Some plant species produce male and female individuals in which the males have an XY genotype and the females have an XX genotype. After double fertilization, what would be the genotypes of the embryos and endosperm nuclei? (A) embryo XY/endosperm XXX or embryo XX/endosperm XXY (B) embryo XX/endosperm XX or embryo XY/endosperm XY (C) embryo XX/endosperm XXX or embryo XY/endosperm XYY (D) embryo XX/endosperm XXX or embryo XY/endosperm XXY

Verified step by step guidance

1. Step 1: Understand the concept of double fertilization. In plants, double fertilization is a process that involves two sperm cells; one fertilizes the egg cell to form a zygote (which develops into the embryo), and the other fertilizes the two polar nuclei to form the endosperm (which provides nutrients to the developing embryo).
2. Step 2: Recall that the genotype of an organism is the set of genes it carries. In this case, the males have an XY genotype and the females have an XX genotype.
3. Step 3: Consider the first fertilization event. The sperm (X or Y) from the male plant fertilizes the egg (X) from the female plant. This results in either an XX (female) or XY (male) embryo.
4. Step 4: Consider the second fertilization event. The other sperm (X or Y) from the male plant fertilizes the two polar nuclei (XX) from the female plant. This results in either an XXX or XXY endosperm.
5. Step 5: Combine the results from steps 3 and 4. The possible combinations are embryo XX/endosperm XXX or embryo XY/endosperm XXY. Therefore, the correct answer is (D) embryo XX/endosperm XXX or embryo XY/endosperm XXY.

Key Concepts

Double Fertilization

Double fertilization is a unique process in angiosperms where one sperm cell fertilizes the egg cell to form the zygote, while another sperm cell fuses with two polar nuclei to form the triploid endosperm. This endosperm provides nourishment to the developing embryo. Understanding this process is crucial for determining the genotypes of the resulting structures in the question.

Genotype and Sex Determination

In many organisms, including some plants, sex is determined by specific genotypes, such as XY for males and XX for females. This genetic basis for sex determination is essential for predicting the genotypes of the embryos produced after fertilization. Recognizing how these genotypes contribute to the offspring's sex is key to answering the question.

Endosperm Development

The endosperm is a tissue that provides essential nutrients to the developing embryo in seeds. Its formation involves the fusion of one sperm cell with two polar nuclei, resulting in a triploid (3n) nucleus. Understanding the genetic contributions to the endosperm is vital for determining its genotype in relation to the fertilization events described in the question.