PIONEER JUNIOR COLLEGE
JC1 H2 BIOLOGY 2010
CELL STRUCTURE AND MEMBRANE TEST
Name: …………………………….
Class: ……………….
Date: ………… Marks:………/30
Section A: Multiple Choice Questions (15 mks)
1
Which pair of organelles has internal membranes?
A
nucleoli and golgi apparatus
B
chloroplasts and mitochondria
C
mitochondria and ribosomes
D
chloroplasts and nucleoli
(B
)
2
The table gives description of four membranous structures in a cell. Which structure
is correctly matched with its functions?
Structure
3
4
Function
A
An extensive network of tubes and sacs, Lipid synthesis
each tube and sac bounded by a single
membrane
B
A spherical sac bound by a single Protein synthesis
membrane
C
A sac bound by two membranes, the inner Packaging of proteins
membrane being highly folded
D
A stack of elongated, curved sacs, each Photosynthesis
sac bound by a single membrane
(A
)
What technique provided the primary evidence for the fluid mosaic model of the cell
surface membrane?
A
Cell fractionation
B
Freeze-fracture
C
Chemical analysis of proteins
D
Microscopic staining
Which of the following statement is true?
(B
)
5
A
Prokaryotes have chromosomes that are found in the nucleus.
B
Animals, plants, fungi and bacteria are examples of eukaryotes.
C
Prokaryotes have nucleoid, ribosomes, cell wall, cell membrane,
flagella, and fimbriae.
D
Prokaryotes are generally bigger in size as compared to eukaryotes.
(C
)
The following contains images of a number of structures that can be seen in a
cell.
1
2
3
4
Identify structures 1 - 4 and the process that occurs in structure 4.
A
B
C
D
6
1
chloroplast
mitochondrion
2
nucleus
Golgi
apparatus
mitochondrion
Golgi
apparatus
chloroplast
nucleolus
3
ribosome
rough ER
4
mitochondrion
chloroplast
smooth
rough ER
ER
Golgi
microfilaments
apparatus
The diagram shows the ultrastructure of a cell.
Process
respiration
photosynthesis
protein
synthesis
cytoskeleton
(B
)
I
III
II
IV
Which of the following structure(s) contain(s) nucleic acids?
7
8
A
I only
B
I and II only
C
I and IV only
D
I, II, III and IV
(C
)
The absence of centrioles from higher plant cells means that during somatic
cell division there is
A
no apparent organiser of mitotic spindles.
B
no equatorial arrangement of chromosomes at metaphase.
C
no new cell wall laid down at telophase.
D
no spindle formed.
(A
)
The diagram represents a model of the structure of a biological membrane.
C
outside
D
A
B
inside
Which of the following represents a glycoprotein?
9
A tadpole’ s tail is gradually broken down during metamorphosis into an adult
frog. Which organelle increases in number in the cells of the tail at this time?
(D
)
10
11
A
centrioles
B
Golgi apparatus
C
lysosome
D
Pinocytic vesicles
(C
)
A higher concentration of sodium ions in extracellular fluid versus cytosol is
most likely maintained by
A
Blocking any passage of sodium ions through the plasma membrane
B
Actively transporting sodium ions out of the cell
C
Overcrowding the cell with potassium ions
D
None of the above
(B
)
The figure below is a drawing of an animal cell nucleus as seen using an
electron microscope.
The actual diameter of the nucleus, measured along the line XY is 7.2µm.
What is the magnification of the nucleus?
12
A
65X
B
650X
C
6500X
D
65000X
A certain cell surface membrane is made entirely of phospholipid and is 7nm
thick. A volume of 1mm3 of this phospholipid membrane was homogenised and
dropped onto the surface of water in a large tray. The phospholipid spread out
to form a continuous thin film.
(C
)
What is the expected surface area of this film?
13
A
143 000 mm2 because the phospholipids form a single layer.
B
143 000 mm2 because the phospholipids form a double layer.
C
286 000 mm2 because the phospholipids form a single layer.
D
286 000 mm2 because the phospholipids form a double layer.
The diagram represents a cell membrane.
Which structure allows the diffusion of Cl – ions between the outside and the
inside of the cell?
14
(C
)
The diagram shows the pathway of diffusion of a particle through a cell surface
membrane.
What are the most likely properties of the particle?
Lipid solubility
Relative
molecular mass
Electrically
charged
A
High
High
Yes
B
High
Low
No
C
Low
High
No
(A
)
D
15
Low
Low
Yes
(D
)
Which of the following are types of endocytosis?
A
facilitated diffusion and bulk filtration
B
pinocytosis and phagocytosis
C
osmosis and active transport
D
none of the above
(B
)
Section B: Structured Questions (15 mks)
Question 1
The micrograph below shows part of a cell. Identify the structures indicated by the labels. [4]
A
C
B
H
G
D
E
A – Golgi Apparatus
B – Rough endoplasmic reticulum
C – Smooth endoplasmic reticulum
D – ribosomes
F
E – nuclear pore
F – Nucleus/nucleoplasm
G- Nuclear envelope /Nuclear outer membrane
H - Mitochondrion
Comments:
Please search the internet for more exposure to electron micrographs of organelles. No other
way to familiarize yourselves.
Please ensure that you use the plural and singular terms accurately when naming the
organelles.
(b) An experiment was carried out to determine what happens to amino acids after they are
absorbed by animal cells. The cells were incubated for 5 minutes in a medium containing
radioactively labeled amino acids. The radioactive amino acids were then washed off and
the cells were incubated in a medium containing only non-radioactive amino acids.
Samples of the cells were taken at 5, 10 and 45 minutes after the start of the experiment
and the sites of radioactivity in the cells were determined. The results are given in the table
below. The figures show radioactivity in certain cell organelles expressed as a percentage
of the total radioactivity within the cells.
Percentage of total radioactivity
Organelles
Rough endoplasmic
reticulum
Golgi apparatus
Secretory vesicles
At 5 min
At 10 min
At 45 min
80
10
10
80
5
30
0
5
60
(i) Explain why the radioactivity is associated mainly with the rough endoplasmic reticulum
after the first 5 minutes of the experiment. [1]
RER has ribosomes which are the sites of protein synthesis;
(ii) Explain the changes in the pattern of radioactivity in the cell during the remaining 40
minutes of the experiment. [3]
Comments:
 The question did not describe the changes. So please describe the trend/changes as
seen in the table first before explaining.
 As you are describing the trend/changes, always remember to quote values to support
your observation.
 Many students did not fully describe the function of the GA, thus losing precious marks
too.
1. After about 5-10 mins. there is a decrease radioactivity at RER increase in
Golgi apparatus (quote – decrease from 80% to 10% at RER while increases
from 10% to 80% at GA
2. polypeptides move to Golgi apparatus,
3. where they undergo final chemical modification for next 35 minutes;
4. At 45 mins, there was a decrease from 80% to 30%, while there was an
increase from 5% to 60% at the secretory vesicles (quote) - OWTTSE
5. most proteins have been sorted and packaged into secretory vesicles and
6. budded off from trans face of Golgi for transport to the plasma membrane
(iii) Suggest why the figures in the tables for each time interval total less than 100%. [2]


Amino acids moving between 3 listed organelles eg. in transport vesicles
between RER and GA;
Proteins also synthesized on other organelles such as free lying ribosomes,
mitochondria so the radioactive amino acids may be found there instead;
Question 2
The diagram below shows a plan diagram of a typical membrane which appears in electron
micrograph.
carrier protein
(d)
Channel protein
Y
X
-------------------------------------------------------------------------------------------------------------
Z
(a) What is the likely composition of layer Y? [1/2]
Comments:
Students must mention that the phosphate head or fatty acid tails belong to phospholipid
molecules.
hydrophilic/charged/polar phosphate head of phospholipids (reject: polar/hydrophilic
heads)
(b) What is the likely composition of layer Z? [1/2]
Hydrophobic hydrocarbon/fatty acid tails of phospholipids (reject: hydrophobic tails)
(d) Draw on the diagram, a labeled structure which allows Na+ ions to pass through. [1]
(e) Explain how this labeled structure is able to stay in the membrane and how it is able to carry
out its function. [2]


the surface next to phospholipids contains amino acids which are hydrophobic,
forming hydrophobic interactions with the hydrocarbon tails of phospholipid
molecules (hold protein within membrane)
Channel Protein:
 In order for it to be able to function as a channel proteins for polar and charged
particles (eg. ions, amino acids),
 the channel surface of the protein is made up of stretches of amino acids which
are hydrophilic, allowing charged n polar particles to pass through,
Or
Carrier Protein:
 Undergo rapid changes in shape. They exist in 2 forms, known as the ‘Ping’ &
‘Pong’ states.

The diffusing molecule or ion binds to the binding site of the carrier protein (made
up of hydrophilic amino acids), which then undergoes a change in shape,
depositing the molecule or ion on the other side of the membrane.
(d) Explain two ways in which the membrane fluidity is maintained. [2]
Comments:
Explain. Do not simply identify factor only.
1. weak hydrophobic interactions that exist between the hydroC chains in the
hydrophobic core; breaks easily allowing phospholipid molecules to diffuse laterally
in the plane of the membrane
2. unsaturated fatty acid chains which have kinks at the double bonds; disrupt/prevent
the close packing of phospholipid molecules in the membrane
3. cholesterol found wedged between phospholipids; disturbs the close packing of
phospholipids at low temperature & restrain movement of phospholipids at high
temperature.
(in the case of plants, only first 2 answers are accepted)
[Total: 6 marks]