Biology SL
Biology SL
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Theme A - Unity & Diversity
Theme A - Unity & Diversity
Theme B - Form & Function
Theme B - Form & Function
Theme C - Interaction &  Interdependence
Theme C - Interaction & Interdependence
Theme D - Continuity & Change
Theme D - Continuity & Change
IB Resources
Theme A - Unity & Diversity
Biology SL
Biology SL

Theme A - Unity & Diversity

Unlocking Viral Origins Evidence & Hypotheses

Word Count Emoji
514 words
Reading Time Emoji
3 mins read
Updated at Emoji
Last edited on 14th Jun 2024

Table of content

Introduction to viruses

  • What Are They? Tiny particles, smaller than cells, that can infect living organisms.
  • Big Question: Did viruses come before cells, or did cells come before viruses?

The hypothesis of single ancestry

  • The Clue: All viruses have nearly the same genetic code, so maybe they all came from one ancient virus.
  • But Wait, There's a Twist! The wide variety in virus structures hints they might have multiple origins. Imagine a huge family tree with many branches rather than just one.

Viruses as obligate parasites

  • Parasite Alert: Viruses need a host cell to grow, just like a bad roommate needs your fridge.
  • Logical Detective Work: If viruses need cells, then cells must have come first! This inheritance comes from LUCA (Last Universal Common Ancestor).

The two big ideas on virus evolution

  • Progressive Hypotheses: Like building a LEGO set, viruses were built step-by-step using and modifying cell parts.
  • Regressive Hypotheses: Like deconstructing a LEGO set, viruses developed by losing cell parts.

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IB Resources
Theme A - Unity & Diversity
Biology SL
Biology SL

Theme A - Unity & Diversity

Unlocking Viral Origins Evidence & Hypotheses

Word Count Emoji
514 words
Reading Time Emoji
3 mins read
Updated at Emoji
Last edited on 14th Jun 2024

Table of content

Introduction to viruses

  • What Are They? Tiny particles, smaller than cells, that can infect living organisms.
  • Big Question: Did viruses come before cells, or did cells come before viruses?

The hypothesis of single ancestry

  • The Clue: All viruses have nearly the same genetic code, so maybe they all came from one ancient virus.
  • But Wait, There's a Twist! The wide variety in virus structures hints they might have multiple origins. Imagine a huge family tree with many branches rather than just one.

Viruses as obligate parasites

  • Parasite Alert: Viruses need a host cell to grow, just like a bad roommate needs your fridge.
  • Logical Detective Work: If viruses need cells, then cells must have come first! This inheritance comes from LUCA (Last Universal Common Ancestor).

The two big ideas on virus evolution

  • Progressive Hypotheses: Like building a LEGO set, viruses were built step-by-step using and modifying cell parts.
  • Regressive Hypotheses: Like deconstructing a LEGO set, viruses developed by losing cell parts.

Unlock the Full Content! File Is Locked Emoji

Dive deeper and gain exclusive access to premium files of Biology SL. Subscribe now and get closer to that 45 🌟