Download Genetic Traits Assignment

SCT 11
Genetic Traits Assignment
You can examine several “simple” inherited traits right now. The only materials you will
need are taste papers: sodium benzoate, thiorea, or PTC (phenylthiocarbamide).
Procedure:
1. Tear off a piece of taste paper. Place in on your tongue for a few seconds.
Record whether or not there was a certain taste.
2. Can you roll your tongue into a U with a groove down the middle? Can you fold
the tip of it back into your mouth? Many people have the dominant gene for
controlling the tongue muscle. People with the recessive gene cannot roll their
tongues.
3. Hold your hands in front of you with thumbs spread out. Are your thumbs fairly
straight or do they curve like those of a hitch-hiker? Record the shape of your
thumb and which gene you have. The dominant gene is for a bent thumb.
4. Hold your hands in front of you with the palms upward. Roll your fingers to
make a fist. Bend the fist upward, and watch the cords in your wrists. How
many cords are there? Are both wrists the same? Record the number of cords.
Two is the dominant condition, three, the recessive.
5. What is the shape of your earlobes? Record whether you have a free lobe that
hangs below the point where your ear joins your face, or attached lobe. Free
earlobes are dominant.
6. In some people, the hairline drops downward and forms a distinct point at the
centre of the forehead. This dominant condition is called a “widow’s peak”. Do
you have a “widow’s peak” ? Add this trait to your record.
7. Do you have hair on the middle joints of your knuckles? If so, you have the
dominant trait. Add this trait to your record.
8. Is your second toe longer than your big toe? This is a dominant trait with the Big
toe being longer as the recessive trait. Add this trait to your record.
9. Do you have dimples? This is a dominant trait with smooth cheeks as the
recessive trait. Add this to your record.
10. Do you have a protruding jaw like Jay Leno? This is a dominant trait with a
normal jaw as the recessive trait. Add this to your record.
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SCT 11
11. Are you Far-sighted or Near-sighted or have Astigmatism? These are dominant
traits with Normal vision as the recessive trait. Add this to your record.
12. Do you have normal color perception? This is a dominant trait with color
blindness as the recessive gene. Add this to your record.
13. Are you short? This is a dominant trait with tall stature being recessive trait. Add
this to your record.
Follow up Questions
1. Which Trait is the most common in your class? Which is the least common?
2. Do any students have traits that are intermediate between the dominant and recessive
traits? If there are intermediate traits, how many? Describe the intermediate traits.
1. Do dominant traits occur more often then recessive traits? Explain.
2. Predict how your observations might be different if you were to observe four other
classes of students.
3. State a hypothesis to explain why some students have traits that are intermediate.
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SCT 11
Observation Chart
Trait
My phenotype
My genotype
Ability to taste
chemical on
paper
Ability to roll
tongue
Taster
TT or Tt
Shape of thumb
Colour
Perception
Height
Percentage of
class with
dominant trait.
Non taster
Roller
Non roller
Curved
Straight
Number of
Two
Chords on wrist
Three
Shape of ear
Free Lobe
lobe
Attached
Shape of
Widow’s peak
hairline
Straight
Presence of hair Present
on middle joint
Absent
Length of toes
Long Second
toe
Long big toe
Presence of
Dimples
dimples
No Dimples
Jaw Shape
Large Jaw
Eyesight
Class total
rr
LL Ll
Small Jaw
Abnormal
Normal
Normal Colour
Colour Blind
Short Stature
Tall Stature
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