Question

When cell division fails after S - phase (DNA replication) in a diploid cell, the ploidy is

• A. Haploid
• B. Diploid
• C. Tetraploid
• D. Triploid

Answer 1

The correct option is B Diploid

• S or synthesis phase is the period during which DNA synthesis or replication takes place. During this time the amount of DNA doubles. If the initial amount of DNA is denoted as 2C then it increases to 4C.
• Although, there will be no increment in chromosome number: for e.g. if a cell has the 2n number of chromosomes at G${}_1$, even after S phase the number of chromosomes remains the same, i.e., 2n. before the cell enters into the S-phase, it has the DNA in the form of chromatin not chromosome. Chromosomes are formed when the DNA is replicated during the S - phase.

So, the correct option is 'Diploid'.