additional Materials are required.
READ THESE INSTRUCTIONS FIRST
Write your candidate number and name on all the work you hand in.
Write in dark blue or black pen.
You may use a soft pencil for any diagrams, graphs or rough working.
Do not use staples, paper clips, highlighters, glue or correction fluid.
Answer all questions.
You may lose marks if you do not show your working or if you do not use appropriate units.
At the end of the examination, fasten all your work securely together.
The number of marks is given in brackets [ ] at the end of each question or part question.
This document consists of 25 printed pages.
[Turn over
© A.P
9700/02/REV/2014
jfkhan04@gmail.com
June 2006 Paper 2
5
Some bacteria that are found in soils contain the enzyme urease.
For
Examiner’s
Use
Urease catalyses the hydrolysis of urea to form ammonia and carbon dioxide: urea + water
carbon dioxide + ammonia
Some fertilisers added to soils to help crop growth contain urea. Although some crop plants can absorb ammonium ions, most obtain their source of nitrogen as nitrate ions.
The activity of urease can be measured by following the increase in pH as ammonia is produced in the reaction. A student was provided with urease extracted from bacteria and solutions of urea and two chemical inhibitors, thiourea and lead nitrate. The student prepared six reaction mixtures (1 to 6) as shown in Table 5.1 in order to investigate the effect of the two chemical inhibitors on the activity of urease.
Table 5.1 reaction mixture
urea
water
thiourea
lead nitrate
urease
boiled urease 1
2
3
4
5
6
Key
= present in reaction mixture
= absent from reaction
General Certificate of Education
Advanced Subsidiary Level and Advanced Level
CHAPTERS CLASSIFIED:ENZYMES
9700/2
BIOLOGY
Paper 2 Structured Question AS
For year 2014
Candidates answer on the Question Paper.
No Additional Materials are required.
READ THESE INSTRUCTIONS FIRST
Write your candidate number and name on all the work you hand in.
Write in dark blue or black pen.
You may use a soft pencil for any diagrams, graphs or rough working.
Do not use staples, paper clips, highlighters, glue or correction fluid.
Answer all questions.
You may lose marks if you do not show your working or if you do not use appropriate units.
At the end of the examination, fasten all your work securely together.
The number of marks is given in brackets [ ] at the end of each question or part question.
This document consists of 25 printed pages.
[Turn over
© A.P
9700/02/REV/2014
jfkhan04@gmail.com
June 2006 Paper 2
5
Some bacteria that are found in soils contain the enzyme urease.
For
Examiner’s
Use
Urease catalyses the hydrolysis of urea to form ammonia and carbon dioxide: urea + water
carbon dioxide + ammonia
Some fertilisers added to soils to help crop growth contain urea. Although some crop plants can absorb ammonium ions, most obtain their source of nitrogen as nitrate ions.
The activity of urease can be measured by following the increase in pH as ammonia is produced in the reaction. A student was provided with urease extracted from bacteria and solutions of urea and two chemical inhibitors, thiourea and lead nitrate. The student prepared six reaction mixtures (1 to 6) as shown in Table 5.1 in order to investigate the effect of the two chemical inhibitors on the activity of urease.
Table 5.1 reaction mixture
urea
water
thiourea
lead nitrate
urease
boiled urease 1
2
3
4
5
6
Key
= present in reaction mixture
= absent from reaction