Topic 2: Cells
Assessment Statement
2.1 Cell Theory (3 hours)
2.1.1 Outline the cell theory
Response
Campbell pages
Not mentioned explicitly in Campbell
IB says: Include the following:
1. Living organisms are composed of cells
2. Cells are the smallest unit of life
3. Cells come from pre-existing cells
2.1.2
Discuss the evidence for the
cell theory
Not mentioned explicitly in Campbell
2.1.3
State that unicellular
organisms carry out all the
functions of life
IB says: Include metabolism, response homeostasis, growth,
reproduction, and nutrition.
Sample Test Question
2.1.4
Compare the relative sizes of
molecules, cell membrane
thickness, viruses, bacteria,
organelles and cells, using
the appropriate SI unit.
Pg. 93, Figure 6.2
IB says: Appreciation of relative sizes is required, such as molecules
(1 nm), thickness of membranes (10 nm), viruses (100 nm), bacteria
(1 m), organelles (up to 10 m), and most cells (up to 100 m).
The three-dimensional nature/shape of cells should be emphasized.
2009 Specimen paper
2. What is the correct order of
increasing size for the following
biological structures?
I. The width of a virus
II. The width of a bacterium
III. The thickness of a cell
surface membrane
IV. The diameter of a
eukaryotic cell
A. I → III → II → IV
B. I → III → IV → II
C. III → I → II → IV
D. III → II → I → IV
6 May 2009 PM
2.1.5
Calculate the linear
magnification of drawings
and the actual size of
specimens in images of
known magnification
Not specifically discussed in Campbell
IB says: Magnification could be stated (for example, x250) or
indicated by means of a scale bar.
3. The electron micrograph below
shows a section of a liver cell.
b. Compare the relative sizes of
viruses and bacteria to this cell.
6 May 2009 PM
3a. The electron micrograph below
shows a section of a liver cell.
(ii) Calculate the magnification of
this photograph. Show your
working.
2.1.6
Explain the importance of
Pg.98-99
2.1.7
the surface area to volume
ratio as a factor limiting cell
size.
Figure 6.7IB says: Mention the concept that the rate of heat
production/waste production/resource consumption of a cell is a
function of its volume, whereas the rate of exchange of materials
and energy (heat) is a function of its surface area. Simple
mathematical models involving cubes and the changes in the ratio
that occur as the sides increase by one unit could be compared.
State the multicellular
organisms show emergent
properties
Emergent properties of biological systems in general are discussed
on page 9.
IB says: Emergent properties arise from the interaction of
component parts: the whole is greater than the sum of its parts.
2.1.8
Explain that cells in
multicellular organisms
differentiate to carry out
specialized functions by
expressing some of their
genes but not others
2.1.9 State that stem cells retain
the capacity to divide and
have the ability to
differentiate along different
pathways
2.1.10 Outline one therapeutic use
of stem cells.
2.2 Prokaryotic Cells (1 hour)
Pg. 362-363
Pg. 418
Pg. 881-882
Pg. 418
Pg. 881-882
2.2.1
2.2.2
Draw and label a diagram of
the ultrastructure of
Escherichia coli (E. coli) as
an example of a prokaryote.
Pg. 98, Figure 6.6 is a good example
IB says: The diagram should show cell wall, plasma membrane,
cytoplasm, pili, flagella, ribosomes and nucleoid (region containing
naked DNA)
Annotate the diagram from
Pg. 98-99
2009 Specimen Exam
4. In viewing an electron
micrograph of a cell, ribosomes,
pili and a single circular
chromosome are observed.
What other structure is likely to
be present?
A. The rough endoplasmic
reticulum (rER)
B. Mitochondria
C. A nuclear membrane
D. A plasmid
14 May 2008, PM
2. Which pair of features is correct
for both plant and prokaryotic cells?
Plant cell
Prokaryot.
A Able to
Fixed shape
change shape
B Contains
Contains
DNA
naked DNA
associated
with protein
C DNA
DNA
enclosed by
associated
membrane
with protein
D Chloroplasts Chloroplasts
may be
may be
present
present
2.2.3
2.2.4
2.2.1 with the functions of
each named structure.
Pg. 534-537
Identify structures from
2.2.1 in electron
micrographs of E. coli
Pg. 98-99
Pg. 534-537
These pages contain some micrographs for practice as well as a few
pointers on how certain cell parts may look
Pg. 226
State that prokaryotic cells
divide by binary fission
2.3 Eukaryotic cells (3 hours)
2.3.1
Draw and label a diagram of
the ultrastructure of a liver
cell as an example of an
animal cell
Pg. 100 Figure 6.9 is one good example
IB says: The diagram should show free ribosomes, rough
endoplasmic reticulum (rER), lysosome, Golgi apparatus,
mitochondrion and nucleus. The term Golgi apparatus will be used
in place of Golgi body, Golgi complex, or dictyosome.
2.3.2
Annotate the diagram from
Pg. 100
May 2006 PM (SL)
6. (a) Draw a labeled diagram
showing the main features of the
ultra structure of an animal cell
[4]
6. (a) Award [1] for every two of
the following structures,
accurately drawn and correctly
labeled: ribosomes (attached or
free); rough ER; smooth ER;
lysosome; Golgi apparatus/body;
mitochondrion; nucleus; plasma
membrane/cell (surface)
membrane; nucleolus; nuclear
membrane/envelope;
centriole(s); peroxisome;
vesicles; cytoskeleton; [4 max].
Only [3 max] if any plant
structures are included.
2.3.3
2.3.4
2.3.1 with the functions of
each named structure.
Pg. 102-111
Identify structures from
2.3.1 in electron
micrographs of liver cells.
Compare prokaryotic and
eukaryotic cells.
Pg. 102-111 contain multiple micrographs
Pg. 98-99
Does not specifically mention all items required by IB
IB says: Differences should include:
1. Naked DNA versus DNA associated with proteins
2. DNA in cytoplasm versus DNA enclosed in a nuclear envelope
3. no mitochondria versus mitochondria
4. 70s versus 80s ribosome
5. eukaryotic cells have internal membranes that compartmentalize
their functions
2.3.5
State three differences
Pg. 100-101
2009 Specimen Paper
between plant and animal
cells
2.3.6
Outline two roles of
extracellular components
2.4 Membranes (2 hours)
3. Which of the following
structures are present in both
plant and animal cells?
I. Cell wall
II. Chloroplast
III. Mitochondrion
A. I only
B. I and II only
C. I and III only
D. III only
Pg. 118-120
IB says: The plant cell wall maintains cell shape, prevents excessive
water uptake, and holds the whole plant up against the force of
gravity. Animal cells secrete glycoproteins that form the
extracellular matrix. This functions in support, adhesion, and
movement.
2.4.1
Draw and label a diagram to
show the structure of
membranes
Pg. 127
IB says, The digram should show the phospholipid bilayer,
cholesterol, glycoproteins, and integal and peripheral proteins.
Integral proteins are embedded in the phospholipids of the
membrane, whereas peripheral proteins are attached to its surface.
2009 Specimen Exam
5. (a) Draw a labelled diagram
showing the structure of a
plasma membrane.
[4]
5. (a) Award [1] for each of the
following clearly drawn and
labelled correctly.
-- a double layer of
lipid/phospholipid molecules with hydrophilic heads and
hydrophobic tails;
--an integral protein - passing
completely through the lipid
bilayer;
--a peripheral protein - shown
on the surface and not
penetrating the lipid bilayer;
--an integral protein with a pore
passing through its entire length
/ a glycoprotein with the
carbohydrate components
shown/cholesterol as component
in bilayer; [4]
2.4.2
Explain how the
Pg. 124-125
hydrophobic and hydrophilic
properties of phospholipids
help to maintain the
structure of cell membranes
2.4.3
List the functions of
membrane proteins
Pg. 127-129, especially Figure 7.9
IB says, Include the following: hormone binding sites, immobilized
enzymes, cell adhesion, cell-to-cell communication, channels for
passive transport, and pumps for active transport
2.4.4
Define diffusion and osmosis
Pg. 130-133
2.4.5
Explain passive transport
across membranes by simple
Pg. 130-134
May 2006PM (SL)
6(b) Explain the process of
diffusion and facilitated
diffusion
passive transport across the cell
membrane. [8]
(b) passive transport involves
diffusion / movement of molecule
down a
concentration gradient / from
high to low concentration;
osmosis is a form of passive
transport;
osmosis is diffusion of water
across a semi-permeable
membrane;
ATP not required for this
process;
energy for diffusion comes from
the kinetic energy / Brownian
movement of the
diffusing molecules;
some molecules diffuse through
the phospholipids bilayer;
examples of molecules which
diffuse across membrane are
gases / water / lipids /
steroids / hydrocarbons;
larger molecules / hydrophilic
molecules diffuse through
membrane
proteins/channels;
diffusion through membrane
proteins/channels is facilitated
diffusion;
facilitated diffusion is faster
than normal diffusion;
facilitated diffusion is limited by
the number/density of pores; [8
max]
2.4.6
Explain the role of protein
pumps and ATP in active
transport across membranes
Pg. 134
2.4.7
Explain how vesicles are
used to transport materials
within a cell between the
rough endoplasmic
reticulum, Golgi apparatus,
and plasma membrane
Pg. 104-108
2.4.8
Describe how the fluidity of
the membrane allows it to
change shape, break and reform during endocytosis and
exocytosis
Pg. 137-138, including Figure 7.20
14 May 2008 PM
5a Outline the various means of
transfer of different types of
molecules through the plasma
membrane
2009 Specimen Exam
5. Which of the following is a
feature of exocytosis but not
endocytosis?
A. Shape changes of a
membrane
B. Vesicle formation
C. Use of ATP
D. Secretion
2.5 Cell division (2 hours)
2.5.1 Outline the stages in the cell
cycle, including interphase
(G1, S, G2), mitosis, and
cytokinesis
2.5.2
2.5.3
2.5.4
State that tumours (cancers)
are the result of uncontrolled
cell division and that these
can occur in any organ or
tissue
State that interphase is an
active period in the life of
the cell when many
metabolic reactions occur,
including protein synthesis,
DNA replication and an
increase in the number of
mitochondria and/or
chloroplasts
Describe the events that
occur in the four phases of
mitosis (prophase,
metaphase, anaphase, and
telophase)
Pg. 221-226
Pg. 232-233
Pg. 222-223 Figure 12.6
IB says Include supercoiling of chromosomes, attachment of spindle
microtubules to centromeres, splitting of centromeres, movement of
sister chromosomes to opposite poles, and breakage and reformation of nuclear membranes.
Textbooks vary in the use of the terms chromosomes and chromatid.
In this course, the two DNA molecules formed by DNA replication
are considered to be sister chromatids until the splitting of the
centromere at the start of anaphase; after this, they are individual
chromosomes. The term kinetochore is not expected.
2.5.5
Explain how mitosis
produces two genetically
identical nuclei
2.5.6
State that growth, embryonic
development, tissue repair,
and asexual reproduction
involve mitosis
Pg. 219-220
Mitosis is preceded by an exact duplication of chromosomes. During
metaphase of mitosis, the identical sister chromatids line up so that
each sister goes to a different daughter cell.
14 May 2008, PM
3. Which of the following are
associated with mitosis?
I. Tissue repair
II. Chiasmata
III. Asexual reproduction
A. I and II only
B. I and III only
C. II and III only
D. I, II, and III