Question

Response Questions Part A To C The following table presents chromosome data on four species of plants and their F1 hybrids. (NOTE: A bivalent is a pair of homologous chromosomes that are paired in Meiosis. A univalent is just one chromosome that is not pairing with any other chromosome in Meiosis.) Species or Chromsome Number of Bivalents in Metaphase, Meiosis I 10 10 Number of Monovalents in Metaphase. MeiosisI umber 20 20 10 10 20 15 15 10 0 0 20 AxB Ax C AxD Cx D 0 10 a) Deduce the chromosomal origin of species B. b) How many bivalents and univalents would you expect to observe at m eiotic metaphaseI in a hybrid between species C and species B? Explain why. c) How many bivalents and univalents would you exp ect to observe at m eiotic metaphaseI in a hybrid between species D and species B? Explain why.

Answer 1

a)The chromosome origin on B should be from the host species.

b) when there is a hybrid between species C and species D The expected bivalent on meiotic metaphor I will be 5 and univalent will be 0

(Because A×B=20+20÷2=20,A×C=20+10÷2=15 so C×B= 5+5÷2=5)

c)In hybrids D aband B the expected bivalent will be 15 that is 7.5 and monovalebt will be 0