Introduction to the Angiosperms

Home > Biology 103: Botany > Exam Three

Learning Objectives

  1. Compare and contrast fertile and infertile parts of the flower.
  2. Compare and contrast male versus female parts of the flower.
  3. Describe the variation in flower morphology.
  4. Describe how the male gamete (sperm) is formed.
  5. Describe how the female gamete (egg) is formed.
  6. Describe the process of double fertilization and the function of the products.

Solutions

  1. Sepals and petals are infertile. Stamens and carpels/pistils are fertile.
  2. Male parts are the stamen. The filament holds the anther with it's pollen away from the female parts. Female parts are the carpels in the pistil. The stigma catches pollen, and the style brings the pollen to the ovary.
  3. Morphology:
  4. Male gametes are formed in the anther with 4 pollen sacs with microsporocyte cells inside each. Each microsporocyte → meiosis → 4 haploid microspores. 1 microspore → mitosis → 1 vegetative cell and 1 generative cell. Each generative cell → mitosis → 2 generative cells. Each one of these 3-cell matrixs is 1 sperm cell.
  5. Female gametes are formed in the ovule. Megasporocyte → meiosis → 4 haploid megaspores, 3 degenerate. The remaining cell enlarges. Nucleus undergoes mitosis 3 times for 8 nuclei and 7 cells (3 antipodal cells, 2 polar nuclei [1 cell], 2 synergid cells, and 1 egg cell).
  6. Double fertilization occurs when the second generative cell and the 2 polar nuclei meet to become 3n endosperm tissue, which is nutritive for the embryo. In monocots, this stays liquid. In eudicots, this gets absorbed into the cotyledons.

Notes

Angiosperms

Plant Evolutionary Trees

Flower Organization

Flower Parts

Structure of Flowers

Ovaries

Angiosperm Life Cycle

Microgametophyte Development

Megagametophyte Development

Pollination

Fertilization

Endosperm

Seed to Fruit

Monocots versus Eudicots

Characteristics Monocots Eudicots
flower parts usually in 3's usually in 4's or 5's
pollen monoaperturate (having one pore or furrow) triaperturate (having three pores or furrows)
cotelydons one two
leaf venation usually parallel usually netlike
primary vascular bundles in stem scattered arrangement in a ring
true secondary growth, with vascular cambium rare commonly present