1. Aim: What did Mendel learn from his experiments?
Do Now: Many people believe Mendel’s experiments were some of the best in scientific history. Do you agree or disagree? Write at least three sentences to justify your opinion!

2. How did Mendel do this experiment?
Mendel created two “true- breeding” plants, which are plants that reproduce their own kind. Meaning that the purple flowered plants if crossed with each other, would always produce purple offspring. The white flowered plants if crossed with each other would always produce white flowered offspring.

3. Question: What do YOU think his results were?
Mendel’s Experiment
Once Mendel was sure he had true-breeding white flowered plants, and true breeding purple plants, he crossed a white flowered plant with a purple flowered plant.
Question: What do YOU think his results were?

4. Question: What do YOU think his next results were? Why?
Mendel’s Results!
When Mendel crossed a true-breeding white plant and a true breeding purple one, he got 100% purple flowered plants!
Next, he decided to take two of the plants from this new, all purple generation and cross them...
Question: What do YOU think his next results were? Why?

5. Question: Why do you think the white trait reappeared?
Mendel’s Results!
When Mendel crossed this new generation of plants with each other, he discovered that most of the offspring were purple, but some where white! The white trait had somehow reappeared!
Question: Why do you think the white trait reappeared?

6. The Law of Dominance
Mendel concluded that some factors or traits, later called genes, do not disappear but are masked or hidden by other traits.
Some genes are dominant, meaning if they are present then the organism will express (show) that trait.
Some genes are recessive, meaning that if the organism has two recessive genes the recessive trait will be seen, but if there is a dominant gene the recessive trait will be masked or hidden.
Mendel’s Conclusions
Question: Which color flower was dominant in Mendel’s experiment? Explain your answer!

7. Mendel’s Conclusions
Mendel wondered why the recessive trait disappeared, and reappeared again.
He hypothesized that every trait is controlled by two “factors” (genes).
QUESTION: Why might each factor be controlled by two genes? Think about where an organism’s traits come from!

8. Mendel’s Conclusions
The Law of Segregation
For every trait there is a pair of genes that controls the trait, one from each parent.
Each parent randomly passes on one of their two factors to offspring, and the combination will result in the offspring’s traits.
There are three possible combinations of traits --
Dominant/Dominant
Dominant/Recessive
Recessive/Recessive
Question: If an organism has one dominant and one recessive trait, which one will be expressed?

9. Question!
Discuss the following question with your partner, and write your answer in your notebook in complete sentences:
A brown-eyed man mates with a brown- eyed woman. They have a child with blue eyes! The father suspects that the mother is cheating, do you think his reason is valid? How could this happen? Explain!