Practical 3- Week 4 (Ch 30)

gametophyte

(1N) the gamete-producing and usually haploid phase, producing the zygote from which the sporophyte arises. eg. dominant form in bryophytes.

sporophyte

(2N) the asexual and usually diploid phase, producing spores from which the gametophyte arises; stalk/seta, capsule containing spores eg. dominant form in vascular plants; the frond of a fern

Pterophytes

(ferns) vasc. plants: have x&p; ferns first to develop complex stems and large leaves; xylem is lignified, have stems, leaves, and roots; ferns reproduce via spores

What does 'alternation of generations' mean?

(metagenesis) the alternation of a sexual phase and an asexual phase in the life cycle of an organism; is a term used to describe the type of life cycle that occurs when they have distinct sexual haploid and asexual diploid stages

male cones

(microstrobilus) are small and inconspicuous and not as 'woody' as female, shorter life span, and produce pollen

bryophytes

(non-vasc. plants) Bryophyta (Byron = moss, phyton = plant) liverworts, hornworts and mosses growing predominantly in moist environments; 1st group to colonize land, most primitive; produce swimming sperm, have no true vasc. system (x&p), have primitive type of conducting cells to transport water and nutrients around the plant, no lignified tissues, roots, stems and leaves

Gymnosperms

(seed plants and pollen) 'Seeds of change', naked or exposed seeds Phylum Gnetophyta - Gnetophytes Phylum Ginkgophyta - Ginkgo Phylum Cycadophyta - Cycads Phylum Coniferophyta - Conifers first to not need water for reproduction, all have pollen, cones and seeds and the dominant gen. is the sporophyte gen.

What adaptations do Pterophytes have for living on the land?

-How do they avoid drying out on land? cuticle, moist environment, stomata, epidermis -How do they support themselves on land? roots and vasc. tissues, cuticle, leaves -Is the plant differentiated into different parts, if so, what are the various parts? yes: stem (short, compressed), rhizomes and roots, and leaves -Do they have differentiated tissue, if so, what are the various types of tissues? vasc. tissue: x&p, epidermal tissue, ground tissue

What adaptations do Lycophytes have for living on the land?

-How do they avoid drying out on land? thick cuticle, moist environment, stomata -How do they support themselves on land? roots and vasc. tissues to get bigger -Is the plant differentiated into different parts, if so, what are the various parts? yes: stem, roots, and microphylls -Do they have differentiated tissue, if so, what are the various types of tissues? vasc. tissue: x&p, root tissue, stem tissue, microphyll tissue

What adaptations do Bryophytes have for living on the land?

-How do they avoid drying out on land? thin cuticle, moist environment, stomata -How do they support themselves on land? rhizoids -Is the plant differentiated into different parts, if so, what are the various parts? yes: rhizoids, gameto. and sporo. -Do they have differentiated tissue, if so, what are the various types of tissues? gameto. and sporo.; rhizoids, seta, leaflike structures

move from water to land

-develop ways to support themselves on land, -develop ways to obtain water and nutrients from the soil -develop transport systems to transport water and nutrients in and around the algae -develop different reproductive structures and strategies (so that their gametes or spores do not dry out and therefore perish).

moss sp.

-gametophyte dom. gen. -spores formed in capsule of sporophyte, less spores -leaflike structure but no vasc. tissue -no true stem (seca) b/c no vasc. tissue, no lignin -rhizoids for roots, unicellular and filamentous

angiosperm success

-incredible structural diversity -more efficient vascular system -mutualistic associations with animals to assist in pollination -relatively short generation times.

fern frond (leaf)

-much larger leaves w/ vasc. tissue -use vasc. tissues -cuticle present -spores in sori under the leaf

moss "leaf"

-not true leaves b/c no vasc. tissue, small -use diffusion/induction -very small, thin cuticle -spores in capsule of sporophyte

Selaginella sp.

-sporophyte dom. gen. -spores formed in stobili, more spores -microphylls w/ only 1 strand of vasc. tissue (1st true leaves) -1st to have true stem b/c have vasc. tissues, lignin in 25% of CW -1st to have true roots

lycophyte adaptions for land

1. 1st group of plants to develop x&p, vascular tissue is organised in steles 2. tracheids are strengthened with lignin for growth & structural support 3. growth in root and shoot from apical meristems 4. have true roots for attachment and water/nutrient absorption 5. have true leaves (microphylls) w/ single strand of vasc. tissue down length of microphylls

to survive on land

1. avoid drying out (dessication): cuticle 2. uptake nutrients from soil: roots 3. body support: stem 4. reproduction: must protect gametes from external environment 5. possess differentiated cells- b/c air and soil differ in composition and resources: xylem & phloem

why algae would not make good land plants

1. do not have vasc. tissues 2. no cuticle (dessication) 3. no stomata (can't avoid dessication) 4. no true roots 5. need water for reproduction

Phylum Cycadophyta - Cycads

140 species remain (representing 11 genera), restricted to (sub)tropical habitats; distinct trunk and a cluster of leaves at the top of the stem; highly toxic containing both neurotoxins and carcinogenic compounds; male and female cycad plants: -Male cycads produce a large strobili (cone) which contains pollen. -Female cycads produce a large strobili (cone) which contains the eggs. The eggs get fertilised and seeds are formed.

fern life cycle (pterophytes)

2 distinct phases: gameto. and sporo., -gameto.: produce the male and female sex cells (gametes), the female of which, when fertilized, develops into a new sporophyte to continue the cycle -sporophyte dom.: The spores land on the substrate and develop into the gametophyte which is small, inconspicuous and short-lived. -spores protected by thick wall and dispersed by wind

How does the moss gametophyte differ from a liverwort gametophyte?

Liverwort: gametophyte body thallose or foliose Moss: gametophyte body differentiate into prostrate, branched filamentous, thalloid protonema and leafy erect; arrangement of leaves?

Lycophytes

P. Lycophyta, Selaginella sp. (heterosporous) and Lycopodium sp. (homosporous), most ancient living phylum of vasc. plants, only 3 living families w/ 1000 sp., usu. in wet environments, gen. small and can be aquatic, terrestrial, climbing and almost half the species are epiphytes; only plant to have microphylls; sporophyte dom. gen., sperm still needs water to swim to egg (like bryophytes)

hornworts

Phylum Anthocerotophyta, 100 sp., gametophytes like thallose liverworts: rosette or ribbon-like; sporophyte with a foot (to attach to gameto.), and a capsule that is long and cylindrical and contains spores

mosses

Phylum Bryophyta; leaves arranged spirally or alternately around a stemlike axis (not a true stem), usu. 1 cell thick (lack vasc. tissue and stomata); gametophyte dominate generation (actively PS) rhizoids, gametophyte, leaf like structures, sporophyte and capsule

liverworts

Phylum Hepaticophyta, 6000 sp., small, green, terrestrial; no true roots, stems, or leaves; single celled rhizoids that aid in absorption (like roots) and also used to attach them to the substrate; leafy gametophyte (clear stem/leaf differentiation) or appear dorsoventrally flattened, without obvious leaves (thallose liverworts)

What does homosporous mean?

Producing spores of one kind only that are not differentiated by sex, grow into bisexual gametophytes (producing both male and female gametes) ex: horsetails and ferns

What does heterosporous mean?

Producing two types of spores differing in size and sex, the male microspore and the female megaspore, which develop into separate male and female gametophytes ex: most seed-bearing plants, as well as some ferns and other seedless plants

similarities and differences between a gymnosperm and an angiosperm

Similar: both produce seeds Different: A- seeds in fruit, pollinated from animals attracted to flowers G- naked see, wind dispersal

how bryophytes are like terrestrial plants

Some have a cuticle and stomata, produce wind-borne spores that are protected from dehydration by a wax-impregnated wall on the outside of the spores, shelter their archegonia and antheridia inside a jacket of protective cells, most have meristems

moss life cycle

The zygote develops into the sporophyte, which when mature produces spores that are dispersed onto the sediment and a gameto. develops from the spore

from flowers to fruit

after fertilization, petals wither, ovary begins to swell, petals drop off, seed develops inside fruit and fruit gets bigger

Phylum Ginkgophyta - Gingko or maidenhair tree

are 'dioecious', (separate sexes), living fossil, Produces male cones, but no female cones. ovules produced at the ends of stalks. female fruit smells bad; herbal supplement to inc. blood flow to brain ex: Gingko biloba

Describe how Pterophytes reproduce on land?

asexual stage makes spores (sporophyte) and sexual stage involved fertilization (gametophyte)

What is differentiated cells/tissue?

cells that have a specific function, specialized

genera Ephedra

desert habitats throughout the world as a highly-branched shrub with jointed stems and much reduced leaves, used medicinally (methampetamines) • Shrub • Minute, scale-like leaves • Green, photosynthetic stems • Male / Female cones produced on nodes of stem

genera Welwitschia

desert regions w/ Most of the plant body is buried in the sandy substrate; a large bowl-shaped structure extends above the surface which produces only two long, strap-like leaves that continue to increase in length throughout life

Explain why a blade is not considered a 'true' leaf. What is the function of a blade?

does not have vascular elements; function still to get nutrients & PS

seeds

embryo and its food supply surrounded by protective coat. embyro can dry out quickly on land, so they developed hard, resilient coats; various seed dispersal

archegonia

female reproductive structure

angiosperms

flowering plants, one phylum, the Anthophyta, 260,000 spp. advanced vascular tissue, a dominant sporophyte stage, a markedly reduced gametophyte stage, and production of seeds enclosed w/in a fruit; two groups: Monocotyledons and the Eudicotyledons

taxol

from Pacific Yew to treat cancer

sexual phase

gametophyte generation, produces gametes (sex cells)

What might be the advantage of having seeds with a dormant but viable state?

if outside conditions aren't suitable for growth of new seed, can just wait until it gets better

lignin

in all vascular plants, provides structural support - allows the plant to grow large

alteration of generations

involves an alternate doubling and halving of chromosome numbers at each phase

sporophyte of Selaginella sp.

is differentiated into root, stem and Microphylls

giant kelp

large algae that do have specialised cells for transporting nutrients throughout the plant

female cones

larger, harder and live for many years and produce the seeds. pollination and fertilization takes place here

spores

located in small cone like structures called strobili or spores attached to stem

antheridia

male reproductive structure

genera Gnetum

moist, tropical regions where they grow as both as trees and vines; Pinnately veined, opposite leaves

Phylum Coniferophyta - conifers

most diverse phyla, pine cones and seeds ex: pines, spruces, firs, yews and junipers; tallest known plant (giant redwood, Sequoia sempervirens) and the oldest known plant (bristlecone pine, Pinus longaeva).

Why are ferns restricted to a moist environment (hint - look at the lifecycle)?

need water for gametophyte reproduction b/c gameto. is fragile

Why you think bryophytes are restricted to moist environments?

no vasc. tissue or roots to uptake water

Why is the thin, upright shoot of a moss gametophyte not considered to be a true stem?

no vasc. tissues

moss leaves have

no vasc. tissues, but do have cuticle

all plants

non-seed plants, non-vascular (Bryophytes- liverworts, hornworts, and mosses) as well as vascular (Lycophytes- Selaginella sp. and Pterophytes- ferns)

Explain why a stipe is not considered to be a true stem. What is the function of a stipe?

not a true stem b/c it lacks tissues specialized for water and nutrient transport, b/c always in water; does have a special region of cells to transport nutrients

monocotyledons

petals in 3 & 6, scattered bundles, parallel leaf venation

eudicotyledons

petals in 4 & 5, organized bundles, branched venation

algae

plant-like organisms that have chlorophyll and other pigments to carry out photosynthesis; no roots, stems, leaves, vascular tissue (xylem and phloem); water provides support for algae and most of their cells have contact with water which has all nutrients that algae needs, nutrients absorbed through cell wall; in water, sperm from algae are able to swim directly to eggs (simple reproductive structures); single celled, colonial, flat like in structure, leaf like sheets, single filaments, microscopic or 50 long

all seed plants have

pollen grains containing sperm

moss sporophyte

produces spores, typically smaller, simpler, shorter-lived; shows defined (determinate) growth; attached to gameto. throughout life and partly dependent on it for nutrition

What are the advantages of dispersing seeds?

reach more broad locations until find a suitable habitat

pine cones often live up to 3 years b/c

seeds need a lot of time to grow and could have a dry year, so bad time to release seeds

flowers

sexually reproductive part of plant; type of modified leaf

stele

solid core of vasc. tissue, fake vasc. tissue, the central core of the stem and root of a vascular plant, consisting of the vascular tissue (xylem and phloem) and associated supporting tissue

Describe how Bryophytes reproduce on land?

spores released, need water for sperm to swim, sex organs, and zygote

reproduction of conifers

sporophyte dom. gen., (the gametophyte form is confined to the cones). produce male and female cones that can be on same tree; male cone produces pollen which is brought by wind to the female cone with produces the seeds. the zygote is produced in female cone after pollination and fertilization via pollen tube and becomes embryo and integumentary enclosure surrounds it, forming the seed. The seeds are dispersed as the matured and now-fertilised cone opens up. Seeds are dispersed by the wind, settle onto the substrate and grow.

asexual phase

sporophyte generation, produces spores asexually

In the lifecycle of plants, what does 'dominant generation' mean?

the generation that the plant spends most of its life in; occupies largest portion of life cycle

cuticle

the outer protective layer of a leaf

Terrestrial plants

thought to have evolved from algae called Charophytes.

Phylum Gnetophyta - Gnetophytes

three genera: Gnetum, Welwitschia, and Ephedra; vessel elements in the xylem and Gnetophyta strobilus (bridge to angiosperms); all produce a megasporangiate (male) and microsporangiate (female) cone; seeds not enclosed

pollen grains

to transport male gametes (sperm) so no longer needed water

Why are ferns able to grow larger than bryophytes?

tough vasc. tissue w/ lignin enables them to grow larger in response to competition for light

energy storage structures

tubers, bulbs, and the cotyledons of seeds

moss gametophyte

usu. have small leaflike structures (no vasc. tissues) but do have water-conducting tissue; anchored to substrate by rhizoids which have conductive tissues

Describe how Lycophytes reproduce on land?

yes still need water to reproduce on land for sperm to swim to egg (ferns need it too)

some algae body parts

• Holdfast - root-like structure that attaches algae to the substrate • Stipe - a stem-like structure • Blade - leaf-like structure