Campbell Ch. 29: Plant Diversity I: How Plants Colonized Land

Clarophyceans

Green algae that are the closes relatives of land plants

List the four traits that charophyceans only have with land plants

1. Rose-shaped complexes for cellulose synthesis
2. Peroxisome enzymes
3. Structure of flagellated sperm
4. Formation of a phragmoplast

Phragmoplast

structure involved in cell division where it forms between the daughter nuclei

Which relatives gave adaptions which emerged after land plants diverged?

Charophycean

What do biologists think should be done with the plant kingdom and what will retain until the debate is resolved?

Biologists think that plant kingdom should be expanded to include some or all green algae and until the debate is resolved, we will use the embryophyte definition of plant kingdom as Plantae.

1.What are the five traits that appear in nearly all land plants but are absent in the charophyceans?
2. What other additional derived traits did many plant species gain?

1. Alternation of generations
2. Walled spores produced in sporangia
3. Multicellular gametangia
4. Multicellular dependent embryos
5. Apical meristems
2. Cuticle and secondary compounds

What is cuticle?

consists of polyester and wax polymers which acts as a waterproof so that plants won't have excess water loss.

Secondary compounds

many land plants produce these molecules which are products of secondary metabolic pahtways that produce lipids, carbs, amino acids, and other compounds that are similar to all organisms.

Alternation of generations

One of the five traits found in nearly all land plants but absent in charophyceans.
- The life cycle in which sporophyte and gametophyte forms. This is a characteristic of plants and some algae.

Walled Spores Produced in Sporangia

One of the five traits found in nearly all land plants but absent in charophyceans.
-

Multicellular Gametangia

One of the five traits found in nearly all land plants but absent in charophyceans.
- A process in which the the female gametangia, archegonia, produces a single nonmotile egg retained within the organ whole the male gametangia, antheridia, produces sperm

Apical Meristems

One of the five traits found in nearly all land plants but absent in charophyceans.
- Responsible for the teh growth of roots in a plant, this is done by cell dividsion at the tips of shoots and roots.

According to fossil evidence, how long ago were plants on land?

At least 475 million years ago.

What is one way of distinguishing land plants informally?

Through the presence or absence of vascular tissues.

Vascular tissues

cells joined into tubes that transport water and nutrients throughout the plant body.

What opportunities did life on land offer to plants?

1. Unlimited sunlight
2. Abundant carbon dioxide
3. Intially, few pathogens or herbivores

What were the challenges of terrestrial life?

1. Maintaining moisture within cells.
2. Obtaining and transporting resources.
3. Supporting body.
4. Reproducing and dispersing offspring without water.

What structure supported the plant body?

1.Roots or root-like structures anchor the plant into place
2.Lignin: impregnates the conducting vessels of land plants. This supports the plant helping it maximize the surface area exposed to the sun.

What way to transport water and nutrients throughout the body?

Conducting vessels transport water and mineras upward from the roots to the rest of the plant body and transport sugar from leaves to the rest of the body.

What structures conserve water for plants?

1. A waxy cuticle covers the surface of leaves and stems limiting evaporation of water
2. Pores called stomata open to let gases flow in and out but close when water is scarce to reduce evaporation

Dispersal for sex cells and offspring without water

1. Methods of gamete and zygote dispersal that are independent of water (e.g. pollen, seeds)
2. Structures that protect the developing embryo from drying out (e.g. flowers, fruits)

Bryophytes

Nonvalcular plants

What are the three phyla of small herbaceous(non-woody) plants that represent bryophytes?

1. Liverworts
2. Hornworts
3. Mosses

Gametophyte

named for its production by mitosis of haploid gametes

Sporophytes

During meiosis, these are able to produce spores.

In all three bryophyte phyla, gametophytes are _____ and _____ than sporophytes.

Larger and longer-living

Archegonia

Female gametangia

Antheridia

Male gametangia

Features of Bryophyte Gametophytes

-Produce flagellated sperm in antheridia
-Produce ova in archegonia
-Generally form ground-hugging carpets and are at most only a few cells thick

Features of Bryophyte Sporophytes

-Grow out of archegonia
-Are the smallest and simplest of all extant plant groups
-Consist of a foot, a seta, and a sporangium

What are the ecological and economic importance of mosses?

-Retain nitrogen into soil
-Sphagnum(peat moss) is widespread, forming extensive deposits of partially decayed organic material known as peat.
-Sphagnum doesn't decay readily allows corpses to preserve for thousands of years
-Peat is also used as fuel sou

Which type of plants were the prevalent vegetation during the first 100 million years of plant evolution?

Bryophytes and bryophyte-like plants

Which plants began to diversify during the Carboniferous period?

Vascular plants.

Which plants now dominate most landscapes?

Vascular plants.

Which type of plants grow taller; vascular plants or bryophytes?

Vascular plants.

According to fossil records, how long ago did the vascular plants date back?

420 million years.

What differences are there with vascular plants and bryophytes?

1. Vascular plants have branched sporophytes and aren't dependent on gametophytes for nutrition.
2. Vascular plants have branchings that are more complex with multiple sporangia which led to competition for space and sunlight.
3. Sporophytes in vascular p

What are the two types of vascular tissue?

1. Xylem
2. Phloem

Xylem

This is one of the vascular tissues of vascular plants. It conducts most of the water and minerals and includes dead cells called tracheids.

Tracheids

These are part of the xylem which are tube-shaped cells that carry water and minerals up from roots.

Lignin

In vascular plants the water-conducting cells are lignifies which means that their cell walls are strengthened.

Phloem

This is one of the vascular tissues of vascular plants. It arranges cells into tubes that distribute sugars, amino acids, and other organic products.

What are the benefits of lignified vascular tissue?

Since the cell walls are strengthened, the vascular plants grow tall and provide support against gravity, which allows transport of water and mineral nutrients high above the ground.

What are roots and what is their function?

Organs that anchor vascular plants and they enable vascular plants to absorb water and nutrients from the soil.

What stems could roots have evolved from?

Subterranean stems.

Leaves

Organs that increase the surface area of vascular plants, thereby capturing more solar energy that is used fro photosynthesis.

What are two types of leaves?

1. Microphylls
2. Megaphylls

Microphylls

(Leaves with a single vein) Only the lycophytes have these. They are small usually spined shaped leaves supported by a single strand of vascular tissue.

Megaphylls

(Leaves with a highly branched vascular system) Almost all other vascular plants have these.

Where did the microphylls originate from?

Sporangia.

Where did the megaphylls originate from?

Evolved from a series of branches lying close together on a stem.

Sporophylls

Modified leaves that bear sporangia.

Sori

Clusters of sporangia which the fern sporophylls produce.

Homosporous

Most seedless vascular plants are this. They produce one type of spore that develops into a bisexual gametophyte.

Heterosporous

All seed plants and some vascular plants are this. They have two types of sporangia which produces two types of spores that give rise to male and female gametophyte: Megasporangia on megasporophyll and Microsporangium on microsporophyll.

List the two types of sporangia that produces two kinds of spore which gives rise to male and female gametophytes for heterosporous.

Sporophyte:
Megasporangium>Megaspore>Female gametophyte>egg
Microsporangium>Microspore>Male gametophyte>sperm

List the one type of sporangia that produces the single type of spore and bisexual gametophyte for homosporous.

Sporangium on sporophyll> single type of spore>typically a bisexual gametophyte> eggs and sperm.

What are the two phyla of seedless vascular plants?

1. Lycophyta
2. Pterophyta

Phylum Lycophyta

There were two evolutionary lineages of lycophytes: one is the small herbaceous plants and the other are the giant "tree lycophytes" which have thrived for millions of years in moist swamps.
- Includes club mosses, spike mosses, and quillworts.

Phylum Pterophyta

-Ferns are the most diverse seedless vascular plants, with more than 12,000 species
-They are most diverse in the tropics but also thrive in temperate forests
-Some species are even adapted to arid climates
- Includes ferns, horsetails, and whisk ferns an

What are the significance of seedless vascular plants?

-The ancestors of modern lycophytes, horsetails, and ferns grew to great heights during the Carboniferous, forming the first forests
-These forests may have helped produce the global cooling at the end of the Carboniferous period
-The decaying plants of t