Plant life cycles lab 5

Spores

If spores land in a suitable environment that is moist and shaded, they germinate, eventually growing into the heart shaped adult gametophyte.

Antheridia

the male sex organ of algae, mosses, ferns, fungi, and other nonflowering plants.

What does a pollen grain become a mature male gametophyte?

After pollination

D. Phylum angiosperms

All flowering plants are classified in the phylum anthophyta. A unique characteristic of angiosperm is the carpel, a vessel in which ovules are enclosed. After fertilization, the ovule develops into a seed (as in the gymnosperms), while the carpel matures into fruit (unique to angiosperms). Other important aspects of angiosperms reproduction include additional reduction of the gametophyte, double fertilization, and an increase in the rapidity of the reproduction process. The flowers of angiosperms are composed of male and female reproductive process, which are frequently surrounded by attractive or protective leaflike structures collectively known as the perianth.

Corolla

All the petals; collectively

Calyx

All the sepals, collectively

Ovary

Base of carpel; protects ovules inside, matures to from fruit

Petal

Colored, white or even greenish whorl of bracts located just inside the sepals.

Why is wind-dispersed pollen an important phenomenon in the evolution of plans?

Compared to fern and moss, independence from water for fertilization

Flower function

The flower functions both to protect the developing gametes and to ensure pollination and fertilization. Although many angiosperm plants are self-fertile, cross-fertilization is important in maintaining genetic diversity. Plants, rooted and stationary, often require transfer agents to completed fertilization. A variety of insects, birds, and mammals transfer pollen from flower to flower. The pollen then germinates into a pollen tube and grows through the female carpel to deliver the sperm to the egg.

What is the function of the wings on the pollen grain?

The wings enable the pollen grain to be blown to an ovule, where it germinates, forming a slender pollen tube through a weakened area of the pollen wall

Filament

Think stalk that supports the anther

Receptacle

Tip of the pedicel where the flower parts attach

Style

Tissue connecting stigma to ovary, often long and narrow, but may be short or absent; pollen must grow through this tissue to fertilize the egg

Introduction to plant life cycles

A characteristic common to all land plants is the alternation of generations. In alternation of generations, two district multicellular phases exist: A diploid sporophyte alternates with a haploid gametophyte. The primary reproductive function of the gametophyte is to produce gametes (eggs and/or sperm by mitosis.) The primary reproductive function of the other, the sporophyte, is to produce spores by meiosis. During the course of evolution, two major lines of divergence took place in the plant kingdom. The plants in one line had as their dominant phase the gametophyte generation, meaning that the sporophyte was never free-living but permanently attached to and dependent on the gametophyte for nutrition. These plants are represented by the bryophytes and their relatives. It seems that this line exemplifies dead-end evolution-no other group of plants present today arises from it.

How does the female gametophyte in angiosperms differ from the female gametophyte in gymnosperms

Female gametophyte in a flower Gymnosperm in a cone

Carpel

Female reproductive structure, composed of the stigma, style, and ovary, often pear-shaped and located in the center of the flower

Do the spores belong to the gametophyte or sporophyte generation?

Gametophyte

Is the dominant generation for the mosses the gametophyte or the sporophyte?

Gametophyte

Do the spores belong to the gametophyte or the sporophyte generation?

Gametophyte Generation

Are the archegonia and antheridia haploid or diploid? Think about which generation produces them.

Gametophyte produces them.. haploid

Do you think that all pollen germinated indiscriminately on all stigmas? How might pollen germination and growth be controlled?

Genetic isolation

Are the gametes haploid or diploid? Are they produced by mitosis or meiosis?

Haploid, mitosis

What part of the life cycle is represented by the mature pollen grain?

Male gametophyte

Are microspores and megaspores produced by mitosis or meiosis?

Meiosis because they are spores

Are the spores produced by the moss sporophyte formed by mitosis or meiosis? Are they haploid or diploid?

Meiosis, they are haploid

Are the gametes produced by mitosis or meiosis?

Mitosis

A. Phylum Bryophyta: Mosses

Mosses lack vascular tissue and therefore have no true roots, stems, or leaves. However they do have structures that are rootlike, stemlike, and leaflike and perform the same functions as the true organs. •Mosses adapted to: Moist habitat

Sepal

Outer whorl of bracts, which may be green, brown or colored like the petals; may appear as small scales or be petal-like

C. Phylum Coniferophyta: Conifers

Pine life cycle: All gymnosperms are wind-pollinated trees or shrubs, most bearing unisexual, male and female reproductive structures on different parts of the same plant.

C. Phylum Coniferophyta: Conifers

Pine life cycle: all gymnosperms are wind-pollinated trees or shrubs, most bearing unisexual, male and female reproductive structures on different parts of the same plant. •Gymnosperms are heterosporous, producing two kinds of spores: male microspores, which develop into pollen, and female megaspores. The megaspores develops into the female gametophyte, which is of free-living as with ferns but retained within the megasporangium and nourished by the sporophyte parent plant. Numerous pollen grains (the male gametophyte) are produced in each microsporangium, and when they are mature they are released into the air and conveyed by wind currents to the female cone. Pollen tubes grow through the tissues of the megasporangium, and the sperm nucleus is released to fertilize the egg. After fertilization, (12-15 months later) development results in the formation of an embryo.

Stamen

Pollen-bearing structure, composed of filament and anther

Anther

Pollen-producing structure

Stigma

Receptive tip of the carpel, often sticky or hairy, where pollen is placed; important to pollen germination

Spermatogenous tissue

Sperm forming tissue. With maturity gives rise to numerous sterile paraphyses. They do not have a reproductive role but instead function to hold capillary water, preventing the sex organs from drying out.

Are the spores produced by the fern sporophyte formed by meiosis or mitosis?

Spores always formed by meiosis

Is the dominant generation for the fern the gametophyte or the sporophyte?

Sporophyte

Pedicel

Stalk that supports the flower

Archegonial top of a moss

Sterile paraphyses and the archegonia

Fern archegonium

The archegonia secrete chemicals that attract the flagellated sperm, which swim in a water film down a canal within the neck of the archegonium. One sperm fuses with the Egg to produce the first cell of the sporophyte generation, the zygote. With subsequent cell divisions, the zygote develops into a young sporophyte.

Single archegonium

The central core of the archegonial neck contains cells that break down when the egg is mature, liberating a fluid rich in sucrose that attracts sleek that are swimming in few or rainwater. Fertilization of the egg produces the diploid zygote the first cell of the sporophyte generation. Numerous mitomic divisions produce an embryo which differentiated into the mature sporophyte that protudes from the tip of the gametophyte.

Seed

a dormant embryo embedded in nutrient tissue of the female gametophyte and surrounded by the hardened sporangium wall, or seed coat.

B. Phylum Pterophyta: Ferns

•large variation of ferns, as is their distribution and ecology •we typically think of ferns as inhabitants of moist environments but some are found in dry locations. • the sporophyte of many ferns consists of true roots, stems and leaves. •Each sorus is a cluster of sporangia. Each sporangium contains spores •Although the sporangium is part of the diploid (sporophytic) generation, spores are the first cells of the haploid (gametophytic generation)