Beyond Dominant and Recessive: Snapdragons and Blood Types

SubstitutePlans.com
Science · Biology
SP-BIO-009 · Free to print and use in your classroom · substituteplans.com
Page 2
Beyond Dominant and Recessive: Snapdragons
and Blood Types
Science · Biology · Grades 10 · 50 minutes
Time needed
50 minutes (one class period)
Prep
Copy the 2-page worksheet (one per student). No lab materials needed.
Technology
None.
Student
independence
High. Individual work with a partner check.
Copies to make
One 2-page worksheet per student
Materials
Pencils, Worksheet
Goal for today: Students will use Punnett squares to predict offspring in incomplete dominance and codominance and
will tell these patterns apart from simple dominance.
Before the bell
☐ Copy the worksheet, one per student (2 pages).
☐ Write on the board: Incomplete dominance = a blend (RW = pink). Codominance = both alleles show at the
same time (I^A I^B = type AB).
☐ Keep the answer key on your desk. Remind students that this is practice with imaginary parents, and they do
not need to share their own blood types.
Say this to start
So far you may have worked with traits where one allele hides the other. Today we look at two other patterns. In one,
the traits blend. In the other, both traits show at the same time. You will use the same Punnett square method as
before. The key terms are on the board and in the reading.
Run of show
Minutes
What you do
What students do
0–5
Take attendance. Hand out the worksheet and read the
directions aloud.
Look over the worksheet.
5–13
Tell students to read the passage silently. Read the two
board definitions aloud.
Read silently and underline the definitions.
13–27
Tell students to complete Part A: both snapdragon squares
and questions 1–4.
Fill in the squares and answer the
questions.
27–41
Tell students to complete Part B: the blood type square and
questions 5–11.
Fill in the square and answer the questions.
41–46
Read the square answers and questions aloud from the
key. Students check their own work.
Correct mistakes in a different color.
46–50
Collect the worksheets and place them in a stack for the
teacher.
Hand in the worksheet.

SubstitutePlans.com
Science · Biology
SP-BIO-009 · Free to print and use in your classroom · substituteplans.com
Page 3
If things go wrong
• If students ask whether blood type matters for their own health: tell them this is a genetics practice and to
ask a doctor or the school nurse for personal questions. Do not collect real blood types.
• If students are confused by I^A and i: I^A and I^B are two different alleles, and i is a third. The letter i is
recessive to both.
• If a student finishes early, use the early finisher list.
• If the room gets loud, move to silent work for five minutes.
Early finishers
• Cross a pink snapdragon (RW) with a white snapdragon (WW) on the back. Give the genotype and phenotype
ratios.
• Explain in two sentences how codominance is different from a blend.
Support and challenge
• Support: Provide the squares’ first row and let students complete the rest, using the board definitions.
• Challenge: Ask students to explain why two type A parents could have a type O child, using a Punnett square.
Notes for the teacher (you fill this in)
Jot a few lines before you leave. A full Daily Sub Report is in the free Sub Survival Kit at SubstitutePlans.com.
How far the class got / what to pick up next:
Students who were especially helpful:
Anything the teacher should know: