two
A DNA molecule consists of two long polynucleotide chains composed of four types of nucleotide subunits.
Escherichia first isolated and characterized was in 1885
The chromosomal mutation in the zygote can be traced back to "Chromosome 6 in the egg cell".
<u>Option: B</u>
<u>Explanation:</u>
In germ cells i.e. egg or sperm cells, the mutations in chromosome often happen during the meiosis phase. The number of chromosomes in egg cells or sperm cells must be haploid, so that diploid chromosomes form zygote on fertilization. Chromosome mutation in meiosis leads in an additional set of chromosomes or structural defects in the chromosome.
Chromosomal mutations are often caused by chemical agents or by mutagens.
The homologous chromosomes are segregated from sister chromatids throughout cell division, any abnormality at this point allows the chromosomes to be unequally divided or not disjuncted, same is observed in the situation seen in egg cell chromosome 6.
Population , we breath , you breath CO2 is increasing , so stop breathing and die somewhere lol. (ok just kidding)