This document contains a biology exam with multiple choice questions testing knowledge of cell structure and function. It includes questions about: - Striated muscle cells and exceptions to the cell theory - How stem cells can help treat Stargardt's disease - Identifying organelles such as mitochondria in electron micrographs - Where 70S ribosomes are located and membrane protein functions - Osmosis and the effects of solutions of different salt concentrations on cells - Types of cellular movement such as facilitated diffusion and active transport - Cell division processes like mitosis and cytokinesis - Evidence for the endosymbiotic theory from mitochondrial DNA - Key aspects of the cell theory including that cells come from pre-

1. Topic 1 1819 [50 marks]
1.
Which feature of striated muscle cells allows them to be considered as a possible exception to the cell theory?
A. They are found in multicellular organisms.
B. They contain more than one nucleus.
C. They are specialized for movement.
D. They do not carry out mitosis.
Markscheme
B
2.
Which characteristic of stem cells makes them useful for treating Stargardt’s disease?
A. They can differentiate into retinal cells.
B. They are readily available from especially created embryos.
C. They transport white blood cells to the eyes.
D. They divide by binary fission so provide sufficient cells.
Markscheme
A
3.
The following electron micrograph which shows part of two adjacent liver cells.
What is the structure labelled Y?
A. Nucleus
B. Starch grain
C. Lysosome
D. Mitochondrion
[1 mark]
[1 mark]
[1 mark]

2. Markscheme
D
4.
Where can 70S ribosomes be found?
A. On membranes of the Golgi apparatus
B. In prokaryotic cells
C. On membranes of the rough endoplasmic reticulum
D. In nuclei
Markscheme
B
5.
Which are functions of membrane proteins?
A. Hormone binding sites and DNA replication
B. Cell adhesion and translation
C. Cell to cell communication and protein pumps
D. Passive transport and glycosis
Markscheme
C
6. What feature of cell membranes allows endocytosis to occur?
A. Fluidity of phospholipid bilayer
B. Presence of protein pumps
C. Presence of carrier proteins
D. Glycoprotein binding sites
Markscheme
A
7.
The salt concentration inside an animal cell is 1.8 %. The salt concentration in the surrounding medium becomes 5 %. What will be
the likely response?
A. The cell will gain water from the medium.
B. The cell will lose salt to the medium.
C. The cell will remain unchanged.
D. The cell will shrink from loss of water.
Markscheme
D
[1 mark]
[1 mark]
[1 mark]
[1 mark]

3. 8. The diagram is a model of one type of movement across a membrane.
What is this type of movement?
A. Simple diffusion
B. Facilitated diffusion
C. Osmosis
D. Active transport
Markscheme
B
9.
Why do crop plants dry out when a field is irrigated with water contaminated by sea water?
A. The plants lose water by active transport.
B. The plants gain salt by osmosis.
C. The plants gain salt by diffusion.
D. The plants lose water by osmosis.
Markscheme
D
10. Cells in the adrenal gland produce the hormone epinephrine and store it in vesicles. To release epinephrine these vesicles are
carried to the plasma membrane and fuse with it. What process is occurring?
A. Expulsion
B. Exchange
C. Excretion
D. Exocytosis
Markscheme
D
[1 mark]
[1 mark]
[1 mark]

4. 11.
The statement relates to Pasteur’s experiments.
What did this statement suggest?
A. Mold evolved by endosymbiosis.
B. Oxygen is required for anaerobic respiration.
C. Cells can only be formed by division of pre-existing cells.
D. Nutrients are a requirement for mold growth.
Markscheme
C
12. Which mitotic phase is labelled X in the micrograph of an onion (Allium cepa) root tip?
A. Prophase
B. Metaphase
C. Anaphase
D. Telophase
Markscheme
B
13.
What is the process shown in this image?
A. Binary fission of a prokaryotic cell
B. Telophase II in a eukaryotic cell
C. End of mitosis in a prokaryotic cell
D. Cytokinesis of a eukaryotic cell
[1 mark]
[1 mark]
[1 mark]

5. Markscheme
A
14.
During which stage does the cell surface area to volume ratio decrease?
A. Interphase
B. Metaphase
C. Telophase
D. Cytokinesis
Markscheme
A
15.
During which stage of the cell cycle are the numbers of mitochondria increased in a cell?
A. Cytokinesis
B. Interphase
C. Meiosis
D. Mitosis
Markscheme
B
16.
What is evidence for the endosymbiotic theory?
A. RNA can catalyse metabolic reactions.
B. Meteorites contain organic molecules.
C. Amino acids can be synthesized from inorganic compounds.
D. Mitochondria possess their own DNA.
Markscheme
D
17.
Which of the following will contribute to the cell theory?
I. Living organisms are composed of cells.
II. All cells come from pre-existing cells by mitosis.
III. Cells are the smallest units of life.
A. I only
B. II only
C. I and III only
D. I, II and III
Markscheme
C
[1 mark]
[1 mark]
[1 mark]
[1 mark]

6. 18. Which functions of life are carried out by all unicellular organisms?
Markscheme
B
19.
What is a difference between a cell in the G phase and a cell in the G phase of the cell cycle?
A. A cell in the G phase would be smaller than a cell in the G phase.
B. A cell in the G phase would have more mitochondria than a cell in the G phase.
C. A cell in the G phase would have more DNA in its chromosomes than a cell in the G phase.
D. DNA replication occurs in the G phase but not in the G phase.
Markscheme
B
1 2
2 1
2 1
1 2
1 2
20.
A botanist measures a leaf and finds it is 24 cm long and 8 cm wide. His drawing of the leaf is 4 cm wide. Which was the
magnification and length of his drawing, assuming that the proportions of the drawing were correct?
Markscheme
D
21. (i) State the process that divides one nucleus into two genetically identical nuclei.
(ii) Explain how the cell cycle is controlled.
[1 mark]
[1 mark]
[1 mark]
[5 marks]

7. Markscheme
(i) mitosis
(ii)
a. cell cycle is a sequence of stages / cell cycle is G , S, G and mitosis
b. (control of the cell cycle) by cyclins/cyclin
c. levels of cyclins rise (and fall)/fluctuate during the cell cycle/surge at different times/have to reach a certain concentration
d. conditions inside as well as outside the cell affect regulation
e. four cyclins/different cyclins to enter different stages of/events in the cell cycle / cyclins regulate the sequence/timing of the cell cycle /
cyclins trigger the next stages
The idea of different cyclins acting at different phases must be clear.
f. cyclin-dependent kinases / cyclins bind to kinases and activate them
g. kinases phosphorylate other proteins
h. phosphorylated proteins perform specific functions in the cell cycle
1 2
22. Draw a labelled diagram of a eukaryotic plant cell as seen in an electron micrograph.
Markscheme
Cell wall shown with two continuous lines to indicate the thickness
Plasma membrane/cell membrane shown as a single continuous line
Accept inner line of wall as membrane if clearly labelled.
Nuclear membrane/nucleus shown with double membrane and nuclear pores
Vacuole «membrane»/tonoplast shown as a single continuous line
Chloroplast/plastid shown with a double line to indicate the envelope and thylakoids/grana
Mitochondrion shown with double membrane/cristae
23a. Draw a labelled diagram to show the structure of membranes.
Markscheme
Award [1] for each structure clearly drawn and correctly labelled.
phospholipid bilayer – with head and tails;
hydrophilic / phosphate / polar heads and hydrophobic / hydrocarbon / fatty acid / non-polar tails labelled;
integral/intrinsic protein – embedded in the phospholipid bilayer;
protein channel – integral protein showing clear channel/pore;
peripheral/extrinsic protein – on the surface;
glycoprotein with carbohydrate attached; (carbohydrate should project outwardly from membrane protein)
cholesterol – shown embedded in bilayer; (must appear in hydrophobic region)
thickness indicated (10 nm); (allow answers in the range of 7 nm to 13 nm)
23b. Explain passive transport and active transport across membranes.
[4 marks]
[6 marks]
[8 marks]

8. Markscheme
diffusion/facilitated diffusion and osmosis are passive;
do not require energy/ATP;
diffusion is movement from high to low concentration/down a (concentration) gradient;
facilitated diffusion uses (protein) channels/carrier proteins;
osmosis is water movement from lower to higher solute concentration / from higher to lower water potential/concentration;
across a partially permeable membrane;
active transport/formation of vesicles require energy;
in the form of ATP;
active transport moves materials up/against the (concentration) gradient/from low to high concentration;
protein pumps required;
endocytosis into cells / exocytosis out of cells;
example of active or passive transport; (e.g. sodium potassium pump for active transport / oxygen exchange in alveoli for passive
transport)
24a.
The micrograph shows a cell from the root of an onion ( Allium cepa) during mitosis.
Calculate the magnification of the image.
Markscheme
136 (accept answers in the range of 132 to 140)
24b. Deduce the stage of mitosis shown in the micrograph.
Markscheme
anaphase
25a.
State the property of stem cells that makes them useful in medical treatment.
Markscheme
has the ability to differentiate (into specialized tissue)
25b. Explain how multicellular organisms develop specialized tissues.
[1 mark]
[1 mark]
[1 mark]
[2 marks]

9. Printed for Dubai American Academy
© International Baccalaureate Organization 2018
International Baccalaureate® - Baccalauréat International® - Bachillerato Internacional®
Markscheme
only some genes are expressed in each cell type/tissue;
tissues therefore develop differently/become differentiated;
example of differentiated cell and the function of tissues;
26a.
This image shows a normal red blood cell.
These images show two red blood cells that have been placed in solutions with different concentrations of solutes.
Deduce, with a reason, which red blood cell has been placed in a hypertonic solution.
Markscheme
cell 2 because it has plasmolized/lost water/volume has decreased
26b. State what change there has been in the cell surface area to volume ratio in red blood cell 1.
Markscheme
decreased
[1 mark]
[1 mark]