Some dioecious species have the XY genotype for male and XX for female. 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. Understand the concept of dioecious species, which are species where individuals are distinctly male or female, typically determined by their chromosomes. In this case, males are XY and females are XX.
2. Recall the process of double fertilization, which is unique to angiosperms (flowering plants). This process involves two sperm cells: one fuses with the egg cell to form the zygote (which develops into the embryo), and the other fuses with two polar nuclei to form the triploid endosperm.
3. Determine the possible combinations of gametes from male and female parents. Male gametes can be either X or Y, and female gametes are X.
4. Analyze the fusion possibilities: one sperm (X or Y) fuses with the egg (X) to form the embryo. The other sperm (X or Y) fuses with two polar nuclei (XX) from the female to form the endosperm.
5. Match the possible combinations of embryo and endosperm genotypes based on the fusion of gametes: embryo XY or XX, and endosperm XXX or XXY.

Key Concepts

Dioecious Species

Dioecious species are those that have distinct male and female individuals, each producing different types of gametes. In the context of plants, dioecy means that male plants produce pollen (sperm) and female plants produce ovules (eggs). Understanding this concept is crucial for analyzing the genetic outcomes of fertilization in these species.

Double Fertilization

Double fertilization is a unique process in angiosperms where one sperm fertilizes the egg to form the zygote, while another sperm fuses with two polar nuclei to form the triploid endosperm. This endosperm serves as a nutrient source for the developing embryo. Recognizing this process is essential for predicting the genotypes of the resulting embryos and endosperm nuclei.

Genotype and Nuclei Composition

The genotype refers to the genetic constitution of an organism, represented by the alleles it possesses. In the context of the question, understanding how the genotypes of the embryos and endosperm are derived from the parental genotypes (XY for males and XX for females) is key to determining the correct answer. The composition of the endosperm nuclei, being triploid, is particularly important in this analysis.