Biology 1002 Section 5: Flowering Plants: Reproduction and Development

sporophyte

In angiosperms the _______ is the dominant generation

flowers, double fertilization, fruits

The angiosperm life cycle is characterized by "three F's", which are:

Carpels

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

Stigma

The sticky part of a flower's carpel, which receives pollen grain.

Style

The stalk of a flower's carpel, with the ovary at the base and the stigma at the top.

Ovary

A flower structure that encloses and protects ovules and seeds as they develop.

Stamen

the male reproductive organ of a flower

Anther

the part of a stamen that contains the pollen.

Filament

the stalk of a stamen

Petals

modified leaves which are usually bright in color to attract pollinators.

Sepals

Leaflike parts that cover and protect the flower bud

Pistal

a single carpel or a group of fused carpels

Receptacle

The base of a flower; the part of the stem that is the site of attachment of the floral organs.

Pollination

The transfer of pollen from male reproductive structures to female reproductive structures in plants

wind, water, animals

The three methods of pollination are:

Coevolution

Process by which two species evolve in response to changes in each other

biotic pollination

pollination by living agent such as animals, about 80% of pollination

abiotic pollination

pollination by a nonliving agent such as wind, about 20% of pollination

The flowers of wind-pollinated plants

are usually green and inconspicuous

Bees

Are the most important insect pollinators

development of male gametophytes in pollen grains

-Each anther develops 4 microsporangia (pollen sacs)

-Within sporangia are diploid cells called microsporocytes

-Each microsporocyte undergoes meiosis to produce 4 haploid microspores

-Each microspore undergoes unequal mitosis, producing haploid male gametophyte consisting of 2 cells, generative cell within larger tube cell, 2 cells and spore wall make up pollen grain

-gametophyte becomes mature when generative nucleus divides forming 2 sperm. Occurs after pollen grain lands on stigma

development of female gametophytes

-embryo sac develops inside each ovule

-2 integuments surround a megasporangium (gap call micropyle)

-one cell in megasporangium, the megasporocyte, undergoes meiosis, produces 4 haploid megaspores, 1 survives

-nucleus of megaspore undergoes 3 mitotic divisions without cytokinesis producing one large cell with 8 nuclei

-multinucleate mass divided by membranes to form multicellular female gametophyte, the embryo sac

-1 egg, 2 synergids, 3 antipodal cells, 2 polar nuclei

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.

ovule

Each _________ develops into a seed

seed

consists of an embryo packaged with a store of food within a protective coat

ovule's integument

The seed coat develops from

endosperm

In angiosperms, a nutrient-rich tissue formed by the union of a sperm with two polar nuclei during double fertilization. Provides nourishment to the developing embryo in angiosperm seeds.

cotyledons

seed leaves

Dormancy in seeds

When a seed does not germinate immediately after leaving the parent plant; it will remain dormant until conditions are ideal.

rainfall, heat, cold

Breaking of seed dormancy often requires environmental cues such as _________ (3)

Germination

the process whereby seeds or spores sprout and begin to grow

Imbibition

Seed germination initiated by ___________, the uptake of water

eudicot germination

- root formation

- emergence of hypocotyl

- hypocotyl pulls up 2 cotyledons

- expansion and greening of cotyledons

- development of epicotyl

- expansion of foliage leaves

- elongation of internodes to form shoot

monocot germination

- roots from stem base

- coleoptile grows straight out of the ground

- then shoot emerges aboveground

- remains of grain stay underground

functions of fruit

Protects enclosed seeds and aids in seed dispersal by wind or animals

pericarp

The thickened wall of a fruit.

Simple fruits

fruits derived from a single carpel or several fused carpels (ex. pea pod or nut, nectarine)

aggregate fruit

results from a single flower that has more than one separate carpel, each forming a small fruit (ex. raspberry)

Multiple fruits

develop from a group of flowers called an inflorescence

Accessory fruit

contains other floral parts in addition to ovaries

water, wind, animals

Methods of fruit and seed dispersal (3)