The Cell Theory Debate

When there is evidence to disprove a theory scientists have to start doubting the theory. This is particulary difficult to do when the theory has obvious uses, and if the theory has been accepted for a long time. Cell theory is an example of a theory where it can be applied to nearly all organisms but with a few specific exceptions. Should we abandon the theory?

Make a four slide presentation

  1. what is cell theory
  2. what evidence is there that supports it?
  3. what examples of cells are there which don't support it. (fungal hyphae, skeletal muscles, amoeba)
  4. should we keep it

Read page 6 of the Clegg Text book before you start.

 

Table of Key information to Include.

2.1.1

Outline the cell theory.

2

Include the following.

  1. Living organisms are composed of cells.
  2. Cells are the smallest unit of life.
  3. Cells come from pre-existing cells.
  

2.1.2

Discuss the evidence for the cell theory.

3

Evidence...

  1. There are lots of Observations of living things made of cells
  2. Cells can survive on their own, but organelles can't, - so organelles aren't smallest units of life because they can't live on their own. Cells can.

    Viruses can't do any metabolism themselves, they need to be inside a host cell. They are smaller than cells, but not capable of 'living' without host cells.
  3. Cells can been seen to divide using Mitosis in the microscope, this is evidence for (c)

 

  

2.1.3

State that unicellular organisms carry out all the functions of life.

1

This is evidence that contradicts Cell theory
Single celled organisms are not made of cells, their bodies are not subdivided.

One cell is actually an organism.. It can do everything an organism can...Including: metabolism (eg respiration), response, homeostasis, growth, reproduction and nutrition.

Other evidence that contradicts Cell theory.....

Fungal hyphae and Skeletal muscle is not really made of cells....... they have multinucleate cytoplasm.