Question

Identify the CORRECT sequence of subphases given below in the prophase of Meiosis I.

• A. Zygotene → Leptotene → Pachytene → Diplotene → Diakinesis
• B. Leptotene → Zygotene → Pachytene → Diplotene → Diakinesis
• C. Diplotene → Pachytene → Leptotene → Zygotene → Diakinesis
• D. Diakinesis → Diplotene → Pachytene → Zygotene → Leptotene

Hint:

The key event in Pachytene is crossing over, where homologous chromosomes exchange genetic material, contributing to genetic diversity.

Answer 1

The Correct Option is B

Step 1: Understand the phases of prophase I in meiosis.
Prophase I is a critical phase in meiosis, and it is subdivided into five stages:
Leptotene: The chromosomes start to condense, becoming visible under a microscope.
Zygotene: Homologous chromosomes begin to pair up through a process known as synapsis.
Pachytene: During this phase, crossing over occurs, where segments of chromosomes are exchanged between homologous chromosomes.
Diplotene: The paired chromosomes begin to separate but remain attached at points called chiasmata, where crossing over occurred.
Diakinesis: This is the final phase where the chromosomes fully condense, and the nuclear envelope starts to break down, preparing for the next stage of meiosis.


Step 2: Identify the correct sequence.
The correct order in Prophase I is:
Leptotene → Zygotene → Pachytene → Diplotene → Diakinesis. Therefore, the correct option is Option 2.