BIOL0601Provincial Biology: Module 1: Cell Biology. Assignment 1
BIOL0601 Module 1 Assignment 1
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BIOL0601Provincial Biology: Module 1: Cell Biology. Assignment 1
Introduction
BIOL0601 Provincial Biology
Assignment 1
Instructions:
Print Students
Answer questions in the spaces provided on the paper. If you need more space,
append a sheet and make sure that you clearly identify the page with your name,
the assignment title and the question number. Answers to the long answer
questions are to be done on a separate paper. Make sure that you clearly identify
this page with your name, the assignment title and the question number.
Only submit your work to your tutor when all the work in the assignment (questions
and labs) has been completed.If you are sending your file to your tutor
electronically, ensure that it has a file name that includes the course name,
assignment number and your name.
e.g. BIOL0601_A1_Chiu.doc (with your name in place of “Chiu.”)
Topic
Marks
Diagrams
7
Terms and Definitions
10
Matching
4
Short Answer Questions
28
Long Answer Questions
11
Lab 1A
10
Lab 1B
10
Lab 1C
10
Lab 1D
10
Total marks
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/100
/100
BIOL0601Provincial Biology: Module 1: Cell Biology. Assignment 1
A Diagrams
1.
Refer to Figure 1.2 in your text to answer this question. (2marks)
For each of the following items, indicate the level of biological organization at which it would be
found.
a. A heart
organ
b. Your pet dog
organism
c. You and the people that live around you.
community
d. a carrot
organism
2.
Place the name and the function of each of the lettered structures in the spaces below. (5 marks)
A
centrosomes
B
vessicle
C
endoplasmic reticulum
D
mitochondrion
E
Golgi complex
Name
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Function
consisting of two centrioles, the central microtubule organizing
centre
a membrane bound sac that contains and transports
substances
both rough and smooth; a system of membranes for the
processing of proteins and lipids and their transport within the
cell
a cellular organelle in which the majority of the energy is
extracted from glucose and stored in ATP
processes, packages and transports molecules about the cell
BIOL0601Provincial Biology: Module 1: Cell Biology. Assignment 1
B Terms
1. Complete the following crossword. You may place your answers in the spaces with the
clues.(7marks)
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BIOL0601Provincial Biology: Module 1: Cell Biology. Assignment 1
C Matching
1. Match each of the chemical structures with the correct name by placing the correct letter beside the
name. (4 marks)
-A-
-B-
-C-
-Da) unsaturated fat
D
b) saturated fat
B
c) amino acid
A
d) steroid
C
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BIOL0601Provincial Biology: Module 1: Cell Biology. Assignment 1
D Short Answer Questions
1. List the six characteristics of life (3 marks)
a
Living things are organized
b
Living things acquire materials and energy
c
Life is homeostatic
d
Living things respond to stimuli
e
Living things reproduce and develop
f
Living things adapt and evolve
2. Louis Pasteur said "In the fields of observation chance favours only the prepared mind", and so it was
with Alexander Fleming and the discovery of penicillin. Fleming was a bacteriologist in search of a
substance that would kill bacteria and not harm humans. One of his main pieces of equipment was a
petri dish with agar, a medium on which bacteria could be grown. The difficulty in working with petri
dishes was contamination. Frequently, many of the prepared petri dishes had to be discarded
because of contamination. One day as he was working through a batch of newly prepared petri
dishes, the pile of contaminated dishes was building. Normally, these dishes would just be discarded,
but this day he noticed something. One of the petri dishes had a mold growing on it and the area
around the mold was clear, indicating that there were no bacteria growing in the immediate vicinity of
the mould. He remembered the antibacterial agent that he was looking for and wondered if this might
be it. He began to experiment with the mold, and the rest is history. The mold was called Penicillium
notatum, and when the active ingredient was finally extracted from it, it was called penicillin.
a) Consider the steps of the scientific method as listed in your text. What hypothesis might Fleming
have used to guide his experiments? (1 mark)
That the presence of the mold prevents the growth of bacteria
(note: the book does not use the If…then form of a hypothesis)
b) Briefly describe the experiments that Fleming might have conducted to show that it was the
moldthat was preventing the bacteria from growing. Be sure to mention the control group and the
experimental group. (3 marks)
-petri dishes would be set up and divided into two groups (experimental and control)
-all dishes would be inoculated with the experimental bacterium
-half the petri dishes would be inoculated with the mold, the other half would be left untouched
-the ones left untouched are called the control group.
-the dishes are incubated and allowed to grow.
-if the hypothesis is correct, the growth of bacteria would be shown to be prevented by the
presence of the mold.
c) What would Fleming have done if his experiments did not support his hypothesis? (1 mark)
As with any experiment, if the hypothesis proves to be incorrect, a new hypothesis is formulated
which serves as the basis for new experimentation
3. Compare and contrast ionic, polar covalent bonding and covalent bonding. (3 marks)
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BIOL0601Provincial Biology: Module 1: Cell Biology. Assignment 1
A chemical bond is formed when a pair of electron is shared between two atoms. The bond type is
determined by how the pair is shared.
-a covalent bond is formed when the pair of electrons is shared equally between two atoms (they
each have an equal share and therefore the bond is non-polar
-an ionic bond is formed when one atom has exclusive control over the electron pair forming two
charged particles (ions); effectively one atom has lost its electron and has a positive charge and the
other has gained an electron and has a negative charge
-a polar covalent bond is intermediate between these two; the electron pair is unequally shared
forming the polar covalent bond in which one end is slightly positive and the other is slightly negative
4. Oxygen has two isotopes: oxygen 16 and oxygen 18.
a) Draw a diagram like the ones in your text(Figure 2.2) to illustrate these two isotopes (1 mark)
b) Identify the similarities and differences between these two isotopes. (2 marks)


Isotopes are chemically identical (have the same electronic configuration) and have the
same number of electrons and protons.
Isotopes have different masses due to different numbers of neutrons in the nucleus – in this
case 8 and 10
5. Multicellular organisms are made of many small cells rather than a smaller number of larger cells.
a. Explain why cells are small? (2 marks)
Cells are small because of the surface area to volume relationship. The smaller the cell, the
larger the surface area to volume ratio:
cell 1
1 cm3 SA/vol ratio = 6 cm2/1 cm3 or 600 mm2/1000 mm3 or 6/10
cell 2
2 mm3 SA/vol ratio = 6 mm2/1 mm3 or 6/1
The smaller cell has a larger SA/volume ratio
This is important because a cell must exchange materials with its environment. This is done by
the process of diffusion which happens through the cell membrane. The larger the SA/volume
ratio for the cell, the better it will be able to exchange materials through diffusion.
b. What advantage does an organism have by being made up of many cells? (1 mark)
A single cell has to carry out all the life functions by itself. In a multicellular organism, cells can
specialize to carry out a specific function. Division of labour among the cells makes the
organism more efficient.
7. Define the terms acid and base. How are acids and bases related to each other and what is the
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BIOL0601Provincial Biology: Module 1: Cell Biology. Assignment 1
importance of pH to biological systems? (2 marks)
An acid is a substance that forms hydrogen ions in water solution. A base is a substance that forms
hydroxyl ions in water solution. A hydrogen ion and a hydroxyl ion form water. The process is called
neutralization.
The pH of biological systems must be kept within a certain range because enzymes are sensitive
to pH and can stop function if the pH is not within a certain range.
8. Define the term buffer and describe how the bicarbonate buffer helps to maintain human bold pH
within a narrow range. (4 marks)
A buffer is a chemical compound that can maintain pH within a narrow range despite the addition of
acid or base. The following chemical equations represent the bicarbonate buffer:
H2O + CO2 <===> H2CO3 <=== >
H+
+
HCO3-
The bicarbonate buffer is formed by the dissolving of carbon dioxide gas in the water of plasma.
The bicarbonate ion, HCO3- is the central ion in the blood buffer system.
In the presence of excess acid, H+, H2CO3 is formed which breaks down to H2O and CO2 thus
getting rid of the excess acid.
In the presence of base, the OH- combines with H+ to form water and carbonate ion, CO22neutralizing the excess base.
9. Identify the four parts of the endomembrane system. (2 marks)
a. the nuclear envelop
b. the endoplasmic reticulum
c. the Golgi apparatus
d. the lysomes and vessicles
10. In the Matching section, molecule D illustrates a certain type of molecule made up of several parts.
1. Name the components of this molecule. (1 mark)
D is a triglyceride. It is made up of 3 fatty acids and a glycerol molecule.
2. Name and describe the process whereby these components were assembled into this
molecule. (2 marks)
The process by which this molecule is assemble is called dehydration synthesis.
A molecule of water is removed from between the two molecules (glycerol and fatty acid)
bonding the two molecule together.
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O
~~ C - O - C ~~ + H2O
=
=
O
~~ C - OH + HO - C ~~
BIOL0601Provincial Biology: Module 1: Cell Biology. Assignment 1
Long Answer Questions
Answer the following questions on a separate piece of paper. Each of your answers should be two to
three paragraphs long. Use your own wording.
1. "If the water molecule was not polar, life on Earth would not be possible" Discuss this statement in the
light of what you have learned about water and its importance to life. In your answer, refer to at least
three of the properties of water. (6 marks)
In the answer the student must refer to at least three of the characteristics of water (1 mark each) and
state why this characteristic is important for life on Earth (1 mark each)
-
water exists in all 3 states on Earth and is liquid at room temperature
water has a high heat capacity and its temperature rises and falls slowly
water has a high heat of vaporization; water can absorb large quantities of heat while
changing only a small amount in temperature
solid water (ice) is less dense than liquid water.
water molecules are cohesive but still flow freely
water is considered a “universal solvent”; it dissolves a wide range of materials
2. Define endosymbiosis and discuss how it is thought to be involved in the evolution of eukaryotic cells.
What evolutionary advantage did this process confer upon cells? (5 marks)
Endosymbiosis is a hypothesis that states that smallerthat certain complex cellular organelles (the
mitochondrion and the chloroplast)did not evolve on their own but were once free living cells that
were ingested by a primitive prokaryotic cell, were not digested, and formed a symbiotic relationship
with the primitive cell.
-
early cells were prokaryotic (unbounded cellular organelles)
eukaryotic cells are very complex
the bounded nucleus evolved by an invagination of the cellular membrane to form an
enclosing nuclear membrane
the mitochondrion and chloroplast are very complex themselves have similarities to
eukaryotic cells
a prokaryotic cell was injected but not digested and formed a symbiotic relationship with the
injecting cell; it provided energy (ATP, sugar) to the cell and the cell provided refuge
Bonus Question (optional)
Section 1.5 of your text refers to “Science and Social Responsibility”. Pick an issue from the media
(TV, newspaper, radio, ….) and discuss the issue from this perspective (5 bonus marks)
Bonus marks can be added to the total marks up to a maximum of 99. The awarding of the marks is
up to the tutor. However, for a full 5 bonus marks the answer must be a serious attempt to deal with
the subject of social responsibility and not just a frivolous attempt at the bonus. Award 5, 3 or 1 bonus
marks
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BIOL0601Provincial Biology: Module 1: Cell Biology. Assignment 1
Module 1 Lab Exercises
When performing lab exercises remember the following:
Prepare your laboratory space before starting the lab. Check for safety issues, and collect all all
equipment together before starting the exercise.
Charts have been prepared into which you can enter your observations and data. Make the entries as
you do the experiment so that it is fresh in your mind and you can make accurate observations. Do not
write data or observations on scrap paper - it can too easily become lost.
When you have completed the lab exercise, immediately clean up your workspace and put equipment
and chemical away.
Once everything is done, you may begin to answer the questions at the end of the lab write-up.
The Metric Kitchen
In the Science laboratory, measures are normally given in metric units. Even recipes are now starting to
use metric measures. The following table will help you convert these measures to use the non-metric
equipment in your kitchen.
Liquids can be converted to liters or milliliters with the following table. Small volumes (less than about 1
fluid ounce or 2 tablespoons) of ingredients such as salt, herbs, spices, baking powder, etc. should also
be converted with this table. Do not use this table to convert other non-liquid ingredients.
Volume Conversions: Normally used for liquids only
Customary quantity
Metric equivalent
1 teaspoon
5 mL
1 tablespoon or 1/2 fluid ounce
15 mL
1 fluid ounce or 1/8 cup
30 mL
1/4 cup or 2 fluid ounces
60 mL
1/3 cup
80 mL
1/2 cup or 4 fluid ounces
120 mL
2/3 cup
160 mL
3/4 cup or 6 fluid ounces
180 mL
1 cup or 8 fluid ounces or half a pint 240 mL
1 1/2 cups or 12 fluid ounces
350 mL
2 cups or 1 pint or 16 fluid ounces 475 mL
3 cups or 1 1/2 pints
700 mL
4 cups or 2 pints or 1 quart
950 mL
4 quarts or 1 gallon
3.8 L
Length Conversions
1 inch
2.54 cm
Dry Weight (Mass) Conversion
1 oz
1 lb
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28.35 g
0.454 kg or 454 g
BIOL0601Provincial Biology: Module 1: Cell Biology. Assignment 1
Lab 1A: Doing Science Safely
Introduction
The Science laboratory can be a very dangerous place. Special equipment, dangerous chemicals, and
fire are just some of the hazards encountered in a working scientific laboratory. You will however be
performing your lab work in your homes; most likely in the kitchen. We feel very safe in our homes but
there are still hazards that we must pay attention to in order for the lab exercises to be successful and
fun. This video ( name the video ) was produced to help you complete your lab exercises in a safe
manner.
Method
Read the questions in the “Thinking About the Results” section. Keep these in mind as you watch the
video. You may wish to make notes during the video to help you and answer these questions. We will
call the location where you do your lab exercises your “laboratory space”.
Thinking About the Results
1. Where in your home is your laboratory space?
_____________________________________________________________
2. Name at least two hazards that you can identify in your laboratory space. (2 marks)
_____________________________________________________________
3. What would you do to neutralize these hazards? (1 marks)
_____________________________________________________________
4. What will you do in the case of a chemical (or any) spill. (1 marks)
_____________________________________________________________
5. Describe the things that you will have to deal with when you have finished a lab exercise. (1
marks)
cleanup and disposal of used materials
Grading
The intention of this lab is to get the student to carefully consider their home environment from an
experimental safety point of view.
If the student has made a serious attempt and has clearly made a conscientious effort, award a 10.
If it is clear that the student has rushed the job or not taken it seriously, but has answered the questions
reasonably, award a 7
If it is clear that the student has not taken this seriously, they should be asked to resubmit the lab. Safety
should always be a top priority and we should not let a student minimize the importance of safety just
because they are doing this at home.
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BIOL0601Provincial Biology: Module 1: Cell Biology. Assignment 1
Lab 1B: Acids and Bases In Your Home
Please note that you do not need to submit your lab work to your tutor. You do need
to submit the completed tables in the Results section and your answers to the
questions in the Thinking About the Results section.
Introduction
The concept of pH (the degree of acidity or alkalinity) is a very important biological concept. Biological
systems function best within a narrow pH range. In section 2.2 of your text buffers are discussed –
substances able to maintain pH within a narrow range. In this lab exercise you are going to investigate
the pH of materials found in your home. You will do this by using pH strips; strips that have been
impregnated with indicator chemicals so that the pH may be determined by the colour of the indicator
Materials
pH test strips
vinegar
baking soda (not baking powder)
orange pekoe tea
a lemon or lemon juice
water that has been at room temperature for at least an hour
Apparatus
a stirrer ( glass rod, wooden skewers, toothpick or ....)
3 small glass jars (like baby food jars)
various household items (3 glasses, tea pot, glass container)
Method
Will That Be Lemon or Milk?
Black teas contain a group of chemicals called polyphenols. They give the tea its
orange-red colour and contribute to the flavour. These chemicals belong to a group
called acid/base indicators. These are chemicals which change colour with the
degree of acidity of a solution. The tea and the test strips that you will use work
because of acid/base indicators.
1. Consider the safety aspects of the experiment. Wear appropriate protective equipment and make
sure that your laboratory space is uncluttered. Collect all materials together in the laboratory space
before you start the experiment. (do this all the time!)
2. Brew a very strong orange pekoe or black tea. Allow it to steep until room temperature. (do not use
herbal teas - they won't work!). Test the pH of the tea and record it in Table 1.2.1
3. Make up a solution of baking soda by placing one teaspoon of baking soda in about 25 mL (⅛ cup)
of water. Stir to dissolve the solid.
4. Place equal quantities (about 60 mL - ¼ cup) of steeped tea in 3 glasses. Place the glasses on
pieces of paper labelled A, B and C. Record your observations about the colour of the tea in the Tea
table. Test each of the glasses with pH paper. Record your observation in the Tea Table 1.2.10
5.
Add 5 mL of lemon juice (1 teaspoon) to glass A, and 5 mL of baking soda solution to glass C.
Record your observations in the Tea table. (statements identifying changes are most helpful)
6. Test the pH of the final tea samples with pH paper. Dip a stick or glass rod into the tea sample and
run it onto the pH test strip. Record the colour of the strip and read the pH from the scale. Test the
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BIOL0601Provincial Biology: Module 1: Cell Biology. Assignment 1
other two tea samples. To avoid contamination, use a clean stick or cleaned glass rod for each new
test. Record your results in the Tea Table 1.2.1.
pH of Various Household Substances.
For liquids
pH is defined in water solution. To test the pH, a stir stick is dipped in the solution and the liquid is
dabbed on that test strip. The colour of the test strip is compared to a colour chart, and the pH is read
from the colour chart.
(note 1: all solutions should be at room temperature when tested)
(note 2: the dip stick must be clean every time. If an absorbent material like wood (toothpick) is used,
use a clean one each time)
For this section record the colour of pH test strip and pH for all tests in Chart 1.2.2
1. Place a small amount of vinegar in a glass container. Test the pH of the vinegar by dipping the stirrer
into the vinegar and dabbing some of the vinegar on the test strip.
2. Place about 10 mL (2 teaspoons) of water in another glass container. Place a small amount of
baking soda into the water and swirl gently until the baking soda is dissolved. Test the pH of the
baking soda solution. (avoid contamination by rinsing your stirrer or using a new one for each new
substance)
3. Test the room temperature water for pH.
4. Test the pH of at least five other substances in your home. Remember to also check for any warning
labels on the materials that you test, and exercise appropriate cautions. Avoid contamination by
using clean glass containers and new stirrers for each of the substances tested. Record all your
results in the chart. Substances you may test could include: milk, a soft drink, yoghurt, salt, ..... (you
may test up to 10 substances)
5. When you have finished, clean up the laboratory space and carefully dispose of waste materials.
Results
Table 1.2.1
Tea
initial colour of tea
colour of tea after
addition
pH of tea before
addition
pH of tea after
addition
glass A
glass B
glass C
they should all look the same – look for a good description
the solution should
no change
the solution should
become lighter in
become darker in
colour
colour
this could depending on the water source
but it should be somewhere between 6 and 7.5
the pH should be
the pH should be
lower
higher
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BIOL0601Provincial Biology: Module 1: Cell Biology. Assignment 1
Table 1.2.2
pH of various household substances
substance
colour of test strip
pH
vinegar
4 or 5
baking soda solution
8 or 9
water
usually 6 - 7
Thinking About the Results
Bear in mind that there are many variables that are beyond control in doing these labs (water
chemistry, inaccurate measuring, lack of experience). Since all of the prep is done by the
student, conditions may vary. Be prepared to “interpret” results and look for trends,
consistency between observations and conclusions, and reasonable conclusions.
1. The water in certain areas in Russia is quite alkaline. Can you suggest why people who live in
areas like this might routinely use lemon in their tea?
They use lemon to make the tea a lighter colour
2. Acidic substances have a pH less than 7. List all the acidic substances that you tested.
Substances listed should be consistent with the data
3. Alkaline or basic substances have a pH greater than 7. List all the alkaline substances that you
tested.
Substances listed should be consistent with the data
4. List any substances that were neither acidic or alkaline. What would substances like this be
called?
The list of neutral substances, if any, will vary. Substances listed should be consistent with the
data
5. Fill in the following chart (round the pH values off to the nearest whole number). Use Figure 2.9 to
determine the hydrogen ion concentrations.
substance
pH
hydrogen ion concentration
vinegar
5
1.0 x 10-5
water
6
1.0 x 10-6
baking soda solution
8
1.0 x 10-8
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BIOL0601Provincial Biology: Module 1: Cell Biology. Assignment 1
6. Look up the ideal pH for the blood. What colour would your test strip have been if you had tested
blood? What would the hydrogen ion concentration have been? (it is OK to say that it would be
between two values)
The pH of blood is listed as 7.35 to 7.45 The colour of the pH paper would be “light yellow
green”
7. Complete the following chart:
pH
1 (acidic)
7 (neutral)
14 alkaline)
hydrogen ion concentration
(write in both decimal and scientific form)
0.1 M
1.0 x 10-1 M
0.0000001 M
1.0 x 10-7 M
0.00000000000001 M
1.0 x 10-14 M
What is the relationship between pH and hydrogen ion concentration?
It is inverse or as the pH rises the hydrogen ion concentration falls (as one goes up, the other
goes down and visa versa)
8. Sometimes one will suffer from an "acid stomach” or "heartburn". What would you take to help
relieve the acid stomach. What would the pH of this substance likely be and why?
One would take an antacid. It is an alkaline substance capable of neutralizing the excess
stomach acid.
Congratulations, you have now completed Lab 1B.
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BIOL0601Provincial Biology: Module 1: Cell Biology. Assignment 1
Lab 1C: Testing for Starch and Fats
The food we eat contains major macromolecules, including carbohydrates, lipids, and proteins. In this
laboratory, you will test for the presence of starch (a carbohydrate) and fats (lipids) in assorted foods.
You will also demonstrate the process of emulsification.
Materials
tincture of iodine
corn starch solution (previously prepared)
vegetable oil
water (let stand overnight)
food samples
Apparatus
eye dropper
2 baby food jars with lids
paper towel
brown paper
plate
Method
Starch test
To observe a positive result (the presence of starch), put a small amount of cornstarch on a clean plate
and add a drop of iodine solution to the cornstarch and note the colour change. (Note: if you do not get
an obvious colour change for the iodine, try diluting some of the iodine with a bit of water and try the test
again on the cornstarch. Do not dilute the whole bottle. Use a separate container.)
To observe a negative result, put a drop of iodine on a clean plate and note the colour.
Record the results in Table 1.3.1
Lipid test
To observe a positive result (the presence of lipid), put a couple of drops of oil onto a piece of paper
towel and allow it to dry for an hour. To observe a negative result, put a couple of drops of water onto a
piece of paper towel and allow it to dry for an hour. Hold both pieces of paper towel up to the light, and
record your observations (what you see) and whether the test areas are translucent or opaque in Table
1.3.1
Table 1.3.1: Record of starch and lipid tests
Positive result
Negative result
A. Starch test
starch solution turns a dark
blue/purple colour
no colour change
B. Lipid test
oil/fat makes brown paper
become opaque
no change in the brown
paper
Food testing
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BIOL0601Provincial Biology: Module 1: Cell Biology. Assignment 1
Select eight different food stuffs, such as flour, milk, bread, fruit, vegetables, or anything you have
around. Do the starch test and the lipid test on each food, and record your observations (what you see)
in Table 1.3.2. Try not to select a food whose preparation involved the addition of fat or oil.
Table 1.3.2: Observations of starch and lipid test for eight different foods. (2 marks)
Food tested
Starch test
observations
Lipid test
observations
The results here will vary depending on the foods tested
Emulsification
An emulsifier is a molecule capable of mixing fats with water so that they will not separate for an
extended period of time. Compare all natural peanut butter with the commercial “kids” type of peanut
butter. With the all natural peanut butter the oil rises to the top, requiring (sometimes messy) mixing. The
“kids” commercial peanut butter has been homogenized. An emulsifying agent has been added to
prevent the oil from separating out and rising to the top.
Lipids are characterized by their inability to dissolve in water; this is because they are non-polar
molecules. Emulsifiers have a polar end and a non-polar end (just like the phospholipids in the cell
membrane). The polar end can associate with water molecules, and the non-polar end associates with
lipids, allowing the lipid to break up into small droplets and be dispersed in the water. Bile salts, which
you will learn about when you study the digestive system, emulsify fats so that they can be more easily
digested. Soaps and detergents are also emulsifiers. Because soap and detergent molecules can bind
to both water and fat molecules, they are used to remove oily materials from surfaces, such as our skin
and our dishes. Oil is emulsified into the wash water and can be rinsed away.
Fill each of the two clear containers one third full with water and one third full with vegetable oil. In one
container only, add a little bit of dish soap or detergent. Record your observations on the oil and water in
Table 3. Tightly cap the containers, and shake both of them vigorously. Record the results in Table
1.3.3. Let both containers sit for an hour, and observe again.
Table 1.3.3: Emulsification of oil and water
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BIOL0601Provincial Biology: Module 1: Cell Biology. Assignment 1
Observations
before shaking
Water + Oil
Observations
immediately after
shaking
Observations after
one hour
oil forms a layer on small droplets of oil
top of the water
are spread through
the liquid
oil will have
separated from the
water (mostly) and
floats on the top
Water + Oil + Soap oil should still form the solution
the solution
layer on top of the (emulsion) is opaque (emulsion) still has
water
(has a milky look)
a milky look
Thinking About the Results
1. List the foods that you tested and the conclusions for each test, present (+) or absent (-).
Food tested
Starch present
Fat present
Again, the results will vary depending on what is tested. It was suggested that the foods tested
not be of the sort that were prepared with oil in the recipe.
2. Define emulsification. How do the results of table 3 illustrate the process of emulsification?
Emulsion: A mixture of two or more liquids that are normally immiscible (not able to mix)
Emulsification: the process of breaking fat droplets into small enough sizes that they disperse in
water.
Oil and water cannot normally mix. The addition of soap breaks the oil up into small enough
droplets that the droplets remain evenly distributed in the liquid.
3. Why was the use of a control important in the tests for starch and oil?
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BIOL0601Provincial Biology: Module 1: Cell Biology. Assignment 1
The purpose of a control is to allow a proper conclusion to be drawn
Congratulations, you have now completed Lab 1C.
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BIOL0601Provincial Biology: Module 1: Cell Biology. Assignment 1
Lab 1D: Using the Pocket Microscopic
Please note that you do not need to submit your lab work to your tutor. You do need
to submit the completed tables in the Results section and your answers to the
questions in the Thinking About the Results section.
Introduction
Despite its small size and “toy-like” appearance, the pocket microscope included in your kit is still a
delicate piece of equipment, and should be treated with care. In this lab exercise, you are going to learn
the basic functioning of the microscope and how to measure the size of a specimen.
Materials
pocket microscope
clean slides and cover slips
clear plastic millimetre ruler
salt
toothpicks, stir sticks or wooden skewers
newspaper, scissors
microscope CD
Method
Read the instructions that are included with the microscope. Be sure to remove the piece of plastic that
is protecting the batteries from being drained during shipment.
Write the names for the following labels
①eyepiece
②zoom wheel
③LED on/off button
④focusing lever
⑤ battery insulate
⑥specimen stage
Drawing the specimen
When drawing a specimen under the microscope, follow these steps:
1 – Use a plain sheet of paper (no lines) and pencil (never ink)
2 – Draw a circle to represent the microscope field (use a glass or anything circular
as a template)
3 – Under the circle, indicate the magnification (in our case 20 X or 40 X – low or
high)
4 – Draw the specimen in proportion to the drawn circle. Do not use shading, unless
absolutely necessary!
5 – Labels should be lined up down the right hand side of the page
6 – Lines from the diagram to the specimen should be horizontal
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BIOL0601Provincial Biology: Module 1: Cell Biology. Assignment 1
Preparing a wet mount
View the demonstration of this procedure on the Microscope CD
Set up the microscope for use.
The Letter “e”
1. Cut a lower case (small) “e” out of the newspaper. Place a drop of water on the letter “e”. Lower
the cover slip as described in “Preparing a Wet Mount”.
2. Hold the slide so that the letter “e” look as it normally would as you place it in the microscope.
Place the slide under the microscope and focus the microscope at lowest power. Describe how
the letter “e” looks (orientation rather than appearance); use words like “normal”, “upside down”,
“backwards”, etc . Move the slide towards and away from yourself. Describe the movement of the
specimen (image). Record your observations in the table. Move the slide to the right and the left.
Record your descriptive words in the Letter Table 1.4.1.
The Size of the Microscope Field
View the demonstration of this procedure on the Microscope CD
3. Place the millimetre ruler under the microscope. Press the light button and adjust the microscope
for the lowest magnification (20x). When the image is in sharp focus, make a drawing of the
image (follow the drawing instructions). Using the divisions on the ruler, measure the diameter of
the field (the bright circle). Record this in the Table 1.4.2.
4. Repeat the previous step with the microscope adjusted for maximum magnification (40x) Record
your results in Table 1.4.2
Salt Crystals
5. Place some salt crystal (table salt) on the glass slide and make a drawing of (one) salt crystal
under the highest power (40x). Estimate how many salt crystal will fit across the diameter of the
microscope field. Enter this number in the Table 1.4.2.
Cheek Cells
6. Using a toothpick or wooden stick, scrape some cheek cells and wipe the cells onto a clean slide.
7. Place the slide under the microscope. Adjust the microscope for highest power. Draw what you
see in the “Unstained Cheek Cells” box.
8. Place a small amount of tincture of iodine on the slide and mix with the cells that are already
there. Wait for a few minutes for the stain to have an effect. The iodine will stain the cells an
amber colour. You will also be able to see some very darkly coloured dots inside the cells. Draw
what you see in the “Stained Cheek Cells” box. (if the cells look very faint, repeat the preceding
steps to stain the specimen more darkly)
9. Estimate the number of cheek cells that would fit across the diameter of the microscope field.
Enter this in the Tablke 1.4.3. If you are finding this difficult, estimate how big the cheek cell is
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BIOL0601Provincial Biology: Module 1: Cell Biology. Assignment 1
compared to a crystal of salt.
The Microscope CD
10. The pocket microscope doesn’t provide the higher magnification required to clearly see parts of
the cell. Using the microscope CD, examine the pictures of (to be identified when the CD is
finished). Draw a diagram of a cell and identify as many parts as you can see.
11. When you have finished, clean up your laboratory space and put the equipment away.
Results
Table 1.4.1
The Letter “e”
descriptive words.
Observations
it is upside down and backwards
Move slide towards you
move slide to the right
the “e”moves away
the “e” moves to the left
Table 1.4.2
Measurement
millimetre ruler – lowest magnification: diameter of field
(nearest 0.5 mm)
millimetrer ruler (highest magnification): diameter of field
(nearest 0.5 mm)
salt crystal: how many crystals fit across the field diameter
(40x)
In any drawing salt crystals will appear to be square
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Observations
approx. 7.5 mm
approx. 5 mm
this will vary but
estimates of 15 – 20
are acceptable
BIOL0601Provincial Biology: Module 1: Cell Biology. Assignment 1
Stained cheek cells.
the stained cheek cell is very small – smaller than a grain of
salt and probably will show no internal structure except for
possibly a dark dot inside the cell (the nucleus)
Table 1.4.3
Cheek Cells
_________ cheek cells
or
_________ compared to a salt crystal
a salt crystal may be estimated to be anywhere from 10 to 5 time larger than a
cheek cell
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BIOL0601Provincial Biology: Module 1: Cell Biology. Assignment 1
Cell from microscope CD ___________________________________
.
insert a picture of the cheek cell taken under your microscope
Drawings: If you submit your assignment by mail, include the drawing. If you submit your assignment
electronically, scan or photograph your drawings with a digital camera or phone and include the scanned
graphics or photos, or use a drawing program to make the drawings (scanning is best here).
Thinking About the Results
1. When you were looking at salt crystals, you probably had to move the image in order to make the
estimate of how many crystals fit into the diameter of the field. What difficulties does one face when
moving the image?
It moves in the opposite direct that you want it to go
In the metric system:
1 m = 100 cm
1 cm = 10 mm
1 mm = 1000 μm (micrometres, and in North America, microns)
2. Using the values in the Measurement table, calculate the diameter of the low and high power
microscope fields.
low power field
_7.5_______ mm ___7500___ μm
high power field
__5________ mm ___5000___ μm
space has been left for you to show calculations
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BIOL0601Provincial Biology: Module 1: Cell Biology. Assignment 1
3. Using your data, calculate the size of a salt crystal in mm and in μm (micrometres)
The student will have to divide the total size of the field by the estimated number of salt crystal lined
up along the diameter of the field
7.5 𝑚𝑚
= 0.5 𝑚𝑚 𝑝𝑒𝑟 𝑐ℎ𝑒𝑒𝑘 𝑐𝑒𝑙𝑙
15 𝑐ℎ𝑒𝑒𝑘 𝑐𝑒𝑙𝑙𝑠
Expect to see a calculation for the high and low power
4. Using your data, estimate the size of a cheek cell in μm (micrometres)
Given the low magnifying power of the pocket microscope, any value will do that looks reasonable.
The value in um will be about 1000 x the value in mm.
5.
This is a micrograph (microscope picture) of a cheek cell taken with the scanning electron
microscope at TRU.
The scale of the photograph is shown at the bottom left of the micrograph. The length of the line
between the two end marks is 30 µm. Using this scale, estimate the length and width of the cheek
cell.
The students don’t need to do a detailed analysis. It is quite alright if they say it is about 40 µm x 60
µm.
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BIOL0601Provincial Biology: Module 1: Cell Biology. Assignment 1
Congratulations, you have now completed Lab 1D.
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