Class Questions
Cell Biology
Cell structure
1. What name is given to the basic units of life that can lead an independent existence?
2a) Name 4 structural features that a typical plant cell and a typical animal cell can have in common.
b) Identify three structural features present in an Elodea leaf cell but absent from a cheek epithelial
cell.
3) Give the function of each of the following structures: Chloroplast, nucleus, cell membrane,
mitochondrion.
4) The rows in the following table give three features characteristic to certain cells.
Row
Features characteristic to cells
1
mitochondria
nucleus
plasmids
2
cytoplasm
nucleus
mitochondria
3
large central
vacuole
cell wall
mitochondria
4
cell wall
chloroplasts
circular
chromosome
5
plasmid
circular
chromosome
cell wall
6
ribosomes
plasmids
mitochondria
a) Which row refers correctly to both plant and animal cells?
b)i) Which row is correct for plant cells and fungal cells?
ii) Which other organelle could allow us to separate plant and fungal cells?
c) Which row refers correctly to a bacterial cell?
5. The diagram shows a view through a 3rd year’s microscope. The
diameter of the field of view is 0.03mm.
a) What is the average diameter of the cells in micrometers (µm)?
b) A human red blood cell is 7µm in diameter. Express this as a
fraction of a mm.
c) If a cell is 0.008mm long, how many µm is that?
1
1. The diagram below shows a light microscope used to view a slide of bacteria
W
X
Z
Y
(a) Which letter identifies the focus control?
Letter _______________
(1)
(b) State the function of the following parts of the microscope,
Stage ___________________________________________________
(1)
Objective lens _____________________________________________
_________________________________________________________
(1)
(c) The microscope has a 15 x eyepiece lens and 10 x, 20x and 40x objective lenses.
What is the highest total magnification available with these lenses?
Space for calculation
Highest total magnification ______________ (1)
2
2. The diagram below shows the light microscope used to view a slide of stained
bacteria.
W
X
Y
Z
(i)
Which letter identifies an objective lens?
Letter _________________
(1)
(ii) Complete the table showing parts of the microscope and their function.
Part of microscope
Function
To hold microscope slide
Eyepiece lens
Mirror/light source
To change distance between stage
and objective lens
(2)
3
3. The diagram below shows a micro-organism called Oedogonium viewed under a
microscope at high power.
0.12mm
(a) Calculate the length of one Oedogonium cell in micrometres.
Space for calculation
_____________ micrometres
(1)
(b) How would reducing the magnification to a lower power affect the number of
cells seen in the field of view?
______________________________________________________________ (1)
(c) The lenses used in the microscope have the following magnifications;
Eyepiece lens
Objective lenses
x 10 magnification
x 4, x 10 and x 40 magnification
Use the information above to calculate total magnifications and then complete
the table below;
Space for calculations
Total magnification
x4
(3)
4
4.The photograph below shows a light microscope used for viewing a slide of microorganisms.
eyepiece lens
objective lenses
stage
light source
Describe the steps which should be taken to set up the microscope for viewing a slide
under the medium power objective lens.
5. The light microscope has an eyepiece
magnification of x 10 and three
objective lenses; x 4, x 10, x 30.
Which line in the table below shows
the correct minimum and maximum
total magnification for this microscope
6. Which of the shown
combinations of microscope lenses
provides the highest total
magnification?
Minimum total
magnification
(5)
Maximum total
magnification
A
x 10
x 30
B
x 10
x 300
C
x 40
x 300
D
x 40
x 1200
Eyepiece lens
magnification
Objective lens
magnification
A
x4
x 100
B
x8
x 80
C
x 10
x 40
D
x 15
x 40
5
7. The diagram below shows a microorganism at a magnification of x 40,000.
The actual size of this micro-organism is
A
B
C
D
0.001 micrometres
1.0 micrometres
1.0 millimetres
40 millimetres
40mm
8. The length of a micro-organism is
0.15 mm,
The length of this micro-organism in
micrometres is,
A
B
C
D
0.00015
0.015
1.5
150
9. The diagram shows a microscope with some parts labelled.
Which line in the table below identifies the correct parts of the microscope
W
X
Z
Y
Part of microscope
W
A objective lens
B
eyepiece lens
X
Y
Z
focus control
stage
mirror
mirror
objective lens focus control
C objective lens eyepiece lens focus control
D eyepiece lens objective lens
mirror
mirror
focus control
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a. Name and give the function of structure Q
(1)
Name _____________________________________________________
Function ___________________________________________________
___________________________________________________
b. Name and give the function of structure R
(1)
Name _____________________________________________________
Function ___________________________________________________
___________________________________________________
c. Name one structure that would be present in both cell Y and cell Z
____________________________________________________________
(1)
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2. (i) Complete the table, naming the parts labelled A – G in the diagram below and
giving one function of each
(7)
A
E
B
C
D
F
G
(ii) Explain how part A in this cell is different from the same structure in a plant cell
___________________________________________________________________ (1)
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3. Which structural feature is common to both plant and animal cells?
A.
B.
C.
D.
Cell wall
Chloroplast
Nucleus
Large central vacuole
(1)
4. Which line in the table describes correctly the structure of bacteria?
Nucleus
Cell
wall
Vacuole
A
Present
Absent
Absent
B
Absent
Present
Absent
C
Present
Absent
Present
D
Absent
Present
Present
(1)
5. Which line in the table identifies correctly the organelle with its function
Mitochondrion
Chloroplast
Ribosome
A
Protein
synthesis
Photosynthesis
Aerobic
respiration
B
Photosynthesis
Aerobic
respiration
Protein
synthesis
C
D
Aerobic
respiration
Photosynthesis
Photosynthesis
Protein
synthesis
Protein
synthesis
Aerobic
respiration
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6. The diagram below shows the structure of a micro-organism
X
cell membrane
DNA
a) Name the type of micro-organism shown in the diagram above
__________________________________________________________________ (1)
b) Identify part X
__________________________________________________________________(1)
c) Identify part Y
__________________________________________________________________ (1)
b) State the function of the following parts
DNA _______________________________________________________________(1)
Cell membrane _______________________________________________________
___________________________________________________________________(1)
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7. The diagram below shows the structure of a bacterial cell and a fungal cell
(not to scale, and some parts not shown)
List the structures;
a) Found in both cells
b) Found in only one of the cells
(A table may be used in your answer)
(5)
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Transport across cell membranes
1a) Name two types of molecules present in the cell membrane.
b) Which of these would be destroyed at 70oC?
2. Define the terms diffusion and concentration gradient.
3a) Name two essential substances that enter an animal cell by diffusion.
b) Name the waste material which diffuses out of an animal cell.
4a) In the lungs, diffusion is very important. Why is this?
b)i) Predict what would happen to the rate of diffusion of CO2 if a person exercised vigorously.
ii) Explain why.
5. Rewrite the following paragraph choosing the correct answer at each underlined choice.
Osmosis is a form of diffusion/ion uptake. It is an active / passive process the requires / does not
require energy. During osmosis, oxygen/water molecules move across a freely / selectively
permeable membrane from a higher/lower water concentration to higher / lower water
concentration along / against a concentration gradient.
6a) With reference to the water concentrations involved, explain why a red blood cell bursts when
placed in water, yet an onion epidermal cell does not.
b) Why does a red blood cell shrink when placed in a concentrated salt solution?
7) The graph shows the rate of potassium ion uptake by human liver cells in different oxygen
concentrations at 30oC
a) When the oxygen concentration is 1%, how many units of potassium would a cell take up in
one hour?
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b) Suggest a reason why the graph levels off at oxygen concentrations above 3.5%
c) When the experiment was repeated at 20oC, the potassium ion uptake decreased. Explain
this observation.
8. The diagrams below represent red blood cells in different solutions as they would appear under a
microscope.
(a)
Use the information in the diagrams to predict the percentage solute concentration of
human blood. Explain your answer.
(b)
What has happened to the cells in diagram B? Explain the change in terms of water
concentrations.
9a) Describe and explain the osmotic effect of very concentrated sugar solution on an onion
epidermal cell.
b) What term is used to describe a cell in this state?
c) How could such a cell be restored to its turgid condition?
10a) Define the term active transport.
b) Copy and complete the table below.
Question
Diffusion
Active transport
What is an example of a substance that moves
through the cell membrane by this process?
Do the particles move from high to low or from low
to high concentration?
Do the particles move along or against a
concentration gradient?
Is energy required?
Is the process passive?
Producing new cells
1a) State the main events that occur during cell division in an animal cell.
b) In what way does cell division in a plant cell differ from that in an animal cell?
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2) Which cell structure controls all the cell activities including cell division?
3) Arrange the stages of mitosis into the correct order.
4) Briefly describe the process of mitosis using the following terms: centromere, chromatid, equator,
spindle fibre.
5) Why is important that the diploid chromosome complement of daughter cells in a Multicellular
organism is maintained?
DNA and the production of proteins
1) What are chromosomes and where are they located in a cell?
2a) What do the letters DNA stand for?
b)How many strands are present in a DNA molecule?
c)i) How many different types of base molecules are found in DNA?
ii) Define the base-pair rule.
3a) By what means is the genetic code present in the DNA of a gene transported from the nucleus to
the cytoplasm of a cell?
b) i) What subunits make up a protein?
ii) Where in the cytoplasm are these subunits assembled into proteins?
iii) What determines the sequence in which these subunits are joined together?
iv) Why is the sequence of these subunits in a protein molecule important?
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Proteins and Enzymes
1. Copy the following sentences and complete the blanks.
The amino acids in a protein are built into a particular order that is determined by the sequence of
the ________ on a portion of DNA in a ________. The sequence of amino acids determines the
protein’s _________ and _________.
2a) What general name is given to biological catalysts?
b) State two properties of a biological catalyst?
3a) Where are enzymes found in a living organism?
b) Of what type of substance are enzyme molecules composed?
c) Briefly explain why enzymes are needed for the functioning of all living cells.
4a) What determines the shape of an enzyme’s active site?
b) What term is used to refer to the substance upon which an enzyme acts?
c) Why is an enzyme said to be specific in its relationship with its substrate?
5) Salivary amylase is an enzyme that digests starch in the human mouth.
a) Compare the rate of amylase activity at 5oC and 25oC.
b) i) Compare the rate of amylase activity at 40oC and 70oC.
ii) Explain the difference in rate in terms of the molecules involved.
6a) Which temperature in Q5 do most enzymes work best at?
b) What term is given to the temperature or pH which the enzyme is most active at?
c)i) Give a temperature at which an enzyme is inactive but capable of activity if the temperature
changes.
ii) Explain your answer.
d) Why does exposure to a strong acid normally result in an enzyme becoming inactive?
7a) What term is used to describe an enzyme which has been made permanently inactive?
b) Which of the following is the optimum range of pH for human pepsin, 2-3, 4-5, 6-7 or 8-9?
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8) The table below gives the results from an experiment set up to investigate the effect of
temperature on the action of a digestive enzyme.
Temperature (oC)
0
5
10
15
20
25
30
35
40
45
50
55
Mass of substrate broken
down (mg/h)
0
1
4
8
14
22
28
31
32
29
18
0
a) Using a piece of graph paper, present the data as a line graph.
b)i) Explain what is meant by the term optimum temperature.
ii) State the optimum temperature for the action of this enzyme.
c)i) By how many times greater was the rate of the enzyme activity greater at 30oC than at 20oC?
ii) Explain the difference in terms of rate of molecular movement and frequency of collisions
between enzyme and substrate molecules at these two temperatures.
d) Which rise in temperature of 5oC brought about the biggest increase in rate of enzyme activity?
e) At the temperature range 50 – 55oC, the molecules are still gaining energy, so why does the
reaction come to a halt at 55oC?
f) Predict the mass of substrate that would be broken down at 75oC.
9a) State the working range for each of the enzymes.
b) Suggest the optimum pH or each enzyme.
c) State which of the enzymes would show optimum
activity in:
i) the human mouth
ii) the human stomach
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Genetic engineering
1a) What is meant by the term genetic engineering?
b) An agent that acts as a carrier between two species is often called a vector. Which part of a
bacterium’s genetic material could this term be used to describe?
2. Arrange the following steps in the correct order.
3
1
2
5
4
6
7
8
3a) Give another example of a product of genetic engineering.
b) Explain why this product is of benefit to human beings.
4) Which stage in genetic engineering is shown
below?
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Respiration
1) Which sugar is the most common source of energy in living cells?
2a) What name is given to the series of enzyme-controlled reactions by which energy stored in sugar
is released?
b) Where does this process occur in living organisms?
3a) Draw a simple labelled diagram of an ATP molecule.
b) In the two-way equation that follows, which numbered arrow represents:
i) energy release?
ii) energy uptake?
1
ADP + Pi
ATP
2
c) Identify the source of energy needed to drive this process of energy uptake.
d) The energy released during the process is put to many uses by living cells. Name three of these
uses.
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