biology quiz 2 term 2 11b

ovaries

angiosperms produce sexual reproductive organs (seeds) which surround and protect the seeds

fruit

after fertilization, ovaries turn into this that surround, protect, and help disperse the seeds, its a structure that contains one or more matured ovaries. the wall of the fruit helps disperse the seeds inside it, carrying them away from the parent plant

how are flowering plants classified?

according to the number of seed leaves or cotyledons in their embryos

monocot

flowering plants with one seed leaf

dicots

flowering plants with two seed leaves

how are angiosperms categorized?

• no. of seed leaves

• strength and composition of stems

• number of growing seasons they live

characteristics + examples of monocots

seeds - single cotyledon

leaves - parallel veins

flowers - floral parts often in multiples of 3

stems - vascular bundles scattered throughout stem

roots - fibrous roots

EX. wheat / corn / rice

characteristics + examples of dicots

seeds - two cotyledons

leaves - branched veins

flowers - floral parts often in multiples of 4 or 5

stems - vascular bundles arranged in a ring

roots - taproot

EX. roses, tomatoes, oaks, clovers, daisies

how are the stems of woody plants made

theyre made of cells with thick cell walls that support the plant body (trees, vines, shrubs)

do herbaceous plants produce wood

no, they do not produce true wood, they have non woody stems (dandelions, zinnias, petunias, sunflowers)

what determines the lifespan of a flowering plant

• genetic factors

• environmental factors

• flowering seasons (annuals, biennials, perennials)

annuals

pass through entire life cycle in one growing season

biennials

live through two growing seasons, seeds and flowers form in the second season

perennials

regrow year after year

whats the point of a flower

to bring together gametes for reproduction and protect the resulting embryo

how are animals / pollinators drawn to flowers

• color

• scent

• shape of the flower

why is pollination from pollinators more effective than wind pollination

because pollination go to flower to flower directly so they can carry pollen from every flower they visit

what are flowers

reproductive organs that are composed of four different kinds of specialized leaves

• sepals

• petals

• stamens

• carpels

sepals

the outermost part of a flower contains these modified leaves, they enclose the bud and protect it as it develops and before it opens

stamens

male reproductive organ of a flower, consists of a stalk (filament) with an anther at its tip, most angiosperms have several stamens

anther

at the tip of the filament of a stamen, this is where the male gametophytes (pollen) is produced

carpels

the innermost structure, the female reproductive parts of a flower, this is where female gametophytes are produced and, later, seeds

theyre fused into a broad base, forming an ovary where the gametophyte is produced

the diameter of the carpel narrows into a stalk called a style, at the top of the style is a sticky/feathery portion (the stigma) which is specialized to capture pollen,

1 carpel or several fused carpels are sometimes called pistil

variety in flowers

in some species, the male and female gametophytes are produced in different plants

some flowers grow very close together to look like one composite structure

some flowers attract a wide variety of pollinators

how does the male gametophyte form

it develops inside the anther

1. meiosis produces four haploid spore cells called pollen spores

2. the nucleus of each pollem spore divides to produce a large tube cell and a smaller generative cell |(these two cells r the gametophyte)

how is the female gametophyte produced

they develop inside the carpels, the ovules are enveloped in a protective ovary (this will grow to be a seed inside a fruit)

1. a single diploid cell goes through meiosis to produce four haploid cells, three of which disintegrate,

2. the remaining cell goes through mitosis, producing eight nuclei

3. cell walls form, which makes 7 cells (six cells with 1 nucleus, the seventh has 2 nuclei)

4. these seven cells are the gametophyte (aka embryo sac)

5. one of the eight nuclei that is closest to the base of the gametophyte is the actual egg cell / gamete

pollination

the transfer of pollen to the female portions of the flower

some plants are wind pollinated, most are insect pollinated (pollinators, mostly bees)

animal pollinated plants have adaptations such as bright colors and sweet nectar to attract and reward animals

how is insect pollination beneficial

it provides a dependable source of food (pollen and nectar) to insects

plants benefit because they take pollen directly from one flower to the next

do plants depend on pollinators

yes, many plant species do bc when insect populations are threatened, that also means that plant populations are threatened and it lowers the productivity of agricultural crops

fertilization

1. a pollen grain lands on the stigma of a flower, it begins to grow a pollen tube

2. the generative cell divides and forms two sperm cells

3. the pollen tube grows into the style, where it eventually reaches the ovary and enters an ovule

4. inside the embryo sac, double fertilization takes place :

1. one of the sperm nuclei fuses with the egg nucleus to produce a diploid zygote that becomes the new plant embryo (zygote)

2. the second sperm nuclei fuses with two polar nuclei in the embryo sac to form a triploid (3N) cell which will grow into a food- rich tissue called the endosperm which nourishes the seedling as it grows

why is the endosperm useful

it stores food which makes the flowering plant spend very little energy producing seeds from ovules until double frtilization takes place

the energy saved can be used to make many more seeds

vegetative reproduction

some flowering plants reproduce asexually, its the formation of new individuals by mitosis, it does not require gametes, flowers, or fertilization ex. sprouting potato, strawberries, cholla cactus

how and why do horticulturists take advantage of vegetative reproduction

they use cuttings or grafting to make many identical copies of a plant or to produce offspring from seedless plants since these plants only need a single parent and can reproduce identical offspring quickly

grafting is used to reproduce seedless plants and varieties of woody plants that will not grow from cuttings

how do fruits form

as angiosperm seeds mature, ovary walls thicken to form a fruit that encloses the developing seeds, so its basically a matured angiosperm ovary that usually have seeds (except for fruits that are selectively bred to be seedless)

fruits arent just apples strawberries and grapes they can also include corn, beans, tomatoes, string beans, cucumbers, etc.

mechanisms of seed dispersal

since fruits are usually eaten by animals, the seeds are covered with a tough coating which allows them to pass through the animal’s digestive system unharmed, the seeds then sprout in the feces of said animal

this benefits the animal by giving it nutrition and it benefits the plant as a method of seed dispersal

other methods of seed dispersal include:

• animals may drop the seed while eating the fruit instead of consuming it

• wind

• sticky fruits stick to the animal and fall in new places

• fruits can fall to the ground and sprout there (ex. coconut)

seed dormancy

all seeds contain plant embryos in this state in which they are alive but not growing, they can be in this state for weeks, months, or even years, it can also help with long-distance seed dispersal so that the plant doesn’t germinate until its in ideal conditions

germination

takes place when growth of the embryo resumes and the seed sprouts into a plant, when it starts, the growing plant unfolds its first leaves, the cotyledons