Green plants

What did the first Plants evolve from?

Green Algae

List examples of the first Plants.

Moss, Liverworts

Describe Green Algae.

Protist. Aquatic. Closest living relative to Land Plants.

Describe Land Plants

First organism that could survive with its tissue exposed to the air. Terrestrial.

Why are Plants studied?

1. Humans are dependent on Plants for basic survival.

2. Plants provide Ecosystem Services.

3. Plants are Primary Producers.

4. Plants provide humans with resources.

5. Certain Plants harm the environment and or humans.

Describe an Ecosystem.

A particular area including all of its organisms as well as its non-living components such as: Atmosphere, Sunlight, Precipitation, Soil, Surface Water, and Nutrients.

Describe the Ecosystem Services provided by Plants.

1. Producing Oxygen via Photosynthesis.

2. Building Soil by providing food for decomposers.

3. Holding Soil and preventing Nutrients from being lost to Wind or Water Erosion.

4. Holding Water in the Soil.

5. Moderating local Climate by providing shade and reducing the impact of Wind on landscapes.

Describe how Plants are Primary Producers.

1. Land Plants are the Primary Producer in terrestrial environments: transferring energy from Sunlight into Sugar which supports all other organisms within the habitat.

2. Land Plants are key to the Carbon Cycle: Photosynthesis.

Describe the resources provided by Plants.

1. Food: crops and fruits.

2. Fuel: wood-burning and fossil fuels.

3. Fiber: raw material for clothing, rope, paper, etc.

4. Building materials: lumber.

5. Medicine: plants provide chemical compounds used in a quarter of all medicine.

How are Plants studied?

1. Comparison of Morphological Traits.

2. Analysis of Fossil Record.

3. Estimation of Phylogenetic Traits.

Describe the Morphological Traits of Green Algae.

Green algae includes species that:

1. Are unicellular, colonial, or multicellular.

2. Live in marine, freshwater, or moist terrestrial environments.

Describe the similarities between Green Algae and Land Plants on a cellular level.

1. Same Chloroplast structure.

2. Similar Thylakoid arrangements.

3. Similarly structured and composed Cell Walls, Sperm, and Peroxisomes.

4. Chloroplast synthesize Starch as a storage product.

List the groups of Green Algae most similar to Land Plants.

1. Zygnematophyceae (Conjugating algae)

2. Coleochaetophyceae (Coleochaetes)

3. Charophyceae (Stoneworts).

List the different types of Land Plants.

1. Nonvascular Plants.

2. Seedless Vascular Plants.

3. Seed Plants.

Describe Vascular Tissue

Specialized groups of cells that conduct Water or dissolve Nutrients throughout the plant.

Describe Nonvascular Plants and list example(s).

Plants that lack Vascular Tissue and reproduce via Spores

these Plants normally stay small and short and live in aquatic environments. Examples: Moss, Liverworts.

Why do Nonvascular Plants tend to stay small and short in stature and live in aquatic environments?

Nonvascular plants have no Vascular Tissue and thus have no way to conduct Water into parts not in contact with Water.

Describe Seedless Vascular Plants and list example(s).

Plants that possess Vascular Tissue and reproduce via Spores. Example: Ferns.

Describe Seed Plants and list example(s).

Plants that possess Vascular Tissue and reproduce via Seeds. Examples: Angiosperms, Gymnosperms.

Describe the difference between the seeds of Angiosperms and Gymnosperms.

1. Angiosperms have "encased" Seeds.

2. Gymnosperms have "naked" Seeds.

Why are Seedless Vascular Plants and Seed Plants able to grow in non-aquatic, terrestrial environments?

The Vascular Tissue of both these types of Land Plants allows Water to travel throughout the entire Plant even if all its parts are not actively in contact with Water.

How does Analysis of Fossil Record support the hypothesis that Land Plants are derived from Green Algae?

Analysis of fossil record shows that Green Algae originated 700-725 mya while Land Plants originated 425 mya.

Describe the major events in the Diversification of Land Plants.

1. Origin of Land Plants (475-416 mya)

2. Silurian-Devonian Explosion (416-359 mya)

3. Carboniferous Period (359-299 mya)

4. Age of Gymnosperms (299-145 mya)

5. Age of Angiosperms (145-0 mya)

Describe Plants during the Origin of Land Plants.

Most of the earliest Plants are microscopic while some are thin sheets of waxy material resembling a Cuticle.

Describe Plants during the Silurian-Devonian Explosion.

Most of the Plants during this event possess virtually all the adaptations which allow them to live in terrestrial environments: Vascular tissue and Toots.

Why is the Carboniferous Period named as such?

Fossils of Plants and their various parts from this time period were found in carbon-rich rock.

What is a Gymnosperm?

A Vascular Plant that reproduces via Seeds which are exposed.

What is an Angiosperm?

A Vascular Plant that possesses Flowers and reproduces via Seeds which are encased in Fruit.

Describe Phylogeny.

A hypothesized evolutionary history of groups of organisms.

List and describe each type of Phylogeny.

1. Monophyletic: Group that includes common ancestor and all of the descendants.

2. Paraphyletic: Group that includes a direct line of ancestors.

3. Polyphyletic: Group that includes the descendants of a common ancestor but not the common ancestor.

Describe the Phylogeny of Green Plants.

Monophyletic

a single common ancestor gave rise to all Green Algae and Land Plants.

Describe the Phylogeny of Green Algae.

Paraphyletic.

What is the closest living algal relative to Land Plants?

Zygnematophyceae (Conjugating algae)

Describe the Phylogeny of Land Plants.

Monophyletic

there was only one successful transition from freshwater environments to land.

What is the most ancient living group of Land Plants?

Nonvascular Plants.

What is the Phylogeny of Nonvascular Plants?

Paraphyletic.

What is the Phylogeny of Seedless Vascular Plants?

Paraphyletic.

Describe the Phylogeny of Vascular Plants.

Monophyletic

Vascular Tissue evolved only once.

Describe the Phylogeny of Gymnosperms and Angiosperms.

Monophyletic

the Seed evolved only once.

How did Green Plants benefit from their transition to non-aquatic environments?

Resources such as Light and Carbon Dioxide were more plentiful.

What are the main adaptations that allowed early Land Plants to live in dry conditions?

1. Prevention of Water loss.

2. Protection from harmful ultraviolet (UV) radiation.

3. Movement of Water throughout the whole Plant.

How do Land Plants prevent Water loss?

Land Plants have a Cuticle which covers it above ground and seals Water within the Plant, preventing its loss.

What is a Cuticle?

A watertight sealant.

What issue does the Cuticle pose for the Land Plant and how does the Land Plant solve this issue?

The Cuticle also prevents Carbon Dioxide from entering the Plant

in order to solve this issue, the Plant possesses a Stomata that allows for gas exchange.

Describe the structure and function of a Plant's Stomata.

The Stomata consists of a pore and specialized guard cells. The pore opens and closes as the specialized guard cells surrounding it change shape and allow for gas exchange.

How does UV Light harm Plants?

UV Light damages the DNA by causing thymine dimers.

Why do algae not suffer so heavily from UV Irradiation?

Algae often live in aquatic environments. Water absorbs UV Light before it can reach the Algae.

How do land plants protect from UV Light?

Land Plants accumulate UV-absorbing compounds, flavonoids, that protect their DNA from damage.

How did the first Land Plants grow and why?

The first Land Plants grew small and low to the ground in order to stay in contact with moist Soil.

After the first Plants began growing on the land, what would they soon have intense competition for?

1. Space

2. Sunlight.

What type of Plant growth is advantageous in a terrestrial environment and why?

Plants which are able to grow tall and upright have an advantage over shorter, lower Plants due to their better access to Sunlight.

List each type of Water-conducting cell.

1. Tracheids.

2. Vessel Elements

What is Lignin?

An extraordinarily strong, cross-linked polymer.

Describe Tracheids and their structure.

Long, thin, tapering Water-conducting cells that have a primary cellulose-based cell wall, a secondary lignin-containing cell wall, and pits in the sides and ends of the cell.

How does water flow efficiently between different Tracheids?

Via pits in the sides and ends of the cell.

What Plants contain Tracheids?

All Vascular Plants.

Describe Vessel Elements and their structure.

The most specialized type of Water-conducting cell. Vessels are short and wide and have gaps on both ends where both cell walls are missing.

What forms wood in the stems and branches of some Vascular Plants?

1. Tracheids

2. A combination of Tracheids and Vessels

What functions do the lifecycles of sexually reproducing Plants serve?

1. Increasing genetic variability due to meiosis and cross-fertilization.

2. Dispersing individuals into new habitats.

What adaptations were instrumental for efficient Plant reproduction in a dry environment?

1. Spores that resist drying because they are encased.

2. Gametes that are produced in complex, multicellular structures.

3. Embryos that are retained and nourished by the parent Plant.

Describe Sporopollenin.

A substance which serves as the tough outer coating of Spores and Pollen.

How does Gametangia found in Land Plants differ from Gametangia in early Plants?

Gametangia found in Land Plants is larger and more complex.

What is the function of Gametangia, and how is Gametangia important to Plant survival?

1. Produce Gametes.

2. Protect Gametes from drying and physical damage.

What contains Gametangia?

All living Land Plants except Angiosperms.

List the two types of Gametangia and describe their differences.

1. Antheridia

Producers of sperm. 2. Archegonia

Producers of eggs.

Describe how the Embryos of Land Plants develop.

In Land Plants, the Embryos are retained and nourished by the parent Plant.

Describe how Land Plants and their ancestors, Green Algae, differ in terms of Embryo development.

In Land Plants, the Embryo remains attached to the parent Plant as it develops. In Green Algae, both Gametes are detached from parent Plants, resulting in Embryos developing separate from their parent Plants.

List the two phases of the Alternation of Generations Life Cycle and describe how they differ.

1. Sporophytes

Diploid. 2. Gametophytes

Haploid.

Describe the sequence of the Alternation of Generations Life Cycle.

1. Sporophytes (2n) produce Spores (n) via Meiosis.

2. Spores (n) grow and produce Gametophytes (n) via Mitosis.

3. Gametophytes (n) produce Gametes (n) via Mitosis.

4. Gametes (n) fuse and produce a Zygote (2n) via Syngamy.

5. Zygotes (2n) grow and produce Sporophytes (2n) via Mitosis.

Describe how the Sporophyte and Gametophyte generations of Nonvascular Plants differ.

In Nonvascular Plants, the Gametophyte generation is dominant while the Sporophyte is small and shorter-lived.

Describe how the Sporophyte and Gametophyte generations of Vascular Plants differ.

In Vascular Plants, the Sporophyte generation is dominant while the Gametophyte generation is small and short-lived.

Describe the Gametophyte generation of Angiosperms and Gymnosperms.

Microscopic, Non-Dominant.

Describe how the transition from Gametophyte-dominant generations to Sporophyte-dominant generations affected the evolution of Plants.

This transition was ultimately advantageous for Plants due to Diploid cells being able to respond better to varying environmental conditions than Haploid cells.

Describe Heterospory.

Production of two distinct types of Spore by different structures.

List the types of Land Plants that are Homosporous.

1. All Nonvascular Plants.

2. Some Seedless Vascular Plants.

Describe how the spores of Homosporous Plants develop.

The Spores of Homosporous Plants develop into a bisexual Gametophytes which then produce both male and female Gametes.

List the types of Spore-producing structures in Heterosporous Plants.

1. Microsporangia

2. Megasporangia

Describe the function of Microsporangia.

Microsporangia produce Microsporocytes that produce Microspores that develop into male Gametophytes which produce Sperm.

Describe the function of Megasporangia.

Megasporangia produce Megasporocytes that produce Megaspores that develop into female Gametophytes which produce Eggs.

What produces four Microspores?

A Microsporocyte.

What produces four Megaspores?

A Megasporocyte.

Describe Pollen.

A multi-cellular male Gametophyte.

Describe a Pollen Grain.

A cluster of pollen, male Gametophytes.

How have Pollen Grains affected the evolution of Land Plants?

Pollen Gains have allowed Land Plants in dry environments to reproduce efficiently.

Describe the disadvantage of Embryo development in Seedless Plants.

For Seedless Plants, the Sporophyte generation has to live in the same location as the parent Gametophyte generation and share resources due to Embryo retention.

Describe a Seed.

A structure that includes an Embryo and a store of Nutrients provided by the mother and surrounded by a tough, protective coat.

Describe the evolutionary advantage of Seeds for Land Plants.

Seeds have allowed the Embryos of Land Plants to become portable and disperse to new locations.

Describe the significance of Angiosperms.

Angiosperms are flowering Plants and are also the most diverse Land Plants living today, with around 350,000 species and more which are discovered every year.

List the parts of the Flower responsible for reproduction.

1. Stamen.

2. Carpel.

Describe the significance of the Stamen for flower reproduction.

The Stamen contains Anther where Microsporangia develop.