Kingdom Plantae Part II

Seed plants-produce seeds in the sporophyte generation. A seed consist of a seed coat, food, and sporophyte embryo. Also spores produced by the sporophyte generation are retained in the plant and are not released into the environment. All seed plants produce two different types of spores (heterospory). Microspores make the male gametophyte (pollen) and megaspores make the female gametophyte inside a structure called the ovule. The female gametophyte never leaves the sporophyte. The ovule eventually becomes the seed once the egg of the female gametophyte is fertilized. Note-sperm cells are not released into the environment like seedless plants. The entire male gametophyte is used to deliver the sperm cells. Seeds and pollen eliminates the necessity of water for reproduction. Both can be carried long distances and have a thick coats to resist drying out.

Which of the following is true?A) Whisk ferns lack vascular tissue.B) Whisk ferns have megaphylls.C) True ferns have megapylls.D) Rhizoids are true roots.

ANS: CWhisk ferns have vascular tissue and true roots. Rhizoids are not true roots rather they are not tissue but just extensions of cells. True ferns have true leaves or megaphylls.

Two major types of seed plants-Gymnosperms and angiosperms. Gymnosperms produce naked seeds (ovule not complete enclosed in sporophyte tissue). Does not produce fruit or flowers.GymnospermsConifers-Largest gymnosperm group 575 species most do not shed their leaves in the fall. Includes pine tree, junipers and sequoias. It takes 2 yrs to produce a seed.

Which of the following would not be found in a seed?A) fruitB) FoodC) EmbryoD) seed coat

ANS: AFruit arises from the ovary, which is found outside the seed. Seeds have a seed coat, food and fruit.

What is the difference between the seed of a gymnosperm and the seed of an angiosperm.A) The seed of an angiosperm is diploid and the seed of a gymnosperm is haploid.C) The seed of an angiosperm is surrounded by tissue from ovary (fruit) and the seed of a gymnosperm is not.B) The seed of an angiosperm is comes from a megaspore and the seed of a gymnosperm comes from a microspore.D) The seed of an angiosperm is a gametophyte and the seed of a gymnosperm is a sporophyte.

ANS: CThe seed of an angiosperm is surrounded by tissue from ovary (fruit) and the seed of a gymnosperm is not. That is why the seeds of the gymnosperm are called “naked seeds”.

Other gymnospermsPhylum Cycadophyta-cycads have large cones and palmlike leaves.Phylum Ginkgophyta-only one species surviving. Diciduous fan leaves with fleshy seeds.Phylum Gnetophyta-species are found in tropics and desert and varies greatly in morphology.

Phylum Anthophyta-Flowering plantsCharacteristics-flowers and the production of seeds. Most successful plant phylum. A flower is a structure specialized for reproduction.

1. Sepal-leaf like and protects the floral bud.

2. Petals-Usually showy with colors to attract pollinators

3. Stamen-male reproductive organ. Contains an anther where male gametophytes or pollen is produced. The anther sits long stalk called the filament, which connects to the base of flower

4. Carpel-female reproductive organ. The swollen bottom or ovary contains one or more ovules where the female gametophyte is found. The ovary connects to a slender structure called the style. At the top of style is the stigma where the pollen lands. A flower may have multiple carples or only one.

A flower can have both male and female reproductive organs. If it does, it is termed perfect but if it does not it is termed imperfect. Male flowers are called staminate flowers and female flowers are called carpellate flowers. If both flowers are on the same plant, then the plant is said to be monoecious but if they are on different plants (male date palms vs. female date palms), then the plant is dioecious. Corn is a monoecious plant with stamenate and carpellate flowers on the same plant. Sagittaria is dioecious. The plant on left is male and the right female.

Which of the following is not found on a flower?A) sepalsB) petalsC) PlasmodesmataD) StamenE) carpels

ANS: CThe four parts to a flower are the petals, sepals, stamen, and carpels. The plasmodesmata are pores between adjacent plant cells.

Microgametogenesis-In the anther chambers there are microspore mother cells (2n). They undergo meiosis to produce 4 microspores (n). The microspores undergoes mitosis to produce a spore with two nuclei, one becomes the tube cell and the other the generative cell. The generative cell will undergo mitosis once more to make two sperm nuclei. This is the male gametophyte. The male gametophyte will form a very drought resistant pollen grain. The shape is species specific.

Pollen gives rise to A) male gametophyteB) MicrosporesC) EggsD) sporophytes

ANS: APollen gives rise to the male gametophyte which has three cells.

Megagametogenesis-Is the formation of the female gametophyte. Inside the ovary, there is one or more ovules. Each ovule has a megaspore mother cell (2n). This cell will undergo meiosis to produce 4 megaspores (n). Three of cells will degenerate but one will survive to give rise to female gametophyte. The megaspore (n) will under-go three mitotic divisions without cytokinesis to give rise to eight nuclei. Division of the cytoplasm will then occur. It will produce seven cells. Three on each end and one in the middle.

The one in the middle will have two distinct nuclei (n+n). On the top are three antipodal cells. These will degenerate. At the bottom, there is a central cell which is the egg cell (n). It is flanked by two living cells called syngerids.

Pollination and fertilization-

Once a pollen falls on the stigma of the carpel, the pollen begins to digest the neck of the style and sending down a pollen tube. This pollen tube will have the tube nucleus in it. It will be followed by the generative nucleus which will undergo mitosis to form 2 sperm nuclei. The pollen tube is making its way to ovule which is housing the female gametophyte. There is an opening in the ovule called the micropylle. The pollen tube sends one sperm nucleus to fertilize the egg, and the second to fertilize the polar nuclei or large central cell. This cell becomes triploid (3n) and is called endosperm.

The structure above is A) a pollen grainB) a sporophyteC) MegaphyllD) female gametophyte

ANS: DThe female gametophyte in the alternation of generations will produce an egg cell. In angiosperms, the female gametophyte is 7 cells large.

This is a case of double fertilization. The fertilized egg or zygote will give rise to the seed embyro, the endosperm will provide nutrients to the embryo. The ovule will become the seed coat. The ovary under the influence of hormomes will become the fruit of the plant. The fruit or pericarp of the plant is used to protect enclosed seeds and aids in their dispersal.

In angiosperms, double fertilization occurs. What cells are fertilized?A) antipodal cell and the central cellB) egg cell and the central cellC) egg cell and a synergidD) antipodal cells and a synergid

ANS: BThe egg cell and the central cell. The egg cell will give rise to the plant embryo and the central cell will give rise to the endosperm.

Different types of fruit and seed. Fruit is used to protect the seed and entice animals to eat to carry the seed to another location.

The egg cell and the central cell are both fertilized, what do they give rise to?A) The egg cell makes the embryo and the central cell make triploid endosperm.C) The egg cell makes the sporophyte and the central cell make gametophyte.B) The egg cell makes the fruit and the central cell make flower.D) The egg cell makes the flower and the central cell make diploid endosperm.

ANS: AThe egg cell makes the embryo and the central cell make triploid endosperm

These are the major groups of flowering plants. The two major ones are the monocots and eudicots (formerly dicots)

Comparison of monocots versus dicots.

A plant had been observed and it has parallel veins, three carpels, six stamen and a fibrous root system. What is the best classification of this plant?A) gymnosperm that is a monocotB) gymnosperm that is a dicotC) angiosperm that is a monocotD) angiosperm that is a dicot

ANS: CThere are four groups of angiosperms but the majority fall into two categories-monocots and dicots. Monocots have parallel veins while dicots have branched veins. Monocots have floral parts in threes and multiples of three while dicots have floral parts in fours or fives and multiples of fours or fives. Monocots have a fibrous root system while dicots have one main root with branching roots coming off.