Question

Arrange the following stages in correct sequence
A. Leptonema
B. Zygonema
C. Diakinesis
D. Pachynema
E. Diplonema
Choose the correct answer from the options given below

• A. A, B, D, E, C
• B. A, B, C, D, E
• C. B, A, C, E, D
• D. E, C, D, A, B

Hint:

Meiosis Prophase I Mnemonic: 'Lazy Zebras Planted Dark Daffodils' $\rightarrow$ Leptotene (A) $\rightarrow$ Zygotene (B) $\rightarrow$ Pachytene (D) $\rightarrow$ Diplotene (E) $\rightarrow$ Diakinesis (C).

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Chronological substages of Prophase I during meiotic cell division: chromatin condensation $ ightarrow$ synapsis $ ightarrow$ crossing-over $ ightarrow$ chiasmata emergence $ ightarrow$ terminalization.
Key Formula or Approach:
\[ \text{Meiotic Prophase I: } \text{Leptotene (A)} \rightarrow \text{Zygotene (B)} \rightarrow \text{Pachytene (D)} \rightarrow \text{Diplotene (E)} \rightarrow \text{Diakinesis (C)} \]

Step 2: Detailed Explanation:
Sequential stages of Meiosis I Prophase I:
1. 1. Leptonema (Leptotene) (A): Chromosomes condense into slender, visible threads ('bouquet stage').
2. 2. Zygonema (Zygotene) (B): Homologous chromosomes pair intimately along their lengths (Synapsis mediated by synaptonemal complex forming bivalents).
3. 3. Pachynema (Pachytene) (D): Tetrads form and genetic recombination crossing-over occurs between non-sister chromatids.
4. 4. Diplonema (Diplotene) (E): Synaptonemal complex dissolves; homologous chromosomes desynapse and remain held together at chiasmata.
5. 5. Diakinesis (C): Complete terminalization of chiasmata and breakdown of nuclear envelope.
Sequence: A $\rightarrow$ B $\rightarrow$ D $\rightarrow$ E $\rightarrow$ C.

Step 3: Final Answer:
Therefore, the correct sequence is A, B, D, E, C, matching option (A).