Download Q1.The effect of watering tomato plants with sodium chloride

Q1.The effect of watering tomato plants with sodium chloride solution on the mass of tomatoes
Type of
tomato plant
Watered with
Normal
Distilled water
Normal
Sodium chloride
solution
GM
Distilled water
GM
Sodium chloride
solution
(a)
Mean mass of tomatoes /
g
fresh mass
dry mass
115.9
6.5
87.8
6.6
101.3
6.4
57.4
6.5
What conclusions can you draw about the effects of watering plants with sodium
chloride solution on the mass of tomatoes?
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(2)
(b)
Use your knowledge of water potential to suggest how watering plants with sodium
chloride solution affects the fresh mass of the tomatoes.
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(Extra space) .................................................................................................
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(3)
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(Total 5 marks)
Q2.
The diagram shows a carrot.
A group of students investigated the effect of sucrose concentration on the length of
cylinders cut from a carrot.
(a)
The students used a cork borer to cut cylinders from the carrot. Describe how the
students should cut these cylinders to make sure that this was a fair test and would
produce reliable results.
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(2)
(b)
They measured the initial length of each cylinder then placed the cylinders into test
tubes containing different concentrations of sucrose solution. Bungs were placed in
the tubes and the tubes were left overnight. Explain why the bungs were placed in
the tubes.
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(2)
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(c)
The students then measured the final lengths of the carrot cylinders. Their results
are shown in the table.
Concentration of sucrose / mol dm–3
(i)
0.0
1.4
0.2
1.4
0.4
1.2
0.6
1.1
0.8
0.9
The students used these results to find the concentration of sucrose that has
the same water potential as the carrot cylinders. Describe how they could
have done this.
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(2)
(ii)
Was it important in this investigation that the carrot cylinders had the same
initial length? Explain your answer.
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(1)
(Total 7 marks)
Q3.
The diagram shows a cholera bacterium. It has been magnified 50 000 times.
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(a)
Name A.
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(1)
(b)
Name two structures present in an epithelial cell from the small intestine that are
not present in a cholera bacterium.
1 ...................................................................................................................
2 ...................................................................................................................
(2)
(c)
Cholera bacteria can be viewed using a transmission electron microscope (TEM) or
a scanning electron microscope (SEM).
(i)
Give one advantage of using a TEM rather than a SEM.
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(1)
(ii)
Give one advantage of using a SEM rather than a TEM.
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(1)
(d)
Calculate the actual width of the cholera bacterium between points B and C.
Give your answer in micrometres and show your working.
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(2)
(e)
An outbreak of cholera occurred in London in 1849. The graph shows the
relationship between the number of deaths from cholera and the height at which
people lived above sea level.
Describe the relationship between the number of deaths from cholera and the height
at which people lived above sea level.
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(2)
(Total 9 marks)
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Q4.
A student investigated the effect of putting cylinders cut from a potato into sodium
chloride solutions of different concentration. He cut cylinders from a potato and weighed
each cylinder. He then placed each cylinder in a test tube. Each test tube contained a
different concentration of sodium chloride solution. The tubes were left overnight. He then
removed the cylinders from the solutions and reweighed them.
(a)
Before reweighing, the student blotted dry the outside of each cylinder. Explain why.
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(2)
The student repeated the experiment several times at each concentration of sodium
chloride solution. His results are shown in the graph.
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(b)
The student made up all the sodium chloride solutions using a 1.0 mol dm–3 sodium
chloride solution and distilled water.
Complete the table to show how he made 20 cm3 of a 0.2 mol dm–3 sodium chloride
solution.
Volume of 1.0 mol dm–3 sodium chloride
solution
Volume of distilled
water
(1)
(c)
The student calculated the percentage change in mass rather than the change in
mass. Explain the advantage of this.
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(2)
(d)
The student carried out several repeats at each concentration of sodium chloride
solution. Explain why the repeats were important.
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(2)
(e)
Use the graph to find the concentration of sodium chloride solution that has the
same water potential as the potato cylinders.
.............................. mol dm–3
(1)
(Total 8 marks)
Q5.
(a)
Give two ways in which active transport is different from facilitated diffusion.
1 ...................................................................................................................
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2 ...................................................................................................................
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(2)
Scientists investigated the effect of a drug called a proton pump inhibitor. The drug is
given as a tablet to people who produce too much acid in their stomach. It binds to a
carrier protein in the surface membrane of cells lining the stomach. This carrier protein
usually moves hydrogen ions into the stomach by active transport.
The scientists used two groups of people in their investigation. All the people produced
too much acid in their stomach. People in group P were given the drug. Group Q was the
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control group.
The graph shows the results.
(b)
(i)
The scientists used a control group in this trial. Explain why.
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(1)
(ii)
Suggest how the control group would have been treated.
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(2)
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(c)
Describe the effect of taking the drug on acid secretion.
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(1)
(Total 6 marks)
Q6.
Scientists use optical microscopes and transmission electron microscopes (TEMs) to
investigate cell structure. Explain the advantages and the limitations of using a TEM to
investigate cell structure.
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(Total 5 marks)
Q7.
The diagram shows a cell cycle.
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(a)
In prophase of mitosis, the chromosomes become visible. Describe what happens in
(i)
metaphase
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(2)
(ii)
anaphase.
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(2)
(b)
(i)
Cells lining the human intestine complete the cell cycle in a short time. Explain
the advantage of these cells completing the cell cycle in a short time.
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(1)
(ii)
The time required for a cell to complete the cell cycle was 4 hours 18 minutes.
Calculate the time required in minutes for this cell to multiply to produce eight
cells.
Show your working.
Answer .....................................................
(2)
(c)
Mikanolide is a drug that inhibits the enzyme DNA polymerase. Explain why this
drug may be effective against some types of cancer.
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(2)
(Total 9 marks)
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Q8.
Yeast is a single-celled eukaryotic organism. When yeast cells are grown, each cell
forms a bud. This bud grows into a new cell. This allows yeast to multiply because the
parent cell is still alive and the new cell has been formed.
Scientists grew yeast cells in a culture. They counted the number of cells present and
measured the total concentration of DNA in the culture over a period of 6 hours. Their
results are shown in the graph.
(a)
Use your knowledge of the cell cycle to explain the shape of the curve for the
number of yeast cells
(i)
between 1 and 2 hours
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(1)
(ii)
between 3 and 4 hours.
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(1)
(b)
Use the curve for the concentration of DNA to find the length of a cell cycle in these
yeast cells. Explain how you arrived at your answer.
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Length of cell cycle ......................................................................................
Explanation ..................................................................................................
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(3)
(Total 5 marks)
Q9.Scientists investigated the effect of bromelain on cancer cells. They took cells from skin
cancers in mice and added them to a liquid growth medium in two dishes.
Four hours later they added a solution of bromelain to one of the dishes. They left the
other dish as a control. They also added a substance to both dishes that is turned purple
by respiring cells.
Both dishes were placed in an incubator. The scientists measured the intensity of the
purple colour at intervals over a period of 100 hours.
(a)
The scientists put the same number of skin tumour cells in each dish at the start of
this investigation. Explain why it was important to put the same number of cells in
each dish.
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(1)
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(b)
The scientists concluded that bromelain did not kill cancer cells but stopped them
dividing. Does the graph support this conclusion? Explain your answer.
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(2)
(c)
An article in a newspaper claimed that these data show that bromelain can be used
to treat cancer.
Give three reasons why we should be careful about accepting this claim.
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(3)
(d)
The rate of cell division is important in investigations into cancer. Suggest why.
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(2)
(e)
Scientists have investigated the effects of bromelain on cancer growth in humans.
Suggest why they gave bromelain in addition to, rather than instead of, the usual
treatment.
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(2)
(Total 10 marks)
Q10.
The diagram shows a cell cycle.
(a)
The table shows the number of chromosomes and the mass of DNA in different
nuclei.
All the nuclei come from the same animal. Complete this table.
Nucleus
At prophase of mitosis
Number of
chromosomes
Mass of DNA / arbitrary units
26
60
At telophase of mitosis
From a sperm cell
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(4)
(b)
If the DNA of the cell is damaged, a protein called p53 stops the cell cycle.
Mutation in the gene for p53 could cause cancer to develop. Explain how.
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(3)
(c)
Drugs are used to treat cancer. At what phase in the cell cycle would each of the
following drugs act?
(i)
A drug that prevents DNA replication
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(1)
(ii)
A drug that prevents spindle fibres shortening
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(1)
(Total 9 marks)
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M1.(a)
No effect on dry mass / small increase in dry mass;
Decrease in fresh mass;
Ignore reference to figures.
2
(b)
Water potential inside tomato plant becomes higher / less negative;
Water drawn out of tomato plants / more difficult for tomato plants to take up
water;
By osmosis;
Most of the fresh mass is (mass of) water;
3 max
[5]
M2.
(a)
Lengthways / down the root;
Through one tissue only / through same part / same proportion of tissues;
2
(b)
To prevent the water from evaporating / prevent evaporation;
Changing the concentrations / water potential (of solution);
2
(c)
(i)
Plot data on a graph;
Find (sucrose concentration) from the graph where the ratio is 1;
2
(ii)
No, because the results are given as a ratio / as a proportion of initial
length;
1
[7]
M3.
(a)
(Plasma / cell) membrane;
Reject: nuclear membrane
1
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(b)
Nucleus / nuclear envelope / nuclear membrane / nucleolus;
Accept: membrane-bound organelles only if an example has
not been given
Mitochondrion;
(Smooth / rough) ER;
Lysosome;
Microvillus / brush border;
Neutral: villi
Golgi;
Linear / non-circular DNA / chromosome;
Neutral: DNA strands
80S / denser / heavier / larger ribosomes;
Neutral: ribosomes
2 max
(c)
(i)
Higher resolution / higher (maximum) magnification / higher detail (of
image);
OR
Allows internal details / structures within (cells) to be seen / cross
section to be taken;
Accept: ‘better’ instead of ‘higher’
Neutral: shorter wavelength
Reject: longer wavelength
Reject: can be used on living specimens
Q Do not accept ‘clearer’ image
1
(ii)
Thin sections do not need to be prepared / shows surface of specimen /
can have 3-D images;
Accept: can be used on thick(er) specimens
Reject: can be used on living specimens
Neutral: refs. to staining / preparation / artefacts / colour
1
(d)
Two marks for correct answer of 0.42 – 0.46;;
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One mark for incorrect answers in which candidate clearly divides measured
width by magnification;
Correct answer = 2 marks outright
Accept: 0.4 or 0.5 only if working is correct for 2 marks
Do not award a mark for 0.4 or 0.5 if there is no working out
Ignore rounding up
2
(e)
As height increases, the number of deaths decrease / inversely proportional /
negative correlation;
Correct reference to increase / decrease at 14-30m;
Accept: converse statement
Must give a trend and not simply give individual points
Do not penalise for ‘more likely to get cholera’
2
[9]
M4.
(a)
Water will affect the mass / only want to measure water taken up or lost;
Amount of water on cylinders varies / ensures same amount of water on
outside;
Neutral: removes water
Accept: ‘(sodium chloride) solution’ for water
Do not accept ‘sodium chloride’
Neutral: refs. to fair testing
2
(b)
4 cm3 (of 1.0 mol dm–3 sodium chloride solution) and 16 cm3 (of distilled water);
Reject: factors and multiples of these figures e.g. 2 cm3 and
8 cm3, as final volume should be 20 cm3
1
(c)
Allows comparison / shows proportional change;
Idea that cylinders have different starting masses / weights;
Reject: if comparison is in context of the start and final mass
of the same cylinder
Neutral: different masses
Neutral: different starting sizes
2
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(d)
(Allows) anomalies to be identified / ignored / effect of anomalies to be
reduced / effect of variation in data to be minimised;
Makes the average / mean / line of best fit more reliable / allows concordant
results;
Accept: ‘outliers’ instead of anomalies
Q Reject: abnormalities
Reject: idea of not recording anomalies / preventing
anomalies from occurring
Accept: ‘cancels out anomalies’ as bottom line response
Q Reject: makes the average / mean more accurate
Neutral: makes the average / mean more valid
Neutral: makes ‘it’ / results / conclusion more reliable
2
(e)
0.35 (mol dm–3)
1
[8]
M5.
(a)
1.
Uses energy / ATP;
2.
Against concentration gradient / low to high concentration;
3.
Does not use channel proteins / only uses carrier proteins;
Assume “it” refers to active transport.
1. Facilitated diffusion is passive - neutral
2. Along / across concentration gradient - neutral
Accept up / down concentration gradient
Accept AT does not need concentration gradient.
2 max
(b)
(i)
To see the effect of the drug / effect not due to anything else in the
tablet;
Neutral “to compare results”
1
(ii)
Placebo / dummy drug / tablet without drug;
(Otherwise) treated the same;
No drug - neutral
Accept: Example e.g. tablet given at same time
2
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(c)
Decrease for 3 hours;
Accept decreases from 1 - 4 hours
1
[6]
M6.
Advantages:
1
Small objects can be seen;
2
TEM has high resolution as wavelength of electrons shorter;
Accept better
Limitations:
3
Cannot look at living cells as cells must be in a vacuum / must cut section /
thin specimen;
4
Preparation may create artefact
5
Does not produce colour image;
[5]
M7.
(a)
(i)
Spindle formed / chromosome / centromere / chromatids
attaches to spindle;
Chromosomes / chromatids line up / move to middle / equator
(of cell);
Do not award second mark for answers referring to
chromosomes ‘pairing up’.
Ignore reference to homologous chromosomes unless
context suggests pairing which negates second mark.
Neutral: Details on nuclear membrane.
Accept: Diagram for second marking point.
2
(ii)
Chromosome / centromere splits / chromatids / ‘chromosomes’ separate
/ pulled apart;
To (opposite) sides / poles / centrioles (of cell);
Reject: Homologous chromosomes separate for first marking
point.
Accept: Diagram for second marking point.
Chromatids / ‘chromosomes’ move to poles / sides /
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centrioles = 2 marks.
2
(b)
(i)
Form / replace cells quickly / rapidly / divide / multiply / replicate rapidly;
Neutral: Repair cells.
Answers must convey idea of ‘speed’.
1
(Ii)
Correct answer = 774 minutes / 12 hours 54mins = 2 marks;;
Incorrect answer but indicates 3 cell cycles involved = one mark;
2
(c)
Prevents / slows DNA replication / doubling / prevents / slows mitosis;
New strand not formed / nucleotides (of new strand) not joined
together / sugar-phosphate bonds not formed;
First marking point must be in context of DNA replication not
cell replication.
Do not negate first marking point if role of DNA polymerase
is described incorrectly e.g. Reject: ‘joins bases / strands
together’.
Role of DNA polymerase must be correct for last marking
point.
2
[9]
M8.
(a)
(i)
Cells are in interphase;
Accept G phase / S phase.
1
(ii)
Cells undergoing mitosis / in telophase / cytokinesis;
Accept all named stages but reject prophase, metaphase or
anaphase on their own.
1
(b)
1.
3 hours;
2.
Time between beginnings / endings DNA replication / Increases /
levelling outs of DNA concentration / for shape (of curve for replication)
to be repeated;
3.
(DNA) replication takes place once per cell cycle;
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Allow close approximation where candidate attempts to be
more accurate.
Principle
What is shown on the graph
3
[5]
M9.(a)
To ensure the colour is the same at the start;
1
(b)
Yes – curve on graph with bromelain present remains approximately constant
/ rises very slightly;
Would decrease if killing of cells occurred / would increase if cells still dividing;
2
(c)
Use of mouse cells (rather than human);
(Carried out) in vitro / not in living organisms;
Only tested on one type of cancer;
Not possible to predict effect on humans (as no data collected);
3 max
(d)
The faster the rate of division the faster the cancer would grow;
By measuring rate of cell division you could see how effective the treatment
was;
2
(c)
Not ethical to replace conventional treatment;
As life of patient is at risk (if bromelain not effective);
2
[10]
M10.
(a)
Nucleus
Number of
chromosomes
Mass of DNA /
arbitrary units
At telophase of mitosis
26;
30;
From a sperm cell
13;
15;
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4
(b)
Cancer cells often have faulty / damaged DNA;
Protein / p53 faulty / not made;
Cell (with faulty / DNA) divides / completes cell cycle;
Uncontrolled division produces cancer;
p53 refers to the protein so do not accept reference to p53
mutating.
3
(c)
(i)
Interphase / S phase / synthesis phase;
1
(ii)
Anaphase / A;
1
[9]
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