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History of Genetics Reading Guide
1.
Using the picture of the cats on page 10, list all of the physical characteristics that may be different
amongst these cats or other cats.
Fur color
Fur length
Ear shape
Nose color
Eye color
Body shape
Tail length
Fur texture
Leg length
Paw size
2. Until around 1900, most people thought that it was a matter of chance if you received a particular physical
trait, such as long hair. What other traits besides physical (ones that you can see) are passed on from
parent to offspring (children)?
3. All living things resemble their
Personality, likes/dislikes, metabolism, talents
parents but each individual has unique characteristics that make them
unique(different) from every other living thing on Earth.
4. A purebred cat is one where an owner knows the parents for at least five generations. Draw a diagram to
figure out how many cats that involves.
63 cats
Fluffy the Purebred Cat
-----------------------------------------------------------------------------------------------------------Generation 1(parents)
-----------------------------------------------------------------------------------------------------------Generation 2(grand-parents)
-----------------------------------------------------------------------------------------------------------Generation 3(and so-on)
-----------------------------------------------------------------------------------------------------------Generation 4
-----------------------------------------------------------------------------------------------------------Generation 5
-----------------------------------------------------------------------------------------------------------5. Give a brief biography of Gregor Mendel.
Mendel was born in Austria in 1822. He was an ordained monk, living in a
monastery in Czeckeslovakia and teaching high school. He enjoyed working in
the garden and greenhouse. His work with pea plants led him to make
several discoveries about the patterns of heredity and how traits can be
passed from parents to offspring. He is known as the ‘father of genetics’.
6. Give the reasons why Mendel chose to work with pea plants.
Mendel worked with pea plants because they grew quickly, reproduced
quickly, and have several physical traits that are easily studied.
7. Define trait:
characteristics that are passed from parents to offspring.
8. Why did Mendel choose to cross-pollinate plants instead of letting them pollinate themselves?
Cross-pollination allowed Mendel to blend plants with different traits.
the study of heredity or the passing of traits from an organism
to its offspring.
9. Define genetics:
10. What did Mendel mean when he called plants true-breeding?
True-breeding means that the plants always produce offspring with the
same traits as the parents.
11. What were the results when Mendel crossed only short plants?
Short parent plants only produced short offspring plants.
12. What were the results when Mendel crossed only tall plants?
Mendel got mixed results, sometimes all tall, sometimes tall and short..
13. What were Mendel’s conclusions from the surprising results of the tall plant crosses?
If the tall plants were true-breeding, then he got only tall offspring plants.
If both plants were not true-breeding, he got some short offspring plants.
14. What were the results when Mendel crossed a true breeding tall plant with a true breeding short plant?
Mendel got all tall plants with true-breeding tall plants and true-breeding
short plants.
15. Define F1 and F2:
F1 is the first generation of offspring (kids). F2 is the second generation of
offspring (grandkids).
16. What were the results when Mendel allowed the F1 generation to self-pollinate?
When the F1 generation self-pollinated, some of the offspring were short.
17. Why were these results surprising?
This was surprising because you had two tall plants producing short plants.
18. Define genes:
the units of heredity.
19. What terms did Mendel use to describe the ‘strength’ of genes?
Mendel used dominant and recessive.
20. How are dominant and recessive traits represented with symbols?
Dominant is represented by a capital letter. Recessive is represented by a
lower-case letter.
21. Every organism has
two forms of the gene for each of their traits.
22. A true-breeding tall plant will have the symbol
23. A hybrid short plant will have the symbol
TT.
Tt.
24. What does a symbol, Tt, represent?
Tt means that the organism has one tall gene and one short gene, it will
appear tall because tall is a dominant trait.
25. How would you symbolize the human dominant trait of right-handedness? Of left-handedness?
The dominant trait would be RR or Rr. The recessive trait would be rr.
26. When Mendel crossed pea plants that produced only round seeds with plants that produced only wrinkled
seeds, all the plants in the F1 generation produced rounds seeds. However, in the F2 generation some plants
produced wrinkled seeds. Which trait, round seeds or wrinkled seeds, is dominant? Recessive?
Since all of the F1 generation had round seeds, the dominant trait is round
(Rr). When two Rr plants were crossed to make the F2 generation, some
plants became rr, or wrinkled.