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Biology Booklet

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Biology Booklet

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Farha Shaheen

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OCR

A LEVEL
BIOLOGY
A WEEKLY REVISION PLAN

|
CONTENTS

Week 1 Cells and molecules

Week 2 Respiration

Week 3 Animal exchange

Week 4 Membranes and cell division

Week 5 Disease

Week 6 Nervous communication

Week 7 Plant Biology

Week 8 Genetics

Week 9 Hormones and homeostasis

Week 10 Ecology and biodiversity

Week 11 Photosynthesis
Week 1
Cells and
molecules
Give the main uses of the following types of microscopes: What are the four different ways to prepare a slide for a Stains are used to increase the c______ of a Key word definitions:
light microscope? How are they different? specimen, ready for viewing under a ______
• Light microscope microscope. Artefacts
1. D__________ stains help to distinguish
between different types of cell (e.g. gram
• Transmission electron microscope staining in _______) or between different
Longitudinal section
2. organelles to help emphasise differences in
structure and therefore possible differences
in f_______.
• Scanning electron microscope Transverse section
3.
Magnification formula triangle:

• Laser scanning confocal microscope Micrograph

4.
Magnification formula triangle:

Resolution
List the correct names for the parts of a light microscope:
Give an exhaustive list of rules for producing a scientific
biological drawing:
Magnification
How do you calculate total magnification of a light
microscope?

Ultrastructure
Cell Structure and Microscopy Revision
OCR Biology A (AS level)
Electron microscopes can only view dead cells due to the Convert the following values into standard Eukaryotic
preparation process of slides. Give two advantages of form:
using an electron microscope over a light microscope. 0.000387 =
920,000 =
6430 =
0.0051 =
Prokaryotic

Feature Light microscope Electron microscopes Name two pieces of equipment used Draw a diagram to show
to measure cells down a light how to convert between
Magnification microscope: cm, mm, µm and nm.
1.
Resolution TEM: SEM: Transport Vesicle
&
Cost 2.
How do you use them?
Mobility
Sample preparation; Simple or Secretory Vesicle
complex?
Likelihood of ‘artefacts’: High or
Low? Nucleolus
Vacuum? Yes or No?
Colouration
Histones
Specimen type (living/dead/both)
Draw a labelled animal cell in the space below: Draw a labelled plant cell in the space below: Draw a labelled prokaryotic cell in the space below:

Cellular feature/organelle Function Use the key word box below to write a detailed description of how various different organelles are used to process,
Ribosome package and secrete proteins:
Nuclear envelope/pores
Vesicles
Smooth endoplasmic reticulum
Flagella/Cilia
Golgi apparatus
Rough endoplasmic reticulum
Centrioles
Cell wall
Plasma membrane
Lysosomes
Cytoskeleton Microfilaments:
Intermediate fibres:
Microtubules:

Which 2 organelles contain a double membrane structure and Key words: RER, Ribosome, Folded, Cisternae, Transport vesicles, Cis face, Golgi apparatus, Modify, Package, Secretory vesicles, Fuse,
their own separate DNA?
Plasma membrane.

Which organelles contain a 9+2 formation in eukaryotes? Give some differences in prokaryotic vs eukaryotic cells in relation to their…
What does this mean? DNA

Organelles

Reproduction
Which organelle(s) is formed from flatted sacs called
cisternae? Average size
Key Term Definitions:
Which are pyrimidines and which are Draw the structure of a DNA Compare the structure of DNA with RNA in the table below:
rWhat are the names of the four
bases in DNA and what are the purines? Describe the difference in nucleotide and an RNA nucleotide. Nucleotides:
complimentary base pairings?
Similarities Differences
their structure.

Strands:

Bases:
Draw and label the bonds used to hold together the structure of DNA.

Double Helix:

What is a ‘kilobase’ of DNA? Explain why DNA Replication must occur before cell division:
Antiparallel:

Nucleic Acids Revision Why is DNA replication described as ‘semi-conservative’? Degenerate:

OCR AS Level Biology

Describes the steps involved in DNA replication. Non-overlapping:

Explain the role of the following two
• enzymes in DNA replication:

DNA Helicase: How was this method of replication first confirmed? Describe
•
the experiment and results.
• Universal:

•
DNA polymerase:
•
Leading Strand:
•

• Lagging Strand:

Draw and label the structure of ATP: Explain how ATP is constantly broken down and resynthesized in a cell. Explain how the hydrolysis of
ATP can provide energy for the Okazaki Fragments:
cell.

Hydrolysis:

How is the structure above similar and different to RNA? Condensation:

What are the steps in the central dogma of molecular biology? Explain the role of the following type of RNA: Explain the role of the following enzymes to Key Term Definitions:
transcription:
mRNA: 3’
DNA Helicase:

tNA: 5’

RNA polymerase:
Template strand:
Where does transcription occur?
rRNA:
Where can translation occur?

What is the product of transcription?

Coding strand:
What the product of translation?

Describe the steps involved in transcription: Explain how the following nucleic acid molecules relate to each other during transcription:
Sense strand:
1. The sense strand and the antisense strand?
Diagram:

Antisense strand:
2. The sense strand and the mRNA?

Anticodon:
3. The antisense strand and the mRNA?

Codon:

Describe the steps involved in translation: Explain how a mutation may lead to a change in the primary structure Now explain why the protein may
of a protein. not change at all:
Amino acids:

Mutation:

Protein Synthesis:

Draw the structure of tRNA:

Chromosomes:
On a separate piece of paper: How is transcription different to translation?

Explain the steps in extracting and

purifying a DNA sample from a tissue
sample. The steps must be sequenced
Histone Proteins:
correctly and each steps purpose must
be clear.
Questions
Q1.

The diagram below shows a typical animal cell as seen using an electron microscope.

(a) Name the organelles labelled A, B and C shown on the diagram.

(3)

.............................................................................................................................................

(b) Give the letter of the organelle that doubles just before mitosis and then separates to
opposite poles of the cell during mitosis.

(1)

.............................................................................................................................................

(d) Place a cross ( ) in the correct box next to the following statements.

(2)

(Total for question = 7 marks)

Q2.

As part of the immune response, a B cell has to be activated. It then divides to form a clone of
cells. These cells then differentiate into plasma cells, which produce antibodies.

(i) Name the type of division that occurs when B cells are cloned.

(1)

.............................................................................................................................................

(ii) Suggest how a microscope slide could be prepared to observe cell division in B cells.

(3)

.............................................................................................................................................

(Total for question = 4 marks)

Q3.

The phenotype of an organism may be affected by both genotype and the environment. For
example, the risk of developing skin cancer is affected by the activity of the p53 gene and
exposure to ultraviolet (UV) light.

(a) The p53 gene plays an important role in the cell cycle in humans.

Explain the role of the cell cycle.

(2)

.............................................................................................................................................

(b) The p53 gene is called a 'tumour suppressor gene'. Cancers can form when the p53 gene
does not function properly. UV light can cause mutations in this gene. The mutant gene results in
the production of p53 mutant cells which may become cancerous.

(i) Name one environmental factor, other than UV light, that can cause a cell to become
cancerous.

(1)

.............................................................................................................................................

(ii) Suggest how the cell cycle will be affected in cells that have become cancerous.

(2)

.............................................................................................................................................

(c) In an investigation, isolated skin cells were exposed to UV light for different lengths of time.
The number of p53 mutant cells produced was recorded.
The graph below shows the effect of UV light on the number of p53 mutant cells produced.

(i) Use the graph to find the number of p53 mutant cells produced after an exposure time of 12
a.u.

(1)

.............................................................. a.u.

(ii) Using the information in the graph, describe the effect of exposure to UV light on the number
of p53 mutant cells produced.

(3)

.............................................................................................................................................

(iii) Name the type of cell division responsible for the increase in number of the p53 mutant cells.

(1)

.............................................................................................................................................

(d) When cells divide out of control to produce a tumour, the cells may not become specialised.

Describe the process by which cells usually become specialised following cell division.

(3)

.............................................................................................................................................

.............................................................................................................................................
.............................................................................................................................................

.............................................................................................................................................

(Total for question = 13 marks)

Q4.

Active transport and facilitated diffusion are two ways in which some molecules can move
through cell membranes.

High concentrations of sodium chloride in blood plasma can damage red blood cells.

Explain the effects on red blood cells of high concentrations of sodium chloride in blood plasma.

(3)

.............................................................................................................................................

(Total for question = 3 marks)

Q5.

The questions below refer to some important biological molecules.

Place a cross in the most appropriate box that describes the structure or role of these
biological molecules.

(a) Disaccharides can be split by

(1)

A hydrolysis of glycosidic bonds

B condensation of glycosidic bonds

C hydrolysis of ester bonds

D condensation of ester bonds

(b) Amylose is an example of a

(1)

A monosaccharide

B disaccharide

C polysaccharide

D trisaccharide

(c) The role of starch is to

(1)

A be a source of energy to plants

B store energy in all living organisms

C store energy in plants

D store energy in animals

(d) Proteins are polymers of amino acids joined by peptide bonds formed between the

(1)

A R groups
B R group and the amino group

C R group and the carboxyl group

D carboxyl group and the amino group

(e) The three-dimensional structure of a protein is held together by

(1)

A peptide, hydrogen and ionic bonds

B hydrogen, ester and ionic bonds

C disulphide bridges and ester bonds

D disulphide bridges, hydrogen and ionic bonds

(f) DNA consists of mononucleotides joined together by bonds between

(1)

A two pentose sugars

B one ribose sugar and one phosphate group

C one deoxyribose sugar and one phosphate group

D two phosphate groups

(g) Water is described as a dipolar molecule because it has a

(1)

A positively charged hydrogen end and a negatively charged oxygen end

B positively charged hydrogen end and a positively charged oxygen end

C negatively charged hydrogen end and a negatively charged oxygen end

D negatively charged hydrogen end and a positively charged oxygen end

(Total for question = 7 marks)

Q6.

Insulin is a protein produced by beta cells in the pancreas. Insulin is synthesised on

ribosomes, then modified and packaged in vesicles. It is stored in these vesicles until
it is secreted.

The diagram below shows the organelles involved in this process of modifying and
packaging the insulin in vesicles.

*
Using the information in the diagram, describe how insulin is modified, packaged
and secreted by the cell.

(4)

.............................................................................................................................................

.............................................................................................................................................
Q7.

Protein synthesis in cells involves molecules of DNA and RNA.

(a) The table below describes some features of the molecular structure of DNA and RNA. Place a
tick ( ) in the box next to each statement to show whether it applies to DNA only, RNA only or
to both DNA and RNA.

(2)

(b) The diagram below shows the sequence of the last six amino acids in a protein molecule.

The tRNA anticodon that corresponds to each amino acid is also shown.

Using this information, explain how each of the following processes leads to the synthesis of this
sequence of amino acids.

(i) The formation of mRNA during transcription in the nucleus

(3)

.............................................................................................................................................

(ii) The translation of mRNA into the sequence of amino acids in a ribosome

(3)

.............................................................................................................................................

(c) Suggest why the final triplet of nucleotides, on the strand of mRNA involved in the synthesis
of this sequence of amino acids, did not correspond with any anticodon on tRNA.

(2)

.............................................................................................................................................

(Total for question = 10 marks)

Mark Scheme

Q1.
Q2.
Q3.
Q4.
Q5.
Q6.

Q7.
Powered by TCPDF (www.tcpdf.org)
Week 2
Respiration
Draw the structure of the inner mitochondrial membrane. Annotate What does RQ tell you? Define:
with the process of oxidative phosphorylation. Substrate level phosphorylation:-

How do you calculate Respiratory

quotient (RQ)?
Decarboxylation:-

What do the different values mean?

Oxidation:-

Draw then summarise lactate fermentation in 2 What is a respirometer?

Reduction:-
sentences only.

Describe how a respirometer shows the rate of oxygen

uptake in mm3/min-1:
Chemiosmosis:-

Draw then summarise ethanol fermentation in 3 Why should the experiment be carried out in a water
sentences only. bath? Proton gradient:-

What ‘experimental control’ should be set up and why?

Electron transport chain:-

Explain the importance of fermentation to anaerobic

respiration. Respiratory Quotient:-
What are the three stages of aerobic respiration? List all the coenzymes required for aerobic Draw the labelled structure of a mitochondrion.
respiration and explain the role of each molecule.

Which of these stages still occurs during anaerobic

respiration?

Which stages produce carbon dioxide?

Summarise the link reaction in 2 sentences including Draw the process of glycolysis and summarise the
its location. Respiration Revision net products.

Draw the Krebs cycle. Summarise the net products.

With reference to the particular stage of respiration,

explain why oxygen is required for aerobic
respiration.

Now summarise the process in 5 bullet points only.

Why is the rate of respiration temperature

dependent?

Where does glycolysis take place?

Questions

Q1.

Respiration is a vital process in living organisms.

All organisms carry out glycolysis. The Krebs cycle also occurs in some organisms.

(a) The diagram below shows some of the stages in glycolysis, using the hexose sugar glucose.

Name the molecules R and S shown in the diagram.

(2)

Molecule R ...........................................................

Molecule S ...........................................................

(b) The diagram below shows some of the stages in the Krebs cycle.
(i) Name molecule T and use the information in the Krebs cycle diagram to give a reason for your
answer.

(2)

.............................................................................................................................................

(ii) Using information in the diagram, suggest what would happen in the Krebs cycle if acetyl CoA
became unavailable.

(3)

.............................................................................................................................................

(b) The hydrogen (H) from the Krebs cycle enters the electron transport chain and oxidative
phosphorylation occurs.
Explain what is meant by the term oxidative phosphorylation.

(3)

.............................................................................................................................................

(Total for question = 10 marks)

Q2.

Florence (Flo-Jo) Griffith-Joyner's world record of 10.49 seconds for the 100 m women's sprint in
1988 is unbeaten.

In this short time, a sprinter such as Flo-Jo could not deliver enough oxygen to her muscles to
maintain aerobic respiration.

*(a) Describe how a sprinter is able to release sufficient energy for the 100 m sprint without
having enough oxygen available for her muscles.

(6)

.............................................................................................................................................

(b) (i) Lactate (lactic acid) can build up in the muscles of a sprinter. Suggest why the build-up of
lactate may prevent any further increase in speed.

(2)

.............................................................................................................................................

(ii) Explain the fate of lactate following a sprint.

(4)

.............................................................................................................................................

.............................................................................................................................................
(Total for question = 12 marks)

Q3.

Carrots are root vegetables that are eaten by many organisms.

An investigation was carried out to study the respiration rate of carrots.

100 g of carrot cubes were placed in a plastic bag containing air. The bag containing the carrot
cubes was stored at 1 °C for three days.

All other variables were kept constant.

The percentages of oxygen and carbon dioxide in the bag were measured at the start of the
investigation and at the end.

The results are shown in the table below.

(a) (i) Suggest two variables, other than temperature, that need to be kept constant in this
investigation so that valid results can be collected.

(2)

.............................................................................................................................................

(ii) Explain the role of oxygen in the cells of the carrot cubes.

(3)

.............................................................................................................................................

(b) Explain how the carrots produce carbon dioxide at the start of this investigation.

(4)

.............................................................................................................................................

(c) The investigation was repeated at storage temperatures of 5 °C and 10 °C.

The table below shows the change in percentage of carbon dioxide in the bag at the end of the
investigation compared with the start of the investigation for all three storage temperatures.
Explain the effect of temperature on the change in the percentage of carbon dioxide in the bag.

(3)

.............................................................................................................................................

(d) Suggest why the carrot tissue could survive when no oxygen was left in the bag.

(1)

.............................................................................................................................................

(Total for question = 13 marks)

Q4. Respiration is a metabolic process which consists of many steps.

(a) The diagram below shows three steps in respiration.

Each box represents a different substance and each step involves an enzyme.
Describe and explain the functions of enzymes in this metabolic process.

(4)

.............................................................................................................................................

(b) The diagram below shows the electron transport chain, which is part of aerobic respiration.

(i) Using the diagram and your own knowledge, describe the role of carrier B.

(3)

.............................................................................................................................................

(ii) Name structure X and explain its role in aerobic respiration.

(3)

.............................................................................................................................................

(c) The diagram below shows a respirometer used to measure the rate of aerobic respiration in
small organisms.
Potassium hydroxide absorbs carbon dioxide.

The table below describes three different situations.

Place a cross in the box that correctly shows the movement of the coloured liquid in the
U-shaped tube for each situation.

(3)

(Total for Question = 13 marks)

Q5.

The tissues of some animals can carry out anaerobic and aerobic respiration.

Three investigations were carried out to study respiration in an animal tissue,

using the apparatus shown below.

The tissue used glucose as the respiratory substrate.

All other variables were kept constant.

The table below shows the three investigations that were carried out and the result
for investigation 1.

(i) Complete the table by placing a cross in one box for each of investigations
2 and 3 to show the response of the coloured liquid.

(2)

(ii) Explain why the coloured liquid did not move in investigation 1.

(3)

.............................................................................................................................................

(iii) Reduced NAD (NADH + H+) would be formed in investigations 2 and 3.

Describe the fate of reduced NAD in aerobic respiration.

(4)

.............................................................................................................................................

Mark Scheme
Q1.
Q2.
Q3.
Q4.
Q5.
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Week 3
Animal
transport +
exchange
Summarise the reversible reaction used to Describe the structure of haemoglobin: 1. Sketch the shape of the oxygen dissociation curve in the Key terms to define:
transport and deliver oxygen below: space below. Remember to label the axis appropriately.
Haemoglobinic acid
2. Highlight which regions represent… The alveoli, resting
tissues and heavily respiring tissues.
Chloride shift

Use the red blood cells shown below to summarise Carbominohaemoglobin

the reactions used to transport carbon dioxide
safely: What happens to the structure as oxygen binds?

AT RESPIRING TISSUES Hydrogen carbonate ions

What is this called? Carbonic acid

Carbonic anhydrase
1. On a separate piece of paper, draw out
the structure of the heart. Ensure it is
fully labelled including adjoining blood Now add a line to show fetal haemoglobin’s affinity
for oxygen compared to adult haemoglobin on the Positive cooperation
vessels and coronary arteries.
2. Write out the route that a RBC would same graph.
take round the heart and body starting in What is the significance of the line being positioned
Bohr effect
the right atrium. in this way?
3. Why is the left side of the heart
thicker?
AT THE LUNGS Affinity
4. Why is it important that the septum
separates the different sides of the
heart? Draw and label an ECG trace in the space below: Diastole
5. Describe what happens to the heart
during…
A) Atrial systole
Systole
B) Ventricular systole
C) Diastole

SAN
On the graph, label the points at which…

A) The AV valves close

B) The semi-lunar valves open AVN
C) The semilunar valves close
D) The AV valves open
Myogenic
On a separate piece of paper, sketch an ECG of…
On the graph, label the points at which…
A) Tachycardia
The first LUB and second DUB sound is B) Bradycardia ECG
produced in a heartbeat. C) Atrial fibrillation
D) Ectopic heartbeat
Describe the similarities and differences Blood vessels can contain many different
Give 3 reasons why multicellular animals Describe the similarities and differences layers/fibres. The layers are listed below.
between single and double closed circulatory
require transport systems: between open and closed circulatory systems: State the function of each layer of the blood
systems:
Sim: Diff: vessel:
• Sim: Diff:
Collagen:

Smooth muscles:
•

What’s meant by a ‘mass transport system’? Elastin:

Give the function of each component of blood: Endothelium:

Plasma:

Platelets:
What is vasodilation and why might it need to be done?
Give 3 ways blood flow assisted in veins: Red blood cells:

1. Leucocytes (WBCs):

What is vasoconstriction and why might it need to be done?

2. Transport in Animals - End of Unit Revision

Chapter 8
3.
Which blood vessels control these two responses?

Comparison Arteries Arterioles Capillaries Venules Veins

Function

Collagen present? If so how much?

Smooth muscle present? If so how
much?
Elastin present? If so how much?
Valves present? Why?

Lumen size

Key Term Definitions

How does tissue fluid form at the arteriole end of capillaries?
Haemocoel

Haemolymph

Oncotic pressure
How is tissue fluid reabsorbed and waste substances removed at the Venuole end of capillaries?
Hydrostatic pressure

Albumin

Lymph
Give 3 functions of the lymphatic system:
Fenestrations
Questions
Q1.

An investigation was carried out to study the effect of caffeine on the heart rate of a chicken embryo.
The heart from a chicken embryo was removed and placed in a glucose solution. The heart rate was
determined and recorded as the base heart rate.
The experiment was repeated using glucose solutions containing five different concentrations of
caffeine.
The heart rate was determined and recorded as a percentage of the base heart rate for each solution.
The graph below shows the results of this investigation.

(a) (i) Suggest why glucose was included in the solutions.

(2)
.............................................................................................................................................

.............................................................................................................................................

(ii) Suggest how the caffeine solutions were prepared to obtain valid results.
(1)
.............................................................................................................................................

.............................................................................................................................................

(iii) State how these results could be made more reliable.

(1)
.............................................................................................................................................

.............................................................................................................................................

(iv) Using the information in the graph, describe the effect of caffeine on the heart rate of the chicken
embryo.
(3)
.............................................................................................................................................

.............................................................................................................................................

(b) (i) Describe how this investigation could be carried out using Daphnia instead of chicken embryos.
(4)
.............................................................................................................................................

.............................................................................................................................................

(ii) Suggest one ethical issue in the use of chicken embryos in this investigation.
(1)
.............................................................................................................................................

.............................................................................................................................................

.............................................................................................................................................
(Total for question = 12 marks)
Q2.

Read through the following passage on the cardiac cycle, then write on the dotted lines the most
appropriate word or words to complete the passage.
The cardiac cycle consists of three stages: atrial systole, ventricular systole and

..................................................................................... .

During atrial systole, the ..................................................................................... contract and the

..................................................................................... are relaxed. The

..................................................................................... valves are open.

During ventricular systole, the ..................................................................................... open as oxygenated

blood is

forced out of the heart through the aorta to the body and through the pulmonary

..................................................................................... to the lungs.

(Total for question = 6 marks)
Q3.

Cardiac muscle is myogenic.

The rhythmic contraction of the heart, in a particular sequence, is a feature of the cardiac cycle.
(a) Explain what is meant by the term myogenic.
(2)
.............................................................................................................................................

.............................................................................................................................................

.............................................................................................................................................
*(b) Describe how the sequence of muscular contraction in the heart is coordinated and how the
movement of blood through the heart is controlled.
(6)
.............................................................................................................................................

.............................................................................................................................................

.............................................................................................................................................
(Total for question = 8 marks)

Q4.

The mammalian lung is adapted for efficient gas exchange.

Describe how the following feature assists in producing an efficient gaseous exchange system.

The lungs are composed of many alveoli. A dense network of capillaries covers the outside of each
alveolus.
(3)
.............................................................................................................................................

.............................................................................................................................................

(Total for question = 3 marks)

Q5.

When exercise begins, both ventilation rate and heart rate increase. This supplies more oxygen to
muscles.
(a) (i) Describe how breathing rate and tidal volume can be determined from a spirometer trace.
(3)
.............................................................................................................................................

.............................................................................................................................................

.............................................................................................................................................
(ii) Explain how you would use breathing rate and tidal volume to calculate ventilation rate.
(1)
.............................................................................................................................................

.............................................................................................................................................

.............................................................................................................................................
(b) An investigation was carried out to study the changes in oxygen uptake by the blood in the lungs
after the first ten seconds of exercise.
Men with artificial pacemakers agreed to exercise with their heart rate controlled at 50 beats per
minute. The ventilation rate and the oxygen uptake at rest were measured. These were also measured,
after the first ten seconds of exercise and the differences recorded.
This was repeated with the heart rate controlled at 100 beats per minute.
The results are shown in the table below.

(i) State one factor, other than heart rate, that could have affected the rate at which blood passed
through the heart.
(1)
.............................................................................................................................................

.............................................................................................................................................
(ii) Using the information in the table, describe the effect of an increase in heart rate on both the
ventilation rate and oxygen uptake by the blood, after the first ten seconds of exercise.
(3)
.............................................................................................................................................
.............................................................................................................................................

.............................................................................................................................................

.............................................................................................................................................
(iii) Explain how an increased heart rate results in increased uptake of oxygen by the blood in the
lungs.
(3)
.............................................................................................................................................

.............................................................................................................................................

.............................................................................................................................................
(iv) What conclusions could be drawn from the results of this investigation?
(2)
.............................................................................................................................................

.............................................................................................................................................

.............................................................................................................................................
(Total for question = 13 marks)
Q6.

A human heart can work effectively for over a hundred years but many people
throughout the world have heart problems.

Explain how the sinoatrial node (SAN) ensures that oxygenated blood enters the
aorta.
(4)
.............................................................................................................................................

.............................................................................................................................................

.............................................................................................................................................
Q7.
Some species of flatworm are found in freshwater streams.
Flatworms obtain oxygen from the water through the surface of their bodies.
The diagram below shows the structure of flatworms.

(a) Using the diagram and your knowledge of gas exchange surfaces, explain how the structure of a
flatworm is adapted to obtain oxygen from the water.
(2)
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................

(b) The table below shows the relationship between the temperature of water and the solubility of
oxygen in water.
(i) Describe the relationship between the temperature of the water and the solubility of oxygen in
water.
(2)
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................

(ii) Using the information in the table and your knowledge of gas exchange and enzymes, suggest
why flatworms are often found in water at a temperature of about 15 °C .
(3)
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................

(c) Flatworms do not have a heart or a circulatory system.

Explain why many animals need a heart and a circulatory system.
(4)
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................

(Total for Question = 11 marks)

Q8.

Blood is carried around the body of many animals in different types of blood vessels. The structures of
these blood vessels relate to their function.
(a) The table below refers to the structure of capillaries and veins. If the statement is correct, place a
tick ( ) in the appropriate box and if the statement is incorrect, place a cross ( ) in the appropriate
box.

(b) Semilunar valves and elastic fibres are found in the aorta. For each of these structures, describe its
location in the aorta and explain its function.
Semilunar valves
(3)
Location

.............................................................................................................................................

Function

.............................................................................................................................................

.............................................................................................................................................
Elastic fibres
(3)
Location

.............................................................................................................................................

Function

.............................................................................................................................................

.............................................................................................................................................
(Total for question = 9 marks)
Mark Scheme
Q1.
Q2.

Q3.
Q4.
Q5.
Q6.
Q7.
Q8.
Week 4
Membranes
and cell
division
Label the diagram below with the phases of What is the purpose of the following checkpoints? How do you calculate mitotic index? Give definitions for:
the cell cycle (including G0). Annotate with G1 checkpoint Specialised cell
what happens during each phase.

Name a type of plant tissue where cells in Tissue

mitosis can be observed.
G2 checkpoint
Organ

Explain the difference between haploid and

Spindle/metaphase checkpoint. Organ system
diploid cells.

How does cytokinesis differ in animal and

OCR AS Level Biology: Cell Division, Cell Cycle and Specialisation
plant cells?

Stages of Mitosis Cytokinesis

Prophase Metaphase Anaphase Telophase

Where do spindle fibres extend from?

Where do spindle fibres attach?

Diagram
Give 2 reasons why mitosis is important to
animals
1.
2.

Explain why mitosis is important to

reproduction

Description
What can happen to cells whose check points are not functioning correctly?
What is a stem cell? What is the difference between adult and What is meristem tissue and Key Term Definitions
embryonic stem cells in humans? where do you find it in plants? Chromosomes
How do stem cells become specialised
cells?
Sister Chromatids
Give some uses of embryonic stem cells:

Chromatin
Explain the difference between the following Explain how plant stem cells are
types of stem cell: different to those in humans.
Centromere
Totipotent:
Give some ethical considerations surrounding the
use of embryonic stem cells:
Telomere
Pluripotent:

Cell potency
Multipotent:

Homologous pair

Stages of Meiosis On a separate piece of

Prophase I Metaphase I Anaphase I Telophase I
paper, give the function and Chiasmata
description of the following
tissue types:
Crossing over
Squamous epithelia
Ciliated epithelia
Independent assortment
Muscle

Description
Prophase II Metaphase II Anaphase II Telophase II Cartilage
Reduction division
Xylem
Phloem

Give some differences between mitosis and meiosis:

Description
Explain how genetic variation arises during meiosis.
On a separate piece of paper, draw a diagram and give the function/description of the following
specialised cell types: Erythrocytes, Neutrophils, Squamous and Ciliated epithelial cells, sperm cells,
palisade cells, root hair cells and guard cells.
Defintions→ Hypertonic solution: Isotonic solution: Hypotonic solution: Exam technique: Describing the effect of different concentration solutions on cells:
1. State where the higher/lower water potential is (inside or outside the cell), and the kind of solution the cells
are in.
E.g. “There is a lower water potential outside the plant as the solution is hypERtonic”
Animal cells 2. State which direction the water is moving by osmosis
(diagram and E.g. “The water moves from high to low water potential out of the plant cell across the plasma membrane by osmosis”
description): 3. State what happens to the cell/plant
E.g. “The cell loses water and shrinks, the cell membrane pulls away from the cell wall causing the plant to wilt”
4. Give the name of the process e.g.
E.g. “so the cell has become plasmolysed”
Plants cells
(diagram and Sometimes large molecules or substances need transport via bulk transport. This can be via endocytosis or exocytosis. Describe the two process
description): AND explain how they are different.

Write a brief method to show how you would practically determine the water potential or
concentration inside potato cells using the following equipment: potato, test tubes, knife, ruler,
borer, distilled water, test tubes, timer, scales, paper towel, pencil, graph paper.
The experiment described in the box to the left can also be done Describe how the plasma membrane can be involved in cell signalling.
using model cells instead of potatoes. The model cells are made from
visking tubing. Why is visking tubing used to make the model cells? Use the following terms in your answer; ligand, receptor, glycoprotein,
shape, specific, intracellular response

What is a selectively permeable membrane?

For the investigation described above, what would the following variables be?

Independent: Sketch what a graph of results might look like for the potato
Explain WHY animals and plant cells respond differently when placed in
experiment and annotate with where you find the concentration of
solutions of different water potential:
the cytoplasm inside the potato:
Dependent:

Control:
Cells contain many membranes, their plasma Use this space to draw and label all the components of the fluid mosaic model Give the function of… Explain how some components of a plasma membrane are involved in cell-
membrane as well as many intracellular of membranes: cell signalling and a cellular response.
Phospholipid bilayers:
membranes. List all the functions of membranes in a
Try and use the following terms in your answer; ligand, receptor, signal transduction,
cell: Cholesterol: glycolipid.
• Channel proteins:
•
• Carrier proteins:
• Glycolipids
•
Glycoprotein:

Fluidity is how mobile the membrane is. The more fluid the membrane, Intrinsic proteins:
the more gaps in phospholipids appear and the more permeable it Extrinsic proteins:
becomes. How do the following affect fluidity and permeability?

1. Temperature Diffusion definition: Explain the difference between channel proteins and carrier proteins:
2. Solvents (like detergents/alcohol)
3. Lipid saturation
4. Cholesterol
What is the difference between simple diffusion and facilitated diffusion? What is a concentration gradient?

Write a brief method for how you would practically investigate

whether temperature affects membrane permeability using the
following equipment; beetroot, colorimeter, water baths, knife, ruler, How do the following impact the rate at which diffusion across a membrane occurs?

borer, cuvettes, distilled water, test tubes, timer. • Surface Area

How do you calculate % change? AS Level Biology
• Temperature
Biological Membranes revision
• Concentration Gradient
How do the following move across a Write a definition for active • Diffusion distance
membrane? transport:

-Small polar molecules

Outline the differences between active transport and diffusion:

-Small non-polar molecules

How does ATP interact with

proteins in the membrane during
-Chloride ions (Cl—)
active transport?

-Carbon dioxide/oxygen
What is meant when we say that a process goes What is the symbol for water potential?
‘down’ or ‘against’ a concentration gradient?
What is the water potential of distilled
water like?
For the investigation described above, what would the following variables be? What does water potential mean?
Do these processes go ‘down’ or ‘against’ a
Independent:
concentration gradient?
What is the water potential of a
Osmosis concentrated solution like?
Dependent: Give a definition for osmosis: Active Transport

Facilitated diffusion What does the presence of solute do to

Control: water potential?
Simple diffusion
Questions
Q1.

Molecules are transported across the cell membrane in a number of different ways.

(a) Describe the structure of a cell membrane.

(3)

.............................................................................................................................................

(b) Cells were placed in a solution containing two different solutes, solute P and solute R.

The diagram below represents the concentration of the two solutes outside one of the cells,
when this cell was placed in the solution.

The cells were left in the solution for 50 minutes.

The diagrams below represent the concentrations of the two solutes, inside and outside the cell
after 10, 20, 30 and 40 minutes in the solution.

(i) Using the information in the diagrams, describe the changes that have taken place in the
concentrations of solute P and solute R, in the 40 minute period.

Suggest an explanation for these changes.

(5)

.............................................................................................................................................

(ii) Complete the diagram below, to show the concentration of solute P and solute R inside and
outside the cell, after 50 minutes.

(1)

(Total for question = 9 marks)

Q2.

The cell vacuoles of beetroot (Beta vulgaris) contain the red pigment betalain.

A student investigated the effect of temperature on the permeability of beetroot cell

membranes.

In this investigation, five pieces of beetroot were used. One piece of beetroot was left in 10 cm3
of distilled water for
20 minutes at 20 °C.

After 20 minutes, the piece of beetroot was removed and the intensity of the colour of the water
was measured using a colorimeter.

This was repeated with the other pieces of beetroot using water temperatures of 40 °C, 60 °C,
80 °C and 90 °C.

(a) The student's results are shown in the graph below.

(i) Using the information in the graph, describe the effect of temperature on the permeability of
the cell membranes.

(2)

.............................................................................................................................................

(ii) Using the information in the graph and your knowledge of membrane structure, explain the
effect of temperature on the cell membranes.

(3)

.............................................................................................................................................

*(b) Using all the information given in the question, describe how this investigation could be
carried out to provide valid and reliable results.

(5)

.............................................................................................................................................

(Total for question = 10 marks)

Q3.

One function of the cell membrane is to control which molecules can enter or leave the cell.

The diagram below represents the structure of the cell membrane.

(a) For each of the statements below, put a cross in the box that corresponds to the correct
statement.

(i) The phospholipids form a bilayer because

(1)

A the hydrophobic heads dissolve in the aqueous (water) environment

B the hydrophobic heads move away from the aqueous environment

C the hydrophobic tails dissolve in the aqueous environment

D the hydrophobic tails move away from the aqueous environment

(ii) The protein, labelled in the diagram, could be involved in

(1)

A endocytosis

B exocytosis

C facilitated diffusion

D phagocytosis

(iii) The fluidity of the membrane is determined by the proportion of

(1)

A cholesterol

B glycoprotein

C phospholipid

D protein

(b) A student carried out an experiment to investigate the effect of temperature on the
permeability of beetroot membranes. Beetroots are root vegetables that appear red because the
vacuoles in their cells contain a water-soluble red pigment. This pigment cannot pass through
membranes.

Six cubes of beetroot were cut. One piece of beetroot was placed into a tube containing 10
3
cm of water and left for 20 minutes at 5 ºC. After the 20 minutes, each piece of beetroot was
removed from the tubes and the colour of the fluid recorded.

The procedure was repeated at five other temperatures.

The results are shown in the table below.

Using the information in the table, describe the effect that temperature has on the permeability
of the membranes of the beetroot cells.

(2)

.............................................................................................................................................

(c) A second student carried out a very similar experiment, using three samples of beetroot at
each temperature. She used a colorimeter to determine the intensity of the colour of the fluid
produced.

The results of her experiment are shown in the table below.

(i) State two variables that both of these students must keep the same if their results are to be
compared.

(2)

1
.............................................................................................................................................

.............................................................................................................................................

(ii) Give two reasons why the results obtained by the second student are more reliable than
those of the first student.

(2)

.............................................................................................................................................

(iii) In the first student's experiment at 5 ºC, the fluid was pale pink but the fluid in the second
student's experiment was colourless.

Suggest an explanation for this difference.

(2)

.............................................................................................................................................

(iv) Each of the students used their own results to describe the effect of temperature on the
permeability of the membranes of the beetroot cells.

Suggest one way in which these two descriptions might differ.

(1)

.............................................................................................................................................

(Total for question = 12 marks)

Q4.

The size and solubility of molecules has an effect on their ability to be taken up by cells.

*(a) Describe an experiment you have carried out to investigate the permeability of cell
membranes.

(5)

.............................................................................................................................................

(b) An investigation was carried out into the permeability of a cell membrane to a number of
different non-polar, organic molecules. The molecules differed in their size and in their solubility
in oil compared with their solubility in water. The higher the solubility, the more soluble the
molecule is in oil compared with water.

The graph below shows the results of this investigation.

The size of the circle drawn on the graph indicates the size of the molecule; the larger the circle,
the larger the molecule.
(i) Describe what relationship, if any, there is between the permeability of this cell membrane
and the size of the molecules.

(1)

.............................................................................................................................................

(ii) Describe what relationship, if any, there is between the permeability of this cell membrane
and the solubility of the molecules in oil compared with water.

(1)

.............................................................................................................................................

(iii) Water is able to diffuse through a cell membrane, even though it is a polar molecule.

On the graph, draw a circle, labelled W, to indicate the permeability of the cell membrane to
water. The size of the circle should represent the size of the water molecule.

(2)

(iv) Use your knowledge of the structure and properties of cell membranes to explain the results
of this investigation.

(3)

.............................................................................................................................................

(Total for question = 12 marks)

Q5.

The stages of mitosis can be observed in cells from growing tissues.

The photograph below shows cells from an onion root tip, as seen using a microscope.

(i) Put a cross in the box next to the row that correctly identifies the stages of mitosis shown
in cell F and cell G.

(1)
(ii) The cells in the photograph are stained to make the chromosomes visible.

Name a stain that can be used to make chromosomes visible in a root tip.

(1)

.............................................................................................................................................

(Total for question = 2 marks)

Q6.

The stages of mitosis can be observed in cells from growing tissues.

The table shows the number of cells, in a root tip, observed at different stages of the cell cycle.

(i) Put a cross in the box next to the stage of mitosis most likely to be observed in this root
tip.

(1)

A anaphase

B metaphase

C prophase

D telophase

(ii) The mitotic index is the percentage of cells in a sample undergoing mitosis.

Calculate the mitotic index for the cells in the table.

Show your working.

(2)
........................................................... %

(Total for question = 3 marks)

Q7.

The stages of mitosis can be observed in cells from growing tissues.

Herbicides are chemicals used to kill weeds. Some herbicides work by disrupting the cell cycle.

An investigation was carried out to study the effect of different concentrations of the herbicide
Agil on mitosis in onion root tips.

Agil concentrations of 0.5 ppm, 1.0 ppm and 1.5 ppm were used. The roots of the onions were
exposed to these concentrations for 48 hours. A control was also used with no Agil present.

Root tip squashes were then prepared and the percentage of cells undergoing mitosis was
recorded for 150 cells for each slide examined.

The table below shows the results of this investigation.

(i) Using the information in the table, describe the effects of Agil concentration on mitosis in
onion root tips.

(2)

.............................................................................................................................................

(ii) The herbicide Agil also increased the number of chromosome abnormalities. These include
chromosome bridges, which prevent anaphase from completing normally.

The graph shows the effect of the concentration of Agil on the percentage of cells with
chromosome bridges.

Suggest how chromosome bridge formation could affect the production of gametes.

(2)

.............................................................................................................................................

(Total for question = 4 marks)

Q8.

The root tip squash procedure can be used to observe cells undergoing mitosis.

(a) Explain the role of mitosis in the development of roots.

(2)

.............................................................................................................................................

(b) (i) The flow chart below describes the stages involved in staining a root tip squash to show
mitosis.

Complete the flow chart by writing the most appropriate word or words on the dotted lines.

(3)

(ii) Describe one safety precaution that should be taken when carrying out this procedure.
(1)

.............................................................................................................................................

*(c) Following mitosis, some cells undergo differentiation to become specialised tissues, such as
xylem.

Explain how cells differentiate to become specialised tissues.

(4)

.............................................................................................................................................

(d) Similar staining techniques can be used to observe cells undergoing meiosis.

(i) Name a process that may be observed in cells undergoing meiosis but not mitosis.

(1)

.............................................................................................................................................

(ii) Explain how meiosis can give rise to genetic variation in the gametes produced.

(2)

.............................................................................................................................................

(Total for question = 13 marks)

Mark Scheme
Q1.
Q2.
Q3.
Q4.
Q5.

Q6.
Q7.
Q8.
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Week 5
Disease
Describe the four broad types of pathogen Explain four factors that
and list all the examples studied for each one. Describe the process of phagocytosis. Explain the difference between ‘direct’
influence disease and ‘indirect’ transmission.
transmission
Bacteria

•
Examples of direct transmissions;
Viruses •

• Example of indirect transmissions

Fungi
•

Protists
List the different diversity of lymphocytes and give their Describe some physical and chemical
functions: plant defences against disease:-
Draw a mind map of all the non specific primary
defences in animals. Describe how each one help to Physical Chemical
stop entry of pathogens.

Communicable disease
(Disease and Immunity)
What is the difference between…

The ‘cell mediated’ and ‘humoral’ response?

Draw and label the structure of an
antibody from memory:
The primary and secondary response?

Why does the primary response take longer than the secondary one ?

Draw a flow chart of the cell mediated response:- Draw a flow chart of the humoral response:-
Key Terms Using labelled diagrams and no more than 2 sentences for each, out line 4 ways that antibodies help to defend against disease .

Neutrophils- 1. 2. 3. 4.
Antigen-presenting cell-

Macrophage-

Major histocompatibility complex-

Opsonins-

Peforins-
Explain the difference between… Give an example of…
Callose-
Active Vs Passive immunity Artificial Vs Natural Immunity Active Artificial immunity-
Variable region-
Active Natural immunity-
Interleukins-
Passive Natural immunity-
Clonal Selection-
Passive Artificial immunity-
Clonal Expansion-

Autoimmune disease-
Two examples of resistant strains of bacteria are… Describe the process of vaccinations leading to
Pharmocogenomics- immunity:-
Synthetic biology- An opportunistic pathogen is…

Allele-
Herd immunity is..
Selection Pressure-

Selective toxicity- Antibiotic resistance can be reduced by…

Immunoglobulins- How could personalised medicine be given in the future?

How do antibiotics destroy bacteria?

Describe how antibiotic resistance develops:-

How do antibiotic resistant alleles become more

common?

Where do most medications come from?

Explain why seasonal flu vaccinations need to be
given:

Why is biodiversity important for drug discovery?

Questions

Q1.

A wound is an injury to living tissue.

Chronic wounds develop if the wound does not heal properly. These wounds may become
contaminated with bacteria.

Ulcers are chronic wounds. The table below shows the types of bacteria found in four different
types of ulcer.

(i) Use the information in the table to give three conclusions about the types of bacteria that
contaminate ulcers.

(3)

.............................................................................................................................................

(ii) Suggest the problems doctors face in prescribing antibiotics for ulcers.

(2)

.............................................................................................................................................

(Total for question = 5 marks)

Q2.

Infection with human immunodeficiency virus (HIV) can lead to the condition known as AIDS.
Patients with AIDS are very susceptible to infections caused by bacteria and viruses.

Phagocytosis by macrophages is a non-specific response to infection.

The ability of macrophages to carry out phagocytosis of bacteria was investigated.

Macrophages from patients with AIDS were compared with macrophages from people who did
not have AIDS.

These macrophages were obtained from the lungs of the individuals and incubated with bacteria
for 60 minutes. The mean number of bacteria per macrophage was recorded at the start of the
incubation period, after 30 minutes and after 60 minutes.

The results of this investigation are shown in the graph below.

It was concluded that there was no significant difference in the ability of these macrophages to
carry out phagocytosis.

Using the information in the graph, suggest why this conclusion was made.

(2)

.............................................................................................................................................

(Total for question = 2 marks)

Q3. Human diseases can be caused by many different types of organism, such as bacteria
and viruses.

(a) Give two differences between the genetic material of bacteria and viruses.
(2)

.............................................................................................................................................

(b) Tuberculosis (TB) is caused when droplets, containing the bacterium Mycobacterium
tuberculosis, are inhaled into the lungs.

In the lungs, large numbers of the bacterium are formed rapidly. These can be ingested by
macrophages. Eventually, tubercles (tissue masses), containing dormant bacteria inside
macrophages, may form.

(i) Describe how macrophages ingest the bacteria.

(2)

.............................................................................................................................................

(ii) Suggest why treatment with antibiotics may not be effective against the dormant bacteria in
the tubercles.

(2)

.............................................................................................................................................

(iii) TB can be prevented by vaccination. Explain how a person can develop artificial active
immunity following vaccination.

(3)

.............................................................................................................................................

(c) In a person with TB, the dormant bacteria in tubercles may be activated after several years.
The bacteria multiply rapidly, resulting in severe lung damage.

The bacteria are released from the tubercles. These bacteria can inhibit the activity of T cells
and infect other organs.

Explain why the activity of these bacteria and the inhibition of T cells means that a person may
quickly develop severe symptoms leading to death.

(4)

.............................................................................................................................................

(Total for Question = 13 marks)

Q4.

In the immune response, antibodies are produced that are specific to the antigens of
the pathogen causing the infection.

(a) Place a cross in the box next to the type of cell that produces antibodies as part
of the immune response.
(1)

A erythrocyte

B macrophage

C plasma cell

D thrombocyte

(b) In pigs, the disease known as post-weaning multisystematic syndrome (PWMS)

is caused by the PCV2 virus. Common symptoms of PWMS include weight loss,
breathing difficulties and enlargement of the lymph nodes. Most pigs diagnosed
with PWMS will have to be destroyed.

A new vaccine has been developed to give gilts (female pigs having their first
pregnancy) active immunity against PWMS. To test this vaccine, gilts were divided
into two groups, A and B.

Group A gilts were vaccinated against PWMS on day 0, at the start of pregnancy.
A second vaccination was given on day 20. A final vaccination was given on
day 140, approximately 20 days before they were due to give birth.

Group B gilts were given no vaccine.

The graph below shows the results of blood tests to measure the concentration of
PCV2 antibodies in these two groups.

(i) Describe how the vaccine gives active immunity against PWMS.

(3)

.............................................................................................................................................

(ii) Apart from having no vaccine, suggest how group B should be treated during
the test. Give reasons for your answer.

(3)

.............................................................................................................................................

(iii) Compare the changes in concentrations of PCV2 antibodies in the blood of

the two groups of gilts during pregnancy.

(3)

.............................................................................................................................................

.............................................................................................................................................
(iv) The table below shows the concentration of PCV2 antibodies detected in
the piglets produced by the two groups of gilts, during the first 40 days after
birth.

Age of piglets Concentration of PCV2 antibodies

/ days / arbitrary units
Group A piglets Group B piglets
0 3.9 0.7
10 3.2 0.8
20 3.0 2.6
40 2.9 2.9

Suggest reasons for the changes in the concentrations of PCV2 antibodies in

group A and group B piglets.

(3)

.............................................................................................................................................

(Total for question = 13 marks)

Q5. Bacteria and viruses can cause human diseases.

(a) Distinguish between the structure of bacteria and viruses

(3)

.............................................................................................................................................

(b) Infection with a bacterium can result in the development of active immunity to that
bacterium. This results in the production of antibodies by plasma cells.

(i) Describe how infection with a bacterium results in the production of plasma cells.

(4)

.............................................................................................................................................

(ii) Explain how antibodies help a person to recover from an infection.

(2)

.............................................................................................................................................

(iii) A person who has had an organ transplant has to take immunosuppressive drugs. This
prevents the immune system from destroying the organ transplant. Some of these drugs work by
inhibiting the production of cytokines.

Suggest what effect these drugs could have on a person infected with a bacterium or a virus.

(4)

.............................................................................................................................................

(Total for Question = 13 marks)

Q6.

An investigation was carried out to study the antimicrobial properties of garlic.

A piece of garlic was crushed with 5 cm3 of sterile water to form a full-strength extract.

Two sterilised paper discs were each soaked in the full-strength extract. Both discs were placed
on an agar plate covered in the bacterium Micrococcus luteus. This plate was incubated at 25 ºC
for 24 hours.

After this time, the diameter of the zone of inhibition around each disc was measured and the
mean diameter was calculated.

This procedure was repeated using different dilutions of the full-strength extract.

The results of the investigation are shown in the table below.

(a) Using the information in the table, describe the effect of the concentration of garlic extract
on the mean diameter of the zone of inhibition.

(3)

.............................................................................................................................................

(b) Suggest which concentration of garlic extract has the strongest antimicrobial properties. Give
an explanation for your answer.

(3)

.............................................................................................................................................

(c) Suggest a suitable control for this investigation.

(1)

.............................................................................................................................................

(d) The discs were sterilised by being placed in alcohol and then left to dry before being soaked
in the extract.
Suggest why the discs should be sterilised before being soaked in the extract.

(2)

.............................................................................................................................................

(e) Suggest how the results in the table might have been different if the discs had not been
allowed to dry after being placed in alcohol. Explain your answer.

(2)

.............................................................................................................................................

(Total for question = 11 marks)

Q7.

Various non-specific responses of the body are involved in resistance to bacterial infections.

(a) Histamine, interferon and lysozyme are three substances involved in non-specific responses
to infection.

For each of the following statements, put a cross in the box next to the name of the substance
involved.

(i) Enzyme released in secretions that break down the cell walls of bacteria.

(1)

A Histamine

B Interferon

C Lysozyme
(ii) Inflammation caused by a chemical released by white cells in connective tissue.

(1)

A Histamine

B Interferon

C Lysozyme

(b) The flow diagram below summarises some of the stages of phagocytosis, a non-specific
response to a bacterial infection.

(i) Identify D, E, F, G and H by writing appropriate terms in the spaces below.

(5)

D ..................................................................................................................

E ..................................................................................................................

F ..................................................................................................................

G ..................................................................................................................
H ..................................................................................................................

(ii) Explain why the processes shown in the flow diagram will only happen in response to some
types of bacteria.

(3)

.............................................................................................................................................

(Total for question = 10 marks)

Mark Scheme

Q1.
Q2.

Q3.
Q4.
Q5.
Q6.
Q7.
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Week 6
Nervous
communication
Questions

Q1.

The diameter of the pupil in the eye is controlled by a nerve pathway.

This nerve pathway contains several neurones.

The diagram below shows a motor neurone and a cell labelled T.

(i) Put a cross in the box next to the correct statement about motor neurones in this pathway.

(1)

A motor neurones transmit action potentials towards the central nervous system

B motor neurones are the only type of neurone to have a cell body

C all motor neurones terminate on effector cells

D motor neurones have shorter axons than relay neurones

(ii) Put a cross in the box next to the name of the main substance found in the part labelled
Q.

(1)

A amylose

B myelin

C myosin

D thylakoid

(iii) The membrane of the neurone is exposed at the point labelled R.

Put a cross in the box next to the correct statement about this part of the membrane.

(1)

A it can become depolarised

B it has a resting potential of +70 mV

C it is part of an inhibitory synapse

D it is thinner at this point

(iv) Explain the role of the part labelled S in the stimulation of cell T.

(3)

.............................................................................................................................................

(Total for question = 6 marks)

Q2. (a) The diagram below shows a motor neurone.

(i) Name the structure labelled P.

(1)

.............................................................................................................................................

(ii) Place a cross in the box to identify the direction of the nerve impulse in the axon of this
motor neurone.

(1)

(b) Eugenol is a drug that inhibits the movement of sodium ions through the cell surface
membranes of sensory neurones.

The table below shows the effect of eugenol concentration on the percentage inhibition of
sodium ion movement.
(i) Describe the effect of eugenol on the percentage inhibition of sodium ion movement.

(2)

.............................................................................................................................................

(ii) Using information from the table, calculate the percentage inhibition of sodium ion
movement at a concentration of eugenol of 0.8 mmol dm−3.

Show your working.

(2)

Answer.....................................................................%

*(c) Eugenol can be used to reduce pain.

Suggest an explanation for how eugenol affects the movement of sodium ions and reduces pain.

(6)

.............................................................................................................................................

(Total for Question = 12 marks)

Q3.

In some organisms, the nervous response to a stimulus can reduce as a result of repetition. This
is known as habituation.

Sea slugs are marine animals which have gills for the uptake of oxygen from seawater.

A sea slug withdraws its gill when its skin is touched. After some time, the gill is exposed again.
With repeated touches, the time taken for it to expose the gill decreases. When the skin is
touched frequently, the gill is not withdrawn.

The diagram below shows some of the neurones (nerve cells) involved in this response.

(a) Place a cross in the correct box in the table below to identify where structures A, B, C and
D, listed in the table, are shown on the diagram.

(3)
(b) (i) Suggest how a repeated stimulus could result in less response from the gill.

(3)

.............................................................................................................................................

(ii) Suggest how this habituation may be of benefit to a sea slug.

(2)

.............................................................................................................................................

(Total for question = 8 marks)

Q4.

(a) The graph below shows the changes in potential difference across the membrane of a
neurone after stimulation.
(i) Using the information in the graph, state the maximum change in potential difference across
the membrane of this neurone during depolarisation.

(1)

.............................................................. mV

(ii) The table below describes three of the stages shown in the graph.

Place a cross in the box ( ) below the letter that correctly links the description to one of the
labels on the graph above.

(3)

*(b) When a nerve impulse reaches a synapse, calcium ions enter the neurone through the
pre-synaptic membrane. This causes a neurotransmitter, such as acetylcholine, to be released.

Describe and explain the sequence of events that occurs at the synapse, after a
neurotransmitter has been released.

(5)

.............................................................................................................................................

(Total for question = 9 marks)

Q5.

Neurones are cells involved in coordination and control within an animal.

Describe how the arrival of a nerve impulse at a synapse causes the release of
neurotransmitters.

(3)

.............................................................................................................................................

(Total for question = 3 marks)

Q6.

The diagram below shows a section through a motor neurone.

(a) Identify structures A, B, C and D by placing a cross in the correct box in the table below.

(4)

(b) Describe the role of the structure labelled C in the conduction of nerve impulses.

(4)

.............................................................................................................................................

(3)

.............................................................................................................................................

(Total for question = 11 marks)

Q7.

Neurones are cells involved in coordination and control within an animal.

The table below shows the concentration of sodium ions and potassium ions in the cytoplasm of
a neurone and in the fluid outside the neurone.

(i) Using the information in the table, comment on the concentration gradients of these ions.

(2)

.............................................................................................................................................

(ii) During an action potential the distribution of sodium and potassium ions changes.

Explain how proteins in the cell surface membrane of this neurone enable the concentrations of
these ions to return to those shown in the table.

(4)

.............................................................................................................................................

(Total for question = 6 marks)

Mark Scheme

Q1.
Q2.
Q3.
Q4.
Q5.
Q6.
Q7.
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Week 7
Plant biology
(b) the types of plant responses (e) Outline the role of hormones in leaf loss in deciduous plants
Stomatal closure Seed germination Leaf abscission
Why do leaves abscise (fall) in temperate winters?
Delete the incorrect word Fill in the blanks 1.
• Water levels increase / decrease in soil
Seed absorbs ……………….. 2.
• Plant shoots / roots produce ABA / cytokinin
Embryo is activated and produces ………………………………. 3.
• Transported to leaves
Stimulates the production of ………………………………………….. Sequence the statements
1 Falling light levels / aging leaf
• Binds to receptors on cell wall / plasma membrane of guard
cells / stomata These break down …………………………………… in the seed Ethene initiates gene switching in abscission zone at base of
leaf stalk
This produces ……………………………………… for anabolism, plus Cells in separation zone retain water and swelling, straining
• Activates changes in ionic concentration as potassium /
energy in the form of ………………, so new plant can grow outer layer
sodium ions leave cell
(germinate) and break through the seed coat. Cellulase digests and weakens cell walls in outer layer of
abscission zone (separation layer)
• Increases / decreases water potential inside cell
Ethene produced in the leaves
Fatty material deposited in cells on stem side of separation
• Water enters / leaves cell via osmosis
layer to prevent entry of pathogen when leaf falls
Gene switching causes production of enzyme cellulase
• Cell becomes turgid / flaccid and stomata close
Auxin production decreases (auxin inhibits abscission)
Vascular bundles sealed off
10 Strain causes leaf to separate from plant, leaving neat
waterproof scar
f) Describe how plant hormones are used commercially
Hormone Where produced? Action? Commercial use
Auxin 1. 1.

2. 2.

3. 3.

4.
Gibberellin 1. 1.

2. 2.

Ethene 1. 1.

ABA 1. 1.

Cytokinin 1. 1.
(a) explain why plants need to respond to their environment Label the diagram to show where meristematic tissue is found.

(a) the types of plant responses

Tropism Nastic response
Speed
Permanence
Direction
Mechanism of response

Examples: 1. 1.
2. 2.
d) experimental evidence for the role of auxins in the control of apical dominance and gibberellin in
3.
the control of stem elongation
4.
1. Outline how the role of auxins in apical dominance could be tested experimentally. [2]

c) explain how plant responses to environmental changes are coordinated by hormones

1. State one similarity and one difference between plant and animal hormones.
2. Design an experiment to investigate the use of a plant hormone on the growth of seedlings. [6]

2. Explain why only certain plant tissues will respond to particular plant hormones.

3. What are antagonistic hormones? Give an example in plants.

4. What are synergistic hormones? Give an example in plants.

Words to use in your answer:
Draw and label a Potometer Water Vapour
Transport In Plants Evaporation
What is the function of the following tissues?: Carbon Dioxide
Diffusion
Xylem vessel elements Stomata
Sieve tube elements Guard Cells
Why does transpiration occur in a plant
Companion Cells that is photosynthesising?
Parenchyma
Meristem

In as much detail as you, explain how the following

adaptations help the xylem vessels transport water &
In no more than 6 bullet points, explain how to minerals.
carefully set it up and how you obtain results. -Unlignified pits

-Tracheids
Draw and label a cross section of ….
The leaf:
-Spirals of lignin

The Stem:
Using one diagram and no more than 3 sentences, explain Draw and label the structure of the xylem
how the phloem is adapted to transport sugars such as tissue.
Sucrose.

The Root:

What factors effect the rate of transpiration?

Define the following terms: Explain how water moves from the soil into xylem Words to use in your answer:
Source vessels in the roots of plants. Apoplast, Symplast, Vacuolar, Water
Potential, Water potential gradient
Minerals, Casparian strip.
Sink
Summarise the evidence for
root pressure:
Assimilates
•

Mass Flow •
Explain how water moves up a plant in the xylem
vessels. •
Xerophytes

Hydrophytes
•

Sieve plates Words to use in your answer:

Adhesion, Cohesion, Transpiration
chain, Lignin, Root pressure
Plasmodesmata On a separate piece of paper:
1. Explain the stages of translocation by 2. Draw the perfect xerophyte
Transpiration Chain mass flow (from source to sink) starting and hydrophyte labelling AND
with hydrogen ions being pumped out of explaining every possible
companion cells. adaption.

Explain why each of the following affects the rate of transpiration…

Temperature Humidity Air movement Light Intensity
Questions
Q1.

The tip of a plant shoot was placed on two agar blocks and light was shone from one side. The
tip was removed and the agar blocks were then placed on a shoot without a tip, as shown in the
diagram below.

(a) In the space below, draw a diagram to show the shoot as it would appear several hours later.

(1)

*(b) Describe the mechanism that causes the change you have drawn.

(4)

.............................................................................................................................................

(4)

.............................................................................................................................................

(Total for question = 9 marks)

Q2.

The table below shows some statements relating to photoreceptors (phytochromes) in plants.

Complete the table with a tick ( ) if the statement is correct or a cross (×) if the statement is not
correct.

(4)

(Total for question = 4 marks)

Q3.

Plants can respond to environmental cues using IAA (auxin) and photoreceptors.

(a) A plant was kept in a cycle of 12 hours in the light and then 12 hours in the dark. This plant
did not flower.
It was then placed in an environment with 15 hours in the light and 9 hours in the dark. The
plant then flowered.

Explain how this change in light conditions stimulated this plant to flower.

(3)

.............................................................................................................................................

(b) IAA in the stem of the plant is involved in phototropism.

(i) Give three similarities between IAA and animal hormones.

(3)

.............................................................................................................................................

(ii) Auxins can be used to kill unwanted plants such as weeds growing in grass.
The auxin stimulate the weeds to grow rapidly.

Suggest an explanation for how auxins stimulate the weeds to grow rapidly but not the grass.

(2)

.............................................................................................................................................

(Total for question = 8 marks)

Q4.

IAA (auxin) is a chemical substance that occurs naturally in plant cells. IAA controls and
coordinates the growth of plants.

There are several pathways for synthesising IAA. One pathway involves the amino acid
tryptophan.

The photograph below shows a plant that has been left near the window for a week.

(i) Put a cross in the box next to the response shown by this plant.

(1)

A light dependent reaction

B photolysis

C photophosphorylation

D phototropism

(ii) Explain the role of IAA in the response shown by the plant in the photograph.

(4)

.............................................................................................................................................

(Total for question = 5 marks)

Q5.

* The photograph below shows a cross–section through part of the stem of a sunflower
(Helianthus annuus) as seen using a microscope.

Describe the structure of the cell wall of a xylem vessel.

(4)

.............................................................................................................................................

(Total for question = 4 marks)

Q6.

Plant cell walls contain cellulose. Cellulose molecules are polymers.

The cell walls in some plant tissues have secondary thickening.

These cell walls may contain a substance called lignin.

(i) Describe the function of lignin in the cell walls of xylem.

(2)

.............................................................................................................................................

(ii) Name one plant tissue, other than xylem, that has lignin in its cell walls.

(1)

.............................................................................................................................................

(iii) Explain how the structure of xylem is related to its function.

(4)

.............................................................................................................................................

(Total for question = 7 marks)

Q7.

The photograph below shows a cross–section through part of the stem of a sunflower (Helianthus
annuus) as seen using a microscope.
(a) Give the letter that correctly identifies the plant tissues shown in the photograph above.

(2)

Sclerenchyma

.................................................................................................
Xylem

.................................................................................................

(b) Statements concerning xylem and sclerenchyma tissue are shown in the table below.

Place a cross in the box to indicate whether each statement is true or false.

(4)

(Total for question = 6 marks)

Q8.
Mineral ions such as calcium, nitrate and magnesium are transported in the xylem
vessels. These mineral ions are dissolved in water.

Describe how the structure of xylem vessels allows them to transport water.

(2)

.............................................................................................................................................

Q9.

The photograph below shows apples on a tree. The mass of apples produced by an apple tree
depends on the type of fertiliser used. Fertilisers provide inorganic ions required by plants.

(a) Plants use inorganic ions. Place a cross ( ) in the box that identifies the correct response.

(i) Plants require the following inorganic ion to make the amino acids required for growth

(1)

A calcium

B nitrate

C phosphate
D sulfate

(ii) Plants require magnesium ions as a component of

(1)

A cellulose

B chlorophyll

C phytochrome

D protein

(b) The graph below shows the effect of different nitrate fertilisers on the mean mass of apples
produced by Golden Delicious and Red Delicious apple trees.

(i) Using the information in the graph, describe the effects of the fertilisers on the mean mass of
Golden Delicious apples produced.

(2)

.............................................................................................................................................

.............................................................................................................................................
(ii) A farmer has decided to plant apple trees.

Suggest how the farmer could use the information given in the graph.

(2)

.............................................................................................................................................

Scientists examined cells from Golden Delicious apples stored for seven months. They compared
the cell structure of apples from trees given ammonium nitrate with those given calcium nitrate.

Golden Delicious apples from trees given calcium nitrate were firmer than those from trees given
ammonium nitrate.

Using information from the diagrams and your knowledge of the structure of plant cell walls,
suggest an explanation for this difference.

(4)

.............................................................................................................................................

(Total for question = 10 marks)

Q10.

Read through the following passage about plant cell walls and transport. Write on the dotted
lines the most appropriate word or words to complete the passage.

(5)

Many β (beta) ........................................................... molecules join together to

form ........................................................... , the polysaccharide found in plant cell walls.

When these polysaccharides are next to each other, ........................................................... bonds

form and a microfibril is made.

To aid transport of materials from one plant cell to the next cell, there are areas

with reduced cell walls called ........................................................... and areas with no cell

walls called ........................................................... .

(Total for question = 5 marks)

Mark Scheme
Q1.
Q2.
Q3.
Q4.
Q5.
Q6.

Q7.
Q8.

Q9.
Q10.

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Week 8
Genetics
Monohybrid Inheritance Dihybrid Inheritance Epistasis
Key Term Definitions
Inheritance of ____ gene. Alleles are either Inheritance of ____ genes. Alleles are either Inheritance of ____ genes. Presence of an allele on one gene ______
__________ or ___________. Letters are __________ or ___________. Genotypes are the phenotype from the other gene. Alleles are either __________ or Homozygous
written… written… ___________. Genotypes are written…
Heterozygous

Very few genes are actually regulated by one Flower petals can be Red (R) or blue (r) and Flower petals can be Red (R) or blue (r). Another gene controls
spotted (n) or not spotted (N). Draw a punnet whether petals can be colourful pigments (P) or colourless so no Gene loci
gene only. Cystic fibrosis is a recessive disease
(f), healthy levels of mucus is dominant(F). Draw square cross between two heterozygous plants pigment is made (p). Draw a punnet square cross between two
a punnet square cross to calculate the chances using a punnet square and work out the heterozygous plants using a punnet square and work out the Allele
of a father with cystic fibrosis and a homozygous phenotypic ratio. phenotypic ratio.
dominant mother having a child with cystic
Genotype
fibrosis

Phenotype

Codominance

Is this dominant or recessive epistasis? Epistasis

If 50 seeds were produced from this cross, how What is the expected phenotypic ratio of the other type of epistasis?
% chance = phenotypic ratio =. Monohybrid
many would be blue with no spots?

2 Hardy Weinberg equations and what they mean: Dihybrid

What is the difference between autosomes and allosomes?
A2 Biology Revision
Sex linkage
Patterns of Inheritance
What does it mean if a gene is sex linked?
Hardy Weinberg Equilibrium

What unrealistic assumptions do the Hardy Weinberg equations make in order for the population to be in
‘equilibrium’ (so that the allele frequencies stay the same). Gene flow
Sex Linkage

Name two examples of sex-linked disorders: Mutation

How are sex linked alleles written (assume it is X-linked)?

Crossing Over
Blood type

Imagine that an allele for an extra ear (h) is carried on the X List the different blood types below and the different genotypes that can lead to each blood group phenotype. Independent assortment
chromosome. Imagine a carrier and a male with an extra ear started a
family. They have a daughter. The daughter meets a guy with no alleles
Genetic drift
for an extra ear and they have children of their own. What is the
probability their daughter gives them a grandchild with an extra ear?
Genetic bottleneck
A type O parent and a heterozygous type B parent have a child. Their child eventually grows up and finds a
partner who has type AB blood. Grandchildren are born. What is the overall probability that the grandparents Founder effect
have a grandchild with type A blood?
Chi squared Types of Variation Artificial selection
What does the chi squared statistical test check for? What type of graph should be used to show the frequency of What are the main stages?
discontinuous variation?

The higher the chi squared value, the lower the probability that differences are due
to___________. When the probability reaches just 5% (or p= ____) we compare our Roughly sketch the shape of a graph showing the frequency of a
calculated chi squared value to a table of ______________ ____________. How is this different to natural selection?
phenotypes for continuous variation.
If the chi squared value is lower than the critical value, the null hypothesis should
____________. This means….

Give some examples of desirable characteristics that could be bred into

Which type of variation is likely to be controlled by multiple genes and
If the chi squared vale is equal to or greater than the critical value, the null hypothesis plants and animals:
multiple environmental factors too?
should be ___________. This means….
Plants Animals

What is chlorosis in plants?

Significant genetic causes of differences between observed and expected phenotypic
ratios:

•
• What the ethical concerns surrounding artificial selection? Give some
Natural Selection
• examples.
• Write a bullet point description of the stages of natural selection that
• lead to a new species/strain of antibiotic resistant bacteria.

Key terms to use; mutation, variation, advantageous allele, selection

pressure, antibiotic survive, reproduce, binary fission, offspring, allele
frequency, speciation.

Types of Selection
Speciation
Explain, using diagrams, the difference between stabilising, directional and disruptive
selection. Give a definition for a species:

Give a definition for speciation:

What are the two types of speciation called and how are they
different?
OCR A Level Biology: Cloning and Biotechnology Revision Key Term Definitions
Sketch a bacterial growth curve, label the
different stages.
Asepsis
How could a colorimeter be used to How could a colorimeter be used to
quantify bacterial growth a liquid quantify bacterial growth a liquid
broth medium? broth medium? Aseptic technique

Clone

Turbidity
Describe what happens during the following stages…

Lag Tick to show whether these statements describe batch (B) or B C Primary metabolites
continuous (C) cultures.
Reactant or substrates are added regularly Secondary metabolites
Log
Products can be collected after a certain period
A fixed quantity of nutrients are provided Penicillin
Stationary The culture is inside an enclosed system
The culture is inside an open system such as a bioreactor Bioremediation
Stationary phase is not observed as waste is not allowed to
Death accumulate and fresh nutrients are supplied persistently
The process stops when the products are made
The yield of useful product is much higher Inoculate

List the factors that affect microbial growth rate Nutrient availability will become a limiting factor
and explain why: Used for producing secondary metabolites Serial dilution
p____ Labour demand is low
T__________ The cost of any contamination is extremely high Bacterial Density
Very difficult and expensive to set up
O_____

W_____ Give three reasons for using List some examples of What type of biological molecules
microorganisms in biotechnology biotechnology processes involving does agar nutrient jelly provide to
N______ 1. microorganisms. microbes?

2.
On a separate piece of paper, describe how
you would set up a culture of E.Coli in a petri
dish. Include as many aseptic techniques as 3.
you can.
Give the different arguments for using microorganisms as food Show how the bacterial growth plates would appear following serial dilution. What is a logarithmic
Advantages Include details of how you would dilute. scale?

10-1 10-2 10-3 10-4 10-5 10-6

Disadvantages
Why do bacterial
population graphs
require one?
What formula would you use to estimate the initial no. of bacterial per ml?

What microorganism is used in Quorn?

Which plate would be most appropriate to use in your estimate and why?

How is this formula used to calculate the Micropropagation

number of bacteria? 1. On a separate piece of paper, describe the steps in this process using the following terms:
Explant, Sterilise, Petri dish, Agar, Callus, Meristem, Mitosis, Aseptic, Separate, Plantlets,
Growth medium
2. Why is micropropagation used sometimes instead of vegetative propagation?

Vegetative propagation
What does the formula Log2(No. of cells) tell
In no more than 6 sentences and 6 drawings, summarise the steps involved taking a cutting.
you?
Explain why each step is necessary.

How do you calculate the generation time of

bacteria?

Describe how asexual reproduction in plants forms

Why does this bioreactor require…. clones

-Aerator/air inlet
-Thermal jacket
Give some examples of natural clones in animals:
-pH probe
-Agitation/stirrer
-Feeding pump
What are some of the arguments against animal cloning? Explain how animal clones are used in…
Medicine

Agriculture

Conservation
Draw an annotated diagram to show the stages of Somatic Cell Nuclear Transfer to clone an animal
such as a sheep.

What is an immobilised enzyme? Why are they used?

Describe the different methods of immobilisation. For each method give an advantage and a
disadvantage of its use.

• Encapsulation

Suggest how might the process might differ if you were trying to clone a fish instead.

• Entrapment

Draw a diagram to show the stages of Therapeutic cloning.

• Adsorption

• Covalent bonding

Give some examples of immobilised enzymes use in the biotechnology industry:

How is this different to SCNT?

Why is this process more favourable than organ donation or transplants?

Questions

Q1.

* Haemoglobin is a protein found in red blood cells that helps transport oxygen in the blood.

In sickle cell anaemia, the presence of the allele (a) in place of the normal allele (A) results in a
change of one amino acid in the haemoglobin molecule.

This mutation changes the properties of haemoglobin and can result in red blood cells becoming
less flexible and blocking small blood vessels.

The frequency of the recessive allele (a) is much higher in populations in West Africa than in
populations in Northern Europe.

People in West Africa have a much higher risk of being infected with malaria parasites and
developing severe anaemia than people in Northern Europe.

People who are heterozygous for sickle cell anaemia have sufficient amounts of normal
haemoglobin to prevent severe anaemia.

One theory suggests that the malaria parasite (Plasmodium sp.) causes red blood cells with any
modified haemoglobin to rupture. This occurs before the parasite can reproduce.

In West Africa, the average life expectancies of people with genotypes AA, Aa or aa are
different.

(i) Using the information above, give an explanation for the difference in life expectancy of
people who do not have the recessive allele.

(2)

.............................................................................................................................................

(ii) Using the information above, give an explanation for the difference in life expectancy of
people in West Africa who have the genotype Aa.

(2)

.............................................................................................................................................

(Total for question = 4 marks)

Q2.

Moyamoya is a rare disorder caused by a dominant allele. This disorder progressively damages
the arteries supplying the brain.

Inherited factors may contribute to the development of moyamoya.

The pedigree diagram below shows a family affected by moyamoya.

(i) Explain how the information in the pedigree diagram suggests that this disorder is due to a
dominant allele.

(3)

.............................................................................................................................................

(ii) Using a genetic diagram, find the probability that the next child born to parents 3 and 4
would be affected by moyamoya.

(3)

Probability ...........................................................

(Total for question = 6 marks)

Q3.

Cystic fibrosis is a genetic disease that can affect many body systems, including the digestive
system. In a carrier of this disorder, preimplantation genetic diagnosis can be used to detect the
presence of an allele for cystic fibrosis.

*(a) Explain how cystic fibrosis affects the digestive system.

(4)

.............................................................................................................................................

(b) Explain how preimplantation genetic diagnosis is performed to detect cystic fibrosis.
(3)

.............................................................................................................................................

(2)

.............................................................................................................................................

(Total for question = 9 marks)

Q4. (a) The diagram below shows part of a DNA molecule.

(i) Place a cross in the box next to the molecule represented by the letter X

(1)

A Deoxyribose

B Phosphate

C Ribose

D Uracil

(ii) Place a cross in the box next to the molecule represented by the letter Y

(1)

A Adenine

B Cytosine

C Thymine

D Uracil

(iii) Place a cross in the box next to the name of the bonds holding the two strands of DNA
together.

(1)

A Ester bonds

B Glycosidic bonds

C Hydrogen bonds

D Peptide bonds

(b) A culture of bacteria had its DNA labelled with the heavy isotope of nitrogen (15N).
The diagram below shows the position of the DNA band in the centrifuge tube when the DNA was
labelled with the heavy isotope of nitrogen, 15N.

The bacterial culture was then allowed to reproduce using nucleotides containing the normal
isotope of nitrogen (14N).

(i) Place a cross in the box below next to the tube showing the correct pattern of DNA after
the bacteria have divided once.

(1)

(ii) Place a cross in the box below next to the tube showing the correct pattern of DNA after
the bacteria have divided twice.

(1)

(1)
.............................................................................................................................................

(d) Achondroplasia is an inherited condition that results in restricted growth in humans. This
condition is caused by a dominant allele (A).

Fetuses which are homozygous for the allele for achondroplasia are rarely born alive.

Two parents who both have achondroplasia would like to have children. They are concerned
about the risk of their child inheriting two dominant alleles and dying before birth.

(i) Describe one advantage and one disadvantage to these parents of genetic screening of their
fetus.

(2)

Advantage:
....................................................................................................................................................

....................................................................................................................................................

Disadvantage:
....................................................................................................................................................

....................................................................................................................................................

(ii) In the space below, draw a suitable genetic diagram to show the probability of a child from
these parents growing up without achondroplasia.

(4)

probability .............................................................

(Total for Question = 12 marks)

Q5.

DNA is found in chromosomes and consists of double-stranded polynucleotide

molecules. The sequence of bases in DNA forms the basis of what is known as the
genetic code.

(a) Explain why a molecule of DNA can be described as a double-stranded

polynucleotide.

(3)

.............................................................................................................................................

*(b) Describe how the sequence of bases in a DNA molecule would be used to form
the primary structure of a protein.

(5)

.............................................................................................................................................

(Total for question = 8 marks)

Q6.

Grey tree frogs are found in the USA.

The photograph below shows a grey tree frog.

Cope's grey tree frog and the eastern grey tree frog are both found in the USA.

These species of grey tree frog are very similar in appearance, but have different mating calls.

A number of scientists believe that the eastern grey tree frog evolved from Cope's grey tree frog
during the last ice age.

These species have different numbers of chromosomes in their nuclei. Cope's grey tree frog has
two copies of each chromosome. The eastern grey tree frog has four copies of each
chromosome. As a result, the cells of the eastern grey tree frog are larger.

(a) The genetic relationship between these two species of grey tree frog has been studied using
DNA profiling (DNA fingerprinting).

A small sample of DNA was taken from each species of grey tree frog. This DNA was amplified,
fragmented and used to produce a DNA profile (DNA fingerprint) for each species.

*(i) Describe how a DNA profile was produced from this small sample of DNA.
(6)

.............................................................................................................................................

(ii) Suggest how these DNA profiles were compared.

(3)

.............................................................................................................................................

(b) Scientists in different parts of the USA are investigating the possibility that the difference in
cell size is responsible for the different mating calls. This is contributing to an understanding of
the evolution of grey tree frogs.

Suggest two ways in which the results of their investigations can be shared.
(2)

.............................................................................................................................................

(Total for question = 11 marks)

Q7.

The photograph below shows a cleft iris, a rare condition in humans. Cleft iris may be
due to the inheritance of recessive alleles.

(i) In the space below, draw a genetic diagram to show the genotypes and
phenotypes of a man with cleft iris and a woman who is heterozygous for this
condition, and all their possible children.

(4)

(ii) State the probability that the first child of these parents will have a cleft iris.

(1)

.............................................................................................................................................

Q8.

Some organisms have been genetically modified to produce proteins including hormones and
vaccines.

The flow diagram below shows part of a process to produce a protein, using genetically modified
plants.

(a) Describe and explain the role of the enzymes involved in stage 1.

(5)

.............................................................................................................................................

(b) Describe the structure of the modified plasmid used in stage 2.

(2)

.............................................................................................................................................

(2)

.............................................................................................................................................

(d) Describe two risks associated with the use of genetically modified organisms.

(2)

.............................................................................................................................................

(Total for question = 11 marks)

Q9.

Cystic fibrosis and albinism are examples of recessive genetic disorders. Krabbe disease is
another example of a recessive genetic disorder.
Krabbe disease is caused by mutations in the GALC gene, resulting in a deficiency of an enzyme
called galactocerebrosidase.

(a) Explain the meaning of each of the following terms.

(i) Mutation

(2)

.............................................................................................................................................

(ii) Recessive

(1)

.............................................................................................................................................

(b) Suggest how a mutation in the GALC gene could result in a change in the enzyme
galactocerebrosidase.

(3)

.............................................................................................................................................

In the space below, draw a genetic diagram to show the possible genotypes and phenotypes of
their children.

Use the genetic diagram to find the probability of these parents having a child with Krabbe
disease.

(5)

Probability ...............................................................................

(d) State how these parents could determine whether or not their unborn child has Krabbe
disease.

(1)

(Total for question = 12 marks)

Mark Scheme

Q1.

Q2.
Q3.
Q4.
Q5.
Q6.
Q7.
Q8.
Q9.
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Week 9
Hormones and
homeostasis
What are the two types of hormone? Sketch and list the stages in the secretion of insulin… Sketch the gross structure of a pancreas and Sketch a cross section of the Islet of
1. label where it ducts secrete to… Langerhans and label its cells…

Sketch and describe how adrenaline affects a cell…

2. Normal blood glucose concentration is 4-6mmol dm-3. Draw a flow diagram to show how blood
glucose concentration is returned to normal when it begins to rise or fall.
3.

What causes type I diabetes and how can it be treated? Use keywords to describe how the heart initiates its own contractions and

Adrenaline prepares the body for activity; list its

effects on the body:
1.
2. Add arrows and labels to the pictures below and underneath the diagram, list the factors that
3. affect the heart rate…
4. What causes type II diabetes and how can it be treated?
5.
6.
7.
8.
9.
2.
The adrenal cortex uses cholesterol to produce
certain steroid hormones. List examples and write
What does the term ‘myogenic’ mean?
down their roles in the body:

List all the keywords from this topic. Use different colours to highlight the keywords in this box and then highlight them in the same colour where you have written them on these two pages…
Define the term homeostasis. List some of the conditions that living organisms need Draw a negative feedback loop with the main features labelled and an example of each feature
to maintain constant in the body: linked to temperature control in the body e.g. ‘Receptor detects change e.g. thermoregulatory
1. centre in the hypothalamus detects change’.
2.
Define the term stimulus.
3.
4.
5.
List the features of a good communication system: 6.
1.
Sketch and label a synapse… Endotherms
2.
Component of If core body temp If core body temp
3. Advantages Disadvantages
body involved too high… too low…
4.
5.

List down the specialised features of neurones…

1.
Behaviour if too hot… Behaviour if too cold…
2.

4. List the steps of transmission of

an impulse across a synapse… How is an action potential transmitted in a myelinated neurone?
5. OCR A Level Biology Unit 1
1.
6. 2. Communication & Homeostasis
3.
7.
4. Ectotherms
8. 5. How it regulates
6. Advantages Disadvantages Adaptations Example
9. body temp
7.
Outline the stages of an action potential and number 8.
them on a sketched graph (in the space below) 9.
1. 10.
2. 11.
3. 12.
4.
5. List seven roles of synapses: What does the term ‘all or nothing’ mean? Sketch and label a sensory neurone:
6. 1.
7. 2.
8. 3.
9. 4.
5.
6.
7. How is an action potential produced when Sketch and label a motor neurone:
List the advantages of myelinated neurones… something puts pressure on a person’s hand?
1(a) Renal glucosuria is a rare condition in which glucose is excreted in the urine despite normal or low blood glucose
levels.

Familial renal glucosuria (FRG) is caused by mutations in the gene coding for the sodium-glucose cotransporter
SGLT2. These mutations cause a reduction in SGLT2 protein or complete loss of SGLT2 protein function.

Fig. 33.1 shows SGLT2 in the plasma membrane of a cell in the kidney nephron.

Fig. 33.1

Name the main area of the kidney, and the precise region of the nephron, in which the cell shown in Fig. 33.1 is
located.

main area of the kidney

precise region of the nephron

[2]

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(b) FRG is classified into type A, type B and type O.

Fig. 33.2 shows the relationship between blood glucose concentration and glucose reabsorption in healthy
individuals and in patients with each type of FRG.

Fig. 33.2

Discuss the evidence in Fig. 33.2 to show that severity of renal dysfunction can vary among patients with FRG.

[3]

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(c)

(i) Patients with FRG often produce excessive quantities of urine. Suggest why.

[1]

(ii) Explain how concentration of urine is regulated in healthy individuals.

[3]

2 CKD patients that develop kidney failure can be treated by dialysis, but this is not a cure. A kidney transplant can
remove the need for dialysis. However, transplantation carries the risk of rejection of the transplanted kidney.

Describe how it might be possible to overcome rejection of a transplanted kidney in the future.

[3]

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3 Antidiuretic hormone (ADH) is required for osmoregulation.

Which of the options, A to D, is a region of the nephron that is responsive to ADH?

A Bowman’s capsule

B collecting duct

C loop of Henle

D proximal convoluted tubule

Your answer [1]

4
Peritoneal dialysis is a form of dialysis that is used to treat kidney failure.

State one advantage and one disadvantage of peritoneal dialysis compared with haemodialysis.
advantage_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

disadvantage_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

[2]

5 The release of thyroxine is regulated by negative feedback and involves two other hormones, as shown in Fig.
32.

Fig. 32

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(i) Identify hormones X and Y.

[2]

(ii) Describe the general features of a negative feedback mechanism.

[3]

6(a) Recent studies, such as those carried out by the World Health Organisation, have noted an increase in the
global incidence of Type 1 diabetes.

Type 1 diabetes occurs due to changes in pancreatic tissue. Fig. 2.1 shows a photomicrograph taken of a
section through pancreatic tissue.

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Fig. 2.1

(i) State the region of the pancreas from which this tissue section has been taken.

[1]

(ii) Which of the secretory vesicles contains the hormone that lowers blood glucose?

[1]

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(b) The hormones produced by the region of the pancreas shown in Fig. 2.1 are both polypeptides.

Explain how these hormones are:

produced by the secretory cells

released from the secretory cells
transported to their target organs.

In your answer you should refer to the organelles shown in the diagram and identify the target organs.

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[8]
7
This question is about the hormonal control of blood glucose concentration in health and disease.

Complete the missing words in the paragraph below to explain the role of insulin in blood glucose homeostasis.

When the concentration of blood glucose rises above a set point, _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ cells in

the _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ of the pancreas are stimulated to release

insulin. Effector cells respond to insulin by increasing the expression of _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ proteins

in the cell surface membrane. This increasesf the uptake of glucose. Liver cells store some excess

glucose in a process known as _ _ _ _ _ _ _ _ _ _ _ _ _ _ . The concentration of blood glucose then falls.

[4]

8 The cytochrome P450 enzyme system (CYP) in the liver is responsible for breaking down recreational drugs.

Repeated use of recreational drugs can result in increased concentrations of CYP enzymes in liver cells.

Outline the possible consequences of increased concentrations of CYP enzymes on the use of recreational
drugs.

[2]

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9 The autonomic nervous system plays an important role in homeostasis.

The box below contains some terms that could be used to describe the features or activity of the two branches of
the autonomic nervous system.

acetylcholine adrenaline decrease glycogenesis

glycogenolysis increase noradrenaline motor sensory

Complete Table 1.1 below by inserting the most appropriate term.

Terms may be used once, more than once or not at all.

Some boxes have been completed for you.

Feature or activity Branch of autonomic nervous system

Parasympathetic Sympathetic

Type of neurone motor

Process triggered in liver cells

Effect on heart rate

Neurotransmitter released at the noradrenaline

SAN

Table 1.1

[4]

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10 Cell theory is one of the unifying concepts in biology. All cells are bounded by a plasma membrane. Animal cells
also have intracellular membranes that form organelles. The chemical composition of these membranes is very
similar to that of the plasma membrane.

Fig.3.1 is an electron micrograph of a section through a liver cell showing some membrane-bound organelles.

(i) Cell theory states that metabolic reactions occur inside cells.

State one metabolic reaction that occurs in organelles such as L.

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[1]

(ii) Using the information in Fig. 3.1, calculate the magnification of the electron micrograph in Fig. 3.1.

Show the steps in your calculation.

Answer _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ [2]

(iii) Rough endoplasmic reticulum (RER) consists of a series of membranes within the cytoplasm of the cell, to
which ribosomes are bound.

Suggest the molecular composition and structure of the membranes to which the ribosomes are bound.

[3]

(iv) * Ribosomes are chemically different from the membranes to which they are bound. Each ribosome is made
of two sub-units. Each sub-unit consists of protein molecules associated with another polymer.

Compare the structure of the other polymer with that of a protein molecule.

[6]

END OF QUESTION PAPER

Question Answer/Indicative content Marks Guidance

1 a main area: (renal) cortex ✓ 2 AO2.1

precise region: proximal convoluted tubule
✓

b no glucose reabsorption at any blood 3 AO3.2

glucose concentration in patients with type
0 FRG ✓
no more glucose reabsorption at blood
glucose concentrations greater than 10
mmol dm-3 in type A patients ✓
glucose reabsorption in type B patients
similar to healthy state ✓

c i diffusion of water (from blood into filtrate), 1 AO2.5 ALLOW water potential of filtrate is very
by osmosis / down water potential gradient low so water remains in the filtrate
✓

ii any 3 from: max 3

(osmoreceptors in) hypothalamus detect AO1.2
water potential (ψ) of blood ✓
If low : ADH / antidiuretic hormone / ORA for any m.p.
vasopressin, released from pituitary (gland)
✓
insertion of aquaporins into collecting duct
cells ✓
more water reabsorbed from collecting
duct (by osmosis) ✓
solute concentration of urine increases ✓
water potential of blood increases ✓

Total 9

2 (have more accurate) match to, antigens 3 max ALLOW more accurate blood grouping
on red blood cells / MHC ✓

use patients’ own stem cells ✓

(which will) differentiate into kidney cells ✓ IGNORE growing kidneys

(not rejected because) genetically identical Examiner’s Comments

/ seen as ‘self’ ✓
This was well answered for at least 1 mark
(could use) induced pluripotent stem cells / with most candidates suggesting using
iPSCs ✓ patients own stem cells. Many candidates
discussed growing whole kidneys without
(these are examples of) therapeutic cloning appreciating the need to differentiate into
✓ cells then tissues first. Many candidates
just discussed immunosuppression without
relating it to a future advance.

Question Answer/Indicative content Marks Guidance

Total 3

3 B 1

Total 1

4 Advantage: 2
1 from:
no need for specialist equipment ✔
can be done, at home / by patient ✔
patient can be mobile during treatment ✔ AW
Examiner’s Comments
Disadvantage: (b) was accessible to, and well answered
1 from: by, most candidates.
risk of infection ✔
required more frequently than
haemodialysis ✔

Total 2

Question Answer/Indicative content Marks Guidance

5 i X: thyrotropin-releasing hormone / TRH ✓ 2 ALLOW thyrotrophin

Y: thyrotropin / thyroid-stimulating hormone DO NOT ALLOW thyroxine stimulating
/ TSH ✓ hormone

Examiner’s Comments

Only the more able candidates were able

to recall TRH and thyrotropin/TSH.

ii any 3 from: max 3

maintain a system around a set ALLOW small fluctuations around a set
point/norm✓ point/norm
AW e.g. ref to parameter too high or too
receptors detect change (from set point) ✓ low
effector(s) produce change/response ✓
to return system to set point/norm ✓
Examiner’s Comments

This question proved demanding, with

most candidates using specific examples
to illustrate their points rather than referring
to the generalisations.
Exemplar 4

This answer covers all the marking points,

Total 5

Question Answer/Indicative content Marks Guidance

6 a i Islet(s) of Langerhans; 1 ACCEPT upper or lower case, phonetic

spelling

Examiner's Comments

This question was almost entirely AO1 but

did contain marks which were synoptic with
F221 (cell structure) and F224 (protein
synthesis).

Most candidates correctly identified the

Islets of Langerhans in (a)(i) from the
photomicrograph. A failure to gain credit
usually resulted from either an imprecise
answer (‘endocrine tissue’) or confusion
with the glomerulus despite the question
clearly being about the pancreas.

ii beta / β (cells); 1 Examiner's Comments

This question was almost entirely AO1 but

did contain marks which were synoptic with
F221 (cell structure) and F224 (protein
synthesis).

In (a)(ii) again most candidates correctly

stated beta cells.

Question Answer/Indicative content Marks Guidance

b 1(gene(s) for hormones) transcribed / 7 ACCEPT hormone / named hormone /

AW, in nucleus; polypeptide for mps 1.2.3. and 4

1 ACCEPT a description of transcription

2hormones / polypeptide / protein / such as ‘mRNA (for hormones) being
synthesised, on ribosomes synthesised’

; 2. ACCEPT mRNA translated on

ribosomes or a description
3(ribosomes / proteins synthesised /
translation) on RER;
4hormones / polypeptides / proteins,

transfer to Golgi (apparatus);

5(golgi) packages / AW, hormones into

vesicles;

6vesicles, fuse with / AW, cell surface DO NOT CREDIT if exocytosis is given as
membrane / hormones released by part of a list
exocytosis;

7 CREDIT this mark if linked to any

7mitochondria provide, energy / ATP, for process from
(named) process;
mp 1,2.,4, 5
DO NOT CREDIT ‘produce energy’
8(hormones) soluble in blood /
transported in, blood / plasma;

9(targets) muscle / liver;

DO NOT CREDIT as part of a list with
other non-target organs
10ref to (hormone binding to) receptors
on cell surface / plasma, membrane (of
cells in target tissues);

Question Answer/Indicative content Marks Guidance

QWC; 1 Award if: mp 8 and 9 have been awarded

plus any two from mps 1,3,5,6,7

Examiner's Comments

In part 2(b), several candidates answered

the question in terms of homeostasis and
wrote excellent answers to a question
which had not been asked. In terms of
homeostasis, a surprising number of
candidates still believe that the alpha and
beta cells are regulated by the
hypothalamus and the pituitary. For those
candidates who did attempt to address the
question recurring errors included using
the terms ‘transcription’ and ‘translation’ as
if they were interchangeable, describing
exocytosis as the release of vesicles into
the blood stream and using the term ‘active
transport’ to describe exocytosis.
Examiners were happy to credit the link
between mitochondria and use of ATP for
exocytosis as ATP would be required, for
example, to move vesicles to the cell
surface membrane. However, the term
‘active transport’ is reserved for
transmembrane transport which requires a
specific ATP- driven protein ‘pump’ - a
different form of transport to exocytosis. As
stated in the introduction, too many
candidates wrote about the release of
glycogen or glucogen from alpha cells.

Total 10

Question Answer/Indicative content Marks Guidance

7 beta / β ✔ 4

islets of Langerhans ✔ ALLOW wrong use of upper and lower

cases
(glucose) transport(er) ✔
ALLOW GLUT (1-4) OR carrier
glycogenesis ✔ DO NOT ALLOW receptor / co-transport

ALLOW glycogen synthesis

Examiner’s Comments
(a) addressed AO1 criteria, part (b)(i) was
focused on AO3, part b(ii) was focused
on AO2 and the Level of Response
question, part (c), addressed
both AO1 and AO2.
(a) was done well although candidates
need to be careful when writing β cells so
not to confuse it with B cells (remembering
that B cells are very different to β cells).
The most common incorrect responses
were channel / receptor proteins and there
was still some evidence of candidates
confusing glycogenesis with glycogenolysis
and occasionally gluconeogenesis.

Total 4

8 idea that higher drug concentration will be 2

needed to achieve same effect ✓

idea of tolerance linked to physical drug

dependency ✓

Total 2

Question Answer/Indicative content Marks Guidance

9 4 DO NOT CREDIT incorrect spelling of

underlined terms since these have been
provided

Examiner's Comments

The commonest mistake was to assume

that, as motor was given for the
parasympathetic then the sympathetic
neurone must be sensory. As in previous
sessions, candidates still confuse the
terms glycogenesis and glycogenolysis.

Total 4

Question Answer/Indicative content Marks Guidance

10 i aerobic respiration OR synthesis of ATP 1 ALLOW Krebs cycle, link reaction,

oxidative phosphorylation, protein
synthesis, (mitochondrial) DNA replication

ii × 5150 (1) (1) 2 Correct answer = 2 marks

ALLOW × 5100 to × 5200

If answer is incorrect look for:

51 to 52 mm OR 5.1 to 5.2 cm (from scale
bar) converted to μm

Answer divided by 10

iii (membranes have) phospholipids and 3 IGNORE ref to glycoprotein or glycolipids

proteins and cholesterol (1)

(phospholipids) arranged as a bilayer (1)

(proteins) free to move / AW, within bilayer

(1)

ref to intrinsic and extrinsic proteins (1)

ref to cholesterol (molecules), spanning

bilayer (1)

iv Read through the whole answer from start 6

to finish, concentrating on features that
make it a stronger or weaker answer using
the indicative scientific content as
guidance. The indicative scientific content
indicates the expected parameters for
candidates' answers, but be prepared to
recognise and credit unexpected
approaches where they show relevance.

Using a ‘best-fit' approach based on the

science content of the answer, first decide
which set of level descriptors, Level 1,
Level 2 or Level 3, best describes the
overall quality of the answer using the
guidelines described in the level
descriptors in the mark scheme.

Once the level is located, award the higher

or lower mark.

The higher mark should be awarded where

the level descriptor has been evidenced

Question Answer/Indicative content Marks Guidance

and all aspects of the communication

statement (in italics) have been met.

The lower mark should be awarded where

the level descriptor has been evidenced
but aspects of the communication
statement (in italics) are missing.

In summary:

The science content determines the

level.
The communication statement
determines the mark within a level.

Level 3 (5–6 marks)

A comparison of proteins and RNA which
is chemically detailed and includes Indicative scientific points may include:
reference to the bonds in the molecules. FOR RNA

There is a well developed description of nucleotide as the monomer

monomers polymers and bonds for both nucleotide structure as a pentose
molecules which is clear and structured to sugar, a phosphate and a
give a comparison. The information (nitrogenous) base
presented is relevant. RNA nucleotide sugar is ribose
4 RNA bases
Level 2 (3–4 marks) RNA bases are adenine, uracil,
A comparison of proteins and RNA with cytosine and guanine.
some chemical detail. There is a adenine and guanine are purines
description of monomers polymers and cytosine and uracil are pyrimidines
bonds for both molecules which is clear condensation reactions (between
and logically structured. The information nucleotides)
presented is relevant. formation of phosphodiester bonds

Level 1 (1–2 marks) FOR PROTEIN

An outline of the structure of RNA or
protein with limited comparative amino acid as monomer
statements. 20 different amino acids
joined by condensation reactions
There is a general description of both formation of peptide bonds
monomers and polymers which may be carboxyl groups and amine groups
unstructured. Some irrelevant or incorrect secondary structure / alpha helix / beta
information may be presented. pleated sheet
hydrogen bonding
0 marks tertiary structure with bonds between R
No response or no response worthy of groups
credit. ionic bonding
disulphide bonding
hydrophobic and hydrophilic
interactions.

Question Answer/Indicative content Marks Guidance

Total 12

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Week 10
Ecology and
biodiversity
What is the difference between biotic and abiotic factors? Can you give What is the difference between intraspecific and interspecific competition?
Ecosystems, Populations & Sustainability Revision Key Term Definitions
some examples of each? Can you give some examples of each type of competition?
Density dependent factor
What is the difference between conservation & preservation? In what
kind of scenario would you use each approach? Density independent factor

Carrying Capacity
Sketch and label the stages of a population growth curve. Compare birth Sketch a rough graph to show the population of two species that show a
rates and deaths rates at each stage. perfect predator-prey relationship. Explain why the populations of the Species
predator and prey species change over time.
List the methods of sustainable timber production. Summarise each Niche
technique with no more than 2 sentences,
Ecosystem

Community

Population

Sustainability

Ecotourism

Succession

Sketch and label the stages of a population growth curve. Compare birth Why might ecosystems require: Deflected Succession
rates and deaths rates at each stage.
-Controlled grazing
Plagioclimax

List the methods of sustainable fishing techniques. Summarise each one Pioneer Species
-Restricted routes or restricted access
with no more than 2 sentences
Competitive exclusion principle

-Fencing

List the biological molecules that contain nitrogen:

-Soil improvements

What is biomass and how do you measure it? -Blocked drainage List the names of the different forms (with chemical
formulae too) which nitrogen takes within the nitrogen
cycle:

What are the units for biomass? -Legal hunting/culling of a species

List the trophic levels in a food chain in the correct order.

-Staff

What does net productivity mean?

Write down an example of a food chain:

-Sustainable development What can a reduction reaction mean?
How do you calculate it?

Why is there only a limited number of trophic levels in a food chain?

What can an oxidation reaction mean?

What does % efficiency of trophic transfers show? Education

Explain some of the ways energy is wasted in food chains:

How do you calculate it?

Create a cartoon strip in the available space and annotate to explain the seral stages of succession and how they change over time. Describe the process of capture-mark-recapture to estimate abundance of
animals:

Why is this done instead of using quadrats?

List some other animal sampling techniques:

Use the available space to draw and annotate the processes, molecules and organisms involved (including types of Use the available space to draw and annotate the processes, forms and organisms involved in the carbon cycle.
bacteria) in the nitrogen cycle.
Questions
Q1.

A wetland is an area where the soil is saturated with moisture either permanently or seasonally.
The distribution and abundance of organisms in a wetland will be influenced by various abiotic
factors including the degree of saturation of the soil by water. Within most wetlands, there will
be areas which are relatively dry and other areas which are submerged under water throughout
the year.

(a) (i) Explain why the degree of saturation of the soil by water is considered to be an abiotic
factor.

(1)

.............................................................................................................................................

(ii) Place a cross in the box next to the biotic factor that might influence the distribution and
abundance of organisms in a wetland.

(1)

A Mineral availability

B pH

C Predation

D Water temperature

(b) A group of students studied an area of wetland. They placed twenty 1m2 quadrats on a line
from a relatively dry area to an area where there was free-standing water. Each quadrat was
divided up into 25 smaller sections.

(i) Place a cross in the box next to the term that describes the technique that uses a line of
quadrats to investigate the distribution of organisms.

(1)

A Transact

B Transcript

C Transect

D Transept

(ii) Suggest why the quadrats were divided up into 25 smaller sections.

(2)
.............................................................................................................................................

.............................................................................................................................................

(iii) The students estimated the percentage cover of each of five species of plant within each
quadrat. They also measured the depth of free-standing water.

The results of this part of the study are shown in Figure 1 and Figure 2.

Use the data in Figure 1 and Figure 2 to complete the table below.

(2)
(iv) Suggest why the students were not able to draw valid conclusions about the effect of
saturation of the soil by water on the distribution of the five plant species.

(3)

.............................................................................................................................................

(Total for question = 10 marks)

Q2.

The distribution and abundance of an organism within its habitat can be influenced by both
abiotic and biotic factors.

(a) Explain the difference between abiotic and biotic factors.

(1)

.............................................................................................................................................

(b) Periwinkles are similar to snails and are one of the common invertebrates found on many
seashores around Britain. A study of the distribution of two species of periwinkle, Littorina
littorea and Littorina obtusata, was carried out.

Areas of a sloping seashore were selected at different heights above sea level. Within each of
these areas, the mean density (individuals per m2) of each of the periwinkle species was
recorded.

(i) Place a cross in the box next to the name of the most suitable piece of apparatus for
obtaining the data for the density of the periwinkles.

(1)

A quadrant

B quadrat
C quadrille

D quartile

*(ii) Explain how this piece of apparatus would be used to obtain the mean density of the two
species of periwinkle in each area.

(3)

.............................................................................................................................................

(iii) Suggest one abiotic factor and one biotic factor that may influence the distribution of the
periwinkles on the seashore.

(2)

Abiotic

.............................................................................................................................................

Biotic

.............................................................................................................................................

(iv) The results of this study into periwinkle density are shown in the graph below.
The three statements below show the conclusions recorded by different students following the
seashore study of periwinkles.
Place a cross in the box next to one statement that could form a valid conclusion using the
information shown in the graph opposite.

(1)

A All periwinkles are affected by the height above sea level

B The height above sea level influences the distribution of different species of periwinkle

C Neither of the species of periwinkle is affected by the height above sea level

(v) With reference to the data in the graph, discuss the validity of statements A, B and C.

(4)

.............................................................................................................................................

(Total for question = 12 marks)

Q3. Lichen consists of two organisms, an alga and a fungus, growing together. The alga
photosynthesises producing carbohydrate for the two organisms and the fungus absorbs and
retains water so that the lichen does not dry out.

The photograph below shows a patch of lichen growing on a wall.

Algae and fungi are eukaryotic organisms.

(a) Place a cross in the box next to the names of cell structures that would be used to classify
algae and fungi as eukaryotic organisms.

(1)

A cytoplasm and large (80S) ribosomes

B cytoplasm and small (70S) ribosomes

C nucleus and large (80S) ribosomes

D nucleus and small (70S) ribosomes

(b) Place a cross in the box next to one difference in cell structure between these two
eukaryotic organisms.

(1)

A algae have chloroplasts, fungi do not

B algae have circular DNA, fungi have linear DNA

C fungi have chloroplasts, algae do not

D fungi have circular DNA, algae have linear DNA

(c) Lichens can reproduce sexually and asexually. Sexual reproduction involves meiosis and
asexual reproduction involves mitosis.

Suggest advantages to lichens of being able to reproduce both sexually and asexually.

(2)

.............................................................................................................................................

(d) The diagram below shows the conditions at four positions, A, B, C and D, on a building.

(i) Place a cross in the box next to the position where the lichen is likely to be most abundant.

(1)

(ii) The abundance of lichen on the walls of this building can be measured by determining the
percentage cover of lichen.
Suggest how the percentage cover of lichen could be determined.

(3)

.............................................................................................................................................

(iii) Explain how light intensity could be measured at the surface of the wall.

(2)

.............................................................................................................................................

(iv) Suggest how the data collected could be used to show whether there is a relationship
between the abundance of lichen and light intensity.

(3)

.............................................................................................................................................

.............................................................................................................................................
(Total for Question = 13 marks)

Q4.

Glaciers are long, large masses of ice that formed thousands of years ago. As a result of warmer
climates, more ice is melting. This is reducing the length of the glaciers. As a result, bare rock
that was once covered by the glacier becomes exposed.

The diagram below shows the length of a glacier 100 years ago and the glacier at present. It also
shows what is now found in a transect taken from where the front edge of the glacier is at
present.

(a) Using the information in the diagram, describe and explain the changes in the distribution of
organisms with distance from the front edge of this glacier.

(3)

.............................................................................................................................................

(b) Epilobium latifolium is a plant that occupies a niche in an area once covered by this glacier.
It is a short flowering plant that grows in clumps.

The photograph below shows three clumps of Epilobium latifolium.

(i) Explain what is meant by the term niche, using the plant Epilobium latifolium as an example.

(3)

.............................................................................................................................................

(ii) Describe how to carry out a study of the distribution of Epilobium latifolium from the front
edge of this glacier.

(4)

.............................................................................................................................................

(iii) Suggest one abiotic factor that might affect the abundance of Epilobium latifolium and
describe how this factor could be measured.

(3)

.............................................................................................................................................

(Total for question = 13 marks)

Q5.

The process of natural selection can lead to the adaptation of organisms to their environment as
well as to evolution.

(a) The diagram below shows two species of invertebrates found in freshwater.

(i) Suggest two features of the mayfly nymph, shown in the diagram above, that makes it
well-adapted to survival in fast-flowing streams. Explain how each feature helps it to survive.

(4)

....................................................................................................................................................................................................................................................................................
......................

(ii) The rat-tailed maggot lives in water which has a low concentration of dissolved oxygen.
Suggest how the structure labelled T helps it to survive in this environment.

(2)

....................................................................................................................................................................................................................................................................................
......................

(b) Adaptation can occur within the same species. Leopards and panthers are members of the
same species found in Africa. Leopards have spotted fur and hunt in open grasslands, whilst
panthers have black fur and hunt in forests.
Suggest how natural selection has led to the evolution of these two different forms of the same
species.

(4)

....................................................................................................................................................................................................................................................................................
......................

(Total for question = 10 marks)

Q6.

The finches of the Galapagos Islands have different shaped beaks to feed on different
food sources.

The photograph below shows one of these finches, the medium ground finch, Geospiza fortis.
The medium ground finch has a deep beak that enables it to crush seeds.
In the 1970s, there was a severe drought on the Galapagos Islands. This caused a
decrease in the production of the seeds eaten by this finch.

The graph below shows the number of medium ground finches, on one of the
Galapagos islands, from 1974 to 1978.

Medium ground finches have a range of beak sizes.

Suggest an explanation for the variation in beak sizes in medium ground finches.

(2)

.............................................................................................................................................

Q7.

Sleeping sickness is caused by an organism called Trypanosoma.

The photograph below shows Trypanosoma, a single-celled eukaryotic organism. It has a

streamlined shape and a flagellum for movement.

There are many species of Trypanosoma and these are responsible for different diseases in
different organisms.

The table below gives information about three species of Trypanosoma.

These three species are related as shown in the phylogenetic diagram below.

(i) Using the phylogenetic diagram, explain which two species of Trypanosoma are most closely
related.
(2)

.............................................................................................................................................

(ii) Name the process that resulted in different species of Trypanosoma developing as parasites
in different groups of animals over time.

(1)

.............................................................................................................................................

(iii) Suggest how molecular phylogeny was used to determine the evolutionary relationships
between these different species of Trypanosoma.

(2)

.............................................................................................................................................

(Total for question = 5 marks)

Q8.

Natural selection can lead to adaptation and evolution.

Ladybird beetles are insects that feed on other insects such as greenfly.

(a) The table below shows two possible adaptations for ladybird beetles due to natural selection.

Place a cross ( ) in the box that best describes whether the adaptation is behavioural,
anatomical or physiological.

(2)

(b) The flow chart below shows some stages of natural selection, using the ladybird beetle as an
example.

(i) Explain what is meant by the term endemic in stage 1.

(1)

.............................................................................................................................................

(ii) Suggest how genetic variation occurs within a population of ladybird beetles in stage 1.

(3)

.............................................................................................................................................

(iii) Explain what could occur in stage 2 to bring about adaptation in the ladybird beetle
population.

(4)

.............................................................................................................................................

(Total for question = 10 marks)

Q9.

Biodiversity, including both species richness and genetic diversity, is an important concept to be
considered when organising captive breeding programmes.

(a) Explain what is meant by each of the following terms.

(3)

Niche

.............................................................................................................................................

Species niche

.............................................................................................................................................

(b) One way to measure genetic diversity is to find the percentage of genes that have different
alleles.

The table below shows the percentage of genes that have different alleles in four types of cat.

*(i) Using the information in the table above and your own knowledge, suggest why the cheetah
is the cat at most risk if the environment changes.

(3)

.............................................................................................................................................

(ii) Cheetahs are unusual amongst the big cats.

A female cheetah often mates with several different males and gives birth to two or three cubs
at a time, each having a different father.

Suggest why this may be advantageous to cheetahs.

(2)

.............................................................................................................................................

(c) Rafa was a male cheetah involved in breeding programmes in several zoos. The table below
shows some data from Rafa's studbook.
Suggest what effect transferring Rafa from one zoo to another had on genetic diversity in this
species.

(2)

.............................................................................................................................................

(d) Place a cross in the box to the right of the statement that correctly describes an endemic
animal.

(2)

(Total for question = 11 marks)

Mark Scheme
Q1.
Q2.
Q3.
Q4.
Q5.
Q6.
Q7.

Q8.
Q9.
Powered by TCPDF (www.tcpdf.org)
Week 11
Photosynthesis
Draw & Label the structure of a Draw & Label the structure of a Thin layer chromatography; Identifying photosynthetic pigments
chloroplast including where the two photosystem. Annotate each label
stages of photosynthesis occur: with it’s function: What is a stationary phase?
What is a mobile phase?
Suggest 3 reasons why different pigments move at different speeds?

How do you calculate an Rf Value?

In no more than 6 bullet points, summarise a method you would use to identify
which pigments are present in a certain species of plant:
•
•
•
Summarise the differences between… •
cyclic photophosphorylation and non-cyclic photophosphorylation
•
•

Draw a labelled diagram to

show what the chromatography
paper would look like at the end
of the experiment:

Explain why the ‘light independent stage’ is not a suitable

Define a limiting factor: name:
Photosynthesis
Light Dependent Stage: Non-cyclic Photophosphorylation Light independent Stage: The Calvin Cycle
1)Label the structures on the thylakoid membrane. Name the enzyme required
2)Describe the process along the membrane (space on other side of sheet) How many cycles are required to produce 1 TP leaving the cycle?
How many cycles are required to synthesize 1 glucose molecule?

Gained from:
Used for:

Used to synthesize:
Limiting Factors
Non –cyclic photophosphorylation written Fill in the table below to compare how each limiting factor affects the rate of photosynthesis.
summary:
Limiting Stage affected & Effect on G3P Effect on TP Effect on RuBP Graph of effect
Factor Why? on rate of
photosynthesis
Light Intensity

Carbon Dioxide

Temperature

Why is water not considered to be a limiting factor?

Give 4 reasons why greenhouses increase the rate of
Photosynthesis photosynthesis:

1.
Explain the role of each of the following: Photorespiration
2.
NADP+: Why does photorespiration occur?
3.

4.
ATP: What is the name of the resulting toxic product?

Describe the following photosynthetic pathways

How is it converted back to glycerate-3-phosphate? giving examples and climates they are found in:
Water:

C3:

Why does this lower the rate at which Triose Phosphate

Rubisco: is produced?
C4:

Photons: CAM:
Questions

Q1.

An experiment was carried out to investigate the effect of temperature on the activity of the
enzyme RUBISCO. This enzyme is involved in the light-independent reaction of photosynthesis.

The RUBISCO was isolated from cotton plants and its activity measured.

The results of this experiment are shown in the table below.

(a) Using the information in the table, explain the effects of temperatures above 40 °C on the
activity of RUBISCO.

(5)

.............................................................................................................................................

.............................................................................................................................................
(b) Name the two substrates that would have been used in this experiment.

(1)

.............................................................................................................................................

(c) Place a cross in the box to complete the following sentences.

(i) The pH was kept constant to make the experiment

(1)

A accurate

B precise

C reliable

D valid

(ii) The optimum temperature of RUBISCO can be determined by

(1)

A measuring the activity at 1°C intervals between 35°C and 40°C

B measuring the activity at 1°C intervals between 40°C and 45°C

C measuring the activity at 1°C intervals between 35°C and 45°C

D repeating the experiment at 35°C, 40°C and 45°C three more times

(Total for question = 8 marks)

Q2.

The removal of carbon dioxide from the atmosphere by green plants involves carbon fixation.

(a) The following statements are about carbon fixation.

(i) Place a cross in the box next to the stage in which RuBP combines with carbon dioxide.

(1)

A The light-dependent reactions of the Calvin cycle

B The light-independent reactions of the Calvin cycle

C The light-dependent reactions of the Krebs cycle

D The light-independent reactions of the Krebs cycle

(ii) Place a cross in the box next to the enzyme that catalyses carbon fixation.

(1)

A GALP

B GP

C NADP

D RUBISCO

(iii) Place a cross in the box next to the site of carbon fixation.

(1)

A Cristae of a mitochondrion

B Granum of a chloroplast

C Matrix of a mitochondrion

D Stroma of a chloroplast

(b) Varieties of the crop plant, maize (Zea mays), are grown in many countries which have
relatively long, warm growing seasons. The seed heads, known as corn cobs, contain grains
(seeds) that are used in the production of many cereal products. A typical corn cob is shown in
the photograph below.

(i) Suggest why the development of corn cobs, suitable for producing cereal products, depends
on the rate of carbon fixation in maize plants.

(3)

.............................................................................................................................................

(ii) As the demand for maize has increased, it has started to be grown in many more regions of
the World. In order to meet this demand, new varieties of maize have been developed from older
traditional varieties by scientific breeding programmes.

The graph below shows the rate of carbon fixation for six new varieties (A to F) of maize at two
different environmental temperatures, 25ºC and 14ºC.

The rate of carbon fixation is higher at 25ºC than at 14ºC for each of the six varieties of maize.
Suggest an explanation for this.

(2)

.............................................................................................................................................

(iii) The table below shows the range of temperatures for the main crop-growing season for
maize, in four regions of the World. The main maize variety grown in three of the regions is also
shown.

Using the data shown in the graph, complete the table by selecting the most suitable maize
variety for Central Europe. Explain the reasons for your choice.

(5)

.............................................................................................................................................

(Total for question = 13 marks)

Q3.

Chloroplasts and mitochondria are both found in plant cells.

The structures found in chloroplasts and mitochondria can be studied using an electron
microscope.

Some structures are found in both chloroplasts and mitochondria.

Other structures are found in either chloroplasts only or mitochondria only.

A Venn diagram can be drawn to represent this information. Structures found in both
chloroplasts and mitochondria are written in the part of the diagram where the circles overlap.

Complete the Venn diagram below by writing the names of two structures in each part of the
diagram.

(3)

(Total for question = 3 marks)

Q4.

In seaweeds that are found on shores around Britain, photosynthesis occurs during the time that
they are submerged at high tide. Seaweeds found near the top of the shore are submerged for
short periods in shallow water. Seaweeds found lower down the shore are submerged for longer
periods in deeper water.

(a) The diagram below shows the double-membrane envelope of a chloroplast.

(i) Complete the diagram to show the structures involved in the light-dependent reactions of
photosynthesis. Label these structures.

(2)

(ii) The table below shows two statements taken from a student's essay about the
light-dependent reactions of photosynthesis.

Complete the following table by placing a tick in the correct column next to each statement to
show whether it is true or false.

(2)

(iii) Explain how oxygen is produced during the light-dependent reactions of photosynthesis.

(2)

.............................................................................................................................................

(b) As light penetrates deeper water, red, orange and yellow wavelengths are absorbed by the
seawater, whereas in shallow water most wavelengths penetrate.

The table below shows the relative rates of photosynthesis in a green seaweed, Ulva lactuca,
and a red seaweed, Schizymenia dubyi, at different wavelengths of light.
The relative rates of photosynthesis are compared with the rate in light with a wavelength of 660
nm (red).

(i) Using the data in the table, suggest where each of these two seaweeds is most likely to be
found on a seashore. Place a tick in the most appropriate box in each column.

(2)

(ii) The table below shows two statements taken from a student's essay about the
light-dependent reactions of photosynthesis.

(4)

.............................................................................................................................................

(Total for question = 12 marks)

Q5.

The diagram below shows part of the carbon cycle. The processes A, B, C, D and E,
transfer carbon.

Explain how carbon dioxide is removed from the air into the oceans by process A.

(2)

.............................................................................................................................................

.............................................................................................................................................
Q6.

The diagram below shows part of the carbon cycle. The processes A, B, C, D and E,
transfer carbon.

Place a cross in the box next to the reaction in process E that uses carbon dioxide.

(1)

A light-dependent reaction

B light-independent reaction

C photolysis

D photophosphorylation

Q7.

Photosynthesis can be divided into two main stages, the light-dependent stage and the
light-independent stage.

(a) Explain why the light-independent stage cannot take place without the light-dependent
stage.

(3)

.............................................................................................................................................

(b) An investigation was carried out by a student, to find the effect of temperature on the rate of
photosynthesis in Elodea canadensis (Canadian pondweed).

The rate of photosynthesis was measured over a period of two hours at a fixed temperature. This
was repeated at different temperatures.

All other abiotic factors were controlled.

The results of this investigation are shown in the graph below.

(i) Place a cross ( ) in the box next to the statement that describes what could be measured to
find the rate of photosynthesis in this investigation.
(1)

A increase in mass of Elodea

B mass of nitrate absorbed

C volume of carbon dioxide produced

D volume of oxygen produced

(ii) The temperatures used in this investigation were 0ºC, 10ºC, 20ºC, 30ºC, 40ºC and 50ºC.

Suggest what the results of the investigation show about the minimum temperature required for
photosynthesis in Elodea. Give a reason for your answer.

(2)

.............................................................................................................................................

(iii) Explain the meaning of the following statement.

"All other abiotic factors were controlled."

(2)

.............................................................................................................................................

(iv) The student, who carried out this investigation, wrote the following as part of her conclusion.

Enzymes control the rate of photosynthesis in Elodea.

Discuss how far the results of this investigation support her conclusion.

(4)
.............................................................................................................................................

.............................................................................................................................................

(Total for question = 12 marks)

Q8.

(a) The diagram below shows some of the steps in the process of photosynthesis.

(i) Place a cross in the box next to the name of molecule P in the diagram.

(1)

A carbon dioxide

B oxidised NADP

C reduced NADP

D RUBISCO
(ii) Name the molecules R and S in the diagram.

(1)

molecule R ...........................................................

molecule S ...........................................................

(iii) Describe how molecule Q is produced.

(4)

.............................................................................................................................................

(b) The electronmicrograph below shows an image of a chloroplast.

(i) Place a cross in the box next to the name of the part labelled Z.

(1)

A carbon dioxide

B oxidised NADP

C reduced NADP

D RUBISCO

(ii) The equation below can be used to calculate the magnification of this chloroplast.

image length = actual length × magnification

The actual length of this chloroplast is 0.007 mm.

Measure the image length between lines W and Y. Use this equation to calculate the
magnification of the image.

(3)

magnification = ...........................................................

(iii) Describe the structure of chloroplasts in relation to their roles in photosynthesis.

(3)

.............................................................................................................................................

(Total for question = 13 marks)

Q9.

(a) The diagram below shows some of the steps in the process of photosynthesis.

(i) Name molecules P and Q in the diagram.

(1)

molecule P ...........................................................

molecule Q ...........................................................

(ii) Place a cross in the box next to the names of molecules R and S in the diagram.

(1)

A ADP and oxidised NADP

B ADP and reduced NADP

C ATP and oxidised NADP

D ATP and reduced NADP

(iii) Describe the role of RUBISCO in the production of GALP in the light-independent reaction.

(4)

.............................................................................................................................................

(b) The electronmicrograph below shows a chloroplast.

(i) Place a cross in the box next to the name of the part labelled Z.

(1)

A cytoplasm

B matrix

C stroma

D thylakoid

(ii) The equation below can be used to calculate the magnification of this chloroplast.

magnification = image length ÷ actual length

Use this equation to calculate the actual length of this chloroplast, between the lines labelled W
and Y.

Show your working.

(3)

(iii) Describe how the membranes inside the chloroplast are involved in photosynthesis.

(3)
.............................................................................................................................................

.............................................................................................................................................

(Total for question = 13 marks)

Mark Scheme

Q1.
Q2.
Q3.
Q4.
Q5.
Q6.

Q7.
Q8.
Q9.
Powered by TCPDF (www.tcpdf.org)

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Recruitment of Junior Assistants, Senior Assistants and Junior Executives in Various Disciplines
4 pages
10 Most Bizarre Festivals
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10 Most Bizarre Festivals
6 pages