Diploid set of Chromosome present in Haplopappus gracilis is
A) 80 B) 16 C) 4 D) 216
Answers
Answer:
Arrange the following in descending order.
(A) A number of bivalents formed during meiosis of a spore mother cell of Ophioglossum.
(B) Number of chromatics seen on equatorial at metaphase I in pollen mother cell of Haplopappus gracilis during meiosis.
(C) Number of chromosomes found at one pole after anaphase II during meiosis in butterfly (Agrodiaetus sps)
(D) The total number of chromosomes found in all daughter cells formed during meiosis from one megaspore mother cell in white potato.
Answer
Correct option is
B
A C D B
The number of bivalents formed during meiosis of a spore mother of Ophioglossum is equal to haploid chromosome number for it i.e. 630.
The number of chromatids seen on the equator at metaphase X in pollen mother cells of Haplopappus gracilis during meiosis is equal to haploid chromosome number for it i.e. 2.
The number of chromosomes found at one pole after anaphase II during meiosis in the butterfly is equal to haploid chromosome number for it i.e. 190.
The total number of chromosomes found in all daughter cells formed during meiosis from one megaspore mother cell in Potato is equal to the number of diploid chromosome number i.e. 24 (the cultivated potato is a tetraploid with n = 12)
Hence, the correct answer is B.
Answer: C) 4
Explanation:
Two cell lines with 6 and 16 chromosomes were obtained from a predominantly diploid (2 n=4) suspension culture of Haplopappus gracilis (Nutt.) Gray. The 6-chromosome line had two normal homologues of each of the two H. gracilis chromosomes; the remaining chromosome I had a deletion in the short arm, while the remaining chromosome II had a translocated piece of chromatin on the short arm forming a larger satellite than normal. The karyotypic composition of the 4- and the 6-chromosome lines remained fairly stable during the in vitro culture. In the 16-chromosome line, however, a dominant karyotype with 13 chromosomes evolved during the in vitro cultivation. Loss of chromosome(s) by fragmentation appears to be the major method of the production of aneuploid cells. Selection was found to be ‘conservative’ in the 4- and the 6-chromosome lines, while the 16-chromosome showed a ‘progressive’ selection.