Download Lab 9 Brennen Forrest

Brennen Forrest
9
Seed Plants
I. GYMNOSPERMS
Life Cycles
Structure 1: sporophyte
Female structure in 4: ovule
Cell divisions occurring between 4 and 5: meiosis
Process occurring between stages 6 and 7: polination
Structures in 10: seedling with roots, stem and cotyledons
6 . Female Gametophyte
7.fertilization
5.Megaspores
8. Zygote
4.Ovule
9.Mature seed
3. longitudal sections
10. Seeds on scale.
2. cones forming
11.seedling
1.sporophyte
1 Seed Plants
Lab activities:
Compare the provided male (staminate) cones, the sites of pollen production, and female (ovulate) cones, the sites of ovule production. The
male cones are small, flimsy and short-lived, while the female cones are large, woody and long-lived (these are typical cones used in
decorations during the winter holidays). What do you think are the reasons for these differences in cone appearance.
-
The male cones are able to flow freely in the wind on the ends of the branches. This allows
for a greater dispersal rate of their pollen.
The female cones are more rigid to not only protect the seedlings, but also to maintain their
shape which is conducive to catching the wind borne pollen.
Male cone
The cone is very small, about ½” in length. The pollen
that falls from it is yellowish in color and has the
appearance of dust. It is surprising that the female and male
cones are similar is shape, but completely different in size.
Pollen grain-What is contained inside the pollen? Microspores
Obtain a fresh female cone, and examine the cone by using your magnifying lens. Sketch the cone,
and identify the sites of ovule production.
At the inner tips of the
scales.
What gamete (reproductive cell) does a pollen grain produce? Male
What gamete does an ovule produce? Female
2 Seed Plants
Pointing a female cone upward, you will find two seeds on the upper surface of each woody scale (if
seeds have not been shed). Tear several scales from the cone, until you find seeds (which should have
thin wings that aid in wind dispersal). Draw a seed below.
Papery wing that allows wind
to carry seed away from parent
plant.
Mature seed
Are there animals that eat these seeds? If so can you name a couple of examples? Where is the nutrition
in these seeds? Birds and squirrels. In the seeds endosperm.
II. ANGIOSPERMS
Flower structures and life cycles
Flower Anatomy
The flower consists of four whorls (circles) of flower parts. All flower parts are attached to the receptacle, the swollen
end of the flower stalk.

Sepals: The outer whorl of flower parts consists of sepals. They are often green or brown and protect the other
flower parts, but some flower have colorful, petal-like sepals. This is often what we think of as the coverings
around the flower “bud.”

Petals: Next, and just inside the sepals (more interior) are the petals, modified leaves that are usually colorful and
map produce scents or nectar (a sugar solution) to attract insects.

Stamens: The next innermost whorl are the stamens, these are the male reproductive organs. Each stamen
consists of a filament (a stalk) and an anther, a sack that produces the pollen.

Pistil(s):The innermost part of the flower consists of one or more pistils, the female flower parts. Each pistil
consists of an ovary (containing ovules, the female gametophytes), a style, and a stigma. The stigma is the top
part of the pistil. It is often feathery or sticky to catch pollen. Pollen lands on the stigma, where it germinates
(begins growth). The pollen grows a root-like tube down through the style into the ovary and next to an ovule.
Then it releases sperm that move into the ovule to fertilize the waiting egg on the inside.
petal
Pistil
stamen
stigma
anther
style
filament
ovary
sepal
ovule
© 2001 Brooks/Cole – Thompson Learning
Used by permission
3 Seed Plants
stamen
Pistil
petal
stigma
style
anther
filament
ovary
ovule
petal
stigma
style
ovary
stamen
ovule
Pistil
stigma
anther
style
filament
ovary
petal
ovule
4 Seed Plants
Periwinkle
None
visible
5
Petals or other parts fused?*
(if “yes”, then describe the ways
that parts are fused)
unknown
Rhododendron
None
visible
5
unknown
Daffodil
None
visible
6 + center
The petals are fused to the center inferior
‘cup’ type petal
Flower name
# sepals
# petals
Ovary inferior or
superior?
inferior
superior
Floral inflorescences
1) Which do you think is more likely to attract pollinators, a single large flower (like a rose or lily) or one with
many clustered flowers that are much smaller? Why do you think so?
Large clusters bring in more pollinators as they present more scent and more color to attract with.
2) What are some disadvantages to making flowers very large?
Larger predator can be able to get to the ovary. Require more time to fertilize.
3) A way to get the advantage of both small flowers and large displays is to group many small flowers
together. A cluster of flowers is an inflorescence. A fragrant hyacinth is an inflorescence, can you think of
2 or 3 other flowers that you saw on your excursion that might be classified as an inflorescence?
Rhododendron and the Periwinkle act similar to this inflorescence.
Composite flowers:
Ray flowers
ray flowers
Disk flowers
sepals
ovule
pistil
ovary
5 Seed Plants
Flowers and pollinators:
Flower species
Periwinkle
Moth
Pollinator
Rhododendron
Butterfly
Daffodil
Bees
Why do you think so?
They do not have rigid petals for
landing of bees. I have seen many
a moth land on them.
Inflorescences with strong scent
and not much of a platform for
bees.
More of a platform for landing on,
plus they are bright yellow.
Fruits
Check off which of the following plant parts you think may be a fruit.
__X__ The pod around a pea e.g. snap peas
__X__ The winged apparatus that allows a maple seed to fly like a helicopter.
__X__ Pineapple
__X__ Apricot
__X__ Hard shell around a hazelnut
1) Why would plants go to the “trouble” of making large, heavy fruits e.g. a peach or apple?
To provide nutrients for the seed when it starts to grow. Also it aids in the distribution of
seed by attracting animals who want to eat the fruit part.
2) When you eat a watermelon or a peach, we throw away the seeds or spit them out, but each and
every one has potential to become a new plant if it were to find fertile soil and the right growing
conditions such as moisture and sun. Why do you think some fruits make so many seeds and others
fewer or only one?
I suspect it is related to the mortalitly rate of the species. If it is high then it makes sense to
start out with many more seeds.
High challenge question:
2) Some fruits have no seeds on the inside e.g. bananas, research why this is so and place that
response into your lab report for one extra credit point.
Bananas actually do have seeds, although they are very small in the culinary versions that
most of us eat. Strawberry seem to have seeds on the outside, but actually each seed
looking thing is a ‘fruit’ that carries an even smaller seed. The red fleshy part is not the fruit.
Also the seeds are not fertilized in that state.
6 Seed Plants