Alternation of generations in plant life cycles In organisms with alternation of generations, which phase represents the haploid, multicellular stage?

Introduction / Context:
Many plants and some algae alternate between multicellular haploid and diploid generations. Knowing which generation is haploid versus diploid is crucial for understanding meiosis, fertilization, and inheritance in plant biology.

Given Data / Assumptions:

• Sporophyte produces spores by meiosis.
• Gametophyte produces gametes by mitosis.
• Fertilization creates a diploid zygote that grows into a sporophyte.

Concept / Approach:
The gametophyte is haploid (n) and multicellular; its cells carry a single set of chromosomes. The sporophyte is diploid (2n). Gametes (n) are single cells, not a multicellular generation. The zygote is diploid and develops into the sporophyte.

Step-by-Step Solution:

Verification / Alternative check:
Mosses emphasize the gametophyte; flowering plants emphasize the sporophyte, but the male and female gametophytes (pollen and embryo sac) are still haploid multicellular structures.

Why Other Options Are Wrong:

• Zygote is diploid and unicellular initially.
• Gamete is haploid but unicellular, not a “generation.”
• Sporophyte is diploid.
• Endosperm is typically triploid (in angiosperms) and not the haploid generation.

Common Pitfalls:
Equating gametes with the gametophyte; the gametophyte produces gametes but is itself a multicellular haploid organism or tissue.

Final Answer:
Gametophyte