Incomplete Dominance and Codominance Crosses
Written by Adi Ackerman, Head Teacher
"Incomplete Dominance and Codominance Crosses" is written for 7th Grade (Ages 12-13), and it covers NGSS MS-LS3-2. A 6th grader who is already steady on living things can use it too, and an older student can use it as a short review.
2 pages in this set
7th grade science worksheet: cross snapdragons and cattle with Punnett squares to tell incomplete dominance from codominance. Answer key included. Part of our heredity living things collection. Aligned to NGSS standards.
How do I use this worksheet?
Start with the gene to protein sheet and the pedigree, then crosses. Use the DNA band sheets as application cases once students understand how gel electrophoresis sorts DNA.
What students will practice
- Students will compare simple dominance, incomplete dominance and codominance.
- Students will fill in Punnett squares for snapdragon and cattle crosses and write the ratios.
- Students will name the pattern shown by the offspring counts of a cross.
Curriculum Links
Next Generation Science Standards
Science · 7th Grade
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FAQ
How do I use this heredity worksheet?
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Start with the gene to protein sheet and the pedigree, then crosses. Use the DNA band sheets as application cases once students understand how gel electrophoresis sorts DNA.
What does this worksheet teach?
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Cross snapdragons and cattle with Punnett squares to tell incomplete dominance from codominance. The directions on the page read: Put one parent's alleles on top and the other's on the side. Fill in each square and line. An answer key is included.
Can I use this heredity worksheet for homeschool or classroom?
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Yes, both. We made it for 7th grade living things, and it works the same at home or at school. At home, a student can work through it alone and then go over it with you, which shows quickly what is solid and what needs another look. In class it works as independent practice, homework or a warm-up, and you can print one copy or a full set.
What is the difference between a gene and a chromosome?
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A gene is one stretch of DNA that holds the instructions for one protein. A chromosome is a long molecule of DNA that can hold hundreds or thousands of genes.
What is a DNA band?
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A band is a group of DNA pieces of the same length on a gel. Samples with matching bands carry matching pieces of DNA.
How do mutations change a protein?
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A substitution, insertion or deletion changes the letters of mRNA, which a cell reads three at a time. The sheet shows when the protein changes and when it does not.
What is incomplete dominance?
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A mixed offspring is a blend between the parents, such as pink snapdragons from red and white parents.
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Worksheet Details
| Grade | 7th Grade |
| Subject | Science |
| Topic | Living Things |
| Standard | MS-LS3-2 |
| Pages | 2 pages |
| Difficulty | Medium |
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