Viruses (Topic A2.3 – AHL Only)

Essential Idea(s): Viruses are diverse structures that rely on host cells for vital functions. They showcase rapid evolution with implications for disease treatment.

 Unit Length: 2 Lessons (AHL Only)

  Guiding Questions

◊ How can viruses exist with so few genes?

◊ In what ways do viruses vary?

IB Statement(s) and Objective(s)

A2.3.1:  Structural features common to viruses

  • Define virus
  • Describe the features shared by all viruses

 

A2.3.2:  Diversity of structure in viruses

  • Outline the structural diversity of the varying types of viruses
  • Give at least 3 examples of viruses

 

A2.3.3:  Lytic cycle of a virus

A.2.3.4:  Lysogenic cycle of a virus 

  • Define bacteriophage 
  • Define lytic cycle and lysogenic cycle
  • Compare and contrast the lytic and lysogenic cycles of lambda phage

 

A2.3.5:  Evidence for several origins of viruses from other organisms

  • Outline the possible origins of viruses
  • Describe the hypothesis that viral structural features are a product of convergent evolution 

 

A2.3.6:  Rapid evolution in viruses

  • Define variation (in a biological context)
  • Explain reasons for very rapid rates of evolution in some viruses
  • Explain the use of R0 as a mathematical tool for understanding viral transmission
  • Describe historic examples of the rapid viral evolution of influenza and of HIV

Activities: = podcast / = inquiry 5 / = Write it Ӕ = The academy  / Ⓡ = Read it

Lab ⓟ/ⓦ/Ӕ: The Evolution of Coronavirus  

(💁/👭[podcast only] – max 3)

How and why did Covid-19 become the virus that caused the worst pandemic in over a century? Start by reading this article about the basic evolution of Covid-19, then explore the questions within this digital lab. Record your answers to the questions in a written document, podcast, or present this as an Ӕ lesson on Covid-19 evolution. 

 

Lab Design ⓟ/ⓦ/Ӕ: The Evolution of Coronavirus  (💁/👭 – max 3)

Take on the role of an epidemiologist – imagine you have access to databases of all of the gene sequences from millions of Coronavirus patients worldwide. You want to identify how quickly the virus is mutating, which will help governments worldwide determine how to proceed with vaccine development and treatment. 

With access to all of this data, design an investigation to determine the mutation rate of the novel Covid-19 virus. You might want to spend some time exploring this Covid-19 data to help you with you investigation. Your design should include: 

  • A research question
  • An independent dependent variable
  • A hypothesis

A background explanation – using scientific reasoning to explain the prediction within your hypothesis 

 

/: Inquiry Q&A on Viruses (💁/ 👭max 2)

Imagine you are trying to uncover the origins of viruses on Earth. How did they start? Where did they start? Create a list of 3 or more inquiry questions related to viral evolution. Partner up with another student and answer their questions. Remember that good inquiry questions are conceptual / open-ended…

Such as: “What features enable some viruses to evolve so quickly?” 

NOT: “What is the basic structure shared by all viruses?” 

Write your questions solo, and then partner up and record yourselves asking each other your 5 questions.

*Try to write questions that cover as many topics from A2.3 as possible!

 

Ӕ: A 3D Tour of Coronavirus (💁)

Watch this 3D tour of Covid-19, and screencast your voice over the audio, explaining the basic structure and function of the parts of the virus (you don’t have to cover the parts that are not in U1/U8). Make sure you do cover: antigens, glycoproteins, RNA, and antibodies. 

 

ⓟ/ⓡ/ⓦ: There are over 100 Definitions for ‘Life’…and All are Wrong (💁/ 👬 max 2)

How hard can this be!? We need a simple definition of ‘life’. Scientists don’t find this to be such an easy question. Read this article (from Stanford Philosophy) or watch this BigThink Video, and respond (either in writing or with a podcast) — Answer/discuss the following: 

  1. Why is life such a difficult concept to define? 
  2. How do viruses reflect the difficulties of an attempt to define “life”?
  3. Why do some virologists think viruses should be considered alive? (Watch the video on this page for help)
  4. What role does evolution play in the definition of life?
  5. Do YOU think viruses should be included in the definition of life? Why or why not?

 

/: The End to AIDS in Sight (💁[if writing] / 👭[podcast only] – max 3)

For those who lived through the AIDS epidemic, it is one of the miracles of modern medicine that scientists are talking about a potential end to AIDS. Read this article and watch this video, and then discuss: 

  • What HIV is (remember to give general explanations on the overall structure and function of viruses) 
  • How HIV affects the immune system
  • How HIV evolved to cause a pandemic
  • How you feel knowing that a possible end of AIDS is in sight

Remember that you can include other topics of discussion to address all the components of the activity you are completing (e.g. podcast, writing).