If a researcher looks at a cell and notices a straight line of sister chromatids, which phase are they viewing? a. interphaseb. prophasec. prometaphased. metaphasee. anaphasef. telophase

D. metaphase

Explanation:

Cell cycle comprises 2 phases (1) Inter phase & (2) Mitotic phase.

In interphase, a cell prepares itself for cell division while in mitotic phase, a cell undergo changes which result in cell division.

Mitotic phase further contains 4 main phases which are mentioned as under:

(1) Prophase

(2) Metaphase

(3) Anaphase

(4) Telophase

In metaphase particularly, all the sister chromatids get arranged along the equitorial plate in the middle of the cell so that the replicated chromatids could be separated from each other with the help of spindle fibers. After separation, each cell i.e. mother cell and daughter cell get one copy of the duplicated chromatids.

1) gene flow

- it is described as the transfer of genes from one population to another population so that frequency of gene is increased.

-a zebra migrates to join a different herd of zebras.

2) natural selection

- a mechanism of evolutionary change in which individuals with advantageous traits survive and reproduce whereas the others ( those that can not adapt) eliminate from the population.

-competition for sunlight leads to taller trees.

3) mutation

- permanent change in the nucleotide sequence of dna ( genetic material) that could have harmful or useful consequences.

-the dna of a snake changes to make its venom stronger.

4) genetic drift - it is a random phenomenon ( that occurs by chance such as fire) that results in change in the gene frequency in a small population.    

-a grassfire randomly sweeps through a population of buffalo and kills most of the animals.

explanation:

answer; i believe that the correct answer is(d) nondisjunction during meiosis;