Genes and the Laws of Inheritance

Lesson Plan

State Standards:

3.4 Distinguish among observed inheritance patterns caused by several types of genetic traits (dominant, recessive, codominant, sex-linked, polygenic, incomplete dominance, multiple alleles).
3.5 Describe how Mendel’s laws of segregation and independent assortment can be observed through patterns of inheritance (e.g., dihybrid crosses).
3.6 Use a Punnett Square to determine the probabilities for genotype and phenotype combinations in monohybrid crosses.
SIS1. Make observations, raise questions, and formulate hypotheses.
SIS3. Analyze and interpret results of scientific investigations.
SIS4. Communicate and apply the results of scientific investigations.

Essential Questions:

  1. How are genetic traits passed from one generation to the next?
  2. How do the laws of inheritance dictate gene expression in organisms?

Lesson Question:

  1. What are the chances of a trait being passed from one generation to the next?
  2. How close to real life genetic crosses compare to predicted outcomes?


Some traits are masked by other traits. In simple Mendelian genetics dominant traits will mask recessive traits. When crossing two different parents we can trace traits and the ability for the parents to pass on certain traits to the offspring. Punnett squares and the law of probability can help predict the likelihood of traits being passed to the next generation and then be compared to the actual outcomes. Traits do not always travel together during gamete formation, this is known as the law of independent assortment, which Mendel saw as he crossed his peas examining two traits at the same time.


Using the Wisconsin Fast Plant you will repeat what Mendel did with his peas. You will grow the plants watching for particular traits. While waiting for germination you will use a Punnett square to predict the different offspring to be produced, after the plants grow you will compare your results with your predicted results.

Using the Wisconsin Fast Plants that were planted 2-3 days ago, make predictions of outcomes and collect data of actual outcomes, pool data with the rest of the class, then analyze the data against the predicted data.

Wisconsin Fast Plants (already germinating)
Laptop with internet connection
Digital camera
Google Apps with a shared spreadsheet

1. Using a Punnett Square, predict the possible outcomes of offspring (8 min)
2. Create a Google document outlining your prediction (5 min)
3. Observe the Wisconsin Fast Plants offspring and photograph the plants (10 min)
4. Record offspring results in shared class spreadsheet (5 min)
5. In your document insert your pictures of plants and create a link to the class spreadsheet (5 min)
6. Compare your observed data with the predicted data and class data, also compare class data with your predicted data, record on your document (10 min)
7. Post analyzed results to class blog (5 min)

Lesson Experiences:


You should be able to describe how traits are masked or covered up in certain generation. You know the difference between dominant and recessive. You are able to utilize the chi-square analysis to determine if your investigation results were valid. You will also be able to present your information in a logical, clear manner.



Image Credit: Wisconsin Fast Plants