Crossing over during meiosis increases genetic diversity in sexually reproducing organisms.
The enzyme Recombinase is required at Pachytene stage of Meiosis I.
(A) Pachytene - Correct: Recombinase (including RAD51 and DMC1) mediates crossing over during pachytene.
(B) Zygotene - Incorrect: Synapsis occurs here, but recombination happens later.
(C) Diplotene - Incorrect: Chiasmata become visible here, but recombination is complete.
(D) Diakinesis - Incorrect: This is the stage of terminalization of chiasmata.
The correct answer is (A) Pachytene, when homologous recombination occurs via recombinase enzymes.
Recombinase is involved in the process of genetic recombination during meiosis. This process occurs during the pachytene stage of Meiosis I when homologous chromosomes exchange segments of genetic material. Recombination is crucial for generating genetic diversity.
Other stages:
Option (A) is correct as recombinase is active during the pachytene stage.
| Column I | Column II | ||
|---|---|---|---|
| 1. | Calotropis | p. | Invertebrates |
| 2. | Pisaster | q. | Distasteful |
| 3. | Monarch butterfly | r. | Cryptically colored |
| 4. | Frogs | s. | Cardioglycoside |
Match Column I and Column I
| Column I | Column II | ||
|---|---|---|---|
| 1 | Narrowly utilitarian argument | p | Conserving biodiversity for major ecosystem services |
| 2 | Broadly utilitarian argument | q | Every species has an intrinsic value and moral duty to pass our biological legacy in good order to future generation. |
| 3 | Ethical argument | r | Receiving benefits like food, medicine & industrial products. |
| Column I | Column II | ||
| 1. | Aneuploidy | p. | Increase in whole set of chromosomes |
| 2. | Monoploidy | q. | Loss or gain of a chromosome |
| 3. | Polyploidy | r. | Two sets of chromosomes |
| 4. | Diploidy | s. | A single set of chromosomes |