S phase of interphase

Introduction:
The cell cycle consists of several phases, including interphase and mitosis. Interphase is the longest phase of the cell cycle and is divided into three stages: G1 phase, S phase, and G2 phase. The S phase, or synthesis phase, is the period during which DNA replication occurs.

Incorrect statement:
The incorrect statement regarding the S phase of interphase is option D, "As DNA is doubled, the number of chromosomes also doubles."

Explanation:
During the S phase of interphase, DNA replication takes place. This involves the synthesis of new DNA strands that are identical to the original strands. However, it is important to note that the number of chromosomes does not double during this process.

Chromosome structure:
Chromosomes are structures that contain DNA molecules. They consist of two sister chromatids joined at a region called the centromere. Each chromatid contains a complete copy of the DNA molecule.

DNA replication:
DNA replication is a complex process that involves the duplication of the DNA molecule. It occurs in the nucleus of the cell during the S phase. The DNA molecule unwinds and separates into two strands, and each strand serves as a template for the synthesis of a new complementary strand.

Centriole duplication:
Centrioles are small, cylindrical structures found in the cytoplasm of animal cells. They play a crucial role in cell division by organizing the microtubules that form the spindle apparatus. Centriole duplication occurs during the S phase of interphase, specifically in the G1 phase. The centrioles replicate to form a pair of centrioles, which are then separated during cell division.

Correct statement:
The correct statement regarding the S phase of interphase is option C, "Centrioles duplicate in the cytoplasm." During the S phase, centriole duplication occurs in the cytoplasm of the cell.

Conclusion:
The S phase of interphase is a crucial stage in the cell cycle where DNA replication takes place. It is important to understand the correct sequence of events and the changes that occur during this phase. Option D is incorrect because the number of chromosomes does not double during the S phase; rather, the DNA is duplicated.

Answer is option D bcoz in S phase only dna content gets double not number of chromosomes hence no. of chromosomes remains same