The origin of cells 1.5

Life has evolved from the first cells to all the cells we find in the huge diversity of today's organisms. This topic covers the origins of cells and the cell theory proposed by Pasteur and Schwaan in an age when spontaneous generation of cells was still believed to occur.

Key concepts

Learn and test your biological vocabulary for 1.5 the origin of cells using these flashcards.


Essentials

These slides summarise the essential understanding and skills in this topic. 
They contain short explanations in text and images - good revision for all students.

Read the slides and look up any words or details you find difficult to understand.

Summary

Summary list for topic 1.5 The origin of cells

  • The first cells must have arisen from non-living material.
  • The origin of eukaryotic cells can be explained by the endosymbiotic theory.
  • Evidence from Pasteur’s experiments falsified the theory that spontaneous generation of cells and organisms occurs.

Mindmaps

These diagram summaries cover the main sections of topic 1.5 Origin of Cells.
Study them and draw your own list or concept map from memory.

Exam style question

Exam style question about endosymbiosis in cells

The question below, requires an understanding of membrane transport and cell organelles, so it is a good test of biological understanding. Write an answer on paper, then check the points in the model answer below.

Outline how evidence supports the idea that endosymbiosis gave rise to eukaryotic cells. [5]

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Extra exam question on the origin of cells  - - -  click the + symbol to open it -- >

Exam style question about the origin of cells

The question below, requires an understanding of the shared genetic code found in the DNA of cells.  It asks students to use their knowledge of the genetic evidence which is used to support claims of a common origin of life to interpret some specific data which has not been seen before.  It is a good test of analytical skills.

Write an answer on paper, then check the points in the model answer below.

The table shows the six codons found in mRNA of living species which code for the amino acid Leucine.  The numbers show the % abundance of each codon relative to all the Leucine codons in the genome of that species.

Discuss to what extent the data for % abundance of each of the Leucine codons supports the claim that life on Earth has a common origin. [4]

leucine codon table

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Extra exam question on the evidence of the common origin of cells   - - -  click the + symbol to open it -- >

Exam style question about evidence.

This question requires knowledge of cell theory and the origin of cells.

Question: Discuss the evidence that all cells have a common origin (4 marks)

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Examiner hint: Discuss requires a logical argument for both points supported by evidence.

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Test yourself

Multiple choice questions

This self marking multiple choice quiz contains questions covering the skills outlined above.


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Drag and drop activities

Test your ability to construct biological explanations using the drag and drop questions below.

The endosymbiont theory of the origin of eukaryotic cells.

Drag and drop the correct term into the gap to describe the endosymbiont theory.

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chloroplasts endosymbionts mutualistic ingested free-living prokaryotes photosynthesise eukaryotic aerobically

Lynn Margulis explained the origin of cells by the endosymbiotic theory. This hypothesises that and mitochondria were originally and, at some point in evolution, were by larger cells. Instead of being digested, they became in a relationship with the larger cell giving the larger cell the ability to and respire .

Explanation/Examiner hint. Describe means give a detailed account.


Just for fun

If you can't see the content below, please click this link to the Origin of cells card match game