During leptotene stage the chromosomes become gradually visible under the light microscope. The beginning of diplotene is recognised by the dissolution of the synaptonemal complex and the tendency of the recombined homologous chromosomes of the bivalents to separate from each other except at the site of crossover. Thus both statement I and II are correct.
Explanation:
Statement I:
As you've indicated, during the leptotene stage, the chromosomes do begin to condense and become gradually visible under the light microscope. While they are not as distinct as in later stages, they are indeed becoming visible. Therefore, Statement I is considered correct.
Statement II:
The diplotene stage is indeed characterized by the dissolution of the synaptonemal complex. This dissolution allows the homologous chromosomes to begin separating, except at the chiasmata. Therefore, Statement II is also correct.
Conclusion:
Both Statement I and Statement II are correct.
Option 1: Both Statement I and Statement II are true
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