Download Reviewing Key Concepts

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Reviewing Key Concepts
Short Answer On the lines provided, answer the following questions.
1. State Mendel’s principle of dominance.
Some alleles are dominant and others are recessive.
2. Which two combinations of alleles could produce a trait controlled
by a dominant allele?
Two dominant alleles or one dominant allele and one recessive allele can produce a trait controlled by a dominant
allele.
3. What combination of alleles could produce a trait controlled by a
recessive allele?
A trait will be controlled by recessive alleles only if the offspring receives 2 recessive alleles.
4. Explain segregation of alleles, using pea plant traits in your example.
When each F1 plant flowers and produces gametes, the two alleles segregate from each other so that each gamete
carries only a single copy of each gene. Therefore, each F1 plant produces two types of gametes – those with the
allele for tallness and those with the allele for shortness.
Reviewing Key Skills
5. Applying Concepts Explain how Mendel’s experiments would have
been different if he had not worked with true-breeding plants.
If they were not true breeding plants then the results of the F1 generation would have been different and he may
not have discovered the principle of dominance. True breeding plants have 2 identical alleles for a gene, so in a
genetic cross each parent contributed only one form of a gene making inheritance patterns more detectable.
6. Comparing and Contrasting Explain the difference between crosspollination and self-pollination in plants.
Self-pollination involves the male part of a flower pollinating the female part of the same flower. Cross-pollination
involves taking the male part of one flower and pollinating the female part of a different flower.
7. Calculating One fourth of the plants resulting from a certain cross
are expected to show a trait controlled by a recessive allele. If 675
plants resulting from the cross display a trait controlled by a
dominant allele, how many plants will show the trait controlled by
the recessive allele?
225 plants
8. Applying Concepts If one of the plants used in the F1 cross had TT
alleles and was combined with a plant with Tt alleles, would the trait
controlled by the recessive allele have been produced in the resulting
F2 generation? Explain your answer.
No in order for the recessive allele trait to be expressed the offspring must inherit 2 copies of the recessive allele.
It’s not possible with these 2 parents.
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