Among eukaryotes, replication of DNA takes place in
Explanation:
In eukaryotes, DNA replication occurs during the S (Synthesis) phase of the cell cycle. During this phase, the DNA is duplicated so that each daughter cell receives an identical copy. Other phases have different roles: G1 is cell growth, G2 checks and prepares for division, and M phase is when mitosis and cytokinesis occur, separating the duplicated chromosomes.
🧠 Did You Know?
DNA replication is a tightly regulated process ensuring each chromosome is copied once before division, preventing errors.
💡 NCERT Memory Line:
DNA replication occurs in the S phase of the cell cycle in eukaryotes.
Which of the following stages of meiosis involves division of centromere?
Explanation:
Centromere division (sister chromatids separate) occurs during anaphase II of meiosis. In meiosis I, homologous chromosomes separate, but sister chromatids stay together at the centromere. During metaphase I/II, chromosomes align at the equator; the centromere does not divide yet. Telophase involves chromosome de-condensation and cytokinesis begins, not centromere splitting. Therefore, the correct stage is Anaphase II, when the centromeres split and sister chromatids move to opposite poles.
🧠 Did You Know?
Only in Anaphase II do the duplicated chromatids become separate chromosomes that migrate to opposite poles.
The process of appearance of recombination nodules occurs at which sub stage of prophase I in meiosis?
Explanation:
The recombination nodules appear during the pachytene stage of prophase I. This is the stage when crossing-over between homologous chromosomes occurs, facilitated by synapsis. Thus, recombination nodules form to mediate genetic exchange.
🧠 Did You Know?
In later stages, chiasmata become visible as remnants of crossing-over during diplotene and are seen until metaphase I.
💡 NCERT Memory Line:
Crossing over and recombination nodules occur during pachytene of prophase I.
Given below are two statements: Statement I: During Go phase of cell cycle the cell is metabolically inactive. Statement II: The centrosome undergoes duplication during S phase of interphase.
In the light of the above statements, choose the most appropriate answer from the option below:
Select the correct statements
A.Tetrad formation is seen during leptotene.
B.During Anaphase, the centromere split and chromatids separate.
C.Terminalization takes place during Pachytene.
D.Nucleolus, Golgi complex and ER are reformed during Telophase.
E.Crossing over takes place between sister chromatids of homologous.
Choose the correct answer from the option given below:
