Look at one of these occurrences and try to analyze what went wrong. Think of another possible “wrong” than the list below.

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“Where they went wrong” assignment

Science has at times really gone off on the wrong track.  In this assignment you will look at one of these occurrences and try to analyze what went wrong.  You may think of another possible “wrong” than the list below.  Some wrong theories resulted from several errors.

List of possible “wrongs”

  1. Ignoring data that contradicts a theory.
  2. Many variables in the observable that makes it difficult to vary just one or a few at a time.
  3. The variables may not be independent.
  4. Equipment that is not sensitive or reproducible enough. This is essentially the observation step of the Scientific Method that has errors.
  5. Math mistakes. Yep sometimes physicists make these too. Not often though.
  6. Incorrect assumptions.
  7. Not actually doing an experiment vis a vis the Scientific Method. This sometimes happens when the accepted theory seems so obviously true.
  8. Not reproducing an experiment vis a vis the Scientific Method. This can happen when the experiments are long and drawn out.
  9. Equipment simply not being available to test the hypothesis.
  10. Confusing correlation with causation.

Topics-

There are some possibilities below.  You may also think of your own “where they went wrong” topic.

Possible topics:

 

https://en.wikipedia.org/wiki/Superseded_theories_in_science

And also.

  1. The UV catastrophe. Also called the Rayleigh–Jeans catastrophe.
  2. The ether theory. Might be spelled aether.  If you get articles about organic separation, then you are looking at the wrong topic. https://en.wikipedia.org/wiki/Aether_theories
  3. The four humors theory. If you are reading things that sound really gross, you are on the right topic.
  4. Heritability theories. Originally a person’s attributes were thought to be some average of their parents’ attributes.
  5. Miasma theory.
  6. Geocentric universe, i.e., earth as the center of the universe.
  7. Flat earth. (sailors actually knew the earth was round but not how big it was.  For this though, you may assume that the stories that they thought they would fall off the edge of the earth are true.)
  8. Two fluid theory of electrostatics.
  9. Four elements theory of compounds of the Greeks.
  10. Darkon theory of light. This is actually a spoof, but you may use it. https://www.osa-opn.org/opn/media/Images/PDFs/11530_23363_110676.pdf?ext=.pdf
  11. Plum pudding model in chemistry.
  12. Alchemy
  13. Aristotle’s theory of free fall.
  14. Cold weather makes you sick.
  15. Polio is caused by ice cream.
  16. Humans only use 10% of their brains.
  17. Sugar turns kids into monsters.
  18. Ulcers are caused by spicy food and stress.
  19. Caloric theory. https://en.wikipedia.org/wiki/Caloric_theory

 

 

What is the difference between a 5% (m/m) glucose solution and a 5% (m/v) glucose solution?

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Chemistry. Questions

7.31 What is the difference between a 5% (m/m) glucose solution and a 5% (m/v) glucose solution?

7.33 Calculate the mass percent (m/m) for the solute in each of the following solutions:

  1. 25 g of KCl and 125 g of H2O
  2. 12 g of sugar in 225 g of tea solution with sugar
  3. 8.0 g of in 80.0 g of solution CaCl2

7.35 Calculate the mass/volume percent (m/v) for the solute in each of the following solutions:

  1. 75 g of in 250 mL of solution Na2SO4
  2. 39 g of sucrose in 355 mL of a carbonated drink

7.37 Calculate the grams or milliliters of solute needed to prepare the following solutions:

  1. 50.0 mL of a 5.0% (m/v) KCl solution
  2. 1250 mL of a 4.0% (m/v) NH4Cl solution
  3. 250. mL of a 10.0% (v/v) acetic acid solution

7.39 A mouthwash contains 22.5% (v/v) alcohol. If the bottle of mouthwash contains 355 mL, what is the volume, in milliliters, of alcohol?

7.41 A patient receives 100. mL of 20.% (m/v) mannitol solution every hour.

  1. How many grams of mannitol are given in 1 h?
  2. How many grams of mannitol does the patient receive in 12 h?

7.43 A patient needs 100. g of glucose in the next 12 h. How many liters of a 5% (m/v) glucose solution must be given?

7.45 Calculate the amount of solution (g or mL) that contains each of the following amounts of solute:

  1. 5.0 g of from a 25% (m/m) LiNO3 solution
  2. 40.0 g of KOH from a 10.0% (m/v) KOH solution
  3. 2.0 mL of formic acid from a 10.0% (v/v) formic acid solution

7.47 Calculate the molarity of each of the following solutions:

  1. 2.00 moles of glucose in 4.00 L of solution
  2. 4.00 g of KOH in 2.00 L of solution
  3. 5.85 g of NaCl in 400. mL of solution

7.49 Calculate the grams of solute needed to prepare each of the following solutions:

  1. 2.00 L of a 1.50 M NaOH solution
  2. 4.00 L of a 0.200 M KCl solution
  3. 25.0 mL of a 6.00 M HCl solution

7.51 What volume is needed to obtain each of the following amounts of solute?

  1. liters of a 2.00 M KBr solution to obtain 3.00 moles

of KBr

  1. liters of a 1.50 M NaCl solution to obtain 15.0 moles of NaCl
  2. milliliters of a 0.800 M Ca(NO3)2 solution to obtain 0.0500 mole of Ca(NO3)2

7.53 To make tomato soup, you add one can of water to the condensed soup. Why is this a dilution?

7.55 Calculate the concentration of each of the following diluted solutions:

  1. 2.0 L of a 6.0 M HCl solution is added to water so that the final volume is 6.0 L.
  1. Water is added to 0.50 L of a 12 M NaOH solution to make 3.0 L of a diluted NaOH solution.
  2. A 10.0-mL sample of a 25% (m/v) KOH solution is diluted with water so that the final volume is 100.0 mL.
  3. A 50.0-mL sample of a 15% (m/v) H2SO4 solution is added to water to give a final volume of 250 mL.

7.57 What is the volume, in milliliters, of each of the following diluted solutions?

  • A 1.5 M HCl solution prepared from 20.0 mL of a 6.0 M

HCl solution

1HC2H3O22

HNO3

H2SO4

  1. A 2.0% (m/v) LiCl solution prepared from 50.0 mL of a 10.0% (m/v) LiCl solution
  2. A 0.500 M H3PO4 solution prepared from 50.0 mL of a 6.00 M H3PO4 solution
  3. A 5.0% (m/v) glucose solution prepared from 75 mL of a 12% (m/v) glucose solution

7.59 Determine the volume, in milliliters, required to prepare each of the following diluted solutions:

  1. 255 mL of a 0.200 M HNO3 solution from a 4.00 M HNO3 solution
  2. 715 mL of a 0.100 M MgCl2 solution using a 6.00 M MgCl2 solution
  3. 0.100 L of a 0.150 M KCl solution using an 8.00 M KCl solution

 

What mass of Al is required to produce 500g of AlCl3? SHOW ALL STAGES OF WORKING!! 2Al(s) + 3Cl2(g) -> 2AlCl3(s) explain how to do it as well.

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Chemistry question

What mass of Al is required to produce 500g of AlCl3? SHOW ALL STAGES OF WORKING!! 2Al(s) + 3Cl2(g) -> 2AlCl3(s) explain how to do it as well.

 

State a hypothesis (or the predicted outcome of the experiment) that you could have been testing using this experimental set up. Were the eukaryotic cells affected by the drug treatment? Briefly explain how you know this information.

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ASSIGNMENT

Answer the following questions to the best of your ability; this exercise is worth 30 points and must be uploaded to Canvas by midnight on Friday of Week 4 (Jan. 27th).  You may work together with a group to complete this exercise, but everyone must submit their completed problem sets separately.  Please note that “work together with a group” does not mean that you can submit identical answers.  In other words, you can consult with your peer(s) on the answer (or the means to come up with the answer) but you need to answer the questions in your own words.

You may provide your answers in a separate file or within this worksheet (save as a .pdf file) but for the latter, remember to TYPE YOUR ANSWERS IN RED (or another color of your choice)!

  1. You are a graduate student aiming to develop new antibiotics, small organic molecules that bind to and prevent the activity of proteins involved in processes essential for cell survival or cell division.  The data below was generated after an experiment, where you added a new antibiotic candidate (“drug”) to cultures of bacteria (prokaryotic cells) or cancer cells (eukaryotic cells).  Over a period of 48 hours, you monitored cellular growth (sampling every 3 hours) and determined how many cells (“cancer” or “bacteria”) were present in your cultures (measured in cells/mL) after the addition of your candidate antibiotic (“+ drug”) or water (“no drug”).  Answer the questions below based on your interpretation of the data.
    • Note that the use of cancer cells as a measure for how eukaryotic cells would respond to a new drug treatment is quite common in molecular and cellular biology.  You will learn more about the use of cancer cells to establish immortalized cell lines in Cellular Biology (TBIOL 303) but for now, assume that the cancerous nature of the eukaryotic cells is irrelevant to the outcome of the experiment.  In other words, any effect observed in these cells will be the result of the drug treatment (and NOT the fact that these are cancer cells).

 

  1. (1.5 points) State a hypothesis (or the predicted outcome of the experiment) that you could have been testing using this experimental set up.

1.(3 points) Were the eukaryotic cells affected by the drug treatment?  Briefly explain how you know this information.  You must refer to the graph as part of your answer.

1.(3 points) Were the prokaryotic cells affected by the drug treatment?  Briefly explain how you know this information.  You must refer to the graph as part of your answer.

1(4 points) You decide to submit your data for publication in the Journal of Bacteriology but Reviewer #2 has requested an additional experiment to confirm your results.  They suggest that you add the drug BEFORE the prokaryotic and eukaryotic cells have reached stationary phase (indicated by the growth curves “leveling out” towards the end of the 48-hour period in previous graph).  In other words, they wanted to see the effect when the drug is added after cellular growth/replication has already started.  Assuming you added your antibiotic candidate mid-way through the experiment (indicated by red arrow), predict what the bacterial and eukaryotic growth curves would look like based on your previous results.  Briefly explain your answer.

1.(4.5 points) Below are four different commercially-available antibiotics used to treat various bacterial infections.  Each antibiotic targets a different macromolecule, resulting in a halt of cellular division and/or cell death.  Briefly research each antibiotic and determine what macromolecule is ultimately affected by the drug and why this would be detrimental to the bacterial cell.  Portions of this table have been filled out for you.

 

Antibiotic Drug Macromolecule Affected

(Specific Target)

 Effect on Bacterial Cell
Ampicillin Polysaccharide (peptidoglycan) Antibiotic targets transpeptidase, an enzyme necessary for the synthesis of peptidoglycan (the polysaccharide component of cell wall).  Since the bacteria cannot complete the biosynthesis of peptidoglycan, they cannot complete binary fission and lyse as a result.
Polymyxins  

 

 

 

  
Ciprofloxacin  

 

 

 

  
Tetracycline  

 

 

 

  

 

 

BONUS (1 point):  Haemophilus influenzae is a Gram-negative bacterium that infects the upper respiratory track and was once thought to be the causative agent of influenza (back before the influenza virus was identified as the cause of the disease).  Unfortunately, you and your friend James come down with flu-like symptoms over winter break but while James is diagnosed with an H. influenzae infection, you are diagnosed as having influenza.  As you leave the hospital, James is prescribed the antibiotic Cefotaxime and he insists that you take the medication even though you have been sent home with instructions to “rest up and drink plenty of fluids.”  Briefly explain to James why your influenza infection must be treated differently than his H. influenzae infection?  In other words, why shouldn’t you take antibiotics to combat viral infections?

 

2.Mice are often used as model organisms to study the genetics underlying aspects of development and disease owing to their high levels of evolutionary conservation/genetic relatedness to humans. With that in mind, the data below was generated in an experiment using cells isolated from two different laboratory mice strains (mouse #1 and mouse #2).  The cells that you isolated from the mice were cultured (in a plastic petri dish with appropriate nutrients and growth factors to promote their growth and survival) in the laboratory for several weeks and had been split into several different dishes when you notice a little problem.  Some of the mouse #2 dishes have cells that are almost all dead and other mouse #2 dishes contain cells that are dividing much more rapidly than the cells from mouse #1.

 

Panel A shows blue-fluorescently stained metaphase chromosomes from the mouse #1 and mouse #2 cells.  Panel B shows the relative fraction of cells found at different phases of mitosis.  In a separate experiment (data not shown), you determined that equal fractions of each cell culture were dividing at the same moment in time but determined that they were progressing through mitosis at different rates.

 

  1. (2 points) What looks different when you compare the chromosomes from mouse #1 and mouse #2 cells (Panel A)?

1.(2 points) Describe the results shown in Panel B.  Refer to Chapter 12 of your textbook if you need to review cell cycle and the stages of mitosis.

 

1.(4 points) How might the difference described in question #2A underlie the results described in question #2B?  Discuss the connection between chromosome structure and cell cycle progression as part of your answer.

1.(3 points) Based on the information provided here, provide a hypothesis that may explain why some of the mouse #2 cells are dying off.

1.(3 points) Propose a follow-up question that you could address using these cells that would build on the results shown here and allow you to better understand the relationship between mouse #2 genetic/physical traits and chromosome condensation or progress through mitosis.

 

 

 

 

 

 

 

What is the consistency (i.e. texture) of the Jell-O made with the canned pineapple compared to the Jell-O made with fresh pineapple? What does this tell you about the reaction that has occurred?

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The Chemistry of Food

Preparation for Lab

Read the lab procedure and answer the embedded questions.  You may need to consult your textbook as well as the supplementary materials posted on Canvas.  Note that you will not be turning in the embedded questions as part of your lab write-up.  Instead, use these embedded questions to guide your preparation for the experiments.

  1. Covalent bonds occur when atoms share…
  2. Building a molecule from simpler components is called anabolism. Breaking a substance down is called…

 

  1. The protein in gelatin that allows it to form a gel is called…
  2. An enzyme in pineapple capable of digesting the protein in gelatin is called…
  3. For each of the following substances, identify whether it is a carbohydrate, lipid, protein, or “other”.
    1. vegetable oil
    2. lactase
  • amylase
  1. starch
  2. lactose
  3. distilled water

 

  1. Each of the following statements applies to one of the tests we will perform in Part III of this lab. Give the name of the appropriate test.

 

  1. Uses strips that change color in the presence of the test substance
  2. Requires that the test solution be heated
  • A very dark colored solution indicates that a lot of starch is present

 

  1. Developing predictions: If the lactase enzyme is effective in breaking down lactose, would you expect to see a positive or negative result for the glucose test (“positive” = glucose is present)?
  2. Developing predictions: If the amylase enzyme is effective in breaking down the cracker, would you expect to see a positive or negative result for the presence of starch?

 

 The Chemistry of Food

Courtesy of Grace Sparks, Seattle Central Community College, and J. Walny, A. Rubenstein, and E. Matthews, Michigan State University.

Carbohydrates, lipids, and proteins are relatively large molecules that play many important roles in living organisms.  The basic framework or “backbone” of all these macromolecules consists of carbon atoms.

  • Why is carbon a particularly useful element to form large molecules?

In lab, we will use a suite of chemical tests to 1) detect the types of molecules present in various food items, and 2) study how enzymes affect the molecules present in food items.

Learning Objectives

  • Make accurate conclusions on the macromolecule content of food based off of your experimental results.
  • Learn and apply the proper terminology to describe the molecular structure of the 4 major categories of biological macromolecule.
  • Learn how to utilize positive and negative controls in the interpretation of experimental results.

Background:  Biological Macromolecules

Carbohydrates come in several basic forms.  The simplest sugars are called monosaccharides, and they contain 3-7 carbon atoms, often bonded together in a ring structure.  Glucose is a very common 6-carbon sugar.  When two monosaccharides bond together, they form a disaccharide, such as sucrose.  Many monosaccharide subunits bonded together forms a polysaccharide, a much more complex carbohydrate.  Starch, cellulose, and glycogen are common examples of polysaccharides.  Our test methods will allow us to easily detect starch and also reducing sugars (detected when copper is reduced to give a red color).  Glucose and fructose should test positive, but sucrose (a disaccharide) may not.

  • If the disaccharide sucrose is made of a glucose bonded to a fructose, do you think copper will give a red color after sucrose is broken down by heat or acid?

There are many different types of lipids.  They are all grouped together as lipids because at least some part of the molecule does not dissolve in water.  Oil and vinegar salad dressing requires vigorous shaking because the oil and vinegar (which is a water-based solution) do not mix well.  We will use a simple test to help determine whether or not lipids are present in our samples.

Most proteins are very large molecules with complex shapes.  These shapes are formed by the interactions among many amino acids subunits bonded in a long chain.  Amino acids join to one another by a specific type of covalent bond called a peptide bond.

Proteins serve many functions, including structures, signaling, and facilitating chemical reactions.  Each function is dependent upon the protein’s folded shape.  Proteins that are chemical catalysts are called enzymes.  Please note that not all enzymes are proteins, but most are!

Read the following protocols to understand how we will test for various biological macromolecules and observe how enzymes can break them down.

 

Lab Protocol

  1. Enzymatic activity of saliva.

Background:  As food is broken down by the teeth by way of chewing (the process of mastication), saliva is provided by the salivary glands.  This is where chemical digestion begins.  Saliva, among other important substances, contains an enzyme called amylase that aids in the breakdown of the polysaccharide starch.  Enzymes are strings of amino acids, joined by peptide bonds, that are responsible for catalyzing both synthesis (anabolic) and decomposition (catabolic) reactions.  Amylase breaks up long starch molecules into smaller sugar molecules.

 Objective:  Investigate enzyme activity for an enzyme that breaks down polysaccharides.

 Materials:

  • Fresh Saltine Crackers
  • Iodine Test Reagent
  • Benedicts Test Reagent
  • Hot Water Bath (90°)
  • Test Tube Holder (1 per group)
  • Test Tubes (4 per group)
  • Sample Cups (2 per group)
  • Spatula
  • Razor Blade
  • positive and negative controls for both tests (at instructor’s station)

Procedure:

Now you will test both an unchewed cracker and a chewed cracker for the presence of sugar and the presence of starch.  Here’s how:

  1. First, chew a cracker for one full minute, then spit it into one of the sample cups. Add enough water to bring it to at least 1 mL.
  2. In a new sample cup, add an unchewed cracker (the same size as the chewed one), and break it up using a spatula. Add enough water to bring it to at least 2 mLs.
  3. Using a 1 mL pipette with the end cut off 0.5 cm from the tip (your instructor can show you how), transfer 1 mL of each sample to two labeled test tubes, one for the Benedict’s test and one for the starch test. You will need to do this for each of the two samples.  When you are finished, you should have a total of 4 tubes to which you will now be ready to add the test reagents.

 

  1. Testing for Sugar (Benedict’s Test)
    1. Using a 1 mL pipette, add 1 mL of Benedict’s solution to each of the cracker sample tubes.

 

  1. Heat the test tubes (use test tube holder) for 3 minutes in a hot water bath.

 

  1. Compare with the class positive and negative controls to determine whether the polysaccharide has been broken down into monosaccharides. A cloudy precipitate will form that varies from green to yellow to orange to red to brown in color depending on the concentration of monosaccharides.

 

  1. Testing for Starch (Iodine Test)
    1. Add 2 drops of iodine to a tube with 1 mL of chewed or unchewed cracker (the ones you set up in step 3).

 

  1. Compare with the class positive and negative controls to determine whether any starch is still remaining (i.e. not yet broken down to sugar). If it changes color to dark blue or black, starch is present.  If the color is brown, no starch is present.

 

  1. Answer the questions for this week’s lab write-up.

 

2.Pineapple flavored Jello?

Background:  Gelatin is obtained from selected pieces of calf and cattle skins, demineralized cattle bones (ossein), and pork skin.  Contrary to popular belief, hoofs, horns, hair, feathers, or any keratin material is not a source of gelatin.  There are two forms of gelatin: Type A, derived from acid processed materials—primarily pork skin; and Type B, derived from alkaline or lime processed materials—primarily cattle or calf hides and ossein.

 

Gelatin is made from a protein called collagen, a long, fibrous protein which comes from the joints of animals.  Gelatin dissolves in hot water and congeals (jells) at cooler temperatures.  As the dissolved gelatin mixture cools, the collagen forms into a matrix that traps the water.  As a result, the mixture turns into the jiggling, wriggling pseudo-solid that we all know and love as Jell-O™.

 

The pineapple belongs to a group of plants called Bromeliads.  The enzyme in fresh pineapple that is responsible for the breakdown of collagen is bromelain.  The process of canning pineapple denatures (unfolds) the bromelain in such a way that it can no longer catalyze the breakdown of gelatin.

 

Objective:  Investigate enzyme activity for an enzyme that breaks down proteins.

 

Materials:

  • Sample Cups (2 per group)
  • Jell-O™ Liquid (sugar free)
  • Fresh Pineapple (1 piece per group)
  • Canned Pineapple (1 piece per group)

 

Procedure:

  1. Observe the sample cups containing the canned pineapple and fresh pineapple. These were prepared 24 hrs ago by adding a piece of either fresh or canned pineapple to a cup of Jell-O.

 

  1. Answer the questions for this week’s lab write-up.

3.Lipids, water, and soap!

Background:  One of the most important characteristics of fats and lipids, in general, is their insolubility in water due to their non-polar  nature.  Lipids are made of long chains of hydrocarbons with relatively little oxygen atoms.  As a result, they tend to be non-polar and therefore do not dissolve in polar substances such as water.  (“Like dissolves like.”)  Polar or charged substances can be dissolved in polar substances and non-polar substances can be dissolved in non-polar substances.

 

In our digestive systems, lipids are, in part, broken down by bile, which is produced by the liver and aids in the digestion of fats in the small intestine.  Bile is not an enzyme, but it does help the enzymes do their job.  Bile helps create microscopic fat globules (a process called emulsification).

 

 

Emulsification is important because it allows lipases (important digestive enzymes that break down fats) to attack and break down the smaller fat globules.  Larger fat globs would mean that the lipases could not access the fats (lipids) on the interior of the lipid globs.

 

 

In this lab, you will use soap to mimic the action of bile.  Soap is unique in that a soap molecule has a polar (charged) end and a non-polar (non-charged) end.  The non-polar end interacts with and dissolves grease, oil, or fat, while the polar end interacts with a polar substance such as water molecules.  In this way, it can separate lipid molecules.

 

Objective:  Investigate the behavior of lipids and use soap to mimic the action of bile.

 

Materials

  • Clean Test Tubes (2 per group)
  • Water
  • Vegetable Oil
  • Dish Soap

 

Procedure:

  • Obtain two clean test tubes (no soap or oil).
  • Fill each 1/3 full with water.
  • Fill each 1/3 full with oil.
  • Add about 1 drop of soap to one of the test tubes.
  • In your lab notebook, draw a “before” picture of the two test tubes.
  • Cover the openings of the test tubes with hands/fingers and shake them vigorously.
  • In your lab notebook, draw an “after” picture of the two test tubes.

 

  1. Answer the questions for this week’s lab write-up.

 

  1. Lactose intolerance and glucose.

Background:  Lactose is the sugar found in milk and therefore has the common name “milk sugar.”  Lactose is a disaccharide composed of glucose and galactose sugar subunits.  When humans ingest milk, lactose must be broken down into glucose before it can be used as an energy source.  The enzyme responsible for breaking down or “digesting” lactose is called lactase.

Normally, all people are born with the ability to make lactase and can easily digest the lactose in mother’s milk and later in dairy products.  However, for some people, increasing age means loss of the production of lactase.  Loss of lactase production can begin as early as two years of age in some individuals and appears to occur more frequently and earlier in individuals of African or Asian heritage.  Individuals who do not produce lactase cannot break down the sugar lactose into its component parts.

Since only glucose passes from the intestines into the blood, lactose sugar remains in the intestinal tract until it leaves the body in the feces.  The lactose, however, is used as an energy source by the fermentative bacteria present in the intestines.  As a result of the bacteria’s fermentation, gas is released.  This can cause bloating, cramps, and diarrhea.  Lactaid and similar over-the-counter medications contain the enzyme lactase.  When these pills are taken in sufficient amounts with dairy products, people who are normally unable to enjoy dairy products can digest lactose and avoid the uncomfortable side effects they normally experience.

Diabetics have a problem where excess glucose appears in the blood and urine, causing damage to organs like the eyes and kidneys.  To monitor this glucose, test strips are sometimes used to test the urine for excess glucose.  A chemical indicator on the end of the dipstick changes color in the presence of glucose.  The glucose test strips that you will be using turns from pink (no sugar) to dark purple (presence of sugar).  Note: An indicator is a substance that changes color in the presence of a particular chemical.  There is an additional indicator at the end of each strip that tests for the presence of albumin, a protein, but you can disregard it for this test.

Objective:  Investigate the enzyme activity of an enzyme that breaks down a disaccharide into two monosaccharides.

 Materials

  • Glucose Test Strips (2 per group)
  • Sample Cups (1 per group)
  • Lactaid Pills (1 per group)
  • Milk

 

Procedure:

  • Answer the first question for this exercise in your lab write-up before proceeding with the lab activity.
  • Fill a sample cup 1/3 full of plain milk.
  • Test the plain milk with a glucose test strip and record the results in your lab notebook.
  • Crush up ½ of a Lactaid pill with a mortar and a pestle.
  • Add the pill powder to the milk.
  • Stir with a fresh glucose test strip (10 seconds minimum) and record the results in your lab notebook.

 

  1. Answer the remaining questions for this week’s lab write-up.

 

 

Lab Write-Up:

You may work together to answer these questions in lab.  For your lab write-up, type your final answers (using complete sentences) into a separate document.

 

 

(Part 1) Enzymatic activity of saliva.

  1. For the chewed cracker…
    1. What color was produced by the Benedict’s test?
    2. What color was produced by the Iodine test?

 

  1. For the unchewed cracker…
    1. What color was produced by the Benedict’s test?
    2. What color was produced by the Iodine test?

 

  1. According to the above results…
    1. What type of carbohydrate(s) (monosaccharides and/or polysaccharides) was (were) present in the chewed sample?
    2. What about the unchewed cracker?

 

  1. Does the amylase enzyme catalyze a catabolic or anabolic reaction? Briefly explain your choice in one complete sentence.

 

(Part 2) Pineapple-flavored Jello-O?

  1. What is the consistency (i.e. texture) of the Jell-O made with the canned pineapple compared to the Jell-O made with fresh pineapple? What does this tell you about the reaction that has occurred?
  2. Which of the 4 types of biological macromolecule allows Jell-O™ to form a gel?
  3. In terms of an enzymatic reaction, is collagen a substrate, an enzyme, or a product? (see figure 8.13 in your book for help)
  4. In terms of an enzymatic reaction, is bromelain a substrate, an enzyme, or a product? (see figure 8.13 in your book for help)
  5. Briefly describe what happens during the cooking of pineapple that affects its interaction with Jell-O™.
  6. What class of monomers (subunits) will the collagen break down into?
  7. Fresh pineapple is used as a meat tenderizer. Based on the results of our study, explain why.

 

 (Part 3) Lipids, water, and soap!

  1. Compare your drawings of the oil/water tube and the soap/oil/water tube before and after shaking. How are the contents of the test tubes different after shaking?
  2. Soaps contain amphipathic molecules, molecules that have distinct polar and non-polar regions. How does this property explain your observations in the “Lipids, water, and soap” experiment?
  3. Look up “bile” in your book. It is a substance manufactured by your gall bladder to help digest food. What category of biological macromolecule would bile help digest?
  4. If bile is not an enzyme, then briefly describe how it helps you digest food?

  (Part 4) Lactose intolerance and glucose.

  1. If lactase (Lactaid) is added to milk, what should happen?
  2. According to your tests, which had a higher concentration of glucose: milk or milk + Lactaid?
  3. The “-ose” ending suggests that lactose is a(n) _
  4. The “-ase” ending suggests that lactase is a(n) __
  5. Is the reaction catalyzed by lactase catabolic or anabolic?

 

 

Pick an element from the periodic table of elements. Identify the valence electrons and the orbitals in which they reside.

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DISCUSSION ESSAY

This is for a discussion board:
For the First part of the post, choose a molecule used in healthcare, industry, or found in a natural source and discuss the importance of this molecule.

The electron configuration of an atom determines the number of electrons available to participate in bonding with another atom. One method of depicting the valence electrons that an atom has is through the Lewis structure. For the second part of the post, pick an element from the periodic table of elements. Identify the valence electrons and the orbitals in which they reside.

Determine the number of theoretical stages required for this separation.

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Absorption and gas stripping

It is desired to absorb 90% of the acetone in a gas containing 1.0 mol % acetone inair in a counter current stage tower. The total inlet gas flow to the tower is 30.0 kg mol/h, and the total inlet pure water flow to be used to absorb the acetone is 90 kg mol H2O/h. The process is to operate isothermally at 300 K and a total pressure of101.3 kPa. The equilibrium relation for the acetone (A) in the gas–liquid is yA = 2.53xA. Determine the number of theoretical stages required for this separation.

 

Choose a scientific paper written in the last year. For your chosen paper, look into the study and discuss how the scientific method was used in this paper.

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DISCUSSION ESSAY

Choose a scientific paper written in the last year. For your chosen paper, look into the study and discuss how the scientific method was used in this paper. Be sure to note they hypothesis, variables, results, etc. discuss if you find this paper as a trustworthy source and why.

Based on Le Chatelier’s principle, what would be observed when the syringe is used to compress this gas mixture?

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SCH 4U – Final Exam

PART A MULTIPLE CHOICE (KNOWLEDGE – 3O)

Identify the letter of the choice that best completes the statement or answers the question.

  1. Which of the following is the electron configuration for neon?
  2. 1s 2 2s 2 2p 4 3s 2 d. 1s 3 2s 3 2p 4
  3. 1s 1 2s 1 2p 6 3s 2 e. 1s 2 2s 2 2p 8
  4. 1s 2 2s 2 2p 6
  5. Iron forms a common ion with a charge of +3. The electron configuration of this ion is:
  6. 1s 2 2s 2 2p 6 3s 2 3p 6 3d 5 d. 1s 2 2s 2 2p 6 3s 2 3p 6 3d 6
  7. 1s 2 2s 2 2p 6 3s 2 3p 6 3d 9 e. 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 3
  8. 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 8
  9. Which of the following is true of orbitals?
  10. They are two-dimensional paths around the nucleus.
  11. They can contain maximum of two electrons.
  12. Their shapes are predicted by Bohr’s equation.
  13. all of the above
  14. none of the above
  15. Which of the following is the electron configuration for the fluoride ion, F ─ ?
  16. 1s 2 2s 2 2p 4 d. 1s 2 2s 2 2p 6
  17. 1s 2 1p 6 e. 1s 2 2s 2 2p 6 3s 1
  18. 1s 2 2s 2 2p 5
  19. In bonding orbital theory, a carbon-carbon triple bond consists of
  20. 3 pi bonds d. 1 sigma bonds + 4 pi bonds
  21. 1 sigma bond + 2 pi bonds e. 3 sigma bonds
  22. 2 sigma bond + 3 pi bonds
  23. A substance is a brittle crystal that conducts electricity in molten liquid state only. Which type of substance is it?
  1. metallic crystal d. molecular crystal
  2. ionic crystal e. frozen gas
  3. covalent crystal
  4. Four pairs of covalently-bonded electrons surrounding a central atom will be arranged
  1. pyramidally d. linearly
  2. spherically e. trigonally
  3. tetrahedrally
  4. The attractive forces that exist between atoms in liquid helium are known as
  5. dipole-dipole forces d. hydrogen bonds
  6. ion-dipole forces e. Van der Waals forces
  7. covalent bonds
  8. Which of these intermolecular forces exist in between water, H 2 O, molecules:
  9. Van der Waals
  10. metallic bonding

III. hydrogen bonding

  1. covalent bonding
  2. I only d. I, III and IV only
  3. I and IV only e. I, II and III only
  4. I and III only
  5. The molar heat of vaporization of water is 42 kJ/mol. How much energy is released

by the condensation of 3.0 g of water?

  1. 0.88 kJ d. 250 kJ
  2. 7.0 kJ e. 0.07 kJ
  3. 130 kJ
  4. When solid ammonium chloride, NH 4 Cl, is added to water, the temperature of the solution decreases. Which statement best describes this observation?
  1. The reaction is exothermic
  2. Heat is released from the system, so it feels cooler.
  3. NH 4 Cl (s) ! NH 4 Cl (aq) + 33.6 kJ
  4. NH 4 Cl (s) ! NH 4 Cl (aq) “#$”%”&”()”*+”
  5. NH 4 Cl (s) + H 2 O (l) ! NH 4 Cl (aq) “#,”%”-“”()”*+
  6. The presence of a catalyst is thought to increase the rate of a reaction by
  7. changing the products that are formed in the reaction
  8. decreasing the enthalpy change of the reaction
  9. increasing the enthalpy change of the reaction
  10. decreasing the activation energy of the reaction
  11. increasing the activation energy of the reaction
  12. In a saturated solution of lead(II) chloride, the concentration of chloride ion is 6.2 x 10 -4 mol/L. The Ksp of lead(II) chloride would be which of the following?
  1. 1.9 x 10 -7 d. 2.3 x 10 -17
  2. 6.0 x 10 -11 e. none of the above
  3. 1.2 x 10 -10

 

  1. The following diagram represents a kinetic energy distribution at two temperatures. In comparing the two temperatures, it is obvious that
  1. d.
  2. e. cannot be determined

 

  1. A full syringe contains this equilibrium:

2 NO 2 (g) ⇌ N 2 O 4 (g) brown gas colourless gas

Based on Le Chatelier’s principle, what would be observed when the syringe is used to compress this gas mixture?

  1. the mixture gets darker d. the mixture gets lighter
  2. the mixture gets darker then lighter
  1. none of the above
  2. the mixture get lighter then darker
  3. The pH of a solution of HCl was found to be 3.4. The concentration of HCl of this solution (in mol/L) is which of the following?
  1. 4.0 x 10 -4 d. 2.5 x 10 -11
  2. 3.4 e. 2.0 x 10 -4
  3. 0.29
  4. The organic compound aniline (C 6 H 5 NH 2 ) acts as weak base. What is the chemical formula of aniline’s conjugate acid?
  5. C 6 H 5 COOH d. OH ─
  6. C 6 H 5 NH ─ e. C 6 H 5 NH 3+
  7. H 3 O +
  8. Bronsted-Lowry defined a base as
  9. a substance that releases H + d. a proton acceptor
  10. a substance that releases OH ─ e. an electron pair acceptor
  11. a proton donor
  12. The oxidation number of chromium (Cr) in the dichromate ion (Cr 2 O 72─ ) is
  13. +2 d. +7
  14. +4 e.
  15. +6
  16. Which substance in the following reaction has undergone reduction?

MnO 4─(aq) + 5 C 2 O 42─(aq) + 16H +(aq) 2Mn 2+(aq) + 10CO 2(g) + 8H 2 O (l)

  1. MnO 4─ d. Mn 2+
  2. C 2 O 42─ e. CO 2
  3. H +
  4. Given the following half-cell reactions:

Fe 2+(aq) + 2e ─

 

State the 5 postulates of kinetic molecular theory that are used to explain the properties of ideal gasses? Which of the postulates apply to real gases?

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Ideal Gas Law — Assignment

Show all calculations including unit conversions.

  1. State the 5 postulates of kinetic molecular theory that are used to explain the properties of ideal gasses? (5 marks)
  2. Which of the postulates apply to real gases? (1 mark)
  3. Calculate the pressure in bars, which 15.00 grams of hydrogen gas (H2) would exert on the walls of a 650.5 mL container at 25.0°C. (5 marks)
  4. Calculate the amount (moles) of ethene (C2H4) gas found in a 0.950 m3 room at (5 marks)
  5. At what temperature in Celsius would 60.55 g of oxygen (02) fill a 505 cm3 container at 15.8 psi? (5 marks)
  6. What volume would 100.5 g of water (H20) fill at 750. mm Hg and 15.0° C? (5 marks)