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A2.2 Cell differentiation - written task

This structured extension question is in the style of the IB exam questions. It has a particular focus on the concept of cell differentiation and the question begins with a little bit of information about a research paper.  This provides some clues to help answer the questions, but not the answers.

Students will need to make links between this example and the concept of cell differentiation, and other examples will need to be known to answer this question well.

  • This could be a classroom task, a revision moment or a homework activity.
  • There is a hidden model answer which appears when the answer is submitted.

In stem cell research (Buttery, 2001) found evidence that supported the hypothesis that supplemental vitamin C improves the differentiation of mouse embryonic stems cell into specialised tissues, including, cartilage, bone, and blood.

The research suggest that Vitamin C may influence stem cell differentiation by modulating DNA and histone demethylation.  This is an excellent example of a cell's environment affecting cell differentiation in bone marrow.

Reference; Buttery L. D., et al, Differentiation of osteoblasts and in vitro bone formation from murine embryonic stem cells, Tissue Engineering. (2001) 
Image source: D.Faure 2024 CC BT

 

 

 

Describe the process of cell differentiation (2 marks)

3 lines
Show model answer


Outline a different example which illustrates how cell differentiation can be initiated (or promoted) by an environmental stimulus.
(2 marks)

3 lines
Show model answer
Model answer
Describe the process of cell differentiation (2 marks)
Cell differentiation is the production of specialised cells or tissues.
It is caused by a change in gene expression.
The genes which are expressed cause the production of new proteins./ New functional proteins change the activity of the cell.

Outline a different example which illustrates how cell differentiation can be initiated (or promoted) by an environmental stimulus.   (2 marks)
One mark for the description of an environmental stimulus (1 mark).
One mark for the explanation of the change to gene expression or cell production (1 mark).

SUGGESTIONS
An example of an environmental stimulus --  the change to the length of day during the seasons.
  • Short days and long nights cause flowering in some species of flowering plants (Angiosperms).
  • Cell differentiation occurs in the buds causing them to form flower tissues and not leaf tissues.
OR
  • Mating seasons affects fertility in small mammals.
  • The production of gametes in ovaries is triggered by an increase in day length.
  • Germ cells develop by (meiosis and) differentiation into mature gamete cells

Teachers note - The example should be correct and relevant but the details of the mechanism are not needed in this topic.

 

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