Question

Match the ploidy or number of nuclei from the List II with the organ of List I 

 Choose the correct answer from the options given below: 
 

• A. A - I, B - II, C - III, D - IV
• B. A - II, B - I, C - III, D - IV
• C. A - III, B - I, C - IV, D - II
• D. A - II, B - III, C - I, D - IV

Hint:

Remember that in angiosperms, the endosperm is always triploid ($3n$) due to triple fusion, whereas in gymnosperms, the endosperm is haploid ($n$) because it develops before fertilization.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
Ploidy refers to the number of chromosome sets in a biological cell.
- Haploid ($n$): Contains one set of chromosomes (found in gametes).
- Diploid ($2n$): Contains two sets of chromosomes (found in somatic plant tissues).
- Triploid ($3n$): Contains three sets of chromosomes (found in the endosperm of angiosperms).
- Anucleated: Cells that lack a nucleus at maturity.

Step 2: Detailed Explanation:
Let us match each plant organ with its ploidy level:
- A. Ovary: The ovary is a maternal, vegetative floral structure belonging to the sporophyte generation of the plant. It is a diploid tissue.
Hence, A matches with II (Diploid).
- B. Egg: The egg cell is the female gamete produced inside the embryo sac (female gametophyte) through mitotic divisions of a haploid megaspore.
Hence, B matches with III (Haploid).
- C. Endosperm: In angiosperms, the endosperm is formed by double fertilization, specifically through triple fusion, where one haploid male gamete ($n$) fuses with the diploid secondary polar nucleus ($2n$).
Hence, C matches with I (Triploid).
- D. Mature sieve tube: Sieve tube elements are specialized cells in the phloem of angiosperms responsible for transporting food. During maturation, they lose their nucleus, ribosomes, and vacuoles to reduce resistance to sap flow.
Hence, D matches with IV (Anucleated).
The correct matching sequence is: A-II, B-III, C-I, D-IV.

Step 3: Final Answer:
The correct option is (D).