Which of the following statements is true regarding a cell at the end of the S phase of the cell cycle? The chromosomes are elongated and unable to be seen under a light microscope.
The cell contains half the normal number of chromosomes.
The cell contains twice the normal number of chromosomes.
The chromosomes lack centromeres.

A. the chromosomes are elongated and unable to be seen under a light microscope.

Explanation:

The chromosomes are decondensed during the S-phase of the cell cycle to facilitate DNA replication and gene expression in other interphase stages. Thus, interphase chromosomes, especially in the S-phase, are decondensed, so they are not detectable under the light microscope. Other choices are deemed incorrect since the number of chromosomes does not increase or decrease during S-phase. Only the DNA content can double or increase in the number of chromatids. Moreover, at the centromere, these sister chromatids are still related.

ans.

dna fingerprinting is defined as a process that determines the dna characteristics of an individual. these dna characteristics are unique among individuals as their fingerprints, so it is known as dna fingerprinting.

steps of dna fingerprinting includes extraction of dna from sample, amplification of dna, restriction digestion of amplified dna, and then analysis of dna by gel electrophoresis, respectively.

thus, the next step performed by the scientist is 'to cut the amplified dna (obtained by polymerase chain reaction) by restriction enzymes that cleave the dna into fragments and their analysis.'