Question

A tetraploid female flowering plant and a hexaploid male flowering plant are crossed, endosperm will be

• A. heptaploid.
• B. triploid.
• C. hexaploid.
• D. pentaploid.

Answer 1

Answer: (A)

Double fertilization is a unique characteristic observed in the Angiosperm group of plants. In this, two fertilizations are observed - $1^{st}$ between the female and male gametic cells forming zygote and $2^{nd}$ is between the second male gamete and polar nuclei forming the primary endosperm nucleus. The ploidy of PEN is 3n (male gamete $\left[1n\right]+$ polar nuclei $\left[2n\right]$ ). If the female plant is tetraploid then polar nuclei will be tetraploid as well. The male plant is hexaploid thus, its male gamete will be triploid. Therefore, the ploidy level of endosperm will $4n+3n=7n\to$ heptaploid.