Please write clearly in block capitals.
Centre number Candidate number
Surname
Forename(s)
Candidate signature
Your text here 1
A-level
BIOLOGY
Paper 1
Thursday 6 June 2019 Morning Time allowed: 2 hours
Materials
For Examiner’s Use
For this paper you must have:
• a ruler with millimetre measurements Question Mark
• a scientific calculator.
1
Instructions 2
• Use black ink or black ball-point pen. 3
• Fill in the boxes at the top of this page. 4
• Answer all questions.
• You must answer the questions in the spaces provided. Do not write 5
outside the box around each page or on blank pages. 6
• Show all your working. 7
• Do all rough work in this book. Cross through any work you do not want
8
to be marked.
9
Information 10
• The marks for the questions are shown in brackets.
• The maximum mark for this paper is 91. TOTAL
*JUN197402101* IB/M/Jun19/E16 7402/1
, 2
Do not write
outside the
Answer all questions in the spaces provided. box
0 1 . 1 Describe how a non-competitive inhibitor can reduce the rate of an
enzyme-controlled reaction.
[3 marks]
*02*
IB/M/Jun19/7402/1
, 3
Do not write
outside the
Pectin is a substance found in some fruit and vegetables. box
A scientist investigated the effect of pectin on the hydrolysis of lipids by a lipase
enzyme.
His results are shown in Figure 1.
Figure 1
0 1 . 2 The scientist concluded that pectin is a non-competitive inhibitor of the lipase enzyme.
Use Figure 1 to explain why the scientist concluded that pectin is a non-competitive
inhibitor.
[1 mark]
Question 1 continues on the next page
Turn over ►
*03*
IB/M/Jun19/7402/1
, 4
Do not write
outside the
The scientist also found that pectin stops the action of bile salts. He prepared two box
suspensions:
• suspension A – lipid and bile salts
• suspension B – lipid, bile salts and pectin.
He did not add lipase to either suspension.
He observed samples from the suspensions using an optical microscope.
Figure 2 shows what he saw in a typical sample from each suspension.
Figure 2
0 1 . 3 Calculate the maximum length of the large lipid droplet marked X in Figure 2.
Using a ruler with millimetre intervals always includes an uncertainty in the
measurement. Use the uncertainty in your measurement to determine the uncertainty
of your calculated maximum length.
You can assume there is no uncertainty in the magnification.
[2 marks]
Maximum length = µm
Uncertainty of your calculated maximum length = µm
*04*
IB/M/Jun19/7402/1
Centre number Candidate number
Surname
Forename(s)
Candidate signature
Your text here 1
A-level
BIOLOGY
Paper 1
Thursday 6 June 2019 Morning Time allowed: 2 hours
Materials
For Examiner’s Use
For this paper you must have:
• a ruler with millimetre measurements Question Mark
• a scientific calculator.
1
Instructions 2
• Use black ink or black ball-point pen. 3
• Fill in the boxes at the top of this page. 4
• Answer all questions.
• You must answer the questions in the spaces provided. Do not write 5
outside the box around each page or on blank pages. 6
• Show all your working. 7
• Do all rough work in this book. Cross through any work you do not want
8
to be marked.
9
Information 10
• The marks for the questions are shown in brackets.
• The maximum mark for this paper is 91. TOTAL
*JUN197402101* IB/M/Jun19/E16 7402/1
, 2
Do not write
outside the
Answer all questions in the spaces provided. box
0 1 . 1 Describe how a non-competitive inhibitor can reduce the rate of an
enzyme-controlled reaction.
[3 marks]
*02*
IB/M/Jun19/7402/1
, 3
Do not write
outside the
Pectin is a substance found in some fruit and vegetables. box
A scientist investigated the effect of pectin on the hydrolysis of lipids by a lipase
enzyme.
His results are shown in Figure 1.
Figure 1
0 1 . 2 The scientist concluded that pectin is a non-competitive inhibitor of the lipase enzyme.
Use Figure 1 to explain why the scientist concluded that pectin is a non-competitive
inhibitor.
[1 mark]
Question 1 continues on the next page
Turn over ►
*03*
IB/M/Jun19/7402/1
, 4
Do not write
outside the
The scientist also found that pectin stops the action of bile salts. He prepared two box
suspensions:
• suspension A – lipid and bile salts
• suspension B – lipid, bile salts and pectin.
He did not add lipase to either suspension.
He observed samples from the suspensions using an optical microscope.
Figure 2 shows what he saw in a typical sample from each suspension.
Figure 2
0 1 . 3 Calculate the maximum length of the large lipid droplet marked X in Figure 2.
Using a ruler with millimetre intervals always includes an uncertainty in the
measurement. Use the uncertainty in your measurement to determine the uncertainty
of your calculated maximum length.
You can assume there is no uncertainty in the magnification.
[2 marks]
Maximum length = µm
Uncertainty of your calculated maximum length = µm
*04*
IB/M/Jun19/7402/1
