1) In the plant Arabidopsisthaliana , two alleles of one gene determine the char
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Question
1) In the plant Arabidopsisthaliana, two alleles of one gene determine the characterdifference of hairy leaves (Hairy) versus smooth leaves (Smooth),and two alleles of a separate gene determine the characterdifference of tall plants (Tall) versus dwarf plants (Dwarf). Thesegenes are on different chromosomes. The results for five matings ofA. thaliana are as follows:
Number of progeny
Parental phenotypes
Hairy Tall
Hairy Dwarf
Smooth Tall
Smooth Dwarf
A
Smooth Dwarf ´ Hairy Tall
303
0
296
0
B
Hairy Dwarf ´ Hairy Tall
208
200
62
69
C
Hairy Dwarf ´ Smooth Tall
83
97
95
88
D
Hairy Tall ´ Smooth Tall
329
98
312
108
E
Smooth Tall ´ Hairy Tall
688
232
0
0
a. For each gene, determinewhich phenotype is dominant.
b. What are the most probablegenotypes for the parents in each cross? Using appropriate symbols,write your answers above each parental phenotype in the tableabove.
Number of progeny
Parental phenotypes
Hairy Tall
Hairy Dwarf
Smooth Tall
Smooth Dwarf
A
Smooth Dwarf ´ Hairy Tall
303
0
296
0
B
Hairy Dwarf ´ Hairy Tall
208
200
62
69
C
Hairy Dwarf ´ Smooth Tall
83
97
95
88
D
Hairy Tall ´ Smooth Tall
329
98
312
108
E
Smooth Tall ´ Hairy Tall
688
232
0
0
Explanation / Answer
smooth leaves (Smooth)---------h
tall plants (Tall) -----T
dwarf plants (Dwarf).-------t
============================================================
A
Smooth Dwarf ´ Hairy Tall
303
0
296
0
Hairy Dwarf
0
Dwarf-----tt Hh----genotype------missing
H,T-----DOMINANT
Smooth Dwarf X Hairy Tall
hhtt TTHH
========================
B
Hairy Dwarf ´ Hairy Tall
208
200
62
69
Hairy Dwarf ´ Hairy Tall
HHtt HhTt
H,T-----DOMINANT
============================================
C
Hairy Dwarf ´ Smooth Tall
83
97
95
88
Hhtt hh Tt -----parent’sgenotypes
D
Hairy Tall ´ Smooth Tall
A
Smooth Dwarf ´ Hairy Tall
303
0
296
0
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