Essential Idea
There is an unbroken chain of life from the first cells on Earth to all cells in organisms alive today.
Understandings
Cells can only be formed by division of pre-existing cells.
The first cells must have arisen from non-living material.
The origin of eukaryotic cells can be explained by the endosymbiotic theory.
Applications
Evidence from Pasteur's experiments that spontaneous generation of cells/organisms does not now occur on Earth.
Skills
None
Guidance
Evidence for the endosymbiotic theory is expected. The origin of eukaryote cilia and flagella does not need to be included.
Students should be aware that the 64 codons in the genetic code have the same meanings in nearly all organisms, but that there are some minor variations that are likely to have accrued since the common origin of life on Earth.
Key Vocabulary
Click HERE for definitions and illustrations.
Endosymbiotic thoery
Endosymbiosis
Eukaryotic cells
Spontaneous generation
Textbook Reading and/or Activities
Click HERE for a pdf of chapter 1.
Pages 39-41
Nature of Science (p.XY)
Worked Example (p.YZ)
Notes
A detailed set of notes, prepared by Bob Smullen, examining all of the IB learning expectations.
Essentially an online textbook outlining the entire subtopic in specific detail. Please use this resource.
i-Biology Notes (Not available)
A detailed set of notes, prepared by Stephen Taylor, examining U1 - U8 and A2 - A3.
i-Biology Study Questions (Not available)
A series of questions, prepared by Stephen Taylor, to help check your understanding of the IB learning expectations. This is VERY GOOD practice.
A detailed set of notes, prepared by Chris Paine, examining all of the IB learning expectations.
A series of questions, prepared by Chris Paine, to help check your understanding of the IB learning expectations. This is VERY GOOD practice.
A detailed set of notes, prepared by Jacob Cedarbaum, examining all of the IB learning expectations.
A series of questions, prepared by Jacob Cedarbaum, to help check your understanding of the IB learning expectations. This is VERY GOOD practice. Answers.
Learning Activities
The University of Utah has prepared this short read (about 5-7 minutes) describing the process by which most scientists think eukaryotic cells evolved.
The University of California, Berkeley has prepared this read (about 5-7 minutes) outlining the evidence supporting the endosymbiotic theory.
Cell Mergers and the Evolution of New Life Forms
From the Huffington Post (2012), this read (about 20 minutes) examines endosymbiosis (symbiogenesis); how it happened (producing eukaryotic cells) and how it continues to happen (the discovery of photosynthetic "animals").
This animated tutorial describes the procedures carried out to test spontaneous generation.
Supplemental Reading
Title
Description
This video introduces the issues related to the origin of life on Earth, including a definition of life, spontaneous generation, Pasteur's swan-neck flask experiment, different cell types, possible origins of organic material and eventually evolution.
Must Watch Videos
This video outlines the process by which organic compounds
likely came into existence through random chemical reactions,
which later led the formation of simple cell-like structures.
This video outlines the process by which scientists think that
eukaryotic cells came into existence. It also examines the
evidence for this thinking.
This video outlines the process and evidence for which most
scientists believe is the origin of eukaryotic cells.
Should Watch Videos
This video describes how primitive cells could have self-assembeled from simple organic compounds present on the ancient Earth. Video Questions
This video describes the evolutionary event of endosymbiosis and its impact on life afterward.
This video describes a variety of competing ideas about how
life may have began on Earth. It's a little long but worth a
watch if you can make time.
This video describes Louis Pasteur's Swan Neck Flask
Experiment, which disproved the idea of spontaneous
generation, as well as Miller and Urey's Experiment, which
wanted to find out if simple organic molecules could form in
the early Earth's environment.