Download Mendel`s Work Notes - Nashua School District

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Mendel’s Work Notes
From Prentice Hall, pages 110-115
MI: Gregor Mendel made important discoveries with pea plants that became the basis
of today’s _______________, or the scientific study of heredity.
SD1: Mendel was a priest that lived in a monastery in central _______________
in the mid-19th century.
SD2: Mendel noticed that some pea plants had _____________, or different
forms of a characteristic, that were the same as their parents, but some did not.
SD3: To find out more about _______________, or the passing of physical
characteristics from parents to offspring, Mendel worked with thousands of pea
plants.
Mendel’s Experiments, page 111
MI: Mendel learned about the inheritance in __________ plants by studying
contrasting traits using a process of cross-pollination.
SD1: In flowers, pistils produce _______________, or female sex cells, while
stamens produce _______________, or male sex cells.
SD2: Pollination occurs when the pollen reaches the pistil of the flower so that
_______________, the process in which an egg and a sperm join to form a new
organism, can occur.
SD3: Normally, pea plants self-pollinate, but Mendel developed his own way to
cross-pollinate by taking _______________ from one plant and brushing onto a
second plant.
Crossing Pea Plants
SD1: Mendel worked with traits that were opposite – like tall and
_______________.
SD2: He began his experiments with _______________ plants, which are
organisms that are the offspring of many generations that have the same trait.
The F1 Offspring
SD1: One experiment crossed tall plants and short plants, which scientists now
call these plants the P generation for _______________ generation.
SD2: The offspring of this cross are called the ___________ generation, which
comes from the word _______________ derived from the Latin words filia
(“daughter”) and filius (“son”).
SD3: All of these plants were tall – there were no _______________ plants!
The F2 Offspring
SD1: Mendel allowed these tall plants to _______________ to see what their
offspring would look like.
SD2: Surprisingly, the F2 generation was _____ (#) tall and ______(#) short.
Experiments With Other Traits
SD1: Mendel repeated this experiment with these other traits:
Seed shape: __________ or __________
Seed color: __________ or ___________
Seed coat color: __________ or __________
Pod shape: __________ or __________
Pod color: __________ or __________
Flower position: __________ or __________
Stem height: __________ or __________
SD2: He observed that only one form of each trait appeared in the _____
generation, while the second form came back in the F2 generation in about
_____(#) of the plants.
Dominant and Recessive Alleles, page 113
MI: Mendel determined that organisms receive one factor for each trait from each
parent and that some factors are stronger or cover up other factors.
Genes and Alleles
SD1: A _______________ is a factor that controls a trait, and
_______________ are the different forms of a gene.
SD2: An organism receives two alleles for every trait – one allele in the
__________ from the mother and one allele in the __________ from the father.
SD3: Some alleles are _______________, which is one whose trait ALWAYS
shows up when present; while other alleles are _______________, which is one
that is hidden whenever the dominant allele is present.
SD4: In pea plants, __________ is dominant to short – so a plant with two
dominant alleles is tall, a plant with one dominant and one recessive allele is also
tall, and only a plant with two _______________ alleles will be short.
Alleles in Mendel’s Crosses
SD1: In the P generation, the purebred tall plants had two (dominant/recessive)
alleles; while the purebred short plants had two (dominant/recessive) alleles.
SD2: The F1 generation had one dominant and one recessive allele, which
means they were _______________ - an organism that has two different alleles
for a trait.
SD3: In the F2 generation, some plants received both dominant alleles, some
plants received both recessive alleles, and some plants received one of each – a
dominant and a recessive allele, which explains why most were (tall/short), but
some were (tall/short).
Symbols for Alleles
SD1: Scientists use a __________ letter for dominant alleles (T) and a
__________ letter for recessive alleles (t).
SD2: So two dominant alleles is written as (TT/Tt/tt), two recessive alleles is
written as (TT/Tt/tt), and one dominant and one recessive allele is written as
(TT/Tt/tt).
Significance of Mendel’s Contributions
SD1: The public generally believed that your traits were a __________ of your
parents’ traits.
SD2: Mendel’s work showed that this was not true – that traits are controlled by
separate _______________ inherited from each parent and that some alleles are
dominant while others are recessive.
SD3: Unfortunately, Mendel was not recognized for his work until much later
when the significance of his experiments led scientists to refer to Mendel the
___________ of Genetics.
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Mendel’s Work Questions
1. Summarize Mendel’s cross between tall and short pea plants. What was
surprising in the F1 and F2 generations?
2. What is a dominant allele? What is a recessive allele?
3. Using the chart on page 113, predict what seed color pea plants of the F1
generation had in Mendel’s crosses. What about F2? Explain your predictions.
4. Can a short pea plant ever be a hybrid for the trait of stem height? Why or why
not? As part of your explanation, write the letters that represent the alleles for
the stem height of a short pea plant.
5. Give an example of a trait in pea plants. Explain what the possible alleles are for
this trait. Identify which allele is dominant and which is recessive.