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EC3 2a Biology Exam
Topic 4.4 Take Home
Date:
Time: 90 minutes
Total marks available: 79
Total marks achieved: ______
Questions
Q1.
Some organelles in plant and animal cells are surrounded by a membrane.
(a) Name two organelles that have a single membrane.
(2)
1 ..........................................................................................................................................
2 ..........................................................................................................................................
(b) The photograph below shows a section through a cell from the stem of a clematis plant.
Put a cross
in the box next to the correct word or words to complete each of the following
statements.
(i) The structures labelled J contain starch and are
(1)
A
B
C
D
amyloplasts
mitochondria
nuclei
vesicles
(ii) The structures labelled K, in the cellulose cell wall, are
(1)
A
B
C
D
middle lamellae
mitochondria
pits
vesicles
*(iii) Compare the structure of starch with the structure of a cellulose molecule.
(4)
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(c) In plant cells, some of the organelles are plastids.
Most flowering plants gain their plastids from the female parent and not the male parent. This is due to
the double fertilisation that occurs in flowering plants.
(i) Describe the process of doublefertilisation in flowering plants.
(3)
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(ii) During the growth of the plant, the cells divide. Before cell division takes place, the plastids divide.
Name the stage of the cell cycle in which plastids would divide.
(1)
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(Total for question = 12 marks)
Q2.
The diagram below shows a cross section through part of a plant stem.
(a) (i) Explain what is meant by the term tissue.
(2)
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(ii) Identify the tissue shown in the diagram.
(1)
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(iii) Place a cross
in the box that completes the following statement.
Letter Q, in the diagram, indicates the
(1)
A
B
C
D
cell surface membrane
envelope
middle lamella
plasmodesmata
(b) The function of the tissue in the diagram is to provide support.
(i) Name two substances found in the secondary cell wall that provide support.
(2)
1
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2
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(ii) Explain how the structure of the cell walls in this tissue enables it to be strong and flexible.
(2)
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(Total for question = 8 marks)
Q3.
Severe headaches are a symptom of migraine.
Sumatriptan is a drug that can reduce the symptoms of migraine.
Adults with migraine took part in a double blind trial to investigate the effects of sumatriptan.
(a) Suggest how the double blind trial for this drug was carried out.
(4)
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(b) Patients with a migraine attack were given either 10mg sumatriptan, 20mg sumatriptan or a placebo to
treat the pain.
Patients recorded how long it took for them to be free of pain.
The results of this drug trial are shown in the graph below.
(i) Place a cross ( ) in the box to complete the following statement.
After 90 minutes, the difference in the percentage of patients free of pain between those taking a
placebo and those taking 20 mg sumatriptan is
(1)
A
37%
B
40%
C
77%
D
79%
(ii) Using the information in the graph, describe the effects of sumatriptan on the treatment of the
symptoms of migraine.
(3)
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(iii) Using the information in the graph, suggest what conclusions can be drawn from this drug trial.
(3)
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(Total for question = 11 marks)
Q4.
New drugs are being developed. However, before a new drug is approved for general use, it must be tested.
(a) Before drugs are tested on humans, they are tested on tissues and animals.
(i) Complete the flow chart to show levels of organisation in multicellular organisms.
(1)
(ii) Suggest why, after testing a drug on tissue samples, the drug is also tested on whole animals.
(3)
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(b) Three-phase testing on humans takes place before a new drug is approved for general use.
The table below shows the test population used in each phase of the test.
(i) Place a cross
in the box that completes the following statement.
The effects of the drug being tested are always compared with the effects of either a placebo or a
pre-existing treatment in
(1)
A
B
C
D
animals
phase 1
phase 2
phase 3
(ii) Suggest two variables that need to be taken into account when selecting volunteers for phase 1.
(2)
1
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2
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(c) In 1775, William Withering tested foxglove extracts to treat the symptoms of a variety of diseases.
He used extracts of various parts of this plant to treat 163 patients.
Compare the reliability of William Withering's trials with those carried out using contemporary drug
testing protocols.
(2)
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(Total for question = 9 marks)
Q5.
Flax (Linum usitatissimum) is grown in many countries as sources of fibres used to make linen cloth.
The photograph below shows part of a fibre from a flax plant, as seen using an electron microscope.
(a) Suggest the type of tissue that forms fibres in flax plants.
(1)
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(b) Flax fibres have a high tensile strength that makes them useful for making cloth.
(i) Describe what is meant by the tensile strength of fibres.
(1)
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(ii) The concentration of calcium ions affects the tensile strength of plant fibres.
Suggest why calcium ions affect the tensile strength of plant fibres.
(2)
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(c) An investigation was carried out into the effects of mineral ion concentrations on the size of fibres
produced by flax plants.
Seedlings of flax plants were grown in different concentrations of mineral ions.
A control group of plants was grown in a standard mineral ion concentration.
This solution contained a low concentration of mineral ions.
Seedlings in group 1 were grown with no mineral ions. Seedlings in group 2 were grown with mineral ion
concentrations five times greater than the control group.
After eight weeks, fibres were extracted from the plants. The diameter and thickness of the cell walls of
the fibres were then measured.
The results are shown in the table below with standard deviations shown as ±.
(i) Use the information in the table to describe the effects of mineral ions on the flax fibres.
(3)
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(ii) It was found that the plants grown in group 2 contained more chlorophyll than the control group.
Suggest an explanation for the difference in chlorophyll content of these two groups.
(2)
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(Total for question = 9 marks)
Q6.
Organisms are made of cells. There are differences in the ultrastructure of prokaryotic and eukaryotic cells.
There are also differences between plant and animal cells.
(a) Place a cross (
) in the box next to the correct words to complete each of the following statements.
(i) Ribosomes are found in
(1)
A
animal cells only
B
eukaryotic cells only
C
prokaryotic cells only
D
eukaryotic and prokaryotic cells
(ii) Amyloplasts are found in
(1)
A
animal cells only
B
plant cells only
C
prokaryotic cells only
D
eukaryotic and prokaryotic cells
(iii) Mitochondria are found in
(1)
A
animal cells only
B
eukaryotic cells only
C
prokaryotic cells only
D
eukaryotic and prokaryotic cells
(iv) Centrioles are found in
(1)
A
animal cells only
B
all eukaryotic cells
C
prokaryotic cells only
D
eukaryotic and prokaryotic cells
(b) Eukaryotic cells contain membrane bound organelles. The diagram below shows one of these
organelles.
(i) Place a cross (
) in the box next to the name of this organelle.
(1)
A
centrioles
B
Golgi apparatus
C
mitochondrion
D
rough endoplasmic reticulum
(ii) Describe the function of this organelle.
(3)
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(Total for question = 8 marks)
Q7.
Packaging materials can be made from plastics produced from oil or bioplastics.
Bioplastics are made from either starch or cellulose.
(a) Starch and cellulose are both polysaccharides found in plants.
(i) The table below lists features of polysaccharides.
Complete the table by placing a cross in the appropriate box (
in cellulose, starch or both.
) to indicate if each feature is present
(4)
(ii) Describe how the structure of starch is related to its function in plants.
(4)
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(b) The photograph below shows a bioplastic wrapper made from starch.
Suggest the advantages of using bioplastic wrappers instead of plastic wrappers made from oil.
(3)
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(Total for question = 11 marks)
Q8.
The photograph below shows a section through the cell walls of two adjacent xylem vessels in the stem of a
plant, as seen using an electron microscope.
(a) Put a cross
in the box next to the correct answer.
(i) The middle lamella is labelled
(1)
A
B
C
D
(ii) The layer that contains secondary thickening is labelled
(1)
A
B
C
D
(iii) Explain how secondary thickening in the cell wall contributes to the physical properties of xylem
vessels.
(3)
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(b) Fibres containing xylem vessels can be used to make textiles.
Fibres from jute plants are used to make rope.
These fibres are extracted in water. The fibres are then hung out to dry, as shown in the photograph
below.
(i) Explain why jute fibres are an example of a sustainable resource.
(2)
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(ii) The tensile strength of jute fibres is affected by humidity, the amount of moisture in the air.
The effect of humidity on the tensile strength of jute fibres is shown in the graph below.
Using the information in the graph, describe the effect of humidity on the tensile strength of jute fibres.
(2)
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(iii) Name two variables that need to be controlled when investigating the effect of humidity on the
tensile strength of jute fibres.
(2)
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2 ..........................................................................................................................................
(Total for question = 11 marks)