Chapter 26 and 32: Seed Plants

What novel derived traits involves the gametophyte in seed plants?

gametophyte reduced to microscopic structure inside sporophyte

What novel derived traits allow seed plants to live fully on land?

pollen and seeds are adaptations for true terrestrial living

What novel derived trait allows seed plants to reproduce without water?

reproduction and zygote development are not water-dependent

What happens to the female gametophyte in seed plants?

it is reduced to only a few cells and is microscopic, not a visible structure

What forms after the egg and sperm fuse in seed plants?

diploid zygote forms, which grows into new sporophyte individual when seed germinates

How is the plant embryo protected and nourished before germination?

It is nourished by nutritive tissue within the seed and protected by a hard outer shell called the seed coat

Why is seed dispersal advantageous?

seeds can travel great distances, reducing competition with parent plant

What is the male gametophyte in seed plants called, and what is it like?

pollen; microscopic and composed of 2 cells

How is pollen dispersed?

wind, water, or animals

What happens when pollen reaches the female gametophyte?

grows a pollen tube toward the egg and produces sperm that travel down tube to fertilize egg

Which spermatophytes are sister taxa?

gymnosperms and angiosperms

What are gymnosperms?

plants that produce seeds without flowers; "naked seed"

What are examples of gymnosperms?

conifers, cycads, ginkgophytes, gnetophytes

What are naked seeds/gymnosperms sheltered by?

woody leaves called sporophylls

What are angiosperms?

flowering seed plants; "seed in a vessel"

Where do fertilization and embryo development occur in angiosperms?

inside plant ovary, which develops into a fruit

What mutualistic relationships do angiosperms have with animals?

animal pollinators and seed distributors

How are male and female gametes produced in gymnosperms?

on separate cones but on the same plant; heterospory

What does it mean if a gymnosperm is monoecious?

"one home": male and female cones are on the same plant

What does it mean if a gymnosperm is dioecious?

"two homes": male cones on one plant, female cones on separate plant

How are gymnosperms pollinated?

by wind

What are tracheids, and what do they do?

perforated, lignified cells that transport water and minerals; dominant xylem cells in gymnosperms

What adaptations allow gymnosperms to survive in dry or cold conditions?

tracheids allow them to live without water for part of the year and survive in cold, dry regions

What are conifers?

dominant phylum of gymnosperms; reduced, needle-shaped leaves; adapted to cold, dry weather

What are cycads?

dominant during prehistoric times; live in mild climates; mistaken for palms

What are gingkophytes?

fan-shaped leaves; only one surviving species called Gingko biloba

What are gnetophytes?

inhabit arid desert regions around the world; unresolved phylogeny

What generation is the conifer tree?

sporophyte (2n) and monoecious

Are conifers heterosporous or homosporous?

heterosporous

What do microsporangia and megasporangia produce?

microsporangia—male microspores

megasporangia—female megaspores

Where are microsporangia located in conifers?

male pollen cones

What are microsporocytes and what do they produce?

diploid (2n) cells inside microsporangium; undergo meiosis to produce 4 haploid microspores

How do microspores develop into pollen?

each 2 haploid microspore undergoes mitosis to form pollen

What surrounds pollen grains for protection?

2 haploid cells surrounded by sporopollenin

What are the two haploid cells that make up the male gametophyte (pollen)?

generative cell and pollen tube cell

What is the function of the generative cell?

undergoes mitosis to produce two haploid sperm cells

What is the function of the pollen tube cell?

undergoes mitosis to form pollen tube

What is the ploidy of microsporangia, and what do they contain?

diploid (2n), containing microsporocytes

Where are megasporangia located in conifers?

female ovulate cones

What are megasporocytes and what do they produce?

diploid (2n) cells within megasporangium; produce 4 haploid megaspores via meiosis

Out of the four haploid cells produced by megasporocytes, how many survive?

one becomes the megaspore, the female gametophyte

The megaspore that survives will produce?

archegonium that produces haploid egg via mitosis

What happens when the pollen grain lands at the base of the female scale?

haploid pollen tube cell germinates and grows pollen tube toward female gametophyte

What does the diploid zygote develop into?

sporophyte embryo via mitosis

What are the three generations of tissue found inside a conifer seed?

seed coat from parental sporophyte, nutritive tissue from female gametophyte, embryo tissue

How long does the fertilization and seed development process take in conifers?

up to 2 years

What is the dominant terrestrial plant group today?

angiosperms

What are the two novel derived traits unique to angiosperms?

flowers and fruits

What is the function of flowers in angiosperms?

To ensure pollination and protect the embryo (seed).

What is the function of fruit in angiosperms?

embryo (seed) protection and seed dispersal

Can angiosperms be monoecious or dioecious?

both

What are the main pollinators for angiosperms?

wind, insects, birds, mammals

What type of xylem cells do angiosperms have and why are they important?

vessel cells; more efficient at conducting water than tracheids

What are flowers composed of?

modified leaves organized around central receptacle

What are the four main parts of a flower?

sepals, petals, stamens, carpels

What are sepals and their function?

green and photosynthetic; protecting flower bud

What is the role of petals?

attract pollinators with colors and scent

What is the female part of the flower called, and what does it include?

carpel (gynoecium or pistil); includes stigma, style, ovary

What is the male part of the flower called, and what does it include?

stamen (androecium); includes anther, filament

What is the "perfect" flower?

have both carpels and stamen; monoecious

What is an imperfect flower?

have carpels OR stamen, not both

What is the function of the stigma?

sticky surface that catches pollen

What is the function of the style?

tube where pollen tube grows toward ovule

What is inside the ovary and what does it become after fertilization?

ovules (megasporangia); each ovule can develop into a seed

How many carpels can a plant have?

one or more

What happens inside the anther?

microsporangia contain microsporocytes (2n), undergo meiosis to produce haploid microspores that will develop into pollen grains via mitosis

What is the filament?

thin stalk that supports the anther

What is the anther?

sac-like structure where microsporangia are located

What happens to the two haploid cells in a pollen grain?

one cell becomes pollen tube cell; other divides via mitosis to form two haploid sperm

How does the surviving megaspore develop into the embryo sac?

it divides three times via mitosis to produce eight nuclei distributed among seven cells

How are the seven cells of the mature embryo sac arranged?

three cells at one pole: 1 egg + 2 synergids (helper cells)

three cells at the other pole: antipodal cells (degenerate)

center cell: 2 polar nuclei (becomes endosperm after fertilization

What does the mature embryo sac contain?

1 egg cell, 2 synergids, 3 antipodal cells, 1 central cell with 2 polar nuclei

How many megaspores are produced per megasporocyte, and. how many survive?

4 haploid megaspores are produced; only 1 survives

What is the purpose of antipodal cells?

provides extra nutrition to embryo or degrade after fertilization

What is the function of synergids?

assist sperm to fertilize egg and polar nuclei

What happens when pollen lands on the stigma?

pollen tube cell germinates, growing down through style and enters ovule through micropyle

Where do the two sperm cells go after forming from the generative cell?

travels down pollen tube, deposited into embryo sac

What is double fertilization in angiosperms?

One sperm fertilizes the egg (forming an embryo), while the other fuses with two polar nuclei to form the triploid endosperm.

What does the triploid cell from double fertilization develop into?

endosperm, nourishes the developing embryo

What does the embryo seed develop into?

radicle (root) and either one or two cotyledons

What are monocots?

one cotyledon; flower parts arranged in multiples of 3 or 6; parallel leaf venation; multiple, fibrous roots; vascular bundles scattered in stem, organized in ring in roots; no true woody tissue

Do monocots have true woody tissue?

no, lack secondary xylem

What are examples of monocots?

grasses, palms, rice, corn, banana

What are eudicots?

two cotyledons; flower parts arranged in 4 or 5; networked leaf venation; one main taproot with smaller fibrous roots attached; vascular bundles in ring in stem, X-shape in the root; woody tissue

What types of plants are considered eudicots?

2/3 of all angiosperms—apples, beans, oaks, roses

What are cotyledons?

embryonic leaves

How is a fruit formed in angiosperms?

walls of ovary thicken after fertilization to form fruit with seed inside

What are examples of fleshy fruits?

berries, apples, tomatoes, eggplant

What are examples of dry fruits?

grains like rice, wheat, nuts

Why are fruits an important adaptation?

aid in seed dispersal

Which fruits are dispersed by wind?

small, light fruits (dandelions)

Which fruits are dispersed by water?

floating fruits (coconuts, mangrove seeds)

How are fruits dispersed by animals?

fruits with burrs attach to fur; fleshy fruits eaten by animals, seeds deposited in feces

What is pollination?

transfer of pollen from anther to stigma in angiosperms, male cone to female cone in gymnosperms

What are the types of pollination?

self pollination and cross pollination

What is self-pollination?

transfer of pollen from male to female on same plant; male cone to female cone in gymnosperms, male flower to female flower in angiosperms

What is cross-pollination?

transfer of pollen from male of one plant to female of another

What are key characteristics of asexual reproduction in plants?

no investment in flowers, pollinators, fertilization; offspring genetically identical to parent; quick and efficient

Why do perennial plants use asexual reproduction?

regenerate after winter dormancy

Which root and stem modifications are used for asexual reproduction?

bulbs (lily), tubers (potato), corms (garlic), rhizomes/stolons (ginger, strawberries)