Angiosperms

what are angiosperms characterized by?

plants with seeds that are contained within a vessel (carpel)

angiosperms are the _______ and most ________ phylum of the plant kingdom

largest, diverse

what percent of plants are angiosperms?

90%

there are about ________ species of angiosperms, with more than _____ families

350,000 and 450

how many phylum of angiosperms are there?

one one → anthophyta

what are the two classes of angiosperms?

eudicots and monocots

when did angiosperms become dominant worldwide?

between 80-90 million years ago

what are the unique features of angiosperms:

flowers, enclosed carpels, double fertilization

give some examples of plants within angiosperm

duckweed

banana plant

coconut palm saguaro cactus

rice california poppy

hepatica

Lilium

snapdragon

are angiosperms heterosporous or homosporous

heterosporous

the female gametophytes of angiosperms can be described as what?

wholly enclosed within sporophyte tissue and reduced to only a few cells

the male gametophytes consist of what?

a germinated pollen grain with three nuclei

T or F: angiosperms have both antheridia and archegonia

False, they have neither

is the megasporocyte diploid or haploid?

diploid

all cells the differentiate in the ovule originate from what?

the megasporocyte

the megasporocyte undergoes what to yield the megaspores?

meiosis

how many megaspores are produced by the megasporocyte?

four

how many of the megaspores degenerate?

three

the _______ differentiates and eventually becomes what?

integument; the seed coat

the opening at one end of the ovule is also known as what?

the micropyle

during gametophyte development, the functional megaspore will begin to enlarge and the nucleus will divide _______.

mitotically

how many times does the functional megaspore divide?

three times

• first nuclear division → 2 nuclei

• each nucleus divides again → 2 nuclei

• third division → 8 nuclei in total

what happens to the 8 nuclei after they are formed?

4 will group at the micropylar end and 4 will group at the opposite end

what happen after the cells travel to either side fo the ovule?

one nucleus from each group migrates into the cell center

when one nucleus from each group travels into the cell center they form what?

polar nuclei (2n)/central cell nuclei

how many cells are in the developing ovule?

7 cells (8 nuclei bc two fused together)

the 3 remaining nuclei at the micropylar end are referred to as what?

egg apparatus

what does the egg apparatus consist of?

an egg cell and 2 synergids

what cell is closest to the micropyle?

the egg cell

the 3 cells on the non-micropylar end become what?

antipodals

the eight-nucleated, seven-celled structure is the mature ___________

megagametophyte

the megagametophyte is also known as what?

the embryo sac

what structure connects the ovule to the ovary?

funiculus

where does the formation of the male gametophyte take place?

in the anthers

what does the anther consist of?

four groups of sporogenous cells, surrounded by several layers of sterile cells

the sterile cells of the anther are also known as what?

the wall of the pollen sac

the sporogenous cells become what?

microsporocytes

are microsporocytes haploid or diploid?

diploid

the microsporocytes produce how many microspores?

a tetrad (4)

are microspores haploid or diploid

haploid

are microspores produced through mitosis or meiosis?

meiosis

microspores divide ________ to form what cells?

mitotically

• a large tube cell

• a small generative cell

the generative nucleus divides to yield what?

2 sperm cells

do the sperm cells have flagella, why or why not?

no, they don’t need them because they use wind for dispersal rather than water

the two sperm cells + a tube cell can also be referred to as a what?

mature microgametophyte

what is pollination?

the transfer of pollen grains from an anther to a stigma

what does fertilization involve?

the union of an egg and a sperm

when does fertilization take place?

may not occur until days or weeks or even months after pollination has taken place

what is unique about angiosperms fertilization?

they have a double fertilization

what occurs after pollination in angiosperms?

pollen grains germinate on the surface of the stigma, forming a pollen tube

what is the function of the pollen tube?

it enters the ovule through the micropyle, the 2 sperm and the tube nucleus within the pollen tube are released to the embryo sac

what does the first sperm cell that enters the ovule do?

unites with the egg cell to form the zygote (2n)

what does the second sperm cell that enters the ovule do?

unites with the central cell nuclei (triple fusion, 2n+n)

what is the 3n structure composed of one sperm cell and the central cell nuclei called?

primary endosperm nucleus

what is the function of the endosperm?

food for the embryo

after double fertilization, the zygote becomes what?

an embryo

after double fertilization, the primary endosperm nucleus becomes what?

endosperm, a nutritive tissue

after double fertilization, the ovule becomes what?

seed

after double fertilization, the ovary becomes what?

fruit (enclose the seed)

after double fertilization, the integument becomes what?

seed coat

what are the two defining characteristics of the angiosperms?

flower and fruit