Question

Chromosomes number in endosperm cell of ``X'' plant and the chromosomes number of gamete of plant ``Y'' are equal. Plants X and Y respectively are

• A. Apple and Rice
• B. Maize and potato
• C. Onion and Rice
• D. Onion and potato

Hint:

{Common Chromosome Numbers ($2n$):} Onion=16, Maize=20, Rice=24, Apple=34, Potato=48, Human=46. Endosperm is $3n$ in Angiosperms.

Answer 1

The Correct Option is D

Step 1: Determine Chromosome Counts for Each Plant:

• Onion (\Allium cepa): Diploid ($2n$) = 16. Haploid ($n$) = 8.
• Potato (\Solanum tuberosum): Tetraploid ($4n$) = 48. Gamete ($2n$) = 24. (Standard value often cited as $2n=48$ in lists, so gamete $n=24$).
• Rice (\Oryza sativa): Diploid ($2n$) = 24. Haploid ($n$) = 12.
• Maize (\Zea mays): Diploid ($2n$) = 20. Haploid ($n$) = 10.
• Apple (\Malus pumila): Diploid ($2n$) = 34. Haploid ($n$) = 17.

Step 2: Calculate Values for Option (D):

• Plant X = Onion: Endosperm is triploid ($3n$). \[ 3n = 3 \times 8 = 24 \]
• Plant Y = Potato: Gamete is haploid ($n$). \[ n = 24 \]

Since $24 = 24$, the condition is satisfied.
Step 3: Check Other Options (Briefly):
(A) Apple Endosperm ($3 \times 17 = 51$) vs Rice Gamete ($12$). No.
(B) Maize Endosperm ($3 \times 10 = 30$) vs Potato Gamete ($24$). No.
(C) Onion Endosperm ($24$) vs Rice Gamete ($12$). No.
Step 4: Final Answer:
The correct pair is Onion and Potato (Option D).