Stem length in plants is controlled by two CODOMINANT alleles of one autosomal - one allele, B, adds 2 cm to the length of the plant, and another allele, b reduces length by 0.5 cm. The base length of the plant's stem is 10 cm. A plant breeder wants to breed plants that are exactly 14.5 cm in stem length. He starts with crossing two heterozygotes, Bb x Bb. gene Assuming that you can ONLY breed plants of the same stem length, what cross(es) would the breeder have to set up in order to achieve this? Let's (i) (ii) that stem length segregates independently from flower color (also a say monogenic, autosomal, biallelic trait). If you crossed a homozygote from (i) i.e. a bb and homozygote red flowers with a plant that is homozygote BB and homozygote white flowers, intercross the F1, and observe the following numbers of progeny in the F2 generation: (iii) Height Flower Color Observed Number 14 cm Red 2 Pink 7 14 cm 14 cm White 7 Red Pink 11.5 cm 11.5 cm 13 11.5 cm White 6. 9 cm Red 9 cm Pink 6. 9 cm White 3 Build a model of inheritance for both traits and test your hypothesis. Show all calculations, explicitly state the null hypothesis (H0) and alternate hypothesis (Ha). |
1-If the breeder starts crossing with two heterozygotes (Bb), then their initial lenghts would be (=10cm +2cm - 0.5cm) 11.5cm
In these plants, the doubling of chromosomes can be induced artificially through tge application of chemical agents such as colchicine. In colchicine-treated cells, the S-phase proceeds normally, but the chromosomes don't segregate during the anaphase. The nuclear membrane forms around the entire set of doubled chromosomes at the telophase, and hence autotetraploids are obtained
In this case, if the plants with Bb genotype will be treated with colchicine, then autotetraploids with genotype "BbBb" will be obtained. Such plants will have a height of [=10+ (2×2) - (2×0.5)] 13cm.
Now, mating of a normally reduced gamete (Bb), and an unreduced gamete (BbBb); both obtained from the autotetraploids can give rise to autotriploid plants with genotype "BbBbBb". These plants will have a height of [=10+ (3×2) - (3×0.5)] 14.5cm
Trending now
This is a popular solution!
Step by step
Solved in 2 steps with 1 images