Lecture 15 Key Concepts/Terms

megaspore

spore that develops into a female gametophyte and is produced by a conifer's female cone

microspore

small haploid spore formed by some plants that develops into a male gametophyte

megasporangium

A plant structure in which megaspores are formed, such as those of the female cones of pines.

microsporangium

a plant structure that produces microspores

integument/seed coat

outer protective layer of a seed

micropyle

minute opening in the wall of an ovule through which the pollen tube enters

what are the three ways that seeds are adaptive?

embyrophytic
dispersal
dormancy

how is dispersal beneficial for seeds?

the hardness of seeds allows them to move farther

what is seed dormancy?

a delay between developing and dispersal or dispersal and developing

homospory

the production of one type of spore

microspore mother cell

a diploid cell that undergoes meiosis to yield a haploid microspore

heterospory

production of different types of spores

pollen

the tiny granules that contain the male gametophyte of seed plants

sperm (plant structure)

seed

ovules

A structure that develops within the ovary of a seed plant and contains the female gametophyte.

megaspore mother cell

a diploid cell that undergoes meiosis to yield a haploid megaspore

female gametophyte

embryo sac; archegonia

male gametophyte

pollen grain; antheridium

egg (plant structure)

develop in ovules, tiny structures embedded in the ovary

naked seeds

Seeds not enclosed in layers of tissue from an ovary, usually lying naked on a scale (as in a pine cone).

pollen tube

A tube that forms after germination of the pollen grain and that functions in the delivery of sperm to the ovule.

Why aren't seed plants dependent on water?

the evolution of seeds, coupled with the evolution of pollen grains with sperm that no longer require water to swim through for fertilization (they have the pollen tube) allows for seed plants to be able to reproduce without water present

features of seed plants

seeds allow for dispersal
seeds allow for dormancy
all heterosporous
dramatic reduction of gametophytic stage
sporophyte is the dominant form

gymnosperms

cycads, ginkgos, gnetophytes and conifers

cycads

ancient (been around since the dinos)
can become very large
slow growing
motile sperm

ginkgos

only one extant species
dioecious
motile sperm

female ginkgos

has fruit on it that smells very very bad lol

male ginkgos

has cones

Gnetophytes

Welwitschia, Ephedra
have vessel cells (like angiosperms) that are homoplasious

Welsitschia

gnetophyte
only two leaves
dioecious

Ephedra

most gnetophytes are these
many medical uses

conifers

gymnosperm; cone-bearing plants; most are evergreen

vessel cells in gnetophytes

vascular tissue that are much more efficient at transporting water than tracheids

vessel cells in angiosperms

most species have tracheids
characterized by primary and secondary cell walls
water conducting cells

key trait of angiosperms

develop flowers

sepal

A leaflike structure that encloses the bud of a flower.

petal

A colorful, leaflike structure of some flowers.

anther

the part of a stamen that contains the pollen (male)

filaments

a slender threadlike object or fiber, especially one found in animal or plant structures (male)

stamen

the male reproductive organ of a flower (anther and filament)

Ovary

Swollen part of pistil that contains the ovule where the ova are produced

Ovules

The female reproductive part of the seed plants that contains the female germ cell and after fertilization becomes the seed.

style

Connects the stigma to the ovary of a flower

stigma

The tip of the female reproductive structure of a flower where the pollen lands

carpel

The female reproductive organ of a flower, consisting of the stigma, style, and ovary.

types of fruits

simple, aggregate, multiple, accessory

apple

single carpel with interior seeds

tomato

true berry with two fused carpels

legume

each seed has a sugary coat, bean is the ovary

peach

drupe, seed is inside a hard pit

aggregate fruits

result from a single flower with multiple separate carpels

multiple fruits

develop from a group of flowers called an inflorescence

egg cell in angiosperms

inside the ovule

synergids

part of the egg apparatus and are thought to help the pollen nucleus reach the egg cell for fertilization

antipodals

Three cells of the mature embryo sac, located at the end opposite the micropyle.

polar nuclei

in anthophytes, the two nuclei in the center of a megaspore

tube cell

produces pollen tube

generative cell

in a pollen grain, the cell that divides mitotically and forms two sperm cells

double fertilization

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.

2N zygote

One sperm nucleus unites with the egg nucleus

3n endosperm

supplies nutrients to the developing embryo as the seed germinates, or as the embryo develops

how is the angiosperm life cycle different than the gymnosperm life cycle?

reduced cell number in female gametophytes
double fertilization
triploid endosperm

What makes angiosperms so successful?

Vessel cells, rapid maturation, pollinators, fruits

Ginkgo biloba

female ginkgo tree, very strong smelling fruit

You hear the familiar jingle "most have cones for seeds, move have needles for leaves" and you automatically think...

A) this song is about the most common group of gymnosperms, the ginkgos!
B) Ephedra is the plant mentioned in this catchy tune
C) that song was written by someone who hasn't take BIO200! It SHOULD go "most have cones for leaves, most have needles for seeds".
D) I'm thinking of that song because stores already have Christmas trees out even though it's not even Thanksgiving!
E) Cycads are really cool!

D) I'm thinking of that song because stores already have Christmas trees out even though it's not even Thanksgiving!