Review the key concepts, formulae, and examples before starting your quiz.
🔑Concepts
Angiosperms are flowering plants where the seeds are enclosed within fruits, unlike Gymnosperms where seeds are naked.
They are classified into two main groups: Dicotyledons (having two cotyledons, reticulate venation, and tetramerous or pentamerous flowers) and Monocotyledons (having one cotyledon, parallel venation, and trimerous flowers).
The male sex organ is the stamen, consisting of a slender filament and an anther. Pollen grains are produced in the anther following meiosis ().
The female sex organ is the pistil or carpel, consisting of an ovary at the base, a long style, and a stigma. The ovary contains ovules.
Each ovule has a megaspore mother cell that undergoes meiosis to form four megaspores (), three of which degenerate, and one develops into the embryo sac.
The embryo sac is a -celled and -nucleate structure consisting of one egg cell, two synergids, three antipodal cells, and one central cell with two polar nuclei.
Double Fertilization is a unique event in Angiosperms: Syngamy (fusion of one male gamete with the egg to form a zygote) and Triple Fusion (fusion of the second male gamete with the two polar nuclei to form a Primary Endosperm Nucleus).
Post-fertilization, the zygote develops into an embryo, the develops into the endosperm (nutritive tissue), ovules develop into seeds, and the ovary develops into a fruit.
📐Formulae
💡Examples
Problem 1:
If a plant species has a diploid chromosome number of , calculate the number of chromosomes in its endosperm, pollen grain, and leaf cell.
Solution:
Endosperm = , Pollen grain = , Leaf cell = .
Explanation:
The leaf cell is vegetative/somatic, so it is . The pollen grain is a gametophyte product (haploid), so . The endosperm is formed by triple fusion and is triploid (), so .
Problem 2:
Describe the components of the egg apparatus in an Angiosperm embryo sac.
Solution:
.
Explanation:
The egg apparatus is located at the micropylar end of the -celled embryo sac. It consists of two synergids (which guide the pollen tube) and one central egg cell (the female gamete).