Unpacking Problem 491. What do a “gene for tassel length” and a “gene for rustresistance” mean?2. Does it matter that the precise meaning of the allelicsymbols T, t, R, and r is not given? Why or why not?3. How do the terms gene and allele, as used here, relate tothe concepts of locus and gene pair?4. What prior experimental evidence would give the corngeneticist the idea that the two genes are on separatechromosomes?5. What do you imagine “routine crosses” are to a cornbreeder?6. What term is used to describe genotypes of the typeT/t ; R/r?7. What is a “pollen parent”?8. What are testcrosses, and why do geneticists find themso useful?9. What progeny types and frequencies might the breederhave been expecting from the testcross?10. Describe how the observed progeny differ fromexpectations.11. What does the approximate equality of the first twoprogeny classes tell you?12. What does the approximate equality of the second twoprogeny classes tell you?13. What were the gametes from the unusual plant, andwhat were their proportions?14. Which gametes were in the majority?15. Which gametes were in the minority?16. Which of the progeny types seem to be recombinant?17. Which allelic combinations appear to be linked in someway?18. How can there be linkage of genes supposedly on separate chromosomes?19. What do these majority and minority classes tell us aboutthe genotypes of the parents of the unusual plant?20. What is a corncob?21. What does a normal corncob look like? (Sketch one andlabel it.)22. What do the corncobs from this cross look like? (Sketchone.)23. What exactly is a kernel?24. What effect could lead to the absence of half the kernels?25. Did half the kernels die? If so, was the female or the maleparent the reason for the deaths?Now try to solve the problem
Unpacking Problem 49
1. What do a “gene for tassel length” and a “gene for rust
resistance” mean?
2. Does it matter that the precise meaning of the allelic
symbols T, t, R, and r is not given? Why or why not?
3. How do the terms gene and allele, as used here, relate to
the concepts of locus and gene pair?
4. What prior experimental evidence would give the corn
geneticist the idea that the two genes are on separate
chromosomes?
5. What do you imagine “routine crosses” are to a corn
breeder?
6. What term is used to describe genotypes of the type
T/t ; R/r?
7. What is a “pollen parent”?
8. What are testcrosses, and why do geneticists find them
so useful?
9. What progeny types and frequencies might the breeder
have been expecting from the testcross?
10. Describe how the observed progeny differ from
expectations.
11. What does the approximate equality of the first two
progeny classes tell you?
12. What does the approximate equality of the second two
progeny classes tell you?
13. What were the gametes from the unusual plant, and
what were their proportions?
14. Which gametes were in the majority?
15. Which gametes were in the minority?
16. Which of the progeny types seem to be recombinant?
17. Which allelic combinations appear to be linked in some
way?
18. How can there be linkage of genes supposedly on separate chromosomes?
19. What do these majority and minority classes tell us about
the genotypes of the parents of the unusual plant?
20. What is a corncob?
21. What does a normal corncob look like? (Sketch one and
label it.)
22. What do the corncobs from this cross look like? (Sketch
one.)
23. What exactly is a kernel?
24. What effect could lead to the absence of half the kernels?
25. Did half the kernels die? If so, was the female or the male
parent the reason for the deaths?
Now try to solve the problem
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