{"id":243658,"date":"2024-01-22T16:00:04","date_gmt":"2024-01-22T08:00:04","guid":{"rendered":"https:\/\/thepiquelab.com\/blog\/?p=243658"},"modified":"2024-04-04T11:56:51","modified_gmt":"2024-04-04T03:56:51","slug":"reproduction-how-well-do-you-know-your-family-tree","status":"publish","type":"post","link":"https:\/\/thepiquelab.com\/blog\/reproduction-how-well-do-you-know-your-family-tree\/","title":{"rendered":"Reproduction: How Well Do You Know Your Family Tree?"},"content":{"rendered":"

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Introduction <\/strong><\/p>\n

Have you ever looked at yourself in the mirror and wonder why you have double eyelids, but your sibling from the same set of parents has single eyelids?<\/p>\n

\"\"<\/p>\n

Well, I have! I have always been amazed by how my brother from the same set of parents can have such different characteristics from me.<\/p>\n

\n

\ud83c\udf1f Fun Fact! \ud83c\udf1f<\/strong><\/p>\n

That\u2019s because siblings (except identical twins) only share about half of their parents\u2019 genetic information!<\/p>\n<\/blockquote>\n

When I was younger, I also remember looking at the bony growth (bunion) beside my big toe and wonder why both of my parents do not have similar feet like mine\u2026 Years later, to my surprise, I found out that my grandmother has a similar bony growth as I do!<\/p>\n

\"\"<\/p>\n

To have a better understanding of why the above observations occur, follow me through this article where I will:<\/p>\n

1) Analyse a question on family tree<\/p>\n

2) Discuss how heredity works<\/p>\n

3) Brainstorm certain characteristics\/ traits that can\/ cannot be inherited!<\/p>\n\n

Let\u2019s Take A Look At This Question<\/strong><\/h2>\n

\"\"<\/p>\n

Source: Singapore Chinese Girls’ School \u2013 2021 P5 CA1 Examination Paper [Q10]<\/em><\/p>\n

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Read Also:<\/h3>\n
    \n
  1. Ultimate Science Practice Series: Reproduction (Practice Questions & Explainer Videos)<\/b><\/a><\/li>\n
  2. 2019 Tao Nan School (TNS) P5 SA1 Examination Paper Analysis<\/b><\/a><\/li>\n<\/ol>\n<\/div>\n

    Thought Process<\/strong><\/h2>\n

    To solve the above question, we need to first know how to analyse a family tree.<\/p>\n

    A family tree consists of different shapes (usually circles and squares) connected with lines. The different shapes represent the different genders.<\/p>\n

    \"\"<\/p>\n

    Let\u2019s start off simple.<\/p>\n

    \"\"<\/p>\n

    With reference to the family tree above, do you know who are these people that are labelled as \u201c?\u201d?<\/p>\n

    Since they are drawn one \u2018level\u2019 above you<\/strong> in the family tree, this means that they are one generation above you<\/strong>. And since they are directly connected<\/strong> to you, they must be your parents<\/strong> (refer to the diagram below)!<\/p>\n

    \"\"<\/p>\n

    Let\u2019s try something new. How about this family tree below? Do you know who is this person that is labelled as \u201c?\u201d?<\/p>\n

    \"\"<\/p>\n

    Since the square<\/strong> was drawn beside you<\/strong><\/span>, this means that this male<\/strong> is in the same generation<\/strong><\/span> as you! Additionally, since this male is also directly connected<\/strong><\/span> to your parents, this male is your brother<\/strong><\/span> (refer to the diagram below).<\/p>\n

    \"\"<\/p>\n

    Let\u2019s increase the difficulty level a little! Study the family tree below. Do you know who are these people that are labelled as \u201c?\u201d?<\/p>\n

    \"\"<\/p>\n

    \u00a0<\/strong>Let\u2019s start off with the shapes beside your father (Refer to the diagram below).<\/p>\n

    \"\"<\/p>\n

    Since the shapes are beside your father<\/span><\/strong>, this means that they are in the same generation as your father<\/span><\/strong>. Who do you think they are? They are your father\u2019s siblings<\/strong>!<\/p>\n

    Do you recall how you address your father\u2019s siblings whenever you meet them during family gatherings? You address them as aunt and uncle. (Refer to the diagram below) So let\u2019s label the two shapes beside your father as \u201cAunt\u201d and \u201cUncle\u201d.<\/p>\n

    \"\"<\/p>\n

    What about the two shapes that are still labelled as \u201c?\u201d in the above diagram?<\/p>\n

    \"\"<\/p>\n

    Notice that the two shapes are drawn one \u2018level\u2019 above<\/span> your father, aunt and uncle<\/strong>, which means that they are one generation above<\/span> your father, aunt and uncle<\/strong>!<\/p>\n

    Since the two shapes are directly connected<\/strong> to your<\/strong> father, aunt and uncle<\/strong><\/span> and are one generation above<\/strong> them<\/strong><\/span>, this means that they must be the parents of your father<\/span>, aunt and uncle<\/span><\/strong> (otherwise known as your paternal<\/span> grandparents<\/strong>), as seen from the diagram below!<\/p>\n

    \"\"<\/p>\n

    \n

    \ud83d\ude80 Key Takeaways On How To Read A Family Tree \ud83d\ude80<\/strong><\/p>\n

    1.\u00a0\u00a0\u00a0 Recognise the gender of the different individuals using the shapes (circle\/ square) given.<\/p>\n

    2.\u00a0\u00a0\u00a0 Determine the relationship between different individuals by looking at how the shapes are connected to each other (beside each other\/above the other).<\/p>\n

    3.\u00a0\u00a0\u00a0 Identify the generation the individual is from by looking at the \u2018level\u2019 the the shapes are drawn at.<\/p>\n<\/blockquote>\n

    Question Analysis<\/strong><\/h2>\n

    After understanding how to analyse a family tree, let\u2019s look at Pauline\u2019s family tree once more and you can try and identify how the different individuals in her family tree are related to Pauline.<\/p>\n

    \"\"<\/p>\n

    \"\"<\/p>\n

    Once you are done, check your answer with the family tree below! Did you manage to get all their relationships to Pauline correct?<\/p>\n

    \"\"<\/p>\n

    Analysis For Part (A)<\/h2>\n

    Now you know who\u2019s who, let\u2019s look at part (a) of the question.<\/p>\n

    \u201c(a) <\/em>Pauline inherited Characteristic P from her aunt\u201d.<\/em><\/p>\n

    To find out which individuals have characteristic P in Pauline\u2019s family tree, let\u2019s look at the key given in the question.<\/p>\n

    \"\"<\/p>\n

    From the key above, we can recognise that the shaded shapes represent individuals who have characteristic P while the non-shaded shapes represent individuals who do not have characteristic P.<\/p>\n

    \"\"<\/p>\n

    As you can see from Pauline\u2019s family tree, Pauline has characteristic P<\/strong>. It may come as a surprise to you, but did you notice anything special about Pauline\u2019s parents? Pauline\u2019s parents do not have characteristic P<\/strong>!<\/span><\/p>\n

    In this case, do you think Pauline inherited characteristic P from her parents? The answer is no!<\/p>\n

    Now, the big question to ask ourselves is: \u201cWho did Pauline inherit characteristic P from then?\u201d<\/p>\n

    Many students would claim that Pauline must have inherited characteristic P from her aunts since Pauline\u2019s aunt 1 and aunt 3 have characteristic P as well.<\/p>\n

    Is the above claim correct? To answer this question, let\u2019s recall how reproduction in animals occur. During the process of fertilisation, the nucleus of an egg cell from the mother<\/strong> fuses with the nucleus of a sperm cell from the father<\/strong>. As such, the genetic information of both parents will be passed down to their offspring, allowing the offspring to inherit certain characteristics\/ traits from both parents<\/strong>.<\/p>\n

    Based on what we mentioned above, do you think you will be able to inherit characteristics\/ traits from your aunt and uncle<\/strong>? The answer is\u2026no! Your aunt\u2019s and uncle\u2019s genetic information are not passed down to you!<\/p>\n

    Once again, referring to the statement from (a): Pauline inherited Characteristic P from her aunt, <\/em>we can conclude the statement should be false. <\/strong><\/span><\/p>\n

    \"\"<\/p>\n

    Source: Singapore Chinese Girls’ School \u2013 2021 P5 CA1 Examination Paper [Q10]<\/em><\/p>\n

    \"\"<\/p>\n

    In that case, who do you think Pauline inherited characteristic P from then? If you are thinking of the \u201cmaternal grandfather\/ paternal grandmother\u201d, you are correct!<\/p>\n

    \n

    \ud83e\udde2<\/strong> Put On Your Thinking Caps <\/strong>\ud83e\udde2<\/strong>\u00a0<\/strong><\/p>\n

    It is certainly possible that we inherit characteristic\/ traits from our (maternal\/ paternal) grandparents as our grandparents are the ones that passed down their genetic information to our parents, where our parents then passed down their genetic information to us!<\/p>\n<\/blockquote>\n

    You can refer to the purple and blue highlights drawn on the family tree below to show how Pauline was able to inherit characteristic P from her maternal grandfather\/ paternal grandmother (and not from her aunt).<\/p>\n

    \"\"<\/p>\n

    \n

    \ud83c\udf1f Fun Fact! \ud83c\udf1f<\/strong><\/p>\n

    As a matter of fact, an average of about 25% of our genetic information is actually inherited from each of our grandparents!<\/p>\n<\/blockquote>\n

    If you want to find out more about the above, you can click on the link below: https:\/\/support.ancestry.com\/s\/article\/Unexpected-Ethnicity-Results?language=en_US<\/a><\/p>\n

    Analysis For Part (B)<\/h2>\n

    Let\u2019s now take a look at part (b):<\/p>\n

    \u201cIf both parents<\/u><\/strong> have Characteristic P,<\/em><\/p>\n

    \u00a0their children will definitely have characteristic P.\u201d<\/em><\/p>\n

    \n

    \u2757\ufe0fTake Note\u2757\ufe0f<\/strong><\/p>\n

    Notice a key phrase<\/strong> in the question, \u201cBased on the family tree above\u201d<\/strong>.<\/p>\n

    It is important to refer to the given family tree to come up with the correct answer!<\/p>\n<\/blockquote>\n

    Using the family tree given in the diagram below, are we able to tell whether statement (b) is true or false?<\/p>\n

    \"\"<\/p>\n

    You would notice from the family tree above that there are no cases<\/strong> where both<\/strong> parents<\/strong> have characteristic P:<\/p>\n

      \n
    1. The maternal grandmother (parent of the mother) does not have characteristic P.<\/li>\n
    2. The paternal grandfather (parent of the father) does not have characteristic P.<\/li>\n
    3. Both the mother and father (parents of Pauline) do not have characteristic P.<\/li>\n<\/ol>\n

      Thus, the statement for part (b) should be: not possible to tell.<\/strong><\/span><\/p>\n

      \"\"<\/p>\n

      Source: Singapore Chinese Girls’ School \u2013 2021 P5 CA1 Examination Paper [Q10]<\/em><\/p>\n

      Analysis For Part (C)<\/h2>\n

      Let\u2019s take a look at part (c):<\/p>\n

      \u201cIf both parents do not have Characteristic P, <\/em><\/p>\n

      their children will definitely not have characteristic P.\u201d<\/em><\/p>\n

      Let\u2019s refer to Pauline and her parents in the family tree below to clarify statement (c).<\/p>\n

      \"\"<\/p>\n

      From the family tree above, we can see that both of Pauline\u2019s parents do not have characteristic P<\/strong>, but Pauline<\/strong><\/span> and her brother have characteristic P<\/strong><\/span>.<\/p>\n

      Therefore, the statement for part (c) is false!<\/strong><\/span><\/p>\n

      \"\"<\/p>\n

      Source: Singapore Chinese Girls’ School \u2013 2021 P5 CA1 Examination Paper [Q10]<\/em><\/p>\n

      Analysis For Part (D)<\/h2>\n

      Last but not least, the question for part (d) is:<\/p>\n

      \u201cUsing the information given in the family tree, explain your answer for (c).\u201d<\/em><\/p>\n

      As discussed in the \u201cPUT ON YOUR THINKING CAPS\u201d section for the analysis for part (a), while both of Pauline\u2019s parents do not have characteristic P, Pauline could still inherit characteristic P from a generation above her parents, who are her grandparents.<\/p>\n

      As such, this is my suggested answer for part (d):<\/p>\n

      \u201c<\/strong>Pauline\u2019s parents do not have characteristic P but Pauline and her brother have characteristic P, which was inherited from their grandparents who have characteristic P.\u201d<\/strong><\/span><\/p>\n

      Food For Thought!<\/strong><\/h2>\n

      Are you able to list some common characteristics\/ traits that you can and cannot inherit from your parents\/ grandparents?<\/p>\n

      Heritable characteristics<\/strong><\/p>\n