Name _______________________________________
Genetics
Section 6.3: Mendel and Heredity
Main Ideas:
 Mendel laid the groundwork for genetics
 Mendel’s data revealed patterns of inheritance
Vocabulary:
 Trait
 Genetics
 Purebred


Cross
Law of Segregation
1. Define the term “traits”.
2. Give three examples of traits which YOU have.
3. What is Genetics?
4. Who was Gregor Mendel and what did he contribute to the study of genetics?
5. Why did Mendel use pea plants for his genetic experiments?
6. What does it mean for a plant like peas to “self-pollinate”?
7. If a pea plant which has always produced purple flowers is mated with another pea plant which has
always produced purple flowers, all of their offspring will also have only purple flowers. What is the
term for this line that only shows the traits of the parents? _____________________
8. What did Mendel do to the pea plant flowers to stop them from self-pollinate?
9. Genetically speaking, what is the term for mating two organisms? ____________
10. Look at Figure 6.9 and discuss his experiment.
a. What was the color of the two Parent plants (P generation)? ___________ & _____________
b. What was the color of all their offspring (F1 generation)? ________________________
c. What happened when he took two plants from the F1 generation and crossed them? What were
the results of the F2 generation?
d. What was the ratio of the purple to white flower producing plants? _____ : _____
11. Mendel was worried that when he crossed the pure purples with the pure white P generation plants, that
the trait for white flowers disappeared or was lost in the F1 purple flowers. Was the trait actually lost?
How could he prove that the white flower trait was not lost but hidden in the F1 plants?
12. Label the generations below according to Figure 6.9
13. Discuss Mendel’s First Law also known as his Law of Segregation
Section 6.4: Traits, Genes and Alleles
Main Ideas:
 The same gene can have many versions
 Genes influence the development of traits
Vocabulary:
 Gene
 Allele
 Homozygous



Heterozygous
Genome
Genotype



Phenotype
Dominant
Recessive
14. What is a gene?
15. What is produced as a result of a gene on DNA? ___________________________
Homologous chromosomes are a pair of chromosomes that have genes located in the same spot or locus on
the chromosome but one of the pair came from the mother and the other one came from the father. The trait
or allele for the gene does not have to be the same. Dad could give you a gene for blue eyes and mom could
give you a gene for brown eyes. We have 23 pairs of homologous chromosomes.
16. What is an allele?
17. What are the different alleles for the gene for hair color in us?
18. If mom gave you an allele for being right handed and dad gave you an allele for being right handed, you
would have two alleles for being right handed and you would be right handed. What is the term for
having two like alleles for a trait? _______________________
19. What if mom gave you a right handed allele and dad gave you a left handed allele. What is the term for
having two different alleles for a trait? _______________________
20. The human genome is made up of 3.2 billion nucleotide pairs (nucleotides are the monomers of DNA).
What is a genome?
21. If you got an allele for having blue eyes from one parent and the allele for having brown eyes from the
other, you may have brown eyes but you are heterozygous for the eye color trait meaning you have
brown allele and a blue allele. Your genetic makeup for eye color describes your ________________
22. For the same trait as above. If you have blue allele and a brown allele, you are most likely going have
brown eyes. We can see this by looking at your eyes. The physical appearance or characteristic of a
trait is called the _________________________.
23. Define what a dominant trait is.
24. Define what it means to be the recessive trait.
25. As you can see from Figure 6.11, having 5 toes is recessive to having more than 5 toes or being
polydactyl. Does the term dominant mean that it is predominant in a population? Discuss this.
26. The right handed allele is dominant over the left handed allele. What symbol will we use to represent the
Right handed allele? ______ What symbol will be used to represent the left handed allele? _____
27. If someone is pure or homozygous for the right handed alleled, we would represent their genotype using
the symbols ______.
If someone had a right and a left handed allele or was heterozygous, their genotype would be written as
________.
If someone was pure or homozygous for being left handed, then their genotype would be ______.
28. If you are right handed (this is your phenotype), there are two possibilities for your genotype. What
could be your genotype for the right handed trait? ________ or _______
Here is where you get your family involved. Check to see what traits are found in your family:
 Hand preference
 Eye color
 Hair color
 Dimples
 If they are flat footed or not
 Can they roll their tongues
 Do they cross their thumbs left over right or right over left