AS Unit 1 Chap 3, 4 and 5
1.
The diagram shows a bacterium.
F
E
D
A
B
C
Identify the structures labelled A to F and give one function of each.
A ................................................................................................................................
Function. ....................................................................................................................
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B ................................................................................................................................
Function. ....................................................................................................................
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C ................................................................................................................................
Function. ....................................................................................................................
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D ................................................................................................................................
Function. ....................................................................................................................
....................................................................................................................................
E .................................................................................................................................
Function. ....................................................................................................................
....................................................................................................................................
F .................................................................................................................................
Function. ....................................................................................................................
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(Total 6 marks)
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2.
The diagram shows a bacterium.
(a)
Give the function of
(i)
organelle X;
...........................................................................................................................
(ii)
organelle Y.
...........................................................................................................................
(2)
S
(b)
(i)
Give two ways in which the structure of this bacterium is similar to the
structure of a cell lining the human small intestine.
1 .........................................................................................................................
............................................................................................................................
2 .........................................................................................................................
............................................................................................................................
(2)
(ii)
Give two ways in which the structure of this bacterium differs from the structure of
a cell lining the human small intestine.
1 ........................................................................................................................
...........................................................................................................................
2 ........................................................................................................................
...........................................................................................................................
(2)
(Total 6 marks)
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3.
The drawing is from an electron micrograph of a bacterium.
(a)
Name parts A and B.
A ..................................................................
B ..................................................................
(2)
(b)
The length of the bacterium between X and Y is 6.5 µm. Calculate the magnification of
the drawing. Show your working.
Answer ...............................................
(2)
(Total 4 marks)
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4.
The diagram shows part of a plasma membrane. The arrows show the path taken by sodium ions
and by substance X when they diffuse through the membrane into a cell.
Substance
X
(a)
Sodium
ions
An optical microscope cannot be used to see a plasma membrane. Explain why.
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(2)
(b)
Give one property of the molecules of substance X which allows them to diffuse through
the membrane at the position shown.
............………..............................................................................................................
............………..............................................................................................................
(1)
(c)
The effect of the concentration of sodium ions in the surrounding solution on their rate of
diffusion across the membrane was investigated. The graph shows the results.
C
Rate of
diffusion
D
B
A
Concentration of
sodium ions outside cell
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(i)
What limits the diffusion of sodium ions across the membrane between
A and B on the graph? Give the evidence for your answer.
Limiting factor .................................................................................................
Evidence ...........................................................................................................
...........................................................................................................................
(2)
(ii)
Explain the shape of the curve between C and D.
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(2)
(Total 7 marks)
5.
The thyroid gland is an organ in the neck. The diagram shows the process in which epithelial
cells from the thyroid gland make and secrete a protein called thyroglobulin.
C Thyroglobulin secreted
Organelle A
Organelle B
Amino acids
(a)
Name
(i)
organelle A;
............................................................................................................................
(1)
(ii)
the process by which thyroglobulin is secreted from the cell at C.
............................................................................................................................
(1)
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(b)
(i)
Describe the part played by the organelles labelled B.
............................................................................................................................
............................................................................................................................
(1)
(ii)
Organelle B is very small. It cannot be seen when thyroid cells are examined with
an optical microscope but it can be seen with an electron microscope.
Explain why this organelle can be seen with an electron microscope.
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(2)
(Total 5 marks)
6.
(a)
An electron microscope has a much greater resolving power than an optical microscope.
(i)
Explain the meaning of the term resolving power.
...........................................................................................................................
...........................................................................................................................
(1)
(ii)
Explain the reason for this difference in resolving power.
...........................................................................................................................
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(1)
The diagram represents the structure of an animal cell as it would appear when seen with an
electron microscope.
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(b)
Name one structure:
(i)
that is present in this cell but would not be in a bacterial cell;
...........................................................................................................................
(1)
(ii)
that is not present in this cell but may be present in a bacterial cell.
...........................................................................................................................
(1)
(c)
Describe one function of the organelle labelled X.
.....................................................................................................................................
.....................................................................................................................................
(1)
(Total 5 marks)
7.
The diagram shows the pathways in the heart for the conduction of electrical impulses during
the cardiac cycle.
(a)
The table shows the blood pressure in the left atrium, the left ventricle and the aorta at
different times during part of a cardiac cycle.
Blood pressure / kPa
Time / s
Left atrium
Left ventricle
Aorta
0.0
0.5
0.4
10.6
0.1
1.2
0.7
10.6
0.2
0.3
6.7
10.6
0.3
0.4
17.3
16.0
0.4
0.8
8.0
12.0
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(i)
At which time is blood flowing into the aorta?
......................................................................................................................….
(1)
(ii)
Between which times are the atrioventricular valves closed?
......................................................................................................................….
(1)
(b)
The maximum pressure in the left ventricle is higher than the maximum pressure in the
right ventricle. What causes this difference in pressure?
.....................................................................................................................................
.....................................................................................................................................
(1)
(c)
The information below compares some features of different blood vessels.
Blood vessel
Property
Mean diameter
of vessel
Mean
thickness of
wall
Artery
Capillary
Vein
4.0 mm
8.0 µm
5.0 mm
1.0 mm
0.5 µm
0.5 mm
Relative thickness (shown by length of bar)
Tissues
present in
wall
Endothelium
Elastic tissue
Muscle
Use the information to explain how the structures of the walls of arteries, veins and
capillaries are related to their functions.
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(Total 9 marks)
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8.
The diagram shows part of a cell that secretes enzymes.
(a)
Give one piece of evidence, visible in the diagram, which shows that this cell is a
eukaryotic cell.
.....................................................................................................................................
.....................................................................................................................................
(1)
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(b)
Some cells similar to that shown in the diagram were grown in a culture. Radioactive
amino acids were added to the solution in which they were being grown. The
radioactivity acts as a label on the amino acid so that it can be detected wherever it is.
This radioactive label allows amino acids to be followed through the cell. At various
times, samples of the cells were taken and the amount of radioactivity in different
organelles was measured. The results are shown in the table.
Time after radioactive
amino acids were
added to the solution/
minutes
Amount of radioactivity present/arbitrary units
Golgi apparatus
Rough endoplasmatic
reticulum
Vesicles
1
21
120
6
20
42
68
6
40
86
39
8
60
76
28
15
90
50
27
28
120
38
26
56
(i)
What happens to the amino acids in the rough endoplasmic reticulum?
...........................................................................................................................
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...........................................................................................................................
...........................................................................................................................
(2)
(ii)
Use the information in the table to draw arrows on the diagram showing the path of
radioactivity through and out of the cell at X.
(3)
(iii)
Name the process which is occurring at point X on the diagram.
...........................................................................................................................
(1)
(Total 7 marks)
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9.
The diagram shows a section through part of a cell as it would appear when seen with an
electron microscope.
Cisterna
B
C
A
(a)
This cell produces and secretes a protein. Describe the part played by organelles A, B and
C in producing and secreting this protein.
.....................................................................................................................................
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(3)
(b)
The table shows information about the different parts of this cell.
Part of cell
Percentage of
total cell volume
Number in
the cell
Cytoplasm surrounding cell organelles
54
1
Mitochondria
22
about 1700
Nucleus
16
1
Lysosomes
11
about 300
Cisternae of rough endoplasmic reticulum
19
1
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(i)
Which organelle is larger, a mitochondrion or a lysosome?
Use calculations based on figures from the table to support your answer.
Larger organelle; ..............................................................................................
(2)
(ii)
In the drawing there appear to be a number of separate cisternae in the rough
endoplasmic reticulum. The table gives the approximate number of cisternae as
one. Suggest an explanation for the apparent difference.
..........................................................................................................................
..........................................................................................................................
..........................................................................................................................
..........................................................................................................................
(2)
(iii)
This cell produces a large amount of protein. Explain how the number of
mitochondria in the cell may be linked to this.
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(3)
(Total 10 marks)
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10.
The drawing shows an electron micrograph of a section through part of an alveolus from a lung.
X
Inside of
alveolus
Cell A
Cell B
(a)
Describe the path of a molecule of oxygen from the air in the alveolus at X to the plasma
membrane of cell A.
.....................................................................................................................................
.....................................................................................................................................
(1)
(b)
Cell A is a eukaryotic cell. Give two features that may be found in a prokaryotic cell
which are not found in cell A.
1 .....................................................................................................................................
........................................................................................................................................
2 .....................................................................................................................................
........................................................................................................................................
(2)
(c)
Cells A and B are biconcave discs. Explain one advantage of a biconcave disc over a
spherical cell of the same volume in transporting oxygen.
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(2)
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(d)
The diameter of a human red blood cell is 7 µm.
(i)
Calculate the magnification of the drawing. Show your working.
Magnification = ...............................
(2)
(ii)
In calculating the magnification, what assumption did you have to make about how
the section was cut?
.....................................................................................................................................
.................................................................................................................................(1)
(Total 8 marks)
11.
Read the following passage.
A red blood cell is packed full of haemoglobin. When mature, it contains none of the
organelles usually found in an animal cell. The nucleus, endoplasmic reticulum.
mitochondria and ribosomes are all absent.
5
10
More is known about the plasma membrane of a human red blood cell than about any
other eukaryotic cell membrane. One reason for this is that the plasma membrane
surrounding a red blood cell can be isolated without being contaminated by internal cell
membranes. Red blood cell plasma membranes or “ghosts” can be prepared by putting
the cells in a dilute salt solution. This causes the cells to swell and burst, leaving only the
plasma membrane.
Red blood cell ghosts have been investigated and found to contain several different
proteins. One of these proteins is spectrin. It is made up of long polypeptide chains which
form a network on the inside of the membrane. Spectrin strengthens the membrane and
is involved in maintaining the three-dimensional shape of the red blood cell.
Use the information from the passage and your own knowledge to answer the following
questions.
(a)
Complete the table by giving two ways in which the structure of a red blood cell differs
from the structure of a bacterial cell.
Red blood cell
Bacterial cell
Contains haemoglobin
Does not contain haemoglobin
Contains spectrin
Does not contain spectrin
(2)
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(b)
Haemoglobin is a protein. Explain why a mature red blood cell cannot make
haemoglobin.
.....................................................................................................................................
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.....................................................................................................................................
(2)
(c)
(i)
Plasma membranes that have been isolated from red blood cells are not
contaminated by internal cell membranes (lines 6 - 7). Explain why.
...........................................................................................................................
...........................................................................................................................
(1)
(ii)
When red blood cells are put in a dilute salt solution they swell (line 8). Use your
knowledge of water potential to explain why.
...........................................................................................................................
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...........................................................................................................................
(2)
(d)
Some people have red blood cells that do not contain spectrin. These red blood cells are
spherical in shape. They also burst more quickly when put in distilled water.
(i)
Explain why more oxygen is taken up by normal red blood cells than by these
spherical cells.
...........................................................................................................................
...........................................................................................................................
(1)
(ii)
Explain why red blood cells that do not contain spectrin burst more quickly when
put into distilled water.
...........................................................................................................................
...........................................................................................................................
(1)
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(e)
Polypeptides such as spectrin are formed from amino acids. Describe the structure of an
amino acid molecule and explain how amino acids link together.
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(6)
(Total 15 marks)
12.
Read the following passage.
5
Human milk contains all the nutrients a young baby needs in exactly the right
proportions. It is formed in the mammary glands by small groups of milk-producing cells.
These cells absorb substances from the blood and use them to synthesise the lipids,
carbohydrates and proteins found in milk. Milk-producing cells are roughly cube-shaped
and have a height to breadth ratio of approximately 1.2 : 1.
The main carbohydrate in milk is lactose. Lactose is a disaccharide formed by the
condensation of two monosaccharides, glucose and galactose. (A molecule of galactose
has the same formula as a molecule of glucose – the atoms are just arranged in a different
way.)
10
Lactose is synthesised in the Golgi apparatus and transported in vesicles through the
cytoplasm. Because lactose is unable to escape from these vesicles, they increase in
diameter as they move towards the plasma membrane. The vesicle membranes fuse with
the plasma membrane and the vesicles empty their contents out of the cell.
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Use the information from the passage and your own knowledge to answer the following
questions.
(a)
(i)
The breadth of a milk-producing cell is 26 µm. Calculate the height of this cell.
Height = .......................... µm
(1)
(ii)
Describe and explain how you would expect the height to breadth ratio of an
epithelial cell from a lung alveolus to differ from the height to breadth ratio of a
milk-producing cell.
.....................................................................................................................................
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.....................................................................................................................................
.....................................................................................................................................
(2)
(b)
How many oxygen atoms are there in a molecule of
(i)
galactose;
.................................................................................................................................(1)
(ii)
lactose?
.................................................................................................................................(1)
(c)
The lactose-containing vesicles increase in diameter as they move towards the plasma
membrane of the milk-producing cell (lines 11-12). Use your knowledge of water
potential to explain why.
.....................................................................................................................................
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.....................................................................................................................................
.....................................................................................................................................(2)
(d)
Suggest one advantage of milk-producing cells containing large numbers of
mitochondria.
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................................................................................................................................(2)
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(e)
Some substances pass through the plasma membrane of a milk-producing cell by
diffusion. Describe the structure of a plasma membrane and explain how different
substances are able to pass through the membrane by diffusion.
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(6)
(Total 15 marks)
13.
(a)
A plant cell was observed with an optical microscope. Describe how the length of the cell
could be estimated.
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(2)
(b)
The water potential of a plant cell is –400 kPa. The cell is put in a solution with a water
potential of –650 kPa. Describe and explain what will happen to the cell.
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(3)
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(c)
A group of students investigated the effect of sucrose concentration on the change in
length of cylinders of tissue cut from a young carrot. They measured the initial lengths
of the carrot cylinders, then placed one in each of a number of sucrose solutions. After
18 hours, they removed the carrot cylinders and measured their final lengths. Some of the
results are shown in the table.
(i)
Concentration of sucrose /
mol dm–3
Percentage decrease in
length of carrot cylinder
0.4
4.2
0.5
8.7
0.6
13.0
0.7
16.8
0.8
18.1
0.9
18.1
1.0
18.1
The carrot cylinders were left for 18 hours in the sucrose solutions. Explain why
they were left for a long time.
...........................................................................................................................
...........................................................................................................................(1)
(ii)
Explain how you would use a graph to predict the concentration of sucrose that
would result in no change in length of the carrot cylinders.
...........................................................................................................................
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...........................................................................................................................
...........................................................................................................................(2)
(iii)
Young carrots store sugars in their tissues but, in older carrots, some of this is
converted to starch. How would using cylinders of tissue from older carrots affect
the results obtained for a sucrose solution of 0.6 mol dm–3? Give a reason for your
answer.
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(2)
(Total 10 marks)
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14.
Liver was ground to produce a homogenate. The diagram shows how fractions containing
different cell organelles were produced from the filtered homogenate.
Spun in centrifuge
at low speed
Supernatant
Spun in centrifuge
at medium speed
Sediment A
Supernatant
Spun in centrifuge
at high speed
Sediment B
Sediment C
(a)
Explain why the homogenate was filtered before spinning at low speed in the centrifuge.
.....................................................................................................................................
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.....................................................................................................................................
(2)
(b)
The main organelles present in sediment B were mitochondria. Suggest the main
organelles present in
(i)
sediment A; ......................................................................................................
(1)
(ii)
sediment C. ......................................................................................................
(1)
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(c)
What property of cell organelles allows them to be separated in this way?
.....................................................................................................................................
.....................................................................................................................................
(1)
(d)
Explain why the organelles in sediment C could be seen with a transmission electron
microscope but not with an optical microscope.
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(2)
(Total 7 marks)
15.
The diagram shows how some organelles may be distinguished from each other.
Organelle found in prokaryotic
and eukaryotic cells
Organelle A
Organelle found only in
eukaryotic cells
Organelle found in
animal cells and in
plant cells. Does not
contain membranes
arranged in stacks
Larger organelle surrounded
by an envelope through which
there are pores. Usually one
per cell.
Organelle C
(a)
(i)
Organelle found in
plant cells. Contains
inner membranes
arranged in stacks.
Organelle B
Smaller organelle surrounded
by an outer membrane. Has an inner
membrane, folded to form cristae.
Many in a cell.
Organelle D
Name organelle B.
...........................................................................................................................
(1)
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(ii)
Describe the function of organelle B.
...........................................................................................................................
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...........................................................................................................................
...........................................................................................................................
(2)
(b)
Which of organelles A, B, C or D
(i)
is a ribosome;
...........................................................................................................................
(1)
(ii)
contains most of the DNA found in a plant cell?
...........................................................................................................................
(1)
(c)
Some liver tissue was ground, filtered and centrifuged to make a suspension of organelle
D.
(i)
Explain why the solution in which the liver tissue was ground should be ice-cold.
...........................................................................................................................
...........................................................................................................................
(1)
(ii)
The ground liver was centrifuged at low speed. The pellet that formed at the
bottom of the centrifuge tube was thrown away and the supernatant centrifuged
again at higher speed. Explain why it was necessary to first centrifuge the
ground liver at low speed in order to obtain a suspension of organelle D.
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(2)
(Total 8 marks)
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16.
(a)
Explain how the shape of a red blood cell allows it to take up a large amount of oxygen in
a short time.
..............................................................................................................….....................
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(2)
Samples of blood were mixed with equal volumes of different liquids. A drop of each
mixture was put on a slide and examined with an optical microscope. The table shows the
appearance of each slide.
Slide
(b)
(i)
Liquid added
Appearance of slide
A
Distilled water
No cells seen. Slide appears a
uniform pale red colour
B
Sucrose solution
Cells are smaller in diameter than in
an untreated sample of blood
C
Detergent (dissolves lipids)
No cells seen. Slide appears a
uniform pale red colour
What does the appearance of slide B tell you about the plasma membrane
surrounding a red blood cell?
............................................................................................................................
............................................................................................................................
(1)
(ii)
Explain the appearance of slide C.
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(2)
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(c)
The blood from which these samples were taken also contained monocytes and
granulocytes. How could you use the appearance of a nucleus to
(i)
distinguish between a monocyte and a red blood cell;
............................................................................................................................
............................................................................................................................
(1)
(ii)
identify a granulocyte?
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(1)
(Total 7 marks)
17.
The diagram shows part of an alveolus and a capillary.
A
Lumen of alveolus
B
Capillary
10µ m
(a)
The rate of blood flow in the capillary is 0.2 mms–1.
Calculate the time it would take for blood in the capillary to flow from point A to point B.
Show your working.
Answer ...................................... seconds
(2)
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(b)
The rate of diffusion of oxygen is affected by the difference between its concentration in
the alveolus and its concentration in the blood.
(i)
Circulation of the blood helps to maintain this difference in oxygen concentration.
Explain how.
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(1)
(ii)
During an asthma attack, less oxygen diffuses into the blood from the alveoli.
Explain why.
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(2)
(c)
Scientists investigated a new drug to treat asthma. People with asthma took part in a trial.
They were divided into two groups, an experimental group and a control group.
(i)
It was important to have a control group in this trial. Explain why.
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
(1)
(ii)
People in the experimental group were given the drug in an inhaler. Describe how
the control group should have been treated.
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(2)
(Total 8 marks)
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18.
(a)
The structure of a cholera bacterium is different from the structure of an epithelial cell
from the small intestine. Describe how the structure of a cholera bacterium is different.
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(5)
(b)
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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(5)
(Total 10 marks)
19.
(a)
(i)
Give two ways in which active transport differs from diffusion.
1..........................................................................................................................
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2.........................................................................................................................
...........................................................................................................................(2)
(ii)
Sodium ions move from the surrounding solution where they are at a low
concentration into the cytoplasm of a cell where they are at a higher concentration.
Cyanide ions stop the functioning of the electron carrier system in mitochondria.
Use these two pieces of information to explain how the addition of cyanide ions
would affect the uptake of sodium ions by a cell.
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...........................................................................................................................(2)
(b)
Two major routes by which molecules are thought to cross membranes are:
1.
by dissolving in the phospholipid layer.
2.
by passing through channels in protein molecules.
These routes are illustrated in the diagram. The graphs show the rate of entry of
molecules into the cell by these two routes in relation to the external concentration of the
molecules.
Outside
Inside
B
Rate
of
entry
into
cell
X
External concentration
Molecules pass through
protein channels
Outside
Inside
B
Rate
of
entry
into
cell
X
External concentration
Molecules pass through
protein channels
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(i)
Explain why curves are similar up to point X
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...........................................................................................................................
...........................................................................................................................
(1)
(ii)
Explain what causes the shapes of the curves to differ after point X.
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...........................................................................................................................
(1)
(Total 6 marks)
20.
The electron micrograph shows a section through a fish gill. The directions of flow of water and
of blood are indicated by arrows.
10 µm
Key
Direction of flow of water
Direction of flow of blood
Source: www.ucdavis.edu/mjguinan
(a)
Calculate the minimum distance that a molecule of oxygen would have to travel from the
water to a red blood cell. Give your answer in micrometres and show your working.
Answer .......................................... µm.
(2)
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(b)
Explain how the relationship between the direction of flow of water and of blood shown
in the micrograph is useful to a fish.
............………..............................................................................................................
............………..............................................................................................................
............………..............................................................................................................
............………..............................................................................................................
............………..............................................................................................................
............………..............................................................................................................
(3)
(Total 5 marks)
21.
The diagram shows an animal cell.
20µm
(a)
The scale bar on the diagram represents a length of 20 µm. Use this to calculate the
magnification of this diagram. Show your working.
Magnification........................
(2)
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(b)
Use a guideline and the appropriate letter to show, on the diagram, a site in this cell where
(i)
the enzymes controlling glycolysis are found (A);
(1)
(ii)
molecules of enzymes are synthesised (B).
(1)
(c)
The number of cristae in the mitochondria of a cell with a high metabolic activity is
greater than the number in a cell with lower metabolic activity. Explain why.
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
(2)
(Total 6 marks)
22.
(a)
The diagram shows the fluid-mosaic model of a cell surface membrane.
(i)
Name the molecules labelled A and B.
A ................…...................................................................................................
B ........................................................................................................................
(1)
(ii)
How does the bilayer formed by substance A affect entry and exit of substances
into and out of a cell?
......................................................................................................................….
...........................................................................................................................
......................................................................................................................….
......................................................................................................................….
(2)
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(b)
A dialysis machine contains artificial membranes which enable urea to be removed from
the blood of a person with kidney failure. The diagram shows a dialysis machine.
Blood with high
urea concentration
Waste dialysis fluid
(contains urea)
Fresh dialysis fluid
(does not contain urea)
Narrow tubes with
artificial membranes
Blood with lower
urea concentration
(i)
By what process does urea pass from the blood into the dialysis fluid?
......................................................................................................................….
(1)
(ii)
Suggest two reasons for keeping the fluid in the dialysis machine at 40 °C rather
than room temperature.
1 ................................................................................................................…….
............................................................................................................................
2 ................................................................................................................…….
...............................................................….....................................................….
(2)
(iii)
The blood and the dialysis fluid flow in opposite directions in the dialysis machine.
Explain the advantage of this.
......................................................................................................................….
...........................................................................................................................
......................................................................................................................….
......................................................................................................................….
(2)
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(iv)
Blood flows through the dialysis machine at a rate of 200 cm3 per minute.
Calculate the total volume which passes through the machine in 5 hours.
Give your answer in dm3 and show your working.
Answer .................................... dm3
(2)
(Total 10 marks)
23.
Emphysema is a disease that affects the alveoli of the lungs and leads to the loss of elastic
tissue. The photographs show sections through alveoli of healthy lung tissue and lung tissue
from a person with emphysema. Both photographs are at the same magnification.
Source: Biophoto Associates, Science Photo Library
Using the evidence given above and your own knowledge, explain why a person with
emphysema is unable to do vigorous exercise.
...............................................................................................................................................
...............................................................................................................................................
...............................................................................................................................................
...............................................................................................................................................
...............................................................................................................................................
...............................................................................................................................................
...............................................................................................................................................
...............................................................................................................................................
(Total 4 marks)
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24.
Answers should be written in continuous prose. Credit will be given for biological accuracy, the
organisation and presentation of information and the way in which an answer is expressed.
Fick’s law states that the rate of diffusion of a substance across a membrane is directly
proportional to the surface area of the membrane and to the difference in concentration on either
side. It is inversely proportional to the thickness of the membrane. Fick’s law can be written in
simple mathematical terms as:
Rate of diffusion ∝
(a)
(i)
Surface area × Difference in concentration
Thickness of membrane
Describe how a large difference in oxygen concentration is maintained between a
fish gill and the surrounding water.
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
(4)
(ii)
Describe the adaptations of a mammalian lung which ensure a short diffusion
pathway for respiratory gases.
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
(3)
(b)
Explain the link between the size of an organism and the way in which its cells are
supplied with oxygen.
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
(6)
(Total 13 marks)
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25.
A person was sitting at rest and breathing normally. A recording was made of the changes in the
volume of air in his lungs over a ten-second period. The diagram shows this recording.
Volume
0
(a)
2
6
4
Time / s
8
10
Describe the part played by muscles in bringing about the change between 3 and 4
seconds.
.....................................................................................................................................
.....................................................................................................................................
(1)
(b)
Describe how an increase in lung volume leads to air entering the lungs.
...........................................………..............................................................................
............……….............................................................................................................
(1)
(c)
(i)
Give the equation which represents Fick’s law.
(ii)
Use Fick’s law to explain how breathing helps to ensure efficient gas exchange.
(1)
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
(2)
(Total 5 marks)
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26.
The diagram shows the heart and the tissues which control the heart beat. The figures on the
diagram show the time in seconds taken for a wave of electrical activity to spread from the
sinoatrial node.
A
0.01 seconds
B
0.04 seconds
C
0.16 seconds
D
0.17 seconds
(a)
(i)
The diagram shows that the valve between the right atrium and the right ventricle is
closed. What does this indicate about the relative pressures in the right atrium and
the right ventricle?
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
(1)
(ii)
Complete the diagram to show whether the valve between the left atrium and the
left ventricle is open or closed.
(1)
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(b)
The rate at which the electrical activity passes from B to C is important in controlling the
heart beat. Explain why.
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
(2)
(c)
The heart rate of a sleeping person is low. Explain how nerves supplying the heart may
produce a low heart rate in a sleeping person.
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................(3)
(Total 7 marks)
27.
(a)
Describe the route taken by a red blood cell from leaving the right ventricle of the heart to
entering the left atrium.
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................(2)
(b)
The drawing shows a red blood cell.
X
Y
Y
X
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(i)
The centre of this cell appears light in colour when seen with an optical
microscope. Explain why.
.....................................................................................................................................
.................................................................................................................................(1)
(ii)
Draw diagrams in the space below to show the appearance of this cell along
Section X-X
Section Y-Y
(2)
(c)
There are no nuclei or other cell organelles in the cytoplasm of red blood cells.
Describe one way in which the structure of a red blood cell
(i)
is similar to the structure of a lymphocyte;
.....................................................................................................................................
.................................................................................................................................(1)
(ii)
is different from the structure of a prokaryotic cell such as a bacterium.
.....................................................................................................................................
................................................................................................................................(1)
(Total 7 marks)
28.
(a)
Explain why both the heart and arteries are described as organs.
.....................................................................................................................................
.....................................................................................................................................(1)
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The table shows changes in the volume of blood in the left ventricle over a period of one
second.
Time / s
Volume of blood as
percentage of maximum
0
70
0.1
100
0.2
70
0.3
30
0.4
0
0.5
35
0.6
60
0.7
70
0.8
70
0.9
100
1.0
70
Use information in the table to answer the following questions.
(b)
What is the approximate length of one cardiac cycle?
.....................................................................................................................................
(1)
(c)
At what time is there least blood in the right ventricle? Explain your answer.
.....................................................................................................................................
.....................................................................................................................................
(1)
(d)
(i)
Between which times are the muscles in the wall of the left atrium contracting?
Give the reason for your answer.
Times ..........................................................................................................................
Reason ........................................................................................................................
.....................................................................................................................................
(1)
(ii)
Between which times are the semilunar valves in the arteries open? Give the reason
for your answer.
Times ..........................................................................................................................
Reason ........................................................................................................................
(1)
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(e)
The maximum volume of blood in the left ventricle is 45 cm3. Calculate the volume of
blood in the left ventricle at 0.5 s. Show your working.
Volume of blood = ................................................. cm3
(2)
(Total 7 marks)
29.
This diagram shows a human heart seen from the front.
BC
D
A
X
Y
(a)
(i)
Which one or more of vessels A to D contains oxygenated blood?
...........................................................................................................................(1)
(ii)
During a cardiac cycle, the pressure of the blood in vessel C is higher than the
pressure of the blood in vessel B. Explain what causes this difference in pressure.
...........................................................................................................................
...........................................................................................................................(1)
(b)
What does the diagram suggest about the pressure in the atria compared to the pressure in
the ventricles at the stage in the cardiac cycle represented in the diagram? Explain your
answer.
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
(2)
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(c)
The wave of electrical activity which coordinates the heart beat is delayed slightly at part
X. It then passes along part Y to the base of the ventricles.
Explain the importance of
(i)
the slight delay at part X;
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
(2)
(ii)
the electrical activity being passed to the base of the ventricles.
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
(2)
(Total 8 marks)
30.
(a)
In the lungs oxygen passes from the alveoli to the blood.
Describe and explain the features that make this process rapid and efficient.
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
(4)
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(b)
The graph shows the pressure changes in the lungs during the period of one breath
(inspiration + expiration) in a person at rest.
Inspiration
Expiration
Increase
D
Pressure
in lungs
A
C
E
Atmospheric
pressure
B
Decrease
0
1
2
Time/s
3
4
Use your knowledge of breathing to explain the changes in pressure during inspiration
and expiration. The letters on the graph are to help you to refer to different parts of the
curve.
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
(6)
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(c)
Mammals such as whales and dolphins that are adapted to live in the sea have to come to
the surface to take air into their lungs. Their lungs are not adapted to extract oxygen from
the water.
Suggest two reasons why it would be very difficult to extract sufficient oxygen from
water by moving water in and out of lungs.
1 ..................................................................................................................................
.....................................................................................................................................
2 ..................................................................................................................................
.....................................................................................................................................(2)
(d)
Explain how the countercurrent principle helps fish to extract oxygen from water.
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................(3)
(Total 15 marks)
31.
Read the following passage.
Several diseases are caused by inhaling asbestos fibres. Most of these
diseases result from the build up of these tiny asbestos fibres in the lungs.
One of these diseases is asbestosis. The asbestos fibres are very small and
enter the bronchioles and alveoli. They cause the destruction of phagocytes
and the surrounding lung tissue becomes scarred and fibrous. The fibrous
tissue reduces the elasticity of the lungs and causes the alveolar walls to
thicken. One of the main symptoms of asbestosis is shortness of breath
caused by reduced gas exchange.
People with asbestosis are at a greater risk of developing lung cancer. The time
between exposure to asbestos and the occurrence of lung cancer is 20–30 years.
5
10
Use information in the passage and your own knowledge to answer the following questions.
(a)
Destruction of phagocytes (lines 4–5) causes the lungs to be more susceptible to
infections. Explain why.
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
(2)
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(b)
(i)
The reduced elasticity of the lungs (lines 6–7) causes breathing difficulty.
Explain how.
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................(2)
(ii)
Apart from reduced elasticity, explain how changes to the lung tissue reduce the
efficiency of gas exchange.
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................(4)
(c)
(i)
Doctors did not make the link between exposure to asbestos and an increased risk
of developing lung cancer for many years. Use information in the passage to
explain why.
...........................................................................................................................
...........................................................................................................................(1)
(ii)
Give one factor, other than asbestos, which increases the risk of developing lung
cancer.
...........................................................................................................................(1)
(Total 10 marks)
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32.
The diagram shows a section through a human heart.
C
B
A
D
(a)
Which of the blood vessels labelled A to D
(i)
takes blood from the heart to the muscles of the arms and legs;
...........................................................................................................................(1)
(ii)
is a vein which contains oxygenated blood?
...........................................................................................................................(1)
(b)
Is the right ventricle filling with blood or emptying? Give two pieces of evidence from
the diagram to support your answer.
Filling or emptying? ..................................................................................................
Evidence
1 ..................................................................................................................................
.....................................................................................................................................
2 ..................................................................................................................................
.....................................................................................................................................(2)
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The graphs show some changes in pressure and volume during part of a cardiac cycle.
Aorta
Pressure
Ventricle
Volume
of
ventricle
X
(c)
Y
Time
Z
Describe what the graphs show about the pressure and volume in the ventricle between
times X and Y.
.....................................................................................................................................
.....................................................................................................................................
(1)
(d)
At point Y, the valve between the aorta and the ventricle opens. Use the information
about pressure on the graph to explain why.
.....................................................................................................................................
.....................................................................................................................................
(1)
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(e)
Explain the changes in the volume of the ventricle between times X and Z.
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
(3)
(Total 9 marks)
33.
The diagram shows a mitochondrion.
(a)
Name the parts labelled X and Y.
(i)
X .............................................................
(ii)
Y ..............................................................
(2)
Scientists isolated mitochondria from liver cells. They broke the cells open in an ice-cold,
isotonic solution. They then used a centrifuge to separate the cell organelles. The diagram
shows some of the steps in the process of centrifugation.
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(b)
Suggest which pellet, A, B or C contained the mitochondria.
(1)
(c)
Explain why the solution used was
(i)
ice-cold
...........................................................................................................................
...........................................................................................................................(1)
(ii)
isotonic.
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................(2)
(d)
People with mitochondrial disease have mitochondria that do not function properly.
Some people with mitochondrial disease can only exercise for a short time. Explain why a
person with mitochondrial disease can only exercise for a short time.
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
(2)
(Total 8 marks)
34.
(a)
The graph shows hourly blood pressure recordings from a group of 65 people.
18
Maximum
16
14
Arterial
blood pressure /
kPa
12
Minimum
10
8
midnight 02.00 04.00 06.00 08.00 10.00 12.00
Time
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(i)
Describe how the mean maximum arterial blood pressure changes over the period
shown in the graph.
............................................................................................................................
............................................................................................................................
(1)
(ii)
In each cardiac cycle, the arterial pressure has a maximum value. Explain the link
between this maximum value and the events of the cardiac cycle.
............................................................................................................................
............................................................................................................................
(1)
(iii)
The recordings shown in this graph were taken from an artery. Describe two ways
in which you would expect blood pressure in a vein to differ from that in an artery.
1 ................………..............................................................................................
...................................................................................................................…......
2 ...................................................................................…...................................
................................................................................................................….........
(2)
(b)
Molecules of different substances differ in size. The relative molecular mass of a
substance gives an indication of the size of its molecules. The table shows the relative
permeability of the wall of a capillary to different molecules.
Substance
Water
Urea
Glucose
Haemoglobin
Albumin (plasma protein)
Globulin (plasma protein)
(i)
Relative molecular mass
Relative permeability of
capillary wall
18
60
180
68 000
69 000
140 000
1.00
0.96
0.60
0.01
0
0
Describe the relationship between molecule size and the permeability of the
capillary wall.
............................................................................................................................
............................................................................................................................
............................................................................................................................
............................................................................................................................
(2)
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(ii)
The water potential of the plasma at the venule end of the capillary is more
negative than the water potential at the arteriole end. Use the table to explain why.
............................................................................................................................
............................................................................................................................
............................................................................................................................
............................................................................................................................
(2)
(iii)
Although the capillary walls are slightly permeable to haemoglobin molecules,
there is no haemoglobin in the tissue fluid. Explain what causes the absence of
haemoglobin in tissue fluid.
............................................................................................................................
............................................................................................................................
(1)
(Total 9 marks)
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