Environmental Engineering Essay

Environmental Engineering Essay.

Assignment  – Connecting Course Content with Current Events; Solid Waste and Superfund

I would like each of you to locate two journal articles, written within the last 5 years, that relate to the content of this course since the first homework.  This includes the Solid Waste Disposal Act, RCRA, and CERCLA.  I recommend using Google Scholar (scholar.google.com) to make finding articles a little easier.  You may need to log into the Pollak Library proxy server to have access to more journals.  Let me know if you need help figuring out the library proxy.

Be certain to cite the articles, using proper APA formatting guidelines.

After reading the article(s), write a three-page, double-spaced review with three goals in mind.  First, critique the article itself.  Is it well-written, well-organized, and does it address pertinent issues?  Second, emphasize how this article exemplifies the original intent of the Act you chose.  Third, describe the aspect of the Law that is being questioned or applied and summarize how this impacts other current events of which you are aware or aspects of your own life.

The assignment is due at midnight on February 16th (that is, at the end of Monday, the beginning of Tuesday).  Use Times New Roman or Calibri font at 12pt.  Use 1-inch margins on all sides

Environmental Engineering Essay

 
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Environmental Issues in Construction

Environmental Issues in Construction.

1

EHST 3060/61:

Environmental Issues in

Construction

 To give a general overview of the various

hazards to which construction workers

may be exposed

 Health hazards

 Physical hazard

 Chemical hazard

 Biological hazard

 Ergonomic hazard

 Safety hazards

 Unsafe act

 Unsafe condition

 Construction work is dynamic, diverse, and

constantly changing. This poses a great

challenge in protecting the health and safety

of construction workers.

 Construction workers are at risk of exposure

to various workplace hazards that can result

in injury, illness, disability, or even death.

 

 Constantly changing job site environments and conditions

 Multiple contractors and subcontractors

 High turnover; unskilled laborers

 Constantly changing relationships with other work groups

 Diversity of work activities occurring simultaneously

 Exposures to health hazards resulting from own work as well as from nearby activities (“bystander exposure”)

 Private industry construction workers had a

fatal occupational injury rate nearly 3 times

that of all workers in the U.S.

 9.7 per 100,000 construction workers

 3.3 per 100,000 workers

 Construction has 3 of the 10 occupations

with the highest fatal injury rates (per

100,000 full-time equivalent workers)

 Roofers at 34.7 fatal work injuries

 Structural iron and steel workers at 30.3

 Laborers at 18.3

 

 

2

 Number: 721 workers

 Percent: 16% of all fatal occupational injuries

1. Falls: 34% of fatal occupational injuries in

construction

 48% of all fatal falls in private industry were to

construction workers.

2. Transportation-related events: 25%

3. Contact with objects and equipment: 19%

4. Exposure to harmful substances and

environments: 16%

1. Falls, slips and trips: 35% of fatal

occupational injuries in construction

2. Roadway (e.g. transportation-related): 12%

3. Struck by object and equipment: 10%

4. Homicide: 1%

http://www.bls.gov/news.release/cfoi.t02.htm

 Hazard – inherent potency to cause harm

to a person

 Risk – probability of being exposed to a

hazard

 

 Health hazards

 Physical

 Chemical

 Biological

 Ergonomic

 Safety hazards

 Unsafe act

 Unsafe condition

Occupational

Disease

Occupational

Injury

Occupations Potential Health Hazards

Brickmasons Cement material, awkward postures, heavy loads

Drywall installers Plaster dust, heavy loads, awkward postures

Electricians Heavy metals in solder fumes, awkward posture, heavy loads, asbestos

Painters Solvent vapors, toxic metals in pigments, paint additives

Pipefitters Lead fumes and particles, welding fumes, asbestos dust

Carpet layers Knee trauma, awkward postures, glue and glue vapor

Insulation workers Asbestos, synthetic fibers, awkward postures

Roofers Roofing tar, heat

Carpenters Noise, awkward postures, repetitive motion

Drillers, earth, rock Silica dust, whole-body vibration, noise

Excavating and loading machine operators

Silica dust, histoplasmosis, whole-body vibration, heat stress, noise

Hazardous waste workers

Heat stress, toxic chemicals

 

 

3

 Different types of energy which may be hazardous to workers

 Noise

 Vibration

 Extreme temperature

 Extreme pressure

 Radiation

What are found

in construction?

 Prolonged exposure to

excessive noise levels

(>85 dB) can cause

noise-induced hearing

loss.

 When you are exposed

to excessive noise

levels, the first stage is

temporary hearing loss.

 Over time, the hearing

loss becomes

permanent.

Probable Noise Levels of Some Common

Construction Equipment at Operator’s Ear

Equipment or Tool Noise level will

probably exceed

Back hoe 85 dB

Bulldozer 87 dB

Chopsaw 92 dB

Grader/scraper 107 dB

Front end loader 90 dB

Jackhammer 102 dB

Nail-gun 97 dB

Router 90 dB

Welding equipment 92 dB

Source: U.W. Dept. of Environmental &

Occupational Health Services – Rick

Neitzel July, 2005

 Type of equipment being operated

 Condition/maintenance of the equipment

 Other equipment running at the same time

 Enclosed or partially enclosed spaces

What factors influence the noise levels to which workers are exposed?

 Can occur from operating large mobile

equipment

 Drillers

 Air hammers

 Pile drivers

 Tractors

 Graders

 Excavators

 Earth-moving equipment

 Other large machinery

Hand-arm vibration can result from using hand-

held power tools (i.e. pneumatic drills and

hammers and disc grinders).

Hand-arm vibration may

cause carpal tunnel

syndrome, a disease that

affects the fingers and hands.

In the long run, permanent

damages to the nerves will

result in a loss of the sense of

touch and dexterity.

 A change in body temperature due to extreme

work environmental conditions can lead to

stress or illness from heat or cold.

Cold temperatures can lead to fatigue,

irregular breathing, confusion, and

hypothermia.

 

 

Heavy work in high temperatures can

cause muscle cramps, dehydration,

and heat stroke.

 

 

4

 Hot conditions

 Prolonged work under direct sunlight in summer

 Wearing impermeable protective clothing when

doing heavy work

 Working in an

enclosed area with a

strong heat source,

poor ventilation, and

high humidity

 Cold conditions

 Cold air temperatures

 Rain, snow, sleet, or other wet weather

conditions

 Windy conditions

 Underground construction work

 Working over water and falling in

 

 X-rays and gamma rays from equipment

used:

 To gauge the density and thickness of pipes

 To inspect welds

 For detecting weakness of metal structures

 Radioactive isotopes from flow meters

 Health effects

 Increased risk of

developing cancer and

genetic disease

 

 Ultraviolet light from sunlight &

welding

 Infrared radiation from torch

welding and cutting

 Radio waves from radio transmission

devices (roof-top dishes &

antennas)

 Lasers used for aligning, ranging,

and surveying are usually low-

powered but can cause eye injuries

if directly viewed for extended time Rooftop radio antenna

Welding ultraviolet light

 Health effects

 Skin cancer

 Eye damage

 Premature skin aging

 Burns

 Liquid

 Gases

 Vapors

 Particulates

 Dust

 Fumes

 Mists

 Smoke

What are found

in construction?

 

 

5

 Chemicals are found in variety of

products used at construction sites.

 Workers may also be exposed to

chemicals generated during construction

activities.

• Welding fumes

• Spray paints

• Cutting oil mists

• Solvents

• Hexavalent chromium

• Asbestos

• Lead

• Silica

• Cadmium

• Carbon monoxide

 Chemicals can enter the body through:

 Inhalation – breathed in; typically

the most common route of entry

 

 Ingestion – accidental swallowing

through eating, drinking or smoking

 

 Absorption – absorbed through

contact with skin or eyes

 Injection – chemical enters the body by skin

puncture rarely occurs (e.g. paint from a high-

pressure spray gun); a minor route of exposure

in construction

 Two types of health effects from chemical exposure

HEALTH EFFECTS EXPOSURE EXAMPLE

ACUTE

Appears immediately or within short time following exposure, (minutes or hours); death possible from some hazardous substances

Typically sudden, short-term, high concentration

Headache, collapse or death from high levels of carbon monoxide

CHRONIC

Usually develops slowly, as long as 15- 20 years or more

Continued or repeated for a prolonged period, usually years

Lung cancer from exposure to asbestos

AVOID BREATHING AIRBORNE

ASBESTOS FIBERS Asbestos pipe insulation

 Construction workers may be exposed to

asbestos during demolition or remodeling of

older buildings built before 1980 which can

contain asbestos insulation, or other asbestos

containing products. Asbestos removal can

only be done by specially trained asbestos

workers.

 Asbestos exposure can cause breathing

problems, lung cancer and cancer of the lung

lining many years after exposure.

Welding on a stainless steel tank,

generating hexavalent chromium Welding in a confined space

 Welding fumes contain a variety of chemicals

depending on what is being welded on,

chemical makeup of welding rods, fluxes and

shielding gases.

 Most hazardous welding activities:

 A variety of solvents with

varying degrees of toxicity

are used in construction

(e.g. paints, glues and

epoxies)

 Generally, the possibility of

exposure to excessive

amounts of solvent vapors

is greater when solvents are

handled in enclosed or

confined spaces.

 

 

6

 Solvents can:

 Irritate your eyes, nose or

throat

 Make you dizzy, high, sleepy,

give you a headache or

cause you to pass out

 Affect your judgment or

coordination

 Cause internal damage to

your body

 Dry out or irritate your skin

 

 

Brick cutting Concrete cutting Blowing concrete dust

with compressed air

 Silica or quartz dust exposure is very

common in construction from drilling, cutting

or grinding on concrete, sandblasting, rock

drilling or in masonry work.

 Exposure to excessive silica dust causes lung

scarring and lung disease over time.

 

 Construction workers can be exposed to lead

on bridge repair work, lead paint removal on

metal structures or buildings or demolition of

old buildings with lead paint, or using lead

solder.

 Lead is highly toxic and can cause severe,

long term health problems

Carcinogens Cancer Caused

Benzene Leukemia

Polyvinyl chloride

(PVC)

Liver cancer

Methylene chloride Pancreatic and liver cancer

Trichloroethylene Bladder cancer, lymphomas

Perchloroethylene Liver and kidney cancer

Polychlorinated

biphenyls (PCB)

Liver, pituitary and

gastrointestinal tumors;

leukemia; lymphomas

Dioxin and furan Leukemia, lymphoma

 Exposure to chemicals or lack of

oxygen in confined spaces can be

deadly.

 Airborne chemicals can quickly

reach dangerous levels in

confined spaces that are not

ventilated.

 Carbon monoxide

 Hydrogen sulfide

 Welding fumes

 Solvent vapors

 

 

 Microorganisms

 Bacteria

 Virus

 Fungi

 Parasites

 Insects

 Organic aerosols

 Plants

 Animals

What are found

in construction?

 

 

7

 Diseases or illnesses can occur

from biological sources

 Virus – West Nile virus; Hantavirus

 Insect – Lyme disease

 Fungi – Histoplasmosis

 Plant toxins – poison oak, sumac,

stinging nettles

 Some of these diseases are minor

infections.

 Others can be serious or deadly.

Poison oak

Stinging nettle

 Exposure may occur during demolition,

renovation, sewer work, work on air

handling systems, or other construction

work from contact with contaminated or

disease-carrying

 Soil

 Water

 Insects (mosquitoes, ticks)

 Bird or bat droppings

 Animals

 Structures

 

Pigeon droppings in

abandoned building

 Ergonomic hazards can cause painful and

disabling injuries to joints and muscles.

 Ergonomic hazards are the most frequently

occurring health hazards in construction and

the cause of most injuries.

 Injuries can occur from:

 Heavy, frequent, or awkward lifting

 Repetitive tasks

 Awkward postures and grips

 Using excessive force, overexertion

 Using wrong tools for the job

or using tools improperly

 Using improperly maintained tools

 Hand-intensive work

 Can lead to musculoskeletal

disorders (MSDs) and injuries

 Strains and sprains

 Tendonitis

 Carpal tunnel syndrome

 Low back pain

 Fatigue

To what health hazards is this construction

worker simultaneously exposed to?

 In some cases, workers can be exposed to

several health hazards at the same time or

on the same worksite over time.

 

 

 

8

 Falls (from heights)

 Trench collapse

 Scaffold collapse

 Electrocution

 Caught-in and –between hazards

 Struck-by hazards

 Failure to use proper PPE

 Using shortcuts in performing a task

Unsafe act

Unsafe conditions

 Falls

 Caught-in or –between

 Struck-by

 Electrocution

 Health hazards

 Physical

 Chemical

 Biological

 Ergonomic

 Safety hazards

 Unsafe acts and

conditions

Occupational

Disease Occupational

Injury

Occupational Hazards  Division of Occupational Safety and Health (DOSH), Washington State Department of

Labor and Industries

 Construction Safety and Health (NIOSH) –

http://www.cdc.gov/niosh/topics/constructi

on/

 Occupational Safety and Health

Administration (OSHA), Construction

Industry: Outreach Training Program –

http://www.osha.gov/dte/outreach/constru

ction/index.html

 

Environmental Issues in Construction

 
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Concentration Gradients and Membrane Permeability

Concentration Gradients and Membrane Permeability. Experiment 2: Concentration Gradients and Membrane Permeability

In this experiment, you will dialyze a solution of glucose and starch to observe:

The directional movement of glucose and starch.
The effect of a selectively permeable membrane on the diffusion of these molecules.
An indicator is a substance that changes color when in the presence of a specific substance. In this experiment, IKI will be used as an indicator to test for the presence of starch.

Materials

(5) 100 mL Beakers
10 mL 1% Glucose Solution, C6H12O6
4 Glucose Test Strips
(1) 100 mL Graduated CyliStructure and Microscopy

Lab 4: Structure and Microscopy (100 points)

Student Name:

Student ID:

Course ID:
-Each question on the lab worksheet must be answered completely, thoroughly, in complete sentences and correctly in order to be considered for full credit
-If the question asks you to do research or find a source, a reputable, credible and/or scholarly source citation must be included in order to be considered for full credit
-If a math formula is required to arrive to an answer, work must be shown otherwise, no credit will be awarded
Pre-Lab Questions
1. What determines if a bacterial cell is Gram-positive or Gram-negative? (5 points)

Amount and location of the peptidoglycan molecule in the prokaryotic cell wall determines whether a bacterial cell is Gram-positive or Gram-negative.

2. In this lab, both viruses and prions were introduced as acellular organisms. Do some research and describe one other type of acellular organism. What characteristics about this organism classify it as acellular? (5 points)

Viroids are another type of acellular organism along with viruses and prions. They are plant pathogens, which consist only of a short strand of circular RNA capable of self-replication.

3. Bacteria have many different shapes that often determine their class. Research and form a hypothesis on the evolutionary reasons for so many different bacterial morphologies. (5 points)

Each bacterial morphology may be a selectable feature to aid survival and may have affected by different physical, environmental, and biological forces to contribute to natural selection.

Reference:

Young, K. D. (2006, September). The Selective Value of Bacterial Shape. Retrieved September 30, 2018, from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1594593/

4. Do a search online or look in your textbook for 1-2 antibiotics that affect Gram-positive bacteria and list them. On what part of the cell do the antibiotics usually work? List one or two antibiotics that affect Gram-negative bacteria? On what part of the cell do the antibiotics usually work? (Be sure to cite your sources in your answer.) (5 points)

5. Why do you think it is important to identify a bacterial disease in a patient before prescribing any antibiotic treatments? (Be specific.) (5 points)

d

Experiment 1 Results Tables
Table 1: Experiment 1 Staining Observations (5 points)

Stain used:

Crystal Violet

Observations:

Purple rod-shape bacteria with white background were observed

Experiment 1 Post-Lab Questions
1. How does crystal violet enhance the visualization of microbial features? (5 points)

Crystal violet enhances the contrast between the microorganism itself and the slide, making the bacteria appear as purple.

2. What are some of the limitations of simple staining? (5 points)

3. Give an example of a situation in a lab or medical setting in which simple staining would be utilized. (5 points)

Simple staining is used to obtain basic information about morphology of one type of microorganism through clear visualization.

Experiment 2 Results Tables
Table 2: Experiment 2 Staining Observations (5 points)

Stain used:

Nigrosin

Observations:

Background is stained, bacteria shows up as clear spiral.

Experiment 2 Post-Lab Questions
1. After visualizing the stained samples either using your microscope or by looking at the sample images provided, describe what physical/visual characteristics you were able to observe after performing the negative staining vs. after performing the simple stain. (5 points)

After looking at the sample images provided, negatively stained bacteria showed up as clear straight spirals against a dark background. Bacteria that are simple stained showed up as dark purple rods-shaped with white background.

2. So far in this lab, you have used one type of simple stain and one type of negative stain, yet there are many other simple and negative dyes available. Pick one simple dye and one negative dye, and discuss how those dyes differ from the ones you used in this lab. Give a scenario in which their use would be appropriate. (5 points)

Methylene blue is another dye that can be used for negative stain.

India Ink is another type of negative stain.

Experiment 3 Results Tables
Table 3: Experiment 3 Staining Observations (5 points)

Stain used:

Crystal violet (primary stain) & Safranin (counterstain)

Observations:

Gram-positive appeared as purple and Gram-negative showed up as pink.

Experiment 3 Post-Lab Questions
1. What color are the Gram-positive bacteria after Gram staining? Gram-negative bacteria? (5 points)

Gram-positive bacteria appear as dark purple or blue due to retaining the primary dye (Crystal Violet) in the cell wall.

Gram-negative bacteria appear as red or pink due to decolorizing to accept the counterstain (Safranin).

2. What different characteristic(s) exist between the two groups that account for the different staining conditions? (5 points)

Gram-positive bacteria are stained purple, and gram-negative bacteria stain as pink. They are two distinct morphological groups of bacteria.

3. Why was the Gram iodine added to the Gram staining procedure? (5 points)

Gram iodine is added as a mordant to stabilize the crystal violet iodine complex so that the dye cannot be removed easily.

4. Why is a counterstain (safranin) added to the Gram staining procedure? (5 points)

A counterstain is used to help identify gram-negative bacteria. Gram-negative bacteria lose the crystal violet and stain red.

5. What are the advantages of performing a Gram stain vs. a simple stain for visualizing bacteria? (5 points)

Gram stain contains two or more different stains and can differentiate the species of bacteria into two main groups (gram-positive and gram-negative) by looking at the color of cells (pink or purple). Simple stain involves single stain and it is used to easily determine cell shape, size, and arrangement.

6. Using either a textbook or a reputable online resource, research some of the typical characteristics of bacteria, and discuss why it might be important for a researcher or a hospital technician to be able to differentiate between Gram-positive and Gram-negative bacteria. (5 points)

7. Did you experience any technical difficulties or atypical results during this experiment? If so, what happened, and how could you avoid these issues in the future? (5 points)nder
4 mL 1% Iodine-Potassium Iodide, IKI
5 mL Liquid Starch, C6H10O5
3 Pipettes
4 Rubber Bands (Small; contain latex, handle with gloves on if allergic)

Permanent Marker
*Stopwatch
*Water
*Scissors

*15.0 cm Dialysis Tubing

*You Must Provide
*Be sure to measure and cut only the length you need for this experiment. Reserve the remainder for later experiments.

Attention!

Do not allow the open end of the dialysis tubing to fall into the beaker. If it does, remove the tube and rinse thoroughly with water before refilling it with the starch/glucose solution and replacing it in the beaker.

Note:

If you make a mistake, the dialysis tubing can be rinsed and used again.

Dialysis tubing must be soaked in water before you will be able to open it up to create the dialysis “bag.” Follow these directions for this experiment:

1. Soak the tubing in a beaker of water for ten minutes.

2. Place the dialysis tubing between your thumb and forefinger, and rub the two digits together in a shearing manner. This motion should open up the “tube” so that you can fill it with the different solutions.

Procedure

1. Measure and pour 50 mL of water into a 100 mL beaker using the 100 mL graduated cylinder. Cut a piece of dialysis tubing 15.0 cm long. Submerge the dialysis tubing in the water for at least ten minutes.

2. Measure and pour 82 mL of water into a second 100 mL beaker using the 100 mL graduated cylinder. This is the beaker you will put the filled dialysis bag into in Step 9.

3. Make the glucose/sucrose mixture. Use a graduated pipette to add 5 mL of glucose solution to a third 100 mL beaker and label it “dialysis bag solution.” Use a different graduated pipette to add 5 mL of starch solution to the same beaker. Mix by pipetting the solution up and down six times.

4. Using the same pipette that you used to mix the dialysis bag solution, remove 2 mL of the dialysis bag solution and place it in a clean beaker. This sample will serve as your positive control for glucose and starch.

a. Dip one of the glucose test strips into the 2 mL of glucose/starch solution in the third beaker. After one minute has passed, record the final color of the glucose test strip in Table 3. This is your positive control for glucose.

b. Use a pipette to transfer approximately 0.5 mL of IKI into the 2 mL of glucose/starch solution into the third beaker. After one minute has passed, record the final color of the glucose/starch solution in the beaker in Table 3. This is your positive control for starch.

5. Using a clean pipette, remove 2 mL of water from the 82 mL of water you placed in a beaker in Step 2, and place it in a clean beaker. This sample will serve as your negative controls for glucose and starch.

a. Dip one of the glucose test strips into the 2 mL of water in the beaker. After one minute has passed, record the final color of the glucose test strip in Table 3. This is your negative control for glucose.

b. Use a pipette to transfer approximately 0.5 mL of IKI into the 2 mL in the beaker. After one minute has passed, record the final color of the water in the beaker in Table 3. This is your negative control for starch.

Note:The color results of these controls determine the indicator reagent key. You must use these results to interpret the rest of your results.

6. After at least ten minutes have passed, remove the dialysis tube and close one end by folding over 3.0 cm of one end (bottom). Fold it again and secure with a rubber band (use two rubber bands if necessary).

7. Test to make sure the closed end of the dialysis tube will not allow solution to leak out. Dry off the outside of the dialysis tube bag with a cloth or paper towel. Then, add a small amount of water to the bag and examine the rubber band seal for leakage. Be sure to remove the water from the inside of the bag before continuing.

Using the same pipette that was used to mix the solution in Step 3, transfer 8 mL of the dialysis bag solution to the prepared dialysis bag.
Figure 4: Step 9 reference.

Figure 4:Step 9 reference.

9. Place the filled dialysis bag in the 100 mL beaker filled with 80 mL of water, leaving the open end draped over the edge of the beaker as shown in Figure 4.

10.Allow the solution to sit for 60 minutes. Clean and dry all materials except the beaker holding the dialysis bag.

11.After the solution has diffused for 60 minutes, remove the dialysis bag from the beaker and empty the contents of the bag into a clean, dry beaker. Label the beaker “final dialysis bag solution.”

12.Test the final dialysis bag solution for the presence of glucose by dipping one glucose test strip into the dialysis bag. Wait one minute before reading the results of the test strip. Record your results for the presence of glucose in Table 4.

13.Test for the presence of starch by adding 2 mL IKI. After one minute has passed, record the final color in Table 4.

14.Use a pipette to transfer 8 mL of the water in the beaker to a clean beaker. Test the beaker water for the presence of glucose by dipping one glucose test strip into the beaker. Wait one minute before reading the results of the test strip, and record the results in Table 4.

15.Test for the presence of starch by adding 2 mL of IKI to the beaker water. Record the final color of the beaker solution in Table 4.

Table 3: Indicator Reagent Data

Indicator

Starch Positive
Control (Color)

Starch Negative
Control (Color)

Glucose Positive
Control (Color)

Glucose Negative
Control (Color)

Glucose Test Strip

n/a

n/a

IKI Solution

n/a

n/a

Table 4: Diffusion of Starch and Glucose Over Time

Indicator

Dialysis Bag After 60 Minutes

Beaker Water After 60 Minutes

IKI Solution

Glucose Test Strip

Post-Lab Questions

1. Why is it necessary to have positive and negative controls in this experiment?

2. Draw a diagram of the experimental set-up. Use arrows to depict the movement of each substance in the dialysis bag and the beaker.

3. Which substance(s) crossed the dialysis membrane? Support your response with data-based evidence.

4. Which molecules remained inside of the dialysis bag?

5. Did all of the molecules diffuse out of the bag into the beaker? Why or why not?

Experiment 1: Diffusion through a Liquid

In this experiment, you will observe the effect that different molecular weights have on the ability of dye to travel through a viscous medium.

Materials

1 60 mL Corn Syrup Bottle, C12H22O11
Red and Blue Dye Solutions (Blue molecular weight = 793 g/mole; red molecular weight = 496 g/mole)
(1) 9 cm Petri Dish (top and bottom halves)

Ruler
*Stopwatch
*Clear Tape

*You Must Provide

Procedure

1. Use clear tape to secure one-half of the petri dish (either the bottom or the top half) over a ruler. Make sure that you can read the measurement markings on the ruler through the petri dish. The dish should be positioned with the open end of the dish facing upwards.

Carefully fill the half of the petri dish with corn syrup until the entire surface is covered.
Develop a hypothesis regarding which color dye you believe will diffuse faster across the corn syrup and why. Record this in the post-lab questions.
Place a single drop of blue dye in the middle of the corn syrup. Note the position where the dye fell by reading the location of its outside edge on the ruler.
Record the location of the outside edge of the dye (the distance it has traveled) every ten seconds for a total of two minutes. Record your data in Table 1 and use your results to perform the calculations in Table 2.
Repeat the procedure using the red dye, the unused half of the petri dish, and fresh corn syrup.

Table 1: Rate of Diffusion in Corn Syrup

Time (sec)

Blue Dye

Red Dye

Time (sec)

Blue Dye

Red Dye

10

70

20

80

30

90

40

100

50

110

60

120

Table 2: Speed of Diffusion of Different Molecular Weight Dyes

Structure

Molecular Weight

Total Distance
Traveled (mm)

Speed of Diffusion
(mm/hr)*

Blue Dye

Red Dye

*Multiply the total distance diffused by 30 to get the hourly diffusion rate

Post-Lab Questions

Record your hypothesis from Step 3 here. Be sure to validate your predictions with scientific reasoning.

Which dye diffused the fastest?

Does the rate of diffusion correspond with the molecular weight of the dye?

Does the rate of diffusion change over time? Why or why not?

Examine the graph below. Does it match the data you recorded in Table 2? Explain why, or why not. Submit your own plot if necessary.

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Concentration Gradients and Membrane Permeability

 
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Biology 45

Biology 45. image18.jpg INCLUDEPICTURE “../images/lab0018banner02.jpg” * MERGEFORMAT image19.jpg

Experiment 1: Microscopic Anatomy of the Reproductive System

Visualizing the microscopic anatomy of the reproductive system will aid in your understanding of its function.

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Materials

Penis (Cross-Section) Digital Slide Image Testis (Cross-Section) Digital Slide Image Sperm Digital Slide Image

Ovary Digital Slide Image Uterus Digital Slide Image

Procedure

1. Examine each of the digital slide images.

2. Label the images provided at the end of the digital slide images.

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Penis (Cross-Section) 100X. The urethra is lined with stratified, squamous epithelium near the bottom of the tubule. The corpus spongiosum, which surrounds the urethra, includes blood sinuses which are often filled with blood. These sinuses are also lined with simple, squamous epithelium. The corpus cavernosa (not pictured) is located just above the corpus spongiosa, and contains erectile tissue. This tissue is filled with empty spaces which fill with arterial blood in a process called tumescense.

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Penis (Cross-Section) 1000X. Blood cells in the corpus spongiosum are visible in this image.

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Testis (Cross-Section) 100X. Testes are dense with seminiferous tubules (approximately 800- 1600 tubules per testis; or, approximately 600 meters of tubules when added together). These tubules are the site for spermatogenesis, and are lined with Sertoli cells. Septa reside between these tubules, and are comprised of connective tissue.

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Testis (Cross-Section) 1000X. Sertoli cells are referred to as “nursery cells” because they help create a healthy environment for spermatogenesis. These cells are directly atop the boundary tissue which surrounds the seminiferous tubules, and are ovular in shape. Meiotic activity produces, primary spermatocytes, secondary spermatocytes, and spermatids. Spermatids are located near the lumen within the tubules, and appear morphologically different based on their respective phases of maturation. Young spermatids have elongated, tail-like structures while more developed spermatids appear boxy and dense.

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Sperm 1000X. Sperm cell anatomy includes a head, a midpiece, and a flagella. The head appears dense and includes the nucleus. The midpiece has a filamentous core with many mitochondrial organelles present on the outside. The flagella is used for motility.

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Ovary 100X. The surface layer of the ovary is composed of a single layer of epithelium, referred to as germinal epithelium. The tunica albuginea is directly below the germinal epithelium and creates a connective tissue capsule surrounding the ovary. The outer layer of the ovary, shown above, is referred to as the cortex and is where follicles reside. Ovaries contain different types of follicle cells referred to as primordial follicles, primary follicles, secondary follicles, and tertiary follicles. A central medulla also exists within the ovary.

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Uterus 100X. The endometrium is a mucosal layer used for egg implantation, and consists of simple columnar epithelium; this includes both ciliated and secretory cells). Note that the precise composition of the endometrium varies by physiological state. The myometrium is a fibromuscular layer. Uterine glands are located in the endometrium

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Uterus 1000X. Uterine glands are lined by ciliated columnar epithelium. They function to secrete biochemical substances required for healthy embryonic development, and become enlarged after impregnation occurs in the uterus.

Post-Lab Questions

1. Label the slide images

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2. What type of epithelium did you observe in the prepared slide of the penis?

3. Which layer of the uterus forms a new functional layer each month?

Experiment 1: Observation of Mitosis in a Plant Cell

image19.jpgIn this experiment, we will look at the different stage of mitosis in an onion cell. Remember that mitosis only occupies one to two hours while interphase can take anywhere from 18 – 24 hours. Using this information and the data from your experiment, you can estimate the percentage of cells in each stage of the cell cycle.

Materials

Onion (allium) Root Tip Digital Slide Images

Procedure

1. The length of the cell cycle in the onion root tip is about 24 hours. Predict how many hours of the 24 hour cell cycle you think each step takes. Record your predictions, along with supporting evidence, in Table 1.

2. Examine the onion root tip slide images on the following pages. There are four images, each displaying a different field of view. Pick one of the images, and count the number of cells in each stage. Then count the total number of cells in the image. Record the image you selected and your counts in Table 2.

3. Calculate the time spent by a cell in each stage based on the 24 hour cycle:

Hours of Stage

=

24 x Number of Cells in Stage

Total Number of Cells Counted

4. Locate the region just above the root cap tip.

5. Locate a good example of a cell in each of the following stages: interphase, prophase, metaphase, anaphase, and telophase.

6. Draw the dividing cell in the appropriate area for each stage of the cell cycle, exactly as it appears. Include your drawings in Table 3.

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Onion Root Tip: 100X

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Onion Root Tip: 100X

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Onion Root Tip: 100X

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Onion Root Tip: 100X

Table 1: Mitosis Predictions

Predictions:

Supporting Evidence:

Table 2: Mitosis Data

Number of Cells in Each Stage

Total Number of Cells

Calculated % of Time Spent in Each Stage

Interphase:

Interphase:

Prophase:

Prophase:

Metaphase:

Metaphase:

Anaphase:

Anaphase:

Telophase:

Telophase:

Cytokinesis:

Cytokinesis:

Table 3: Stage Drawings

Cell Stage:

Drawing:

Interphase:

Prophase:

Metaphase:

Anaphase:

Telophase:

Cytokinesis:

Post-Lab Questions

1. Label the arrows in the slide image below with the appropriate stage of the cell cycle.

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2. What stage were most of the onion root tip cells in? Does this make sense?

3. As a cell grows, what happens to its surface area : volume ratio? (Think of a balloon being blown up). How is this changing ratio related to cell division?

4. What is the function of mitosis in a cell that is about to divide?

5. What would happen if mitosis were uncontrolled?

6. How accurate were your time predication for each stage of the cell cycle?

7. Discuss one observation that you found interesting while looking at the onion root tip cells.

Experiment 3: Following Chromosomal DNA Movement through Meiosis

In this experiment, you will follow the movement of the chromosomes through meiosis I and II to create gametes

Materials

2 Sets of Different Colored Pop-it® Beads (32 of each – these may be any color) 4 5-Holed Pop-it® Beads (used as centromeres)

Procedure Trial 1

As prophase I begins, the replicated chromosomes coil and condense…

1. Build a pair of replicated, homologous chromosomes. 10 beads should be used to create each individual sister chromatid (20 beads per chromosome pair). The five-holed bead represents the centromere. To do this…

a. For example, suppose you start with 20 red beads to create your first sister chromatid pair. Five beads must be snapped together for each of the four different strands. Two strands create the first chromatid, and two strands create the second chromatid.

b. Place the five-holed bead flat on a work surface with the node positioned up. Then, snap each of the four strands into the bead to create an “X” shaped pair of sister chromosomes.

c. Repeat this process using 20 new beads (of a different color) to create the second sister chromatid pair. See Figure 4 (located in Experiment 2) for reference.

2. Assemble a second pair of replicated sister chromatids; this time using 12 beads, instead of 20, per pair (six beads per each complete sister chromatid strand). Snap each of the four pieces into a new five-holed bead to complete the set up. See Figure 5 (located in Experiment 2) for reference.

3. Pair up the homologous chromosome pairs created in Step 1 and 2. DO NOT SIMULATE CROSSING OVER IN THIS TRIAL. You will simulate crossing over in Trial 2.

4. Configure the chromosomes as they would appear in each of the stages of meiotic division (prophase I and II, metaphase I and II, anaphase I and II, telophase I and II, and cytokinesis).

5. Diagram the corresponding images for each stage in the sections titled “Trial 1 – Meiotic Division Beads Diagram”. Be sure to indicate the number of chromosomes present in each cell for each phase.

6. Disassemble the beads used in Trial 1. You will need to recycle these beads for a second meiosis trial in Steps 7 – 11.

Trial 1 – Meiotic Division Beads Diagram

Prophase I Metaphase I Anaphase I Telophase I Prophase II Metaphase II Anaphase II Telophase II Cytokinesis

Trial 2

7. Build a pair of replicated, homologous chromosomes. 10 beads should be used to create each individual sister chromatid (20 beads per chromosome pair). The five-holed bead represents the centromere. To do this…

a. For example, suppose you start with 20 red beads to create your first sister chromatid pair. Five beads must be snapped together for each of the four different strands. Two strands create the first chromatid, and two strands create the second chromatid.

b. Place the five-holed bead flat on a work surface with the node positioned up. Then, snap each of the four strands into the bead to create an “X” shaped pair of sister chromosomes.

c. Repeat this process using 20 new beads (of a different color) to create the second sister chromatid pair. See Figure 4 (located in Experiment 2) for reference.

8. Assemble a second pair of replicated sister chromatids; this time using 12 beads, instead of 20, per pair (six beads per each complete sister chromatid strand). Snap each of the four pieces into a new five-holed bead to complete the set up. See Figure 5 (located in Experiment 2) for reference.

9. Pair up the homologous chromosomes created in Step 6 and 7.

10. SIMULATE CROSSING OVER. To do this, bring the two homologous pairs of sister chromatids together (creating the chiasma) and exchange an equal number of beads between the two. This will result in chromatids of the same original length, there will now be new combinations of chromatid colors.

11. Configure the chromosomes as they would appear in each of the stages of meiotic division (prophase I and II, metaphase I and II, anaphase I and II, telophase I and II, and cytokinesis).

12. Diagram the corresponding images for each stage in the section titled “Trial 2 – Meiotic Division Beads Diagram”. Be sure to indicate the number of chromosomes present in each cell for each phase. Also, indicate how the crossing over affected the genetic content in the gametes from Trial 1 versus Trial 2.

Trial 2 – Meiotic Division Beads Diagram:

Prophase I Metaphase I Anaphase I Telophase I Prophase II Metaphase II Anaphase II Telophase II Cytokinesis

Post-Lab Questions

1. What is the state of the DNA at the end of meiosis I? What about at the end of meiosis II?

2. Why are chromosomes important?

3. How are meiosis I and meiosis II different?

4. Why do you use non-sister chromatids to demonstrate crossing over?

5. What combinations of alleles could result from a crossover between BD and bd chromosomes?

6. How many chromosomes were present when meiosis I started?

7. How many nuclei are present at the end of meiosis II? How many chromosomes are in each?

8. Identify two ways that meiosis contributes to genetic recombination.

9. Why is it necessary to reduce the number of chromosomes in gametes, but not in other cells?

10. Blue whales have 44 chromosomes in every cell. Determine how many chromosomes you would expect to find in the following: Sperm Cell:

Egg Cell:

Daughter Cell from Mitosis:

Daughter Cell from Meiosis II:

11. Research and find a disease that is caused by chromosomal mutations. When does the mutation occur? What chromosomes are affected? What are the consequences?

12. Diagram what would happen if sexual reproduction took place for four generations using diploid (2n) cells.

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Biology 45

 
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