Welcome to Chapter 38: Angiosperm Reproduction and Biotechnology

(1 pt.) Give an overview of Angiosperm Reproduction (you may use a cited diagram from the internet, but also describe it with your own words)
(1 pt. for Marielle)
Angiosperms are plants with flowers. They represent the most advanced condition among terrestrial plants. Their sexual organs are the flower. The angiosperms are vascular seed plants in which the ovule (egg) is fertilized and develops into a seed in an enclosed hollow ovary. The ovary itself is usually enclosed in a flower, that part of the angiospermous plant that contains the male or female reproductive organs or both. Insects pick up the pollen off the anther and rub it off onto the stigma of the plant. The pollen will go into the ovary. Then, fertilization will happen. In the embryo sac the egg and sperm meet. The zygote (2n) becomes and embryo (2n) (sporophyte) and then turns into a fruit (which is developed from the ovary). A seed develops from the ovule, and the germinating seed matures into a sporophye plant with flowers.

external image fleur.jpg

http://www.cartage.org.lb/en/themes/sciences/botanicalsciences/plantreproduction/angiosperms/angiosperms.htm, and AP Bio book page 772

(1 pt.) Define all the bold terms on page 772 (flower parts)
(1 pt. for Sarah)
Sepal- a modified leaf in angiosperms that helps enclose and protect a flower bud before it opens.
Petals- a modified leaf of a flowering plant.
Stamens- the pollen-producing reproductive organ of a flower, consisting of an anther and filament.
Carpels- the ovule-producing reproductive organ of a flower, consisting of the stigma,style, and ovary.
Receptacle- the base of a flower; the part of the stem that is the site of attachment of the floral organs.
Anther- the terminal pollen sac of a stamen, where pollen grains with male gametes form.
Ovary- the portion of a carpel in which the egg-containing ovules develop.
Stigma- the sticky part of a flower's carpel, which traps pollen grains.
Ovules- a structure that develops within the ovary of a seed plant and contains the female
Pistil- a single carpel or a group of fused carpels.

(1 pt.) What are the differences between microspores and megaspores.
(1 pt. for Marielle)
They are both spores from heterosporous plant species, microspores develop into a male gametophyte, and megaspores develop into a female gametophyte.

Information from AP Bio book page 774-75

(1 pt.) What are some strategies that plants use to prevent from self-fertilizing?
(1 pt. for Nathan)

Some plant species are dioecious, and cannot self-fertilize because they have 'genders.' Pin and thrum flower structures discourage self-fertilization because the styles and stamens are different sizes. The most common method is self-incompatibility, where the plant can recognize if the pollen it has been fertilized with is genetically similar. The plant will reject that pollen.

Bio book

(1 pt.) Describe the process of double fertilization. Use your own drawings or cited pictures.
(1 pt. for Marielle)
Double fertilization is a mechanism of fertilization in angiosperms, in which two sperm cells unite with two cells in the embryo sac to form the zygote and endosperm. In this process, one sperm fertilizes an egg to form a zygote. The other sperm combines with the two polar nuclei to form a triploid nucleus in the center of a cell in the embryo sac. The cell gives rise to the endosperm. The union of the two sperm cells with different nuclei of the embryo sac is the double fertilization. It ensures that the endosperm will develop only in ovules where the egg has been fertilized. This prevents angiosperms from squandering nutrients.

external image pollen-doublefertilization.gif external image 2fert.jpg

Information from http://www.uic.edu/classes/bios/bios100/labs/plantdiversity.htm and AP Bio book pages 776-77

(1 pt.) Sketch and describe the structure of a seed.
(1 pt. for Marielle)
external image seed_embryo.gif

In a mature seed, the seed dehydrates and the embryo is surrounded by a food supply and becomes dormant. These are enclosed in a protective seed coat. One type of eudicot seed is a gardern bean. Embryo consists of an elongate structure, embryonic axis, and cotyledons (which are packed with starch before the seed germinates beacuse they abosred carbs from the endosperm when the seed developed). Castor beans retain their food supply in the endosperm and have cotyledons that are very thing (these absorb nutrients from the endosperm and transfer them to the rest of the embryo). The embryo of a monocot has a single cotyledon. Members of the grass family have scutellum.

Information from AP Bio book page 778 and http://www.cartage.org.lb/en/themes/sciences/BotanicalSciences/PlantReproduction/FloweringPlant/FloweringPlant/FloweringPlant.htm

(1 pt.) Describe how seeds develop into seedlings.
(1 pt. for Marielle)
Germination of seeds depends on imbibition. Water causes seed to expand, rupture its coat, and trigger metabolic changes in the embryo. Enzymes digest stored nutrients of endosperm or cotyledons. The first organ to emerge from the germinating seed is the radicle, the embryonic root. Next the shoot tip breaks through the soil surface. Stimulated by light, hypocotyl straightens which raises the cotyledons and epicotyl. The shoot apex and cotyledons are pulled upward. The epicotyl spreads its foliage leaves, and the leaves expand. The cotyledons shrivel and fall away from the seedling.

Information from AP Bio book page 780

(1 pt.) List and describe types of asexual reproduction that flowers undergo.
(1 pt. for Jessica)
The types of asexual reproduction that flowers undergo are
Vegetative reproduction- offspring that are mature vegetation fragments from the parent plant.
Fregmentation- the separation of a parent plant into parts that develop into whole plants.
Apomixis- plants can produce seeds without pollunation or fertilization.

Ap Bio book p. 781-782

(1 pt.) Read and summarize how humans have used artificial selection to change plants.
(1 pt. for Jessica)
How humans have used artificial selection to change plants is by transfering the genes/ or adding desired genes to a specific plant to get certain traits. Dealing with maize, researches found a muant called opaque-2 that has much higer levels of lysine and tryptophan that regular grown corn lacks. By humans using convential methods of hybirdization and artificial selection, plant breeders converted the opaque-2 endosperm into a more desirable type. Today genetically modifying plants is very common for plant improvement.

Ap bio book p. 783

(2 pt.) Summarize the issues surrounding plant biotechnology.
(2 pts. for Nathan)

Basically, introducing a new type of plant into an environment will generate some unpredictable results. Most of the controversy listed in the book involves scientists speculating on potential negative consequences of genetically modified plants. For example, some people believe that modified plants will be unsafe to eat, though there is no evidence to back this up. Another issue is the new plant's impact on other organisms. In one experiment, caterpillars that fed on the leaves of a genetically modified plant died. Though this experiment was discredited, it is an example of what some scientists fear could happen. The most serious issue is the possibility of crop to weed hybridization, where the genes of the modified plant and a weed mix. This would be a problem. If the modified gene makes the crop more resistant to pesticides, for example, hybridization with a weed would create pesticide resistant weeds. Many crops undergo crop to weed hybridization, so it is a very real possibility.

The book

(1 pt.) Evolution Connection on page 787. Rewrite and then answer the question.
(1 pt. Dylon)
With sexual reproduction, some plant species fully self-fertile. others are fully self-incompatible, and some have adopted a "mixed strategy"with partial self-incompatibility. these reproductive strategies differ in their implications for evolutionary potential. how, for example might a self-incompatible species fare as small founder populations or remnant populations in a severe population bottleneck, as compared with self-fertile species.
answer: In a bottle neck the self fertile plants would be able to "clone them selfs and have no genetic shuffling of information. this can be a good or bad thin if the envioment favors there traits it will explode in population and not have to worry about finding a mate, but if the envirment doesnt alow for these genes to survive the species will die out because there is no change in genetic code. if the plant is self-incompatible it needs to have a mate to reproduce so there is always a shuffling of genetics so it will be as ready as it can be for enviromental changes, but if it is in a bottle nech situation and cannot find a mate them the species will die out with no reproduction happening.

(1 pt.) When is it advantageous for a plant to pursue asexual reproduction?
(1 pt. Drew)
When there isnt a huge population of other plants around so the plant wouldnt be depending on others. AP bio book

(1 pt.) When is it advantageous for a plant to pursue sexual reproduction?
(1 pt. Drew)
This would allow a more diverse gene pool so its better for evolution. it would also be better for plants in large groups of the same plants. Ap bio book

(2 pts.) Animal diversity increased rapidly with the evolution of angiosperms. Why do you think that is so? What do angiosperms use animals for?
Woking on it Keyshla. wil answer it in 15 minutes