Week 31 – Bringing It All Together

Now that you have been introduced to toxins, it’s time to bring it all together:

  1. Begin by reading Lesson 74 (Toxicity) in our online chemistry textbook.  Chemistry textbook login instructions are provided at the bottom of this post.
  2. Complete textbook exercises 1-5 on page 384 of the book (the last page of Lesson 74).  (Worth 20 assignment points)
    • Create a Google Doc titled “Week 31 – Student Name” (example: Week 31 – Carter Swart), share the Google Doc with Mr. Swart, and type in your answers to the Doc.
    • Or, answer on paper, take a picture of your work, and email it to Mr. Swart
  3. Need help?  You have options!
    • Click here for more help on understanding toxins.
    • Reach out to a friend a create an online study group.
    • Email Mr. Swart with specific questions.
    • Attend Mr. Swart’s office hours on Tuesday (11am-12pm) and/or Thursday (1pm-2pm) via Zoom.
    • Check out this helpful video tutorial on how to calculate LD50:

Chemistry Textbook Login Instructions:

  • Log in and enter your username and password:
    • Username: full student gmail address.
    • Password: HighlineMM/DD (student birthday, use leading zero if needed, i.e. March 7 = 03/07)
    • Forgot your password?  Click here to reset your password.  Enter your student gmail address and follow the instructions.
  • Work through the practice problems at the end of Lesson 74.
  • Please ask questions about anything from Lesson 74 you do not yet fully understand.

Extend Your Learning!

Wondering about how scientists define the kilogram?  Turns out the way we define the kilogram just changed late in 2018.  Read about it at PBS.org  or watch the video below:

When finished, return to the Week 31 – Toxicity Post.

Week 31 – Bonus Credit Opportunity

Looking to earn some bonus credit and boost your grade?  You’ve come to the right place!  Each week, you will have the opportunity to earn bonus credit for completing extra learning about science.

This week’s bonus credit opportunity is called…What’s in that graph?  With the current COVID-19 outbreak dominating the news right now, science articles are making headlines daily.  To earn +10 bonus credit in the lab report category:

  1. Locate a scientifically credible science article.  Not sure how to tell?  Click here to visit the University of Washington Libraries guide.
  2. Browse the article to be sure it contains at least one graph.  If yes, continue to step 3.  If no, go back to step 1 and try again!
  3. If your article contains at least one graph: Read the article carefully.  Look up words you aren’t sure about.  Decide which one graph you want to analyze.
  4. Open the Week 31 – Bonus Credit Opportunity Google Form and enter the following information:
    • First Name / Last Name / Class Period
    • Title of the article
    • Link to the article (copy the web address and paste it into the field)
    • Title of the graph you selected
    • Type of graph
    • Description of the x-axis 
    • Description of the y-axis
    • Explain the general trend of the graph. What is the graph trying to tell you?

Anticipated FAQs

  1. Question: What kind of article should I be looking for?  Answer: You may select any scientifically credible article that is interesting to you.
  2. Question: Where is a good place to start looking for science articles?  Answer: There are lots of great websites out there.  National GeographicDiscover Magazine, and Smithsonian Magazine all have some great articles, many of which are free.
  3. Question: How do I know if something is scientifically credible?  What does scientifically credible mean?  Answer: Click here to visit the University of Washington Libraries guide.
  4. Question: My article doesn’t have a graph in it.  What should I do? Answer: Find an article that has a graph in it.
  5. Question: How many bonus credit submissions can I make each week?  Answer: You can submit one of each type of bonus credit assignment per week.  Some weeks will have a single bonus credit opportunity.  Other weeks may have more than one.
  6. Question: I still have questions.  What should I do?  Answer: Email Mr. Swart!

Week 31 – Building a Dinosaur from a Chicken

For the final part of our weekly lesson, sit back and enjoy Jack Horner’s entertaining TED Talk in which he describes his research connecting dinosaurs and chickens.  Listen for the terms embryology, the fossil recordatavisms, and behavior.  Write down a definition of these terms in your Week 31 Google Doc.  Include an example of each term from Dr. Horner’s talk.

Return to the Week 31 – Biological Classification post and double-check that you have completed all of the required work for the week.

Week 31 – Biological Classification POGIL

Next, watch the Crash Course video below to learn about the concept of taxonomy:

Then download and complete the Biological Classification POGIL (PDF) and email Mr. Swart with any questions and/or attend office hours.  Options for showing your work include:

  • Print your own copy, fill it out, and then email Mr. Swart with pictures of your completed work, or
  • Write answers to the POGIL questions in your Week 31 Google Doc into a new section titled “Biological Classification POGIL Answers”, or
  • Save a copy of the POGIL as a PDF and upload it to your Google Drive account.  From there, open it and click the “add a comment” button in the upper right part of the screen (looks like a comment box with a + sign inside).  Then highlight the question you are answering and then answer the question in the comment box.

Return to the Week 31 – Biological Classification post and continue our work for the week.

Week 31 – How do our bodies protect us from toxins?

This week, our learning focuses on the topic of toxicity.  It is natural to wonder whether or not something might be harmful.  From life experience, we know that things we eat, drink, breathe, or touch can injure us or make us sick.  Our bodies are constantly working hard to keep out things that might harm us. Examples include:

  • Our skin forms a protective barrier to keep the inside in and the outside out.
  • Our mucous membranes are sticky and “catch” bacteria, viruses, and other particles that we inhale.
  • Our liver filters our blood, removing toxins from anything we might eat through the collective actions of dozens of enzymes within the Cytochrome P450 family.
  • Our innate immune system owes its existence to our evolutionary ancestors.  The innate immune system consists of a variety of molecules that detect common environmental pathogens, like bacterial cell wall components or viral DNA – structures not found in our bodies and therefore indicate an infection.  One important family of cell surface receptors, the Toll-like Receptors (TLRs) were originally discovered in fruit flies, and then scientists found them in humans as well!
  • Our adaptive immune system protects us from new threats.  For example, we are currently under attack by COVID-19, a coronavirus never before encountered by humans.  While our innate immune system may recognize aspects of the virus as a threat (resulting in flu-like symptoms), it’s our adaptive immune response that takes a few weeks to really get going.  Our B cells will produce antibodies against the virus, killing it. Our T cells will recognize virus-infected cells, and our T cells will kill those cells, thus preventing the spread of the virus.

After browsing through the links provided, return to the Week 31 – Toxicity post.

Week 31 – Calculating Toxicity

For this lesson, we need to develop a basic understanding of how toxins can be compared.  We know that bites from snakes and spiders can sometimes be deadly.  But why only sometimes?  We know eating some berries can be deadly, but not all berries are toxic…or are they?  Can anything be toxic if encountered in large enough amounts?

To talk about toxicity, we need to understand the meaning of LD50 (the lethal dose at which 50% of a population of organisms die after exposure to a given amount of a substance).  LD50 is often expressed in mg/kg, which means the number of milligrams (mg) of a substance per kilogram (kg) of organism body mass.  Before we work through an example, take a look at the Lethal Doses Handout.  The first entry is for aspirin (acetysalicylic acid)  Aspirin has an LD50 of 200 mg/kg when fed orally to a rat.

Important Concept: Rats are commonly used for toxicity studies as the way rats metabolize chemicals is similar enough to humans for rats to be a good model organism for predicting toxicity in humans.  A typical lab rat has a mass of up to 0.5 kg, while a typical human may have a mass of 70 kg (equivalent to 154 pounds, 1 kg = 2.2  pounds, or lbs).  You can imagine an experiment where a scientists feeds aspirin in increasing amounts to various groups of rats.  All of the rats have a mass of 0.5 kg.  The first group of rats eats 1 mg of aspirin and the rats all live.  The next group eats 3 mg of aspirin and the rats all live.  Eventually, a group of rats eats 100 mg of aspirin and half of the rats die.  The scientist just found the LD50 of aspirin: 100 mg of aspirin / 0.5 kg of rat body mass = 200 mg/kg.

To figure out how to apply the LD50 of 200 mg/kg to a human with a mass of 70 kg, we need to multiply the LD50 by 70 kg:

200 mg/kg x 70 kg = 14,000 mg aspirin

Aspirin tablets often come in 81 mg doses.  To figure out how many 81 mg aspirin tablets a person would need to eat to have a 50% chance of dying (assuming a mass of 70 kg), we need to divide 14,000 mg by 81 mg/tablet:

14,000 mg x 1 tablet / 81 mg = 172.8 tablets, (about 173 tablets)

To answer the question of how much is too much when it comes to aspirin, taking more than the recommended dose per day is too much.  Anyone contemplating taking 173 tablets of aspirin needs to get help first!

Additional important information:

  • The lower the LD50, the more toxic the substance.
  • 1000 milligrams (mg) = 1 gram (g)
  • 1000 micrograms (mcg, or μg) = 1 mg
  • Water has an LD50 of 90,000 mg/kg = 90 g/kg = 90 mL/kg (water has a density of 1 g/mL) – yes, even drinking too much water can be toxic!  Check out the Material Safety Data Sheet (MSDS) for water.  How much water is toxic to a 70 kg person?  90 mL/kg x 70 kg = 6300 mL = 6.3 L, or a bit over three 2-liter bottles of water.

Before continuing on, complete the Toxicity Exit Task.  Then return to the Week 31 – Toxicity Post.

Week 31 – Toxicity

Welcome to Week 31!  For this week, we will be focusing our learning on the subject of toxicity.  In other words, how much is too much?  Please work through the list of links below.  Each section contains important information and ends with a portion of the weekly assignment.  You can complete it all in one sitting or break it up as needed.  Ready, set, go!

  1. Toxicity Entry Task (Entry Task)
  2. How do our bodies protect us from toxins?
  3. Calculating Toxicity (Exit Task)
  4. Bringing it all together (Lesson 74 Exercises)
  5. Chemistry Refresher…review now before it’s too late!
  6. Unit 4 Honors Project…the wait is over!

You did it!  Just to make sure, here’s a checklist of items you must complete this week by Sunday, April 26 at 11:59pm:

    • Toxicity Entry Task (worth 5 assignment points)
    • Toxicity Exit Task (worth 5 assignment points)
    • Lesson 74 textbook exercises (worth 20 assignment points)

Remember, you can email me any time.  Office hours for Science are Tuesdays from 11am-12pm and Thursdays from 1pm-2pm.  Check your student Gmail for Zoom instructions.

Finally, by popular demand…click here for the Week 31 Bonus Credit Opportunity!

Week 31 – Timeline of Biological Classification

We continue our investigation into the history of biological research by moving past Charles Darwin and learning about the work of Carl Linnaeus, the “father” of modern taxonomy.  To begin this week’s assignment, follow the steps:

  1. Create a Google Doc titled “Week 31 – Your Name” (example: Week 31 – Carter Swart).
  2. Create a section titled History of Taxonomy
  3. To place the concept of taxonomy into historical perspective:
    • Click the links below
    • Read about the subject
    • Briefly summarize the historical importance of each of the 5 people into your Google Doc.  (For reference, a link to a previous lesson about Watson & Crick’s discovery of the structure of DNA is also included, as are links to the texts by Darwin and Linnaeus.  These do not need to be read or summarized but are good review materials).

Return to the Week 31 – Biological Classification post and continue our work for the week.

Week 31 – Biological Classification

Welcome to Week 31!  For this week, we will be focusing our learning on how scientists have tried to make sense of the world by organizing organisms into groups based on similarities they share.  Please work through the list of links below.  Each section contains important information and ends with a portion of the weekly assignment.  You can complete it all in one sitting or break it up as needed.  Ready, set, go!

  1. Timeline of Biological Classification (required)
  2. Biological Classification POGIL (required)
  3. Building a Dinosaur from a Chicken (required)
  4. Biology Refresher…review now before it’s too late!
  5. Biology Honors Credit…push yourself!

You did it!  Just to make sure, here’s a checklist of items you must complete this week by Sunday, April 26 at 11:59pm:

  • Timeline of Biological Classification section of Google Doc (worth 10 assignment points)
  • Biological Classification POGIL (worth 60 assignment points)
  • Building a Dinosaur from a Chicken section of Google Doc (worth 10 assignment points)

Remember, you can email me any time.  Office hours for Science are Tuesdays from 11am-12pm and Thursdays from 1pm-2pm.  Check your student Gmail for Zoom instructions.

Finally, by popular demand…click here for the Week 31 Bonus Credit Opportunity!