CASE ANALYSIS SHEET
1.
Recognize potential issues and major topics in the case What is this case about?
Underline and list terms or phrases that seem to be important.
Then, list 3-4 biology-related topics or issues in the case.
Inheritance
Reproduction in humans
Probability
Family
Twins
2. What specific questions do you have about these topics? By yourself, or better yet in a group, list what
you already know about this case in the “What Do I Know?” column. List questions you would like to learn
more about in the “What Do I Need to Know?” column.
What Do I Know?
What Do I Need to Know?
 Tongue rolling is heritable
 Process of meiosis, crossing over
and assortment leads to variations
in sperm and eggs
 They are fraternal twins
 Tongue rolling is controlled by
dominant gene
 One parent is homozygous
recessive and other is
heterozygous for tongue rolling
 Twins are born during same birth
event
 Is tongue rolling
dominant/recessive? Single gene
or multiple genes?
 Identical twins? Vs. fraternal?
 Why are the fraternal twins
different?
 What would be the difference
between identical twins and
fraternal twins with regard to
tongue rolling
 How does environment affect the
development of twins (turning
genes on and off)
 How long can one twin survive in
the mother after the first one is
born?
3. Put a check mark by 1-3 questions or issues in the “What do I need to know?” list that you think are
most important to explore.
Waterman, M. A. and Stanley, E. D. 2004. ICBL Case Analysis Worksheet. NIE Workshops 2015
US-04
4. What kinds of references or resources will help you answer or explore these questions?
Identify two different resources and explain what information each resource is likely to
give that will help you answer the question(s). Choose specific resources or types of
resources.
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Textbook, chapter on inheritance
Search fraternal twins survival in mother
YouTube on twins biology
Google scholar: inheritance biology twins pdf or ppt
Cold Spring Harbor DNA lab
OMIM online Mendelian inheritance in Man
Google search: chances of having twins
Interview with distant family member who had Fertility
treatment resulting in quadruplets
Email an expert, such as someone at NUS or NTU or family
doctor
Research journal, e.g., Nature, looking for articles on twins
McGraw Hill website with flash video on mitosis
Learn.genetics.utah.edu
Waterman, M. A. and Stanley, E. D. 2004. ICBL Case Analysis Worksheet. NIE Workshops 2015
US-04