Question

A tomato plant heterozygous for stem color and fasciation (the dominant alleles linked on the same chromosome) is pollinated by a plant heterozygous for stem color and homozygous recessive for fasciation (that is nonfasciated). 29. What alleles will the sperm carry?_ What alleles will the eggs carry? 30. What are the genotypes of the progeny? What are the phenotypes of the progeny? 31. If the dominant alleles for stem color and fasciation are commonly located on the same chromosome, how could the dominant allele for one of these characteristics and the recessive allele for the other be on the same chromosome? Part C. Incomplete Dominance Not all characteristics, or traits, exhibit complete dominance. That is, one pair of alleles may not necessarily be dominant over the other, so that the heterozygous condition is phenotypically expressed in traits that are intermediate between the dominant and recessive characteristics. A representative case of incomplete dominance is the inheritance of hair on tomato stems. The homozygous condition HH results in a completely hairless stem, and the homozygous condition hh results in a very hairy stem. However, the heterozygous condition Hh produces stems with relatively few large hairs. 32. A very hairy plant (genotype ) is crossed with a hairless plant (genotype ).

Answer 1

The plant which is being pollinated will produce eggs and the plant which uses its pollen will produce sperms. Thus

29. alleles on the egg- S, s, f and F

alleles on the sperm- S,s and f

where genes for stem colour is denoted by S and s and genes for fascination is by F and f.

30. Genotypes of the progeny-

SsFf X Ssff

SsFf

Phenotype- Dominant stem colour and fascinated.

31.

32. hh X HH

	h	h
H	Hh	Hh
H	Hh	Hh

all the plants obtained will contain few large hairs.