Bio Chapter 39

What does the term "alternation of generation" refer to in angiosperms?

2 multicellular life cycle stages, Diploid-spore-producing sporophyte that produces spores by meiosis. Haploid, gamete-producing gametophyte that produces gametes by mitosis. Moss - Sporophytes small and dependent on gametophyte, Flowering plant - Sporophyte larger and independent while dependent gametophyte few-celled and contained within flowers

Match the following: androecium, sepal, calyx, carpels, corolla, petals, stamens , gynoecium, perianth, calyx and corolla

4 flower organs occur in concentric rings or whorls, matched: Sepal - calyx Petals - corolla Stamens - androecium Carpels - gynoecium Perianth - calyx and corolla

___ - staminate and pistillate flowers on different plants

Dioecious

___ - produces the male gametophyte and fosters their early development

Stamens

___ - produced by sporophyte integuments

Tough Seed Coats

What is the function of the callose plugs in the pollen tube?

Callose plugs concentrate the cytoplasm at the tip to maintain turgor pressure, for pollen tube growth

___ - Vase-shaped structures that produce, enclose, and nurture female gametophytes

Carpels

- structure that encloses and helps disperse seeds

Fruit

___ - induces aleurone to release sugars from stored starch

Gibberellic acid

___ - staminate and pistillate flowers on same plant

Monoecious

Explain the function of double fertilization in angiosperms.

One of the 2 sperm cells fertilizes the egg to produce the diploid zygote, Other sperm fuses with 2 nuclei located in a different cell, this produces endosperm by mitosis. The zygote develops into an embryo, and endosperm develops a nutritive tissue that is usually triploid

___ - produces and nourishes one or more ovules

Ovary

The fruit wall is also called the ___.

Pericarp

___ - the plant structure usually serves to attract pollinators

Petals

One or more carpels form the ___.

Pistil

Describe three different forms of asexual reproduction in plants.

The 3 forms: 1. Roots, stems and leaves can function in asexual reproduction - examples: Aspen root sprouts, Kalanchoe leaves form plantlets, sucker shoots, potato "eyes" 2. Somatic embryogenesis - Production of plant embryos from body (somatic) cells and embryos do not dehydrate and become dormant 3. Apomixis - Fruits and seeds are produced in the absence of fertilization, Meiosis produces diploid megaspores (no meiosis II), diploid eggs develop into normal individuals without fertilization - parthenogenesis and parthenocarpic fruit develops without fertilization.

Normally, when are mature sperm produced in angiosperms?

When the haploid generative cell traveling down the pollen tube divides by mitosis and becomes two haploid sperm cells.

___ - develop from fertilized ovules

Seeds

___ - function to protect unopened flower bud

Sepals

Describe the process that occurs from the beginning of pollination through the development of the fruit. 20pts.

A mature sporophyte is signaled by day length and temperature to produce flowers via the SAM(shoot apical meristem). The flowers containing the gametophyte generation mature and begin producing gametes. The stamens produce the male gametophytes. Pollen grains, immature male gametophytes, are produced and released into the air or carried by animals/insects to another flower or the same flower. The pollen grains come into contact with the stigma where, if recognized, they begin to germinate. Pollen grain produces a pollen tube that grows through the micropyle and delivers two sperm to the female gametophyte. One sperm fertilizes the egg and another fertilizes surrounding haploid cells to form a zygote and the endosperm respectively. The resulting seed is then covered in a fruit that developed from the ovary wall. This fruit aids in dispersal of the seed by enticing animals too eat it. If the seed finds favorable conditions, the embryo will take up water, become metabolically active, and begin to grow. The resulting seedling then grows into a mature sporophyte.

Describe the unique nature of each of the two "generations" in angiosperms.

Diploid-spore-producing sporophyte that produces spores by meiosis. Haploid, gamete-producing gametophyte that produces gametes by mitosis.

The pollen grain germinates to produce the ___.

Pollen Tube

___ - are immature male gametophytes

Pollen grains

___ - a term for pollen grains finding their way to stigma

Pollination

Flowers are produced by the ___.

Shoot apical meristems

Label the following:

Slide 20 in chapter 39

Describe how the pistil controls pollen germination.

Stigma and the style determine whether or not pollen grains germinate and pollen tubes grow they have self-incompatibility (SI) - rejection of too genetically similar pollen. Recognition involves interaction between proteins of pollen and pistil cells and it influences the ability of pollen to rehydrate.

Describe the mechanism(s) that prevents pollination and fertilization between two different species of angiosperms.

The stigma allows only the correct genotype to germinate. The stigma will reject pollen that is too genetically similar. The pistil cells recognize the shape and the protein composition of the pollen wall. The pistil will not allow the pollen grain to rehydrate and thus become active unless it recognizes it.