Question

Select the correct statements from the list given below:
A. Isolation distance is necessary to maintain genetic purity of seeds
B. Isolation distance is needed to maintain physical purity of the seeds
C. More isolation distance is required in rice than maize seed production
D. More isolation distance is required in pigeonpea than soybean
E. GM crops are grown in isolation to avoid pollen movement to other related species
Choose the correct answer from the options given below:

• A. A-C-E only
• B. A-D-E only
• C. C-D-E only
• D. B-C-D only

Hint:

Isolation distance maintains genetic purity (A). Pigeonpea (cross-pollinated) requires more isolation than soybean (D). GM crops require isolation to prevent gene flow (E).

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Isolation distance provides spatial separation to prevent genetic cross-pollination and contamination in seed multiplication plots.

Step 2: Detailed Explanation:
Evaluating the statements:
- Statement A is TRUE: Spatial isolation is maintained specifically to prevent unwanted outcrossing and maintain varietal genetic purity.
- Statement B is FALSE: Physical purity (absence of weed seeds/inert matter) is maintained through seed processing/cleaning, not spatial field isolation.
- Statement C is FALSE: Maize is cross-pollinated (requires $200\text{--}400\,\text{m}$ isolation), whereas rice is strictly self-pollinated (requires only $3\,\text{m}$ isolation).
- Statement D is TRUE: Pigeonpea is often cross-pollinated by insects ($20\text{--}40\%$ cross-pollination, requires $100\text{--}200\,\text{m}$ isolation), whereas soybean is strictly cleistogamous/self-pollinated ($3\,\text{m}$ isolation).
- Statement E is TRUE: Isolation distances around GM crops prevent transgenic pollen escape to wild relatives or non-GM crops.

Step 3: Final Answer:
Hence, statements A, D, and E only are correct.