Please write clearly in block capitals.
Centre number Candidate number
Surname
Forename(s)
Candidate signature
I declare this is my own work.
Time allowed: 2 hours
Materials
For this paper you must have:
• a rul
...
Please write clearly in block capitals.
Centre number Candidate number
Surname
Forename(s)
Candidate signature
I declare this is my own work.
Time allowed: 2 hours
Materials
For this paper you must have:
• a ruler with millimetre measurements
• a scientific calculator.
Instructions
• Use black ink or black ball-point pen.
• Fill in the boxes at the top of this page.
• Answer all questions.
• You must answer the questions in the spaces provided. Do not write
outside the box around each page or on blank pages.
• If you need extra space for your answer(s), use the lined pages at the end of
this book. Write the question number against your answer(s).
• Show all your working.
• Do all rough work in this book. Cross through any work you do not want
to be marked.
Information
• The marks for the questions are shown in brackets.
• The maximum mark for this paper is 91.
A-level
BIOLOGY
Paper 1
2
*02*
IB/M/Jun22/7402/1
Do not write
outside the
There are no questions printed on this page box
DO NOT WRITE ON THIS PAGE
ANSWER IN THE SPACES PROVIDED
3
*03*
Turn over ►
IB/M/Jun22/7402/1
Do not write
outside the
Answer all questions in the spaces provided. box
0 1 . 1 Describe the structure and function of the nucleus.
[4 marks]
Question 1 continues on the next page
4
*04*
IB/M/Jun22/7402/1
Do not write
outside the
box 0 1 . 2 Name the main polymer that forms the following cell walls.
[1 mark]
Plant cell wall
Fungal cell wall
Scientists investigated the effect of the number of fungal species in soil on the
diversity of plant species.
Table 1 shows their raw data for soil containing 14 fungal species.
Table 1
Plant species Total shoot biomass / g m–2
Poa compressa 2
Achillea millefolium 4
Aster cordifolius 5
Aster novae-angliae 7
Chrysanthemum leucanthemum 15
Daucus carota 36
Fragaria virginiana 51
0 1 . 3 Suggest one reason the scientists used biomass instead of the number of individuals
of each plant species when collecting data to measure diversity.
[1 mark]
5
*05*
Turn over ►
IB/M/Jun22/7402/1
Do not write
outside the
box 0 1 . 4 The scientists used this equation to calculate the plant species index of diversity.
?? = 1 −��
??
??�
2
where n = shoot biomass of each plant species
and N = total shoot biomass of all plant species
Use this equation to calculate the index of diversity for the data in Table 1.
[2 marks]
Index of diversity
Question 1 continues on the next page
6
*06*
IB/M/Jun22/7402/1
Do not write
outside the
box Figure 1 shows the plant species index of diversity the scientists calculated when the
soil contained 0, 1, 2, 4 and 8 fungal species.
Figure 1
0 1 . 5 Sometimes farmers stop growing crops on an area of land to allow the natural
ecosystem to recover. The plant species index of diversity of these areas previously
used to grow crops is different from nearby land that has never been used to grow
crops.
Suggest and explain how the plant species index of diversity would be different in
these areas previously used to grow crops.
Use Figure 1 and your knowledge of the effect of farming on biodiversity in your
answer.
[2 marks]
10
7
*07*
Turn over ►
IB/M/Jun22/7402/1
Do not write
outside the
box 0 2 . 1 Clostridium difficile is a bacterial species that causes disease in humans.
Antibiotic-resistant strains of C. difficile have become a common cause of infection
acquired when in hospital.
Explain how the use of antibiotics has led to antibiotic-resistant strains of bacteria
becoming a common cause of infection acquired when in hospital.
[3 marks]
0 2 . 2 Scientists suggested that factors, other than antibiotic use, led to the increase in
antibiotic-resistant C. difficile infections. One suggested factor is people eating more
trehalose in their diet.
Trehalose is a disaccharide formed from two glucose molecules.
Name another disaccharide formed from two glucose molecules.
[1 mark]
Question 2 continues on the next page
8
*08*
IB/M/Jun22/7402/1
Do not write
outside the
Scientists investigated the effect of trehalose on the growth rate of C. difficile. box
They grew populations of non-resistant and antibiotic-resistant C. difficile on separate
agar plates with:
• no carbohydrate added
• trehalose added.
They measured the growth rate of the C. difficile.
Figure 2 shows the scientists’ results.
Figure 2
0 2 . 3 Describe how the scientists could use aseptic techniques to transfer
0.3 cm3 of C. difficile in liquid culture from a bottle onto an agar plate.
[3 marks]
9
*09*
Turn over ►
IB/M/Jun22/7402/1
Do not write
outside the
box 0 2 . 4 Use Figure 2 to evaluate whether more trehalose in the diet could be a factor in the
increased number of antibiotic-resistant C. difficile infections.
[3 marks]
Turn over for the next question
10
10
*10*
IB/M/Jun22/7402/1
Do not write
outside the
0 3 box . 1 Give two features of all prokaryotic cells that are not features of eukaryotic cells.
[1 mark]
1
2
Many multicellular organisms produce antimicrobial polypeptides (APs) that protect
them against prokaryotes.
Figure 3 shows how one type of AP acts on the cell-surface membrane of
prokaryotes.
Figure 3
0 3 . 2 This AP has a secondary structure in a helical shape.
Tick () the box to show which type of bond maintains the helical structure of the
polypeptide.
[1 mark]
Disulfide
Hydrogen
Ionic
Peptide
11
*11*
Turn over ►
IB/M/Jun22/7402/1
Do not write
outside the
box 0 3 . 3 The amino acids on one side of each AP helix have hydrophobic properties.
The amino acids on the opposite side of each helix have hydrophilic properties.
Figure 4 shows this.
Figure 4
Suggest how these properties of the APs allow them to become positioned across the
membrane (as shown in Figure 3) and make a channel through which ions can pass.
[2 marks]
Question 3 continues on the next page
12
*12*
IB/M/Jun22/7402/1
Do not write
outside the
Figure 5 shows further information about a channel formed in the cell box -surface
membrane by the APs.
Figure 5
0 3 . 4 Use Figure 5 to calculate the cross-sectional area of the channel through which ions
can pass.
Assume the cross-sectional area is circular.
Use π = 3.14 in your calculation. Give your answer in nm2 and to 1 decimal place.
[2 marks]
Answer nm2
13
*13*
Turn over ►
IB/M/Jun22/7402/1
Do not write
outside the
box 0 3 . 5 The APs damage prokaryotic cells but do not damage the eukaryotic cells in the
organisms that produce them.
Prokaryotic cell membranes do not contain cholesterol.
Assess why the APs do not damage the eukaryotic cells of the organisms that
produce them.
[2 marks]
0 3 . 6 Scientists observed these APs on prokaryotes using a transmission electron
microscope. They stained the APs using a monoclonal antibody with gold attached
to it.
Suggest how these techniques allowed observation of APs on prokaryotes.
[3 marks]
11
14
*14*
IB/M/Jun22/7402/1
Do not write
outside the
There are no questions printed on this page box
DO NOT WRITE ON THIS PAGE
ANSWER IN THE SPACES PROVIDED
15
*15*
Turn over ►
IB/M/Jun22/7402/1
Do not write
outside the
box 0 4 . 1 Describe viral replication.
[3 marks]
0 4 . 2 Complete Table 2 by putting a tick () where the feature is part of a cell cycle
involving mitosis or a cell cycle involving binary fission.
[2 marks]
Table 2
Feature Cell cycle involving:
mitosis binary fission
Replication of linear
DNA
Replication of circular
DNA
Produces 2 daughter
cells
Produces 4 daughter
cells
Happens in prokaryotic
cells
Happens in eukaryotic
cells
Question 4 continues on the next page
16
*16*
IB/M/Jun22/7402/1
Do not write
outside the
box Figure 6 represents a cell undergoing meiosis. It shows the chromosomes in the
parent cell and in the two cells formed after the first meiotic division.
The second division of meiosis proceeds normally except that non-disjunction occurs
in the chromosome labelled N.
Figure 6
0 4 . 3 Complete Figure 6 to show the chromosomes inside the daughter cells formed after
the second meiotic division.
[2 marks]
17
*17*
Turn over ►
IB/M/Jun22/7402/1
Do not write
outside the
Doctors studied babies born with a mutation caused by chromosome box
non-disjunction during gamete formation in their mother.
They determined each mother’s age at the time of childbirth and whether the
non-disjunction happened in the first meiotic division (MM1 error) or in the second
meiotic division (MM2 error).
Figure 7 shows the doctors’ results.
Figure 7
0 4 . 4 A student concluded that there were more mothers of age ˃37 with MM2 errors than
with MM1 errors.
Using Figure 7 and suitable calculations show why this conclusion is not valid.
[2 marks]
9
18
*18*
IB/M/Jun22/7402/1
Do not write
outside the
box 0 5 Two enzymes, P and Q, are proteins with quaternary structure which catalyse the
same reaction, but they have different amino acid sequences.
0 5 . 1 Define the quaternary structure of a protein.
[1 mark]
0 5 . 2 Explain how two enzymes with different amino acid sequences can catalyse the
same reaction.
[2 marks]
Scientists investigated the effect of pH 8.4 and pH 7.5 on the activity of enzymes
P and Q.
Figure 8 shows their results.
Figure
[Show More]
